Protocol for solid-phase microextraction method development

Lab-made automated parallel-dispersive pipette extraction device for the determination of polycyclic aromatic hydrocarbons in distilled beverages (sugarcane spirits) using HPLC-DAD

This work describes the development of a new automated parallel dispersive tip microextraction method (Au-Pa-DPX) for the determination of eleven polycyclic aromatic hydrocarbons (PAHs) in four samples of Brazilian sugarcane spirit beverages, with separation and detection done by the HPLC-DAD. The results obtained with the Au-Pa-DPX approach were also compared with those obtained via the conventional parallel manual DPX method with the same samples and optimized extraction process. Desorption solvent and cycles of desorption, cleaning and extraction were optimized using response surface methodology and univariate approaches. For the Au-Pa-DPX method, the coefficient of determination (R2) ranged from 0.9948 to 0.9997. The limits of detection and quantification were all 0.303 μg l-1 and 1.00 μg l-1, respectively. Interday and intraday precision ranged from 7.6 % to 31.7 % and 0.40 % to 15.8 %, respectively. For the manual parallel DPX method, the interday and intraday precision ranged from 8.2 % to 38.1 % and 5.40 % to 18.7 %, respectively. The relative recovery values obtained with the proposed method ranged from 53.29 to 124.94 %. The enrichment factors ranged from 15.13 to 22.35. The sum of PAH concentrations in the four samples ranged from undetected to 25.58 μg l-1. These results, when correlated to other methods, highlight the gains in regards to precision obtained with the automated apparatus. Furthermore, when compared to other methods from the literature, it is an interesting green alternative for the determination of these analytes and this sample, with high throughput (4.67 min per sample), low consumption of solvents and samples, generating less waste and reducing health risks to the analyst.

Quantitative analysis and characterization of floral volatiles, and the role of active compounds on the behavior of Heortia vitessoides

This study explores the role of floral volatile organic compounds (FVOCs) in insect behavior, focusing on Aquilaria sinensis (AS), a valuable tropical plant threatened by Heortia vitessoides Moore. Despite H. vitessoides' attraction to AS and non-host plants like Elaeocarpus decipiens (ED) and Dalbergia odorifera (DO), little is known about their chemical interactions. FVOCs from these plants were analyzed at 9:00 and 18:00 using GC×GC-QTOF-MS and HS-SPME. The results showed that ED exhibiting the highest concentration (92.340 ng/mg), followed by DO (75.167 ng/mg) and AS (64.450 ng/mg). Through GC-EAD and EAG, a total of 11 FVOC compounds with electrophysiological activates were identified. These compounds, except linalool, showed dose-dependent responses. Y-Tube bioassays confirmed phenylethyl alcohol or the mixture of EAD-active compounds produced positive chemotactic responses in both males and females. FVOCs have the potential to be used as a natural and sustainable alternative to chemical insecticides in pest control.

Characterization of a mixed mode fluorocarbon/weak anion exchange sorbent for the separation of perfluoroalkyl substances

The ubiquitous presence and persistence of per- and polyfluoroalkyl substances (PFAS) in the environment have raised concerns in the scientific community. Current research efforts are prioritizing effective PFAS remediation through novel sorbents with orthogonal interaction mechanisms. Recognized sorption mechanisms between PFAS and sorbents include hydrophobic, electrostatic, and fluorine-fluorine interaction. The interplay of these mechanisms contributes significantly to improved sorption capacity and selectivity in PFAS separations. In this study, a primary/secondary amine-functionalized polystyrene-divinylbenzene (Sepra-WAX) polymer was modified to create a fluorinated WAX resin (Sepra-WAX-KelF-PEI). The synthesis intermediate (Sepra-WAX-KelF) was also tested to assess the improvement of the final product (Sepra-WAX-KelF-PEI). The adsorption capacity of Sepra-WAX, Sepra-WAX-KelF, and Sepra-WAX-KelF-PEI, and their interactions with PFAS were evaluated. The effect of pH, ionic strength, and organic solvents on PFAS sorption in aqueous solution was also investigated. The sorbents showed varied adsorption capacities for perfluorooctanoic acid, perfluoropentanoic acid, perfluoro-n-decanoic acid, and hexafluoropropylene oxide dimer acid, with the average extraction capacity of the four analytes being Sepra-WAX-KelF-PEI (523 mg/g) > Sepra-WAX (353 mg/g) > Sepra-WAX-KelF (220 mg/g). Sepra-WAX-KelF-PEI provided the highest adsorption capacity for all analytes tested, proving that the combination of electrostatic and hydrophobic/fluorophilic interactions is crucial for the effective preconcentration of PFAS and its future applications for PFAS remediation from aqueous solutions.

Automated Method for the Sensitive Analysis of Volatile Amines in Seawater

Methylamines are polar, volatile, and organic nitrogen-containing compounds. They are challenging to analyze, limiting our understanding of their occurrence and role within the marine nitrogen cycle. We describe an automated headspace solid-phase microextraction method, coupled with gas chromatography and nitrogen phosphorus detection (HS-SPME-GC-NPD), for analyzing methylamines in seawater. Three SPME conditions were investigated: temperature, equilibration, and extraction. The method was 6-24 times more sensitive to trimethylamine (TMA) than to dimethylamine (DMA) and monomethylamine (MMA). DMA and TMA were detected in small seawater volumes (2.5-10 mL), at volumes 100-400 times that previously reported. Detection limits of 19.1, 6.6, and 4.1 nM (nMol L-1) for MMA, DMA, and TMA, respectively, were measured in 10 mL sample volumes. Sample throughput was 4-6 times greater than previously reported similar methods. According to the Blue Applicability Grade Index (BAGI) metric, the method was considered "practical" and scored 62.5. The method was used to measure methylamines in seawater samples collected from the Southern Ocean. DMA and TMA were detected at concentrations from < LoD-35 nM and < LoD-48 nM, respectively. This study offers a systematic and standardized method for MA analysis in seawater and can significantly advance understanding of their role in marine systems.

Quantification of prohibited substances and endogenous corticosteroids in saliva using traditional, alternative microextraction-based, and novel 3D printed sample-preparation methods coupled with LC-MS

Oral fluid has gained significant interest as an alternative matrix for drug testing due to its easy and non-invasive collection. Despite these advantages, achieving suitably low limits of detection remains a clear challenge in the use of oral fluids for drug screening. In this study, we demonstrate that the application of commercially available SPME fibers followed by liquid chromatography tandem mass spectrometry can enable the comprehensive detection and confirmation of drugs in oral fluid samples. To this end, we develop and test a sample-preparation protocol for a panel of 46 drugs covering the most popular drugs of abuse and doping agents available worldwide. Human saliva samples were collected using a Salivette® device (CE IVD certified) and sampled using SPME devices coated with a C18 extraction phase. The proposed protocol was validated with respect to its lower limits of quantification (LLOQ), linearity, matrix effects, precision, and extraction recovery. Linearity was confirmed for all compounds (R2 > 0.97), except for testosterone (R2 = 0.953) and metandrostenolon (R2 = 0.958). Furthermore, 4 compounds suffered from matrix effects, with less than 10 % deviation from acceptance criteria. After analytical validation, saliva samples from volunteers were analyzed to determine free concentrations of cortisol at different times after awaking. Finally, a 3D-printed prototype device was designed and successfully applied to extract small molecules, thus demonstrating a new modern low-cost approach for bioanalysis.

