Fizzy Extraction of Volatile and Semivolatile Compounds into the Gas Phase

Ultrasensitive and Green Bubbling Extraction Strategies: An Extensible Solvent-Free Re-Enrichment Approach for Ultratrace Pollutants in Aqueous Samples

Ultratrace organic pollutants in the environment pose severe threats to human health; hence, their accurate detection is essential. In this study, we develop a secondary solvent-free enrichment strategy based on bubbling extraction (BE). Especially, we used BE solid-phase microextraction and BE carbon nanotube paper absorption to capture aerosols from a liquid water surface, desorb analytes, and analyze the analytes using mass spectrometry. The application of a solvent-free enrichment strategy helps overcome technical challenges in implementing BE technology, including reproducibility, quantification, and sensitivity. This approach objectively demonstrates the enrichment efficiency of BE, resulting in improved mass spectrometry response and quantification. It effectively tackles the difficulties in detecting and quantifying ultratrace environmental pollutants in mass spectrometric analysis. The present study successfully conducted a quantitative analysis of 16 polycyclic aromatic hydrocarbons and 7 antibiotics in 48 environmental water samples. This strategy proved effective in detecting the presence and distribution of polar and nonpolar environmental pollutants in rivers and lakes. Moreover, this strategy has several advantages, such as ultrahigh sensitivity at the femtograms per liter level, good greenness, multiplexed quantitation, low sample consumption, and ease of operation. Overall, the utilization of the ultrasensitive and environmentally friendly BE approach presents a reliable and adaptable method for the identification of ultratrace environmental pollutants in water specimens, thereby enabling early monitoring of pollutant levels.

Carbon Dioxide Microbubble Bursting Ionization Mass Spectrometry

Aerosols generated by bubble bursting have been proved to promote the extraction of analytes and have ultrahigh electric fields at their water-air interfaces. This study presented a simple and efficient ionization method, carbon dioxide microbubble bursting ionization (CDMBI), without the presence of an exogenous electric field (namely, zero voltage), by simulating the interfacial chemistries of sea spray aerosols. In CDMBI, microbubbles are generated in situ by continuous input of carbon dioxide into an aqueous solution containing low-concentration analytes. The microbubbles extract low- and high-polarity analytes as they pass through the aqueous solution. Upon reaching the water-air interface, these microbubbles burst to produce charged aerosol microdroplets with an average diameter of 260 μm (8.1-10.4 nL in volume), which are immediately transferred to a mass spectrometer for the detection and identification of extracted analytes. The above analytical process occurs every 4.2 s with a stable total ion chromatogram (relative standard deviation: 9.4%) recorded. CDMBI mass spectrometry (CDMBI-MS) can detect surface-active organic compounds in aerosol microdroplets, such as perfluorooctanoic acid, free fatty acids epoxidized by bubble bursting, sterols, and lecithins in soybean and egg, with the limit of detection reaching the level of fg/mL. In addition, coupling CDMBI-MS with an exogenous voltage yields relatively weak gains in ionization efficiency and sensitivity of analysis. The results suggested that CDMBI can simultaneously accomplish both bubbling extraction and microbubble bursting ionization. The mechanism of CDMBI involves bubbling extraction, proton transfer, inlet ionization, and electrospray-like ionization. Overall, CDMBI-MS can work in both positive and negative ion modes without necessarily needing an exogenous high electric field for ionization and quickly detect trace surface-active analytes in aqueous solutions.

Analyte recovery in LC-MS/MS bioanalysis: An old issue revisited

There are several challenges associated with LC-MS/MS bioanalytical method development and validation. Low and variable recovery of some analytes, especially the more hydrophobic ones, is often challenging. Analytes can be lost to various extents throughout the process of sample collection, storage, before, during, and/or after sample preparation and analysis. The calculation of overall extraction recovery can detect problems of low recovery during sample preparation but does not identify the source(s) of analyte losses. Low overall analyte recovery is the net result of losses that can happen for multiple reasons at all steps of sample preparation and analysis. Therefore, identifying the source(s) of analyte loss during sample preparation can help guide the optimization the bioanalysis conditions to minimize these losses. In this article we propose a practical protocol to systematically identify and quantify the sources of low analyte recovery. This allows the proper choice of strategies to optimize the relevant bioanalytical conditions to minimize analyte losses and improve overall recovery.