Advanced micro-extraction techniques (SPME, HiSorb) for the determination of goat cheese whey wastewater VOCs

HiSorb and solid-phase microextraction (SPME), two environmentally friendly micro-extraction techniques based on the same fundamental principles, were evaluated for their extraction efficiency of volatile organic compounds (VOCs) from goat cheese whey wastewater. For this purpose, a sample preparation method based on the headspace-HiSorb technique was developed and evaluated for its efficiency in terms of the amount of extracted compounds and reproducibility of results. Thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) and GC/MS analytical methods were used to perform the wastewater analysis, respectively. The experimental parameters of HiSorb were evaluated in terms of probe coating, extraction time, stirring speed, sample volume, extraction temperature and salt addition. Under optimal extraction conditions, it was observed that the use of the divinylbenzene/carbon wide range/polydimethylsiloxane (DVB/CWR/PDMS) triple coating for HiSorb and DVB/Carboxen (CAR)/PDMS for SPME, was best suited to extract a broader range of VOCs with higher peak intensities. A total of 34 VOCs were extracted and determined with the DVB/CWR/PDMS HiSorb probe, while only 23 VOCs were determined with the conventional DVB/CAR/PDMS SPME fiber. The DVB/CWR/PDMS HiSorb probe has a higher adsorbent capacity which results in a higher sensitivity for VOCs compared to the DVB/CAR/PDMS SPME fiber. Furthermore, the HiSorb technique exhibits better reproducibility, as indicated by the lower relative standard deviation (RSD) of 3.7% compared to 7.1% for SPME. Therefore, the HiSorb technique is an effective method for detecting VOCs in complex matrices, such as wastewater.

Solid-Phase Microextraction Techniques and Application in Food and Horticultural Crops

Solid-phase microextraction (SPME) is a sample preparation technique which utilizes small amounts of an extraction phase for the extraction of target analytes from investigated sample matrices. Its simplicity of use, relatively short sample processing time, and fiber reusability have made SPME an attractive choice for many analytical applications. SPME has been widely applied to the sampling and analysis of environmental, food, aromatic, metallic, forensic, and pharmaceutical samples. Solid phase microextraction is used in horticultural crops, for example, to determine water and soil contaminants (pesticides, alcohols, phenols, amines, herbicides, etc.). SPME is also used in the food industry to separate biologically active substances in food products for various purposes, for example, disease prevention, determining the smell of food products, and analyzing tastes. SPME has been applied to forensic analysis to determine the alcohol concentration in blood and that of sugar in urine. This method has also been widely used in pharmaceutical analysis. It is a solvent-free sample preparation technique that integrates sampling, isolation, and concentration. This review focuses on recent work on the use of SPME techniques in the analysis of food and horticultural crops.

Application of solid-phase microextraction arrows for characterizing volatile organic compounds from 3D printing of acrylonitrile-styrene-acrylate filament

3D printing is an extensively used manufacturing technique that can pose specific health concerns due to the emission of volatile organic compounds (VOC). Herein, a detailed characterization of 3D printing-related VOC using solid-phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS) is described for the first time. The VOC were extracted in dynamic mode during the printing from the acrylonitrile-styrene-acrylate filament in an environmental chamber. The effect of extraction time on the extraction efficiency of 16 main VOC was studied for four different commercial SPME arrows. The volatile and semivolatile compounds were the most effectively extracted by carbon wide range-containing and polydimethyl siloxane arrows, respectively. The differences in extraction efficiency between arrows were further correlated to the molecular volume, octanol-water partition coefficient, and vapour pressure of observed VOC. The repeatability of SPME arrows towards the main VOC was assessed from static mode measurements of filament in headspace vials. In addition, we performed a group analysis of 57 VOC classified into 15 categories according to their chemical structure. Divinylbenzene-polydimethyl siloxane arrow turned out to be a good compromise between the total extracted amount and its distribution among tested VOC. Thus, this arrow was used to demonstrate the usefulness of SPME for the qualification of VOC emitted during printing in a real-life environment. A presented methodology can serve as a fast and reliable method for the qualification and semi-quantification of 3D printing-related VOC.

A Solid-Phase Microextraction-Liquid Chromatography-Mass Spectrometry Method for Analyzing Serum Lipids in Psoriatic Disease

Approximately 25% of psoriasis patients have an inflammatory arthritis termed psoriatic arthritis (PsA). There is strong interest in identifying and validating biomarkers that can accurately and reliably predict conversion from psoriasis to PsA using novel technologies such as metabolomics. Lipids, in particular, are of key interest in psoriatic disease. We sought to develop a liquid chromatography-mass spectrometry (LC-MS) method to be used in conjunction with solid-phase microextraction (SPME) for analyzing fatty acids and similar molecules. A total of 25 chromatographic methods based on published lipid studies were tested on two LC columns. As a proof of concept, serum samples from psoriatic disease patients (n = 27 psoriasis and n = 26 PsA) were processed using SPME and run on the selected LC-MS method. The method that was best for analyzing fatty acids and fatty acid-like molecules was optimized and applied to serum samples. A total of 18 tentatively annotated features classified as fatty acids and other lipid compounds were statistically significant between psoriasis and PsA groups using both multivariate and univariate approaches. The SPME-LC-MS method developed and optimized was capable of detecting fatty acids and similar lipids that may aid in differentiating psoriasis and PsA patients.

Investigation of the adsorption/desorption mechanism of perfluoroalkyl substances on HLB-WAX extraction phases for microextraction

The C-F alkyl structural backbone of per- and polyfluoroalkyl substances makes this class of molecules resistant to heat and degradation, leading to their high persistence and mobility in the environment and bioaccumulation in the tissues of living organisms. In this study, 15 PFAS with an alkyl chain length from C₄ to C₁₄, currently monitored by the U.S. Environmental Protection Agency (EPA), were preconcentrated by solid-phase microextraction (SPME) and analyzed by liquid chromatography-tandem mass spectrometry. The adsorption and desorption mechanisms of PFAS onto ion-exchange extraction phases was evaluated to understand the extraction process of PFAS from various environmental matrices under different conditions. This was achieved using two SPME geometries, namely fibers and thin films. The use of thin films resulted in a twofold improvement in extraction efficiency compared to fibers, especially for the short-chain PFAS. Methanol:water (80:20, v/v) was chosen as the optimized desorption solution, with ammonium formate added to minimize carryover. Extraction time profiles for both SPME geometries showed faster equilibration with thin films (30 min) compared to fibers (90-120 min). The linear dynamic range obtained with this method using fibers and thin films ranged from 10 to 5000 ng L^-1 and 2.5-5000 ng L^-1, respectively, with acceptable accuracy (70-130%) and precision (<15%). LOD ranged within 2.5-10 ng L^-1 for fibers and 0.01-0.25 ng L^-1 for thin films. Investigating the factors affecting PFAS recovery in complex samples enabled the quantitative assessment of PFAS contamination in various environmental water samples such as seawater, melted snow and biospecimens like human plasma. A 96-SPME holder was used for validation, which is compatible with sampling in 96-well plates and ensures high throughput in the analysis of real samples. The total concentration of PFAS detected in seawater and snow was 51.3 ng L^-1 and 16.4 ng L^-1, respectively.

Non-invasive Sampling of Human Body Fluids Using In Vivo SPME

Noninvasive body fluids offer attractive sources to gain insights into human health. The in vivo solid-phase microextraction (SPME) technique is a fast and versatile sample preparation technique for the noninvasive sampling of human body fluids in various fields. This chapter summarizes the applications of SPME coupled with mass spectrometry (MS)-based approaches for noninvasive investigations of human body fluids, including urine, sweat, and saliva. New features of noninvasive SPME sampling and MS-based analysis are highlighted, and the prospects on their further development are also discussed.

Quantitative determination of pesticides in human plasma using bio-SPME-LC-MS/MS: a robust tool to assess occupational exposure to pesticides

Analysis of biofluids, such as plasma, can be used to investigate occupational pesticide exposure in the agricultural industry. Considering the chemical complexity and variability of plasma samples, any protocol for pesticide analysis should achieve efficient sample cleanup to minimize matrix effects and enhance method sensitivity through analyte pre-concentration. In this work, a high-throughput method was developed for analysis of 79 pesticides, commonly used in agricultural practices, in human plasma, using biocompatible solid-phase microextraction (SPME) coupled to liquid chromatography-tandem mass spectrometry. An SPME method was developed using a biocompatible hydrophilic-lipophilic balance/polyacrylonitrile (HLB/PAN) extraction phase and demonstrated negligible matrix effects. The performance of the developed SPME method was compared to a QuEChERS -Quick, Easy, Cheap, Effective, Rugged, and Safe- method, the most common sample preparation and cleanup approach for pesticide analysis in complex matrices. Comparable accuracy and precision were achieved for both methods, with accuracy values within 70-120% and relative standard deviation < 15%. Overall, the developed SPME and QuEChERS methods extracted 79 out of 82 monitored pesticides in human plasma. The SPME protocol demonstrated higher sensitivity than the QuEChERS method and a drastic reduction of matrix effects.

The determination of volatile amines in aquatic marine systems: A review

This review provides a critical assessment of knowledge regarding the determination of volatile, low molecular weight amines, and particularly methylamines, in marine aquatic; systems. It provides context for the motivation to determine methylamines in the marine aquatic environment and the analytical challenges associated with their measurement.While sensitive analytical methods have been reported in recent decades, they have not been adopted by the oceanographic community to investigate methylamines' biogeochemistry and advance understanding of these analytes to the degree achieved for other marine volatiles. Gas chromatography, high performance liquid chromatography, ion chromatography and infusion-mass spectrometry techniques are discussed and critically determined, alongside offline and online preconcentration steps. Interest in the marine occurrence and cycling of methylamines has increased within the last 10-15 years, due to their potential role in climate regulation. As such, the need for robust, reproducible methods to elucidate biogeochemical cycles for nitrogen and populate marine models is apparent. Recommendations are made as to what equipment would be most suitable for future research in this area.

Volatile metabolome and floral transcriptome analyses reveal the volatile components of strongly fragrant progeny of Malus × robusta

Floral fragrance is an important trait that contributes to the ornamental properties and pollination of crabapple. However, research on the physiological and molecular biology of the floral volatile compounds of crabapple is rarely reported. In this study, metabolomic and transcriptomic analyses of the floral volatile compounds of standard Malus robusta flowers (Mr), and progeny with strongly and weakly fragrant flowers (SF and WF, respectively), were conducted. Fifty-six floral volatile compounds were detected in the plant materials, mainly comprising phenylpropane/benzene ring-type compounds, fatty acid derivatives, and terpene compounds. The volatile contents were significantly increased before the early flowering stage (ES), and the contents of SF flowers were twice those of WF and Mr flowers. Odor activity values were determined for known fragrant volatiles and 10-11 key fragrant volatiles were identified at the ES. The predominant fragrant volatiles were methyl benzoate, linalool, leaf acetate, and methyl anthranilate. In the petals, stamens, pistil, and calyx of SF flowers, 26 volatiles were detected at the ES, among which phenylpropane/benzene ring-type compounds were the main components accounting for more than 75% of the total volatile content. Functional analysis of transcriptome data revealed that the phenylpropanoid biosynthesis pathway was significantly enriched in SF flowers. By conducting combined analyses between volatiles and differentially expressed genes, transcripts of six floral scent-related genes were identified and were associated with the contents of the key fragrant volatiles, and other 23 genes were potentially correlated with the key volatile compounds. The results reveal possible mechanisms for the emission of strong fragrance by SF flowers, and provide a foundation for improvement of the floral fragrance and development of new crabapple cultivars.

The flavors of edible mushrooms: A comprehensive review of volatile organic compounds and their analytical methods

Due to their distinctive flavors, edible mushrooms have gained attention in flavor-related research, and the quality of their flavors determines their consumption. The odor is a vital element of food flavor that significantly impacts consumers' perceptions and purchase decisions. The volatile organic compounds (VOCs) of the odorant ingredient is the primary factors affecting scent characteristics. VOCs analysis and identification require technical assistance. The production and use of edible mushrooms can be aided by a broader examination of their volatile constituents. This review discusses the composition of VOCs in edible mushrooms and how they affect flavors. The principles, advantages, and disadvantages of various methods for extraction, isolation, and characterization of the VOCs of edible mushrooms are also highlighted. The numerous VOCs found in edible mushrooms such as primarily C-8 compounds, organic sulfur compounds, aldehydes, ketones, alcohols, and esters are summarized along with their effects on the various characteristics of scent. Combining multiple extraction, isolation, identification, and quantification technologies will facilitate rapid and accurate analysis of VOCs in edible mushrooms as proof of sensory attributes and quality.

Optimization of a static headspace GC-MS method and its application in metabolic fingerprinting of the leaf volatiles of 42 citrus cultivars

Citrus leaves, which are a rich source of plant volatiles, have the beneficial attributes of rapid growth, large biomass, and availability throughout the year. Establishing the leaf volatile profiles of different citrus genotypes would make a valuable contribution to citrus species identification and chemotaxonomic studies. In this study, we developed an efficient and convenient static headspace (HS) sampling technique combined with gas chromatography-mass spectrometry (GC-MS) analysis and optimized the extraction conditions (a 15-min incubation at 100 ˚C without the addition of salt). Using a large set of 42 citrus cultivars, we validated the applicability of the optimized HS-GC-MS system in determining leaf volatile profiles. A total of 83 volatile metabolites, including monoterpene hydrocarbons, alcohols, sesquiterpene hydrocarbons, aldehydes, monoterpenoids, esters, and ketones were identified and quantified. Multivariate statistical analysis and hierarchical clustering revealed that mandarin (Citrus reticulata Blanco) and orange (Citrus sinensis L. Osbeck) groups exhibited notably differential volatile profiles, and that the mandarin group cultivars were characterized by the complex volatile profiles, thereby indicating the complex nature and diversity of these mandarin cultivars. We also identified those volatile compounds deemed to be the most useful in discriminating amongst citrus cultivars. This method developed in this study provides a rapid, simple, and reliable approach for the extraction and identification of citrus leaf volatile organic compound, and based on this methodology, we propose a leaf volatile profile-based classification model for citrus.