Catalytic Oxygenation-Mediated Extraction as a Facile and Green Way to Analyze Volatile Solutes

Sparging-based methods have long been used to liberate volatile organic compounds (VOCs) from liquid sample matrices prior to analysis. In these methods, a carrier gas is delivered from an external source. Here, we demonstrate "catalytic oxygenation-mediated extraction" (COME), which relies on biocatalytic production of oxygen occurring directly in the sample matrix. The newly formed oxygen (micro)bubbles extract the dissolved VOCs. The gaseous extract is immediately transferred to a separation or detection system for analysis. To start COME, dilute hydrogen peroxide is injected into the sample supplemented with catalase enzyme. The entire procedure is performed automatically-after pressing a "start" button, making a clapping sound, or triggering from a smartphone. The pump, valves, and detection system are controlled by a microcontroller board. For quality control and safety purposes, the reaction chamber is monitored by a camera linked to a single-board computer, which follows the enzymatic reaction progress by analyzing images of foam in real time. The data are instantly uploaded to the internet cloud for retrieval. The COME apparatus has been coupled on-line with the gas chromatography electron ionization mass spectrometry (MS) system, atmospheric pressure chemical ionization (APCI) MS system, and APCI ion-mobility spectrometry system. The three hyphenated variants have been tested in analyses of complex matrices (e.g., fruit-based drinks, whiskey, urine, and stored wastewater). In addition to the use of catalase, COME variants using crude potato pulp or manganese(IV) dioxide have been demonstrated. The technique is inexpensive, fast, reliable, and green: it uses low-toxicity chemicals and emits oxygen.

Low-cost and open-source strategies for chemical separations

In recent years, a trend toward utilizing open access resources for laboratory research has begun. Open-source design strategies for scientific hardware rely upon the use of widely available parts, especially those that can be directly printed using additive manufacturing techniques and electronic components that can be connected to low-cost microcontrollers. Open-source software eliminates the need for expensive commercial licenses and provides the opportunity to design programs for specific needs. In this review, the impact of the "open-source movement" within the field of chemical separations is described, primarily through a comprehensive look at research in this area over the past five years. Topics that are covered include general laboratory equipment, sample preparation techniques, separations-based analysis, detection strategies, electronic system control, and software for data processing. Remaining hurdles and possible opportunities for further adoption of open-source approaches in the context of these separations-related topics are also discussed.

Harnessing bubble behaviors for developing new analytical strategies

Gas bubbles are easily accessible and offer many unique characteristic properties of a gas/liquid two-phase system for developing new analytical methods. In this minireview, we discuss the newly developed analytical strategies that harness the behaviors of bubbles. Recent advancements include the utilization of the gas/liquid interfacial activity of bubbles for detection and preconcentration of surface-active compounds; the employment of the gas phase properties of bubbles for acoustic imaging and detection, microfluidic analysis, electrochemical sensing, and emission spectroscopy; and the application of the mass transport behaviors at the gas/liquid interface in gas sensing, biosensing, and nanofluidics. These studies have demonstrated the versatility of gas bubbles as a platform for developing new analytical strategies.

Effervescence-Assisted Microextraction-One Decade of Developments

Dispersive microextraction techniques are key in the analytical sample treatment context as they combine a favored thermodynamics and kinetics isolation of the target analytes from the sample matrix. The dispersion of the extractant in the form of tiny particles or drops, depending on the technique, into the sample enlarges the contact surface area between phases, thus enhancing the mass transference. This dispersion can be achieved by applying external energy sources, the use of chemicals, or the combination of both strategies. Effervescence-assisted microextraction emerged in 2011 as a new alternative in this context. The technique uses in situ-generated carbon dioxide as the disperser, and it has been successfully applied in the solid-phase and liquid-phase microextraction fields. This minireview explains the main fundamentals of the technique, its potential and the main developments reported.

Rapid detection of perfluorinated sulfonic acids through preconcentration by bubble bursting and surface-assisted laser desorption/ionization

We developed a preconcentration method in which aerosol droplets containing enriched perfluorinated sulfonic acids (PFSs) are generated through bubble bursting and collected. The droplets were subjected to PFS analysis of perfluorohexane sulfonic acid (PFHxS) and perfluorooctanesulfonic acid (PFOS) through surface-assisted laser desorption/ionization-time-of-flight mass spectrometry; silver nanoplates (AgNPts) were assisting materials. The method was highly efficient, with an approximately three-order magnitude enhancement (5 × 10-13 to 1 × 10-11 M). Ultralow PFS concentrations (0.5 ng/L of PFOS; 0.4 ng/L of PFHxS) were detected in preconcentrated tap water containing PFSs. Our method has potential for rapid real-world PFS detection in water.