Optimization of headspace solid-phase microextraction of volatile organic compounds from dry soil samples by porous coatings using COMSOL Multiphysics

Headspace solid-phase microextraction (HSSPME) is one of the simplest and cost-efficient sample preparation approaches for determination of volatile organic compounds (VOCs) in soil. This study was aimed at the development of the model for numerical optimization of HSSPME of volatile organic compounds from dry soil samples by porous coatings using COMSOL Multiphysics (CMP). ‘Transport of Diluted Species in Porous Medium’ physics was used for modeling. Effect of sample mass, pressure, fiber-headspace and soil-headspace distribution constants on extraction profiles and time of 95% equilibrium has been studied using the developed model. Equilibrium extraction under atmospheric pressure (1 atm) can take up to 97 min, while under vacuum (0.0313 atm) – 2.3 min. Equilibration time under vacuum was 42-43 times lower than under 1 atm at all studied distribution constants and sample masses. The developed model was modified for optimization of pre-incubation time using ‘Transport of Diluted Species’ physics. According to the obtained plots, 95% equilibration time can reach 13.3 min and depends on both sample mass and soil-headspace distribution constant of the analyte. The developed model can be recommended for optimization of pressure, preincubation and extraction time when fiber-headspace and soil-headspace distribution constants, soil porosity and density are known.

A New Trend and Future Perspectives of the Miniaturization of Conventional Extraction Methods for Elemental Analysis in Different Real Samples: A Review

Sample preparation is one of the viable procedures to be used before analysis to enhance sensitivity and reduce the matrix effect. The current review is mainly emphasized the latest outcome and applications of microextraction techniques based on the miniaturization of the classical conventional methods based on liquid-phase and solid-phase extraction for the quantitative elemental analysis in different real samples. The limitation of the conventional sample preparation methods (liquid and solid phase extraction) has been overcome by developing a new way of reducing size as compared with the conventional system through the miniaturization approach. Miniaturization of the sample preparation techniques has received extensive attention due to its extraction at microlevels, speedy, economical, eco-friendly, and high extraction capability. The growing demand for speedy, economically feasible, and environmentally sound analytical approaches is the main intention to upgrade the conventional procedures apply for sample preparation in environmental investigation. A growing trend of research has been perceived to quantify the trace for elemental analysis in different natures of real samples. This review also recapitulates the current futuristic scenarios for the green and economically viable procedure with special overemphasis and concentrates on eco-friendly miniaturized sample-preparation techniques such as liquid-phase microextraction (LPME) and solid-phase microextraction (SPME). This review also emphasizes the latest progress and applications of the LPME and SPME approach and their future perspective.

A new headspace solid-phase microextraction coupled with gas chromatography-tandem mass spectrometry method for the simultaneous quantification of 21 microbial volatile organic compounds in urine and blood

Mold growth can cause the development of several metabolites including microbial volatile organic compounds (mVOCs). These latter may be considered as potential biomarkers of fungal presence and have been detected in human biological matrices such as urine and blood. Exposure to molds and their metabolites (e.g., mVOCs, mycotoxins) in occupational settings, is responsible for several health effects. Thus, this exposure cannot be neglected and must be evaluated. Herein, a method has been developed to quantify 21 mVOCs in urine and human blood by headspace solid phase micro-extraction (HS-SPME) coupled with gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS). The parameters influencing the extraction process, such as the type of fiber, the incubation and extraction time and temperature and the desorption time, have been optimized to ensure better mVOCs extraction. The developed method showed good linearity over the concentration range of the compounds (R² ˃ 0.995) for all the mVOCs in all the matrices. The low limits of detection (LOD) ranging from 0.7 to 417 ng/L in urine and from 1 to 507 ng/L in blood, make the developed methods sensitive and effective for biomonitoring of exposure at low levels. Recoveries, at low and high concentrations, were between 87% and 120% in urine and between 83% and 118% in blood. The repeatability and the intermediate precision in terms of coefficients of variation (CV%) was lower than 13% and 8.58% respectively for all compounds in all matrices. These values show satisfactory accuracy and precision of the developed method. Thus, this practical, simple, and sensitive method is well suited for the simultaneous quantification of target mVOCs.

Quantification of trace transformation products of rocket fuel unsymmetrical dimethylhydrazine in sand using vacuum-assisted headspace solid-phase microextraction

Quantification of unsymmetrical dimethylhydrazine transformation products in solid samples is an important stage in monitoring of environmental pollution caused by heavy rockets launches. The new method for simultaneous quantification of unsymmetrical dimethylhydrazine transformation products in sand samples using vacuum-assisted headspace solid-phase microextraction without addition of water followed by gas chromatography-mass spectrometry is proposed. Decreasing air evacuation time from 120 to 20 s at 23 °C resulted in increased responses of analytes by 25-46% and allowed obtaining similar responses as after evacuation at -30 °C. The best combination of responses of analytes and their relative standard deviations (RSDs) was achieved after air evacuation of a sample (m = 1.00 g) for 20 s at 23 °C, incubation for 30 min at 40 °C, and 30-min extraction at 40 °C by Carboxen/polydimethylsiloxane (Car/PDMS) fiber. The method was validated in terms of linearity (R²=0.9912-0.9938), limits of detection (0.035 to 3.6 ng g^-1), limits of quantification (0.12-12 ng g^-1), recovery (84-97% with RSDs 1-11%), repeatability (RSDs 3-9%), and reproducibility (RSDs 7-11%). It has a number of major advantages over existing methods based on headspace solid-phase microextraction-lower detection limits, better accuracy and precision at similar or lower cost of sample preparation. The developed method was successfully applied for studying losses of analytes from open vials with model sand spiked with unsymmetrical dimethylhydrazine transformation products. It can be recommended for analysis of trace concentrations of unsymmetrical dimethylhydrazine transformation products when studying their transformation, migration and distribution in contaminated sand.

Optimization of Headspace Solid-Phase Micro-Extraction Conditions (HS-SPME) and Identification of Major Volatile Aroma-Active Compounds in Chinese Chive (Allium tuberosum Rottler)

In order to rapidly and precisely identify the volatile compounds in Chinese chive (Allium tuberosum Rottler), seven key parameters of headspace solid-phase micro-extraction conditions (HS-SPME) from Chinese chive were optimized. A total of 59 volatile compounds were identified by using the optimized method, including 28 ethers, 15 aldehydes, 6 alcohols, 5 ketones, 2 hydrocarbons, 1 ester, and 2 phenols. Ethers are the most abundant, especially dimethyl trisulfide (10,623.30 μg/kg). By calculating the odor activity values (OAVs), 11 volatile compounds were identified as the major aroma-active compounds of Chinese chive. From the analysis of the composition of Chinese chive aroma, the “garlic and onion” odor (OAV = 2361.09) showed an absolute predominance over the other 5 categories of aroma. The results of this study elucidated the main sources of Chinese chive aroma from a chemical point of view and provided the theoretical basis for improving the flavor quality of Chinese chive.

Advanced Solid-Phase Microextraction Techniques and Related Automation: A Review of Commercially Available Technologies

The solid-phase microextraction (SPME), invented by Pawliszyn in 1989, today has a renewed and growing use and interest in the scientific community with fourteen techniques currently available on the market. The miniaturization of traditional sample preparation devices fulfills the new request of an environmental friendly analytical chemistry. The recent upswing of these solid-phase microextraction technologies has brought new availability and range of robotic automation. The microextraction solutions propose today on the market can cover a wide variety of analytical fields and applications. This review reports on the state-of-the-art innovative solid-phase microextraction techniques, especially those used for chromatographic separation and mass-spectrometric detection, given the recent improvements in availability and range of automation techniques. The progressively implemented solid-phase microextraction techniques and related automated commercially available devices are classified and described to offer a valuable tool to summarize their potential combinations to face all the laboratories requirements in terms of analytical applications, robustness, sensitivity, and throughput.

Vacuum-assisted headspace thin-film microextraction: Theoretical formulation and method optimization for the extraction of polycyclic aromatic hydrocarbons from water samples

The thin films used in headspace thin-film microextraction (HS-TFME) enable higher sensitivity and superior extraction rates compared to other microextraction approaches, largely due to their greater surface area-to-volume ratio and extraction-phase volume. Nonetheless, analytes exhibiting a low affinity for the headspace and/or large partitioning between the extraction phase and headspace will still require more time to reach equilibrium. In this paper, we detail the development of a new method, termed as vacuum-assisted HS-TFME (Vac-HS-TFME), and we demonstrate how its use of vacuum conditions can accelerate the extraction kinetics of analytes with long equilibration times. The pressure-dependence of the extraction process was formulated and related to improvements in gas-phase diffusivity when lowering the total pressure. Four low-molecular-weight polycyclic aromatic hydrocarbons (PAHs) were used to experimentally verify the improvements in extraction efficiencies enabled by Vac-HS-TFME (vs. HS-TFME). To this end, the effects of temperature and extraction time on Vac-HS-TFME were investigated, with the results being compared to those obtained via regular HS-TFME. Furthermore, the use of a high-capacity sorbent in TFME allowed the positive effects of temperature and vacuum conditions to be combined successfully. Extraction-time profiles constructed at 30 and 50 °C revealed substantial acceleration in the overall extraction kinetics when sampling under vacuum conditions. At 50 °C, all of the analytes extracted via Vac-HS-TFME reached equilibrium within 45 min, whereas only two reached this state under atmospheric pressure. Vac-HS-TFME's analytical performance was evaluated under optimized conditions, and the results were compared to those obtained with regular HS-TFME. The findings revealed that for the two lighter PAHs, the performance of the two methods was similar since they were extracted close or at equilibrium. However, the calibration models for the two heavier PAHs tested here were linear over a wider concentration range (50-10000 ng L^-1) when using Vac-HS-TFME, had superior intra-day repeatability (7.4% and 6.7% vs. 11% and 9.3% with regular HS-TFME), and the limits of detection were lower compared to regular HS-TFME (15 and 11 ng L^-1 compared to 136 to 100 ng L^-1 with regular HS-TFME). Finally, the analysis of spiked wastewater effluent samples showed that the matrix did not affect extraction. The proposed Vac-HS-TFME approach combines the advantages of low-pressure sampling and high-capacity sorbent, and has a great potential for future applications in food, flavour, environmental, and biological analyses.

Developments of Microextraction (Extraction) Procedures for Sample Preparation of Antidepressants in Biological and Water Samples, a Review

Antidepressants are an important class of drugs to treat various types of depression. The determination of antidepressants is crucial in biological samples to control adverse effects in humans and study pharmacokinetics and bioavailability. Direct measurement of antidepressants in biological and water samples is a considerable challenge for analysts due to their low concentration, the high matrix effects of real samples, and the presence of metabolites of these drugs in biological samples. The challenge leads to using sample preparation processes as a critical step in determining antidepressants. Extraction and microextraction procedures have been widely utilized as sample preparation procedures for these drugs. The purposes of extraction or microextraction methods for antidepressant medications are to preconcentrate the analyte, reduce the matrix effects, increase the selectivity of the procedures, and convert the sample to a suitable format for introducing it into detection systems. In the review, the various extraction and microextraction methods of these drugs in biological, real water, and wastewater samples were investigated. The theory of each technique was briefly addressed to understand the features and factors affecting each method. The extraction and microextraction methods were classified based on their application for antidepressants, and the advantages and disadvantages of each technique were reviewed. The new developments to overcome the limitations of each procedure were discussed. The investigation indicated the number of applications of liquid-phase microextraction for extracting antidepressants has been almost equal to that of solid-phase microextraction.

Optimization of SPME-Arrow-GC/MS Method for Determination of Free and Bound Volatile Organic Compounds from Grape Skins

(1) Background: Solid phase microextraction (SPME)-Arrow is a new extraction technology recently employed in the analysis of volatiles in food materials. Grape volatile organic compounds (VOC) have a crucial role in the winemaking industry due to their sensory characteristics of wine.; (2) Methods: Box–Behnken experimental design and response surface methodology were used to optimise SPME-Arrow conditions (extraction temperature, incubation time, exposure time, desorption time). Analyzed VOCs were free VOCs directly from grape skins and bound VOCs released from grape skins by acid hydrolysis.; (3) Results: The most significant factors were extraction temperature and exposure time for both free and bound VOCs. For both factors, an increase in their values positively affected the extraction efficiency for almost all classes of VOCs. For free VOCs, the optimum extraction conditions are: extraction temperature 60 °C, incubation time 20 min, exposure time 49 min, and desorption time 7 min, while for the bound VOCs are: extraction temperature 60 °C, incubation time 20 min, exposure time 60 min, desorption time 7 min.; (4) Conclusions: Application of the optimized method provides a powerful tool in the analysis of major classes of volatile organic compounds from grape skins, which can be applied to a large number of samples.

Optimization of HS-SPME for GC-MS Analysis and Its Application in Characterization of Volatile Compounds in Sweet Potato

Volatile compounds are the main chemical species determining the characteristic aroma of food. A procedure based on headspace solid-phase microextraction (HP-SPME) coupled to gas chromatography-mass spectrometry (GC-MS) was developed to investigate the volatile compounds of sweet potato. The experimental conditions (fiber coating, incubation temperature and time, extraction time) were optimized for the extraction of volatile compounds from sweet potato. The samples incubated at 80 °C for 30 min and extracted at 80 °C by the fiber with a divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) coating for 30 min gave the most effective extraction of the analytes. The optimized method was applied to study the volatile profile of four sweet potato cultivars (Anna, Jieshu95-16, Ayamursaki, and Shuangzai) with different aroma. In total, 68 compounds were identified and the dominants were aldehydes, followed by alcohols, ketones, and terpenes. Significant differences were observed among the volatile profile of four cultivars. Furthermore, each cultivar was characterized by different compounds with typical flavor. The results substantiated that the optimized HS-SPME GC-MS method could provide an efficient and convenient approach to study the flavor characteristics of sweet potato. This is the basis for studying the key aroma-active compounds and selecting odor-rich accessions, which will help in the targeted improvement of sweet potato flavor in breeding.