Effervescence-assisted spiral hollow-fibre liquid-phase microextraction of trihalomethanes, halonitromethanes, haloacetonitriles, and haloketones in drinking water

A new analytical method was optimized to determine 18 disinfection by-products (DBPs) in drinking water, including four different chemical groups. For this purpose, spiral-shaped hollow-fibre liquid phase microextraction with 1-octanol as the acceptor solvent assisted by effervescence was applied using a homemade supporting device that was specifically designed for this application. The device was printed in a 3D printer and allows for an increased fibre surface even with a low sample volume, which significantly facilitates the extraction. The samples were analysed by gas chromatography coupled to both an electron capture detector and a mass spectrometer for the quantification and unequivocal identification of the analytes, respectively. Effervescence was generated using citric acid and bicarbonate at a molar ratio 1:2, which significantly improves the extraction efficiency and reduces mechanical operations, since stirring and modifiers are not required. The results showed enrichment factors ranging from 13.1 to 140.1. Satisfactory recoveries (80-113 %) were obtained, with relative standard deviations from 3 to 15 % and good linearity. The detection limits (ng L^-1) ranged from 10 to 35 (trihalomethanes), 12 to 220 (halonitromethanes), 17 to 79 (haloacetonitriles) and 10 to 16 (haloketones). The applicability of the method was assessed in 6 local water distribution systems.

Elevating Chemistry Research with a Modern Electronics Toolkit

With the rapid development of high technology, chemical science is not as it used to be a century ago. Many chemists acquire and utilize skills that are well beyond the traditional definition of chemistry. The digital age has transformed chemistry laboratories. One aspect of this transformation is the progressing implementation of electronics and computer science in chemistry research. In the past decade, numerous chemistry-oriented studies have benefited from the implementation of electronic modules, including microcontroller boards (MCBs), single-board computers (SBCs), professional grade control and data acquisition systems, as well as field-programmable gate arrays (FPGAs). In particular, MCBs and SBCs provide good value for money. The application areas for electronic modules in chemistry research include construction of simple detection systems based on spectrophotometry and spectrofluorometry principles, customizing laboratory devices for automation of common laboratory practices, control of reaction systems (batch- and flow-based), extraction systems, chromatographic and electrophoretic systems, microfluidic systems (classical and nonclassical), custom-built polymerase chain reaction devices, gas-phase analyte detection systems, chemical robots and drones, construction of FPGA-based imaging systems, and the Internet-of-Chemical-Things. The technology is easy to handle, and many chemists have managed to train themselves in its implementation. The only major obstacle in its implementation is probably one's imagination.

Online Scavenging of Trace Analytes in Complex Matrices for Fast Analysis by Carbon Dioxide Bubbling Extraction Coupled with Gas Chromatography-Mass Spectrometry

Carbon dioxide (CO₂) microbubbles can selectively enrich organic solutes from sea spray aerosols. Common bubbling extractions are normally followed by off-line separation/detection through methods such as mass spectrometry, chromatography, and spectroscopy. However, it is necessary to establish extractions with online separation and identification systems to improve efficiency and minimize sample loss. In this study, CO₂ is used to form microbubbles in the sample solution, and trace analytes in the solution are transported to the gas phase by bubble bursting. Analytes at the liquid-gas interface are directly released into the trapping device, followed by thermal desorption for gas chromatography-mass spectrometry. For polycyclic aromatic hydrocarbons, the dependence of the extraction efficiency on various parameters has been analyzed. The method reported here provides high efficiency and minimizes the loss of trace volatiles with a better signal strength and signal-to-noise ratio than other gases. These features make the proposed method a rapid method to detect and quantify volatile/semivolatile analytes in complex liquid matrices. In addition to the preconcentration of organics, metal ions, and inorganic anions, a noticeable decrease of metal-organic compounds in the aqueous solution was shown for the first time. We finally propose a simple model of chemical partitioning in CO₂ bubbling extraction of liquid samples for guiding online monitoring of trace analytes in real-world samples.