The investigation of the volatile metabolites of lung cancer from the microenvironment of malignant pleural effusion

For malignant pleural effusions, pleural fluid cytology is a diagnostic method, but sensitivity is low. The pleural fluid contains metabolites directly released from cancer cells. The objective of this study was to diagnose lung cancer with malignant pleural effusion using the volatilomic profiling method. We recruited lung cancer patients with malignant pleural effusion and patients with nonmalignant diseases with pleural effusion as controls. We analyzed the headspace air of the pleural effusion by gas chromatography-mass spectrometry. We used partial least squares discriminant analysis (PLS-DA) to identify metabolites and the support vector machine (SVM) to establish the prediction model. We split data into a training set (80%) and a testing set (20%) to validate the accuracy. A total of 68 subjects were included in the final analysis. The PLS-DA showed high discrimination with an R² of 0.95 and Q² of 0.58. The accuracy of the SVM in the test set was 0.93 (95% CI 0.66, 0.998), the sensitivity was 83%, the specificity was 100%, and kappa was 0.85, and the area under the receiver operating characteristic curve was 0.96 (95% CI 0.86, 1.00). Volatile metabolites of pleural effusion might be used in patients with cytology-negative pleural effusion to rule out malignancy.

The Effect of Carnosol, Carnosic Acid and Rosmarinic Acid on the Oxidative Stability of Fat-Filled Milk Powders throughout Accelerated Oxidation Storage

The in vitro antioxidant effects of the most potent antioxidants of rosemary, namely carnosol, carnosic acid and rosmarinic acid (c: ca: ra) were assessed in fat-filled milk powders (FFMPs) under accelerated conditions (40 °C and relative humidity (RH) 23%) over 90 days. Lipid oxidation was assessed in FFMPs by measuring peroxide values (PVs), thiobarbituric acid reactive substances (TBARS) and aroma volatiles using headspace (HS) solid-phase microextraction (SPME) coupled to gas-chromatography-mass spectrometry (GC-MS). The antioxidant potency of c: ca: ra exhibited a concentration-related effect (308 ppm > 200 ppm > 77 ppm), with the highest concentration being the most effective at controlling the formation of TBARS and PVs. At a concentration of 308 ppm c: ca: ra were particularly effective (p < 0.05) in inhibiting all the evaluated oxidation indices (primary and secondary) compared to the control samples, but in some cases less effectively (p < 0.05) than butylated hydroxyanisole: butylated hydroxytoluene (BHA: BHT) (200 ppm).

High-throughput biomonitoring of organophosphate flame-retardant metabolites in urine via 96-blade solid-phase microextraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry

Organophosphate flame retardants (OPFRs) are widely used in consumer products and building materials, but their propensity for migration poses a problem with respect to polluting indoor environments, water, soil, and dust. OPFR metabolites in urine samples are appropriate biomarkers for assessing exposure risk levels. In this paper, a high-throughput method that couples 96-blade solid-phase microextraction with ultra-performance liquid chromatography-tandem mass spectrometry (SPME-UPLC-MS/MS) is applied for the simultaneous detection of four OPFR metabolites in urine samples. The results indicated that the best extraction was achieved using 96 blades coated with hydrophilic-lipophilic balance weak anion exchange (HLB-WAX). The proposed SPME method's extraction efficiency was maximized by optimizing extraction time, pH value, desorption solution, desorption volume, and desorption time, and it was validated in accordance with the Food and Drug Administration's guidelines. The findings indicated that the proposed method has a wide linearity range (0.5-100 ng mL^-1) and low detection limits (0.09-0.14 ng mL^-1). The method's accuracy ranged from 98% to 118%, with intra-day precision ranging from 1% to 10%. In contrast, inter-day precision ranged from 3% to 16%. Accuracy was also evaluated using independent urine samples, which ranged from 78% to 124% with corresponding relative standard deviations (1%-16%). Ultimately, DoCP was detected in two real samples at a concentration of 0.5-1.1 ng mL^-1, and BEHP was detected at a concentration of 0.2-1.2 ng mL^-1. Overall, the proposed SPME-UPLC-MS/MS method is reliable, accurate, and capable of simultaneously determining four OPFR metabolites in urine samples and screening them to assess exposure risk for humans.

Plasmodium falciparum Breath Metabolomics (Breathomics) Analysis as a Non-Invasive Practical Method to Diagnose Malaria in Pediatric

Children under 5 years of age are particularly vulnerable to malaria. Malaria has caused 445,000 deaths worldwide. Currently, rapid diagnostic tests (RDTs) are the fastest method to diagnose malaria. However, there are limitations that exist such as low sensitivity in detecting infections with low parasitemia. Practical, non-invasive and high ability tests to detect parasite are needed to find specific biomarkers for P. falciparum infection to determine the potential of P. falciparum 4 thioether in breathomics analysis by GC-MS as a practical non-invasive method in diagnosing malaria in pediatrics. Literature reviews from Google Scholar and ProQuest were published no later than the last 5 years. The concept of breathomics is that the breath’s volatile organic compounds (VOCs) profile is altered when the health condition changes. Breath samples from individuals infected with P. falciparum malaria were taken by exhalation. Through GC-MS analysis, it was found that 4 thioether compounds (allyl methyl sulfide (AMS), 1-methylthio-propane, (Z) -1-methylthio-1-propene and (E) -1-methylthio-1-propene) underwent a significant change in concentration during the infection. Based on experiments conducted on mice and humans, the breathomics method is known to be able to detect parasitemia levels up to <100 parasites/µL, has a sensitivity level of about 71% to 91% and a specificity of about 75% to 94%. The discovery of 4 thioether compounds by GC-MS is a strong indication of malaria, because it has the potential for high sensitivity and specificity, and the detection power exceeds the ability of RDTs.

Optimization of SPME-GC-MS and characterization of floral scents from Aquilegia japonica and A. amurensis flowers

Background

The floral scents of plants play a key role in plant reproduction through the communication between plants and pollinators. Aquilegia as a model species for studying evolution, however, there have been few studies on the floral scents and relationships between floral scents and pollination for Aquilegia taxa.

Methods

In this study, three types of solid-phase micro-extraction (SPME) fiber coatings (DVB/PDMS, CAR/PDMS, DVB/CAR/PDMS) were evaluated for their performance in extracting volatile organic compounds (VOCs) from flowers of Aquilegia amurensis, which can contribute to the future studies of elucidating the role of floral scents in the pollination process.

Results

In total, 55 VOCs were identified, and among them, 50, 47 and 45 VOCs were extracted by the DVB/CAR/PDMS fiber, CAR/PDMS fiber and DVB/PDMS fibers, respectively. Only 30 VOCs were detected in A. japonica taxa. Furthermore, the relative contents of 8 VOCs were significant different (VIP > 1 and p < 0.05) between the A. amurensis and A. japonica.

Conclusions

The results can be applied in new studies of the relationships between the chemical composition of floral scents and the processes of attraction of pollinator. It may provide new ideas for rapid evolution and frequent interspecific hybridization of Aquilegia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13065-021-00754-1.

Development and perspectives of rapid detection technology in food and environment

Food safety become a hot issue currently with globalization of food trade and food supply chains. Chemical pollution, microbial contamination and adulteration in food have attracted more attention worldwide. Contamination with antibiotics, estrogens and heavy metals in water environment and soil environment have also turn into an enormous threat to food safety. Traditional small-scale, long-term detection technologies have been unable to meet the current needs. In the monitoring process, rapid, convenient, accurate analysis and detection technologies have become the future development trend. We critically synthesizing the current knowledge of various rapid detection technology, and briefly touched upon the problem which still exist in research process. The review showed that the application of novel materials promotes the development of rapid detection technology, high-throughput and portability would be popular study directions in the future. Of course, the ultimate aim of the research is how to industrialization these technologies and apply to the market.

Development of an easy and rapid analytical method for the extraction and preconcentration of chloroquine phosphate from human biofluids prior to GC-MS analysis

A vortex assisted spraying based fine droplet formation liquid phase microextraction (VA-SFDF-LPME) method was developed to determine chloroquine phosphate at trace levels in human serum, urine and saliva samples by gas chromatography–mass spectrometry (GC–MS) with single quadrupole mass analyzer. In the first part, several liquid phase microextraction (LPME) and magnetic solid phase extraction (MSPE) methods were compared to each other in order to observe their extraction ability for the analyte. VA-SFDF-LPME method was selected as an efficient and easy extraction method due to its higher extraction efficiency. Optimization studies were carried out for the parameters such as extraction solvent type, sodium hydroxide volume/concentration, sample volume, spraying number and mixing type/period. Tukey's method based on post hoc test was applied to all experimental data for the selection of optimum values. Optimum extraction parameters were found to be 12 mL initial sample volume, two sprays of dichloromethane, 0.75 mL of 60 g/kg sodium hydroxide and 15 s vortex. Under the optimum conditions, limit of detection and quantification (LOD and LOQ) were calculated as 2.8 and 9.2 μg/kg, respectively. Detection power of the GC–MS system was increased by approximately 317 folds with the developed extraction/preconcentration method. The applicability and accuracy of the proposed method was evaluated by spiking experiments and percent recovery results for human urine, serum and saliva samples were found in the range of 90.9% and 114.0% with low standard deviation values (1.9–9.4).

Antibacterial Activity of Volatile Organic Compounds Produced by the Octocoral-Associated Bacteria Bacillus sp. BO53 and Pseudoalteromonas sp. GA327

The present research aimed to evaluate the antibacterial activity of volatile organic compounds (VOCs) produced by octocoral-associated bacteria Bacillus sp. BO53 and Pseudoalteromonas sp. GA327. The volatilome bioactivity of both bacteria species was evaluated against human pathogenic antibiotic-resistant bacteria, methicillin-resistant Staphylococcus aureus, Acinetobacter baumanni, and Pseudomonas aeruginosa. In this regard, the in vitro tests showed that Bacillus sp. BO53 VOCs inhibited the growth of P. aeruginosa and reduced the growth of S. aureus and A. baumanni. Furthermore, Pseudoalteromonas sp. GA327 strongly inhibited the growth of A. baumanni, and P. aeruginosa. VOCs were analyzed by headspace solid-phase microextraction (HS-SPME) joined to gas chromatography-mass spectrometry (GC-MS) methodology. Nineteen VOCs were identified, where 5-acetyl-2-methylpyridine, 2-butanone, and 2-nonanone were the major compounds identified on Bacillus sp. BO53 VOCs; while 1-pentanol, 2-butanone, and butyl formate were the primary volatile compounds detected in Pseudoalteromonas sp. GA327. We proposed that the observed bioactivity is mainly due to the efficient inhibitory biochemical mechanisms of alcohols and ketones upon antibiotic-resistant bacteria. This is the first report which describes the antibacterial activity of VOCs emitted by octocoral-associated bacteria.

Application of Covalent Organic Porous Polymers-Functionalized Basalt Fibers for in-Tube Solid-Phase Microextraction

To establish an online analytical method towards estrogenic pollutants, a covalent organic porous polymer (COP) was in-situ synthesized on the surface of basalt fibers (BFs) for in-tube solid-phase microextraction (IT-SPME). The extraction tube, obtained via placing the modified BFs into a polyetheretherketone tube, was combined with high-performance liquid chromatography (HPLC) to achieve online IT-SPME-HPLC analysis. The important parameters, including sampling volume, sampling rate, organic solvent content and desorption time, were carefully investigated. Under the optimized conditions, the online analytical method was established for five estrogenic targets, with low limits of detection (0.001–0.005 μg/L), high enrichment factors (1800–2493), wide linear ranges (0.003–20, 0.015–20 μg/L) and satisfactory repeatability. It was successfully applied to detect five estrogens in a wastewater sample and a water sample in a polycarbonate cup. The BFs functionalized with COPs displayed excellent extraction effect for estrogenic pollutants, furthermore it has great potential in sample preparation or other fields.

Oiling-out effect improves the efficiency of extracting aroma compounds from edible oil

Volatile compounds in foods are a significant factor that affects food intake and preference. However, volatile components in edible oils are poorly understood due to a strong matrix effect. In this study, we developed a method of extracting volatile compounds from extra virgin coconut oil (EVCO) by means of oiling-out assisted liquid-liquid extraction (OA-LLE). Consequently, 44 aroma compounds were isolated and identified from only 5 g of EVCO. Various aroma compounds were detected in addition to δ-lactones. The ratio of the natural abundance of the enantiomers of δ-lactones in EVCO was also revealed. Compared with the conventional methods of solvent assisted flavor evaporation (SAFE) and head-space solid-phase micro extraction (HS-SPME), OA-LLE was able to isolate a wide range and large number of volatile compounds from EVCO without leaving oil residues. Therefore, isolating aroma compounds from edible oil based on the oiling-out effect should provide an innovative extraction method.

Solving an MHC allele-specific bias in the reported immunopeptidome

Identification of MHC class I–bound peptides by immunopurification of MHC complexes and subsequent analysis by mass spectrometry is crucial for understanding T cell immunology and immunotherapy. Investigation of the steps for the MHC ligand isolation process revealed biases in widely used isolation techniques toward peptides of lower hydrophobicity. As MHC ligand hydrophobicity correlates positively with immunogenicity, identification of more hydrophobic MHC ligands could potentially lead to more effective isolation of immunogenic peptides as targets for immunotherapies. We solved this problem by use of higher concentrations of acetonitrile for the separation of MHC ligands and their respective complexes. This increased overall MHC ligand identifications by 2-fold, increased detection of cancer germline antigen–derived peptides by 50%, and resulted in profound variations in isolation efficacy between different MHC alleles correlating with the hydrophobicity of their anchor residues. Overall, these insights enabled a more complete view of the immunopeptidome and overcame a systematic underrepresentation of these critical MHC ligands of high hydrophobicity.

An approach is identified to prevent bias in the immunopeptidome towards MHC ligands of lower hydrophobicity and therefore immunogenicity.

Development and comprehensive HS-SPME/GC-MS analysis optimization, comparison, and evaluation of different cabbage cultivars (Brassica oleracea L. var. capitata L.) volatile components

Seven parameters of the headspace solid phase micro-extraction (HS-SPME) for extracting volatile compounds from cabbage were optimized comprehensively for the first time. A total of 75 volatiles were identified and quantified in 10 cabbage cultivars, mainly including aldehydes, hydrocarbons, esters, isothiocyanates, alcohols, ethers, nitriles and thiazoles. Dimethyl ether was the most abundant volatile. There were 24 volatiles with the odour activity values (OAVs) greater than 1 making large contributions to the cabbage flavor. Pungent aroma was the strongest odour, followed by green and fruity aromas. In short, the overall OAV of purple cabbages were generally higher than that of green cabbage. The volatile profile of 10 cabbage cultivars could be distinguished on the basis of radar fingerprint chart (RFC), hierarchical cluster analysis (HCA) and principal component analysis (PCA). Therefore, this study not only developed a feasible method to distinguish different cabbage cultivars, but also established a theoretical basis for the genetic improvement of cabbage flavor.

Development and Validation of a Stability Indicating LC-MS/MS Method for the Determination of Clenbuterol HCl

Clenbuterol hydrochloride (CLT), β₂ adrenergic agonist is used as a bronchodilator in the therapeutic treatment of asthma. It is important to know the stability behaviour of the drug in different degradation conditions as per ICH Q1A (R2) guidelines for safety and efficacy purpose. The main objective of the study is to develop and validate stability indicating LC-MS/MS method for the determination of Clenbuterol HCl. The separation was achieved using Phenomenex Gemini NX C18 (250*4.6 mm, 5 μ) column and the mobile phase consisting of ammonium acetate buffer (5 mM), 0.15% triethylamine (TEA), pH 7.5 with acetic acid: methanol (70:30, v/v) at flow rate 1 ml/min. The detection was done using PDA detector at 245 nm. The validation was performed as per ICH Q2 (R1) guideline. The drug was subjected to stress degradation conditions as per ICH Q1A (R2) guidelines. The significant degradation was observed in acidic (8.78%) and sunlight (liquid) (9%) condition while no degradation was observed in neutral, basic, oxidation and thermal condition. The drug and its degradation products were characterized using LC-MS/MS and the proposed degradation mechanism was communicated. The developed method was found to be stability-indicating, simple, specific, selective, sensitive, linear, accurate, robust and precise and used as a routine analysis in quality control laboratory.

Enhancing enrichment ability of ZIF-8 mixed matrix membrane microextraction by reverse micelle strategy for analysis of multiple ionizable bioactive components in biological samples

Recent research aimed at the design of mixed-matrix membrane (MMM) to be used for microextraction emphasized on membrane extraction phase with high surface area and porosity. This study explored the influence that surfactants have on MMM extraction efficiency for the first time. The zeolitic imidazolate framework 8-based MMM (ZIF-8-MMM) was synthesized by in situ self-assembly of ZIF-8 on the inner wall of a hollow fiber membrane with the aim of fabricating a microextraction device. By prompting the encapsulation of ionizable analytes in the polar core of reverse micelles, the presence of surfactants in extraction solvent assisted the dissolution of analytes in the fiber membrane lumen and enhanced their adsorption onto ZIF-8. Notably, hereby a microextraction method based on the novel ZIF-8-MMM-reverse micelle (ZIF-8-MMM-RM) system was developed and employed for the extraction and quantitation of two alkaloids (berberine and jatrorrhizine) and two flavonoids (wogonin and wogonoside) in biological samples. The main factors affecting microextraction performance, identity of the extraction solvent, surfactant concentration, sample solution pH and extraction time, were investigated in detail. The method showed good linearity (r² > 0.99) and repeatability (RSD < 10%), low limits of detection (0.10-0.31 ng mL^-1) and high relative recoveries (90.03-98.84%). The enrichment factor values ranged between 48.47 and 54.96. Reverse micelle formation prompted by surfactant addition was demonstrated to effectively assist the extraction of multiple ionizable analytes from biological samples, resulting in a marked improvement of ZIF-8-MMM extraction performance.

Solid-Phase Microextraction Fiber in Face Mask for in Vivo Sampling and Direct Mass Spectrometry Analysis of Exhaled Breath Aerosol

Molecular analysis of exhaled breath aerosol (EBA) with simple procedures represents a key step in clinical and point-of-care applications. Due to the crucial health role, a face mask now is a safety device that helps protect the wearer from breathing in hazardous particles such as bacteria and viruses in the air; thus exhaled breath is also blocked to congregate in the small space inside of the face mask. Therefore, direct sampling and analysis of trace constituents in EBA using a face mask can rapidly provide useful insights into human physiologic and pathological information. Herein, we introduce a simple approach to collect and analyze human EBA by combining a face mask with solid-phase microextraction (SPME) fiber. SPME fiber was inserted into a face mask to form SPME-in-mask that covered nose and mouth for in vivo sampling of EBA, and SPME fiber was then coupled with direct analysis in real-time mass spectrometry (DART-MS) to directly analyze the molecular compositions of EBA under ambient conditions. The applicability of SPME-in-mask was demonstrated by direct analysis of drugs and metabolites in oral and nasal EBA. The unique features of SPME-in-mask were also discussed. Our results showed that this method is enabled to analyze volatile and nonvolatile analytes in EBA and is expected to have a significant impact on human EBA analysis in clinical applications. We also hope this method will inspire biomarker screening of some respiratory diseases that usually required wearing of a face mask in daily life.

An Optimization of Liquid-Liquid Extraction of Urinary Volatile and Semi-Volatile Compounds and Its Application for Gas Chromatography-Mass Spectrometry and Proton Nuclear Magnetic Resonance Spectroscopy

Urinary volatile compounds (VCs) have been recently assessed for disease diagnoses. They belong to very diverse chemical classes, and they are characterized by different volatilities, polarities and concentrations, complicating their analysis via a single analytical procedure. There remains a need for better, lower-cost methods for VC biomarker discovery. Thus, there is a strong need for alternative methods, enabling the detection of a broader range of VCs. Therefore, the main aim of this study was to optimize a simple and reliable liquid-liquid extraction (LLE) procedure for the analysis of VCs in urine using gas chromatography-mass spectrometry (GC-MS), in order to obtain the maximum number of responses. Extraction parameters such as pH, type of solvent and ionic strength were optimized. Moreover, the same extracts were analyzed using Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR), to evaluate the applicability of a single urine extraction for multiplatform purposes. After the evaluation of experimental conditions, an LLE protocol using 2 mL of urine in the presence of 2 mL of 1 M sulfuric acid and sodium sulphate extracted with dichloromethane was found to be optimal. The optimized method was validated with the external standards and was found to be precise and linear, and allowed for detection of >400 peaks in a single run present in at least 50% of six samples-considerably more than the number of peaks detected by solid-phase microextracton fiber pre-concentration-GC-MS (328 ± 6 vs. 234 ± 4). 1H-NMR spectroscopy of the polar and non-polar extracts extended the range to >40 more (mainly low volatility compounds) metabolites (non-destructively), the majority of which were different from GC-MS. The more peaks detectable, the greater the opportunity of assessing a fingerprint of several compounds to aid biomarker discovery. In summary, we have successfully demonstrated the potential of LLE as a cheap and simple alternative for the analysis of VCs in urine, and for the first time the applicability of a single urine solvent extraction procedure for detecting a wide range of analytes using both GC-MS and 1H-NMR analysis to enhance putative biomarker detection. The proposed method will simplify the transport between laboratories and storage of samples, as compared to intact urine samples.