Facilitating chemical and biochemical experiments with electronic microcontrollers and single-board computers

Since the advent of modern science, researchers have had to rely on their technical skills or the support of specialized workshops to construct analytical instruments. The notion of the 'fourth industrial revolution' promotes construction of customized systems by individuals using widely available, inexpensive electronic modules. This protocol shows how chemists and biochemists can utilize a broad range of microcontroller boards (MCBs) and single-board computers (SBCs) to improve experimental designs and address scientific questions. We provide seven example procedures for laboratory routines that can be expedited by implementing this technology: (i) injection of microliter-volume liquid plugs into microscale capillaries for low-volume assays; (ii) transfer of liquid extract to a mass spectrometer; (iii) liquid-gas extraction of volatile organic compounds (called 'fizzy extraction'), followed by mass spectrometric detection; (iv) monitoring of experimental conditions over the Internet cloud in real time; (v) transfer of analytes to a mass spectrometer via a liquid microjunction interface, data acquisition, and data deposition into the Internet cloud; (vi) feedback control of a biochemical reaction; and (vii) optimization of sample flow rate in direct-infusion mass spectrometry. The protocol constitutes a primer for chemists and biochemists who would like to take advantage of MCBs and SBCs in daily experimentation. It is assumed that the readers have not attended any courses related to electronics or programming. Using the instructions provided in this protocol and the cited material, readers should be able to assemble simple systems to facilitate various procedures performed in chemical and biochemical laboratories in 1-2 d.

Rapid Extraction and Analysis of Volatile Solutes with an Effervescent Tablet

Extraction of volatile compounds from complex liquid matrices is a critical step in volatile compound analysis workflows. Recently, green chemistry principles are increasingly implemented in extraction processes. Some of the available approaches are solvent-free but still require concentration or trapping of analytes. Here, we propose effervescent tablet-induced extraction (ETIE) as a method of transferring volatile/semivolatile compounds from liquid matrices to the gas phase for analysis. This technique relies on the release of carbon dioxide produced in situ during a neutralization reaction, which occurs when a tablet is inserted into an aqueous sample matrix. In this process, many bubbles of carbon dioxide are instantly formed in the sample matrix. The bubbles rapidly extract and liberate volatile compounds from the sample. The gaseous effluent is then immediately transferred to a detector (atmospheric pressure chemical ionization mass spectrometry (MS) or gas chromatography (GC) hyphenated with MS). ETIE-GC-MS can be used for analysis of volatile compounds present in real samples. The method was validated for analysis of selected ethyl esters present in a yogurt drink. The calibration data set was linear over a range from 5 × 10^-7 to 1 × 10^-5 M. The limits of detection ranged from 1.51 × 10^-7 to 6.82 × 10^-7 M, while the recoveries ranged from 71 to 118%. Inter- and intraday precision of selected ethyl esters in aqueous solution was satisfactory (relative standard deviation, 3.6-18.3%). Furthermore, it is shown that ETIE improves the performance of headspace solid-phase microextraction while eliminating the need for heating and shaking samples.

On the mechanism of automated fizzy extraction

Fizzy extraction (FE) facilitates analysis of volatile solutes by promoting their transfer from the liquid to the gas phase. A carrier gas is dissolved in the sample under moderate pressure (Δp ≈ 150 kPa), followed by an abrupt decompression, what leads to effervescence. The released gaseous analytes are directed to an on-line detector due to a small pressure difference. FE is advantageous in chemical analysis because the volatile species are released in a short time interval, allowing for pulsed injection, and leading to high signal-to-noise ratios. To shed light on the mechanism of FE, we have investigated various factors that could potentially contribute to the extraction efficiency, including: instrument-related factors, method-related factors, sample-related factors, and analyte-related factors. In particular, we have evaluated the properties of volatile solutes, which make them amenable to FE. The results suggest that the organic solutes may diffuse to the bubble lumen, especially in the presence of salt. The high signal intensities in FE coupled with mass spectrometry are partly due to the high sample introduction rate (upon decompression) to a mass-sensitive detector. However, the analytes with different properties (molecular weight, polarity) reveal distinct temporal profiles, pointing to the effect of bubble exposure to the sample matrix. A sufficient extraction time (~12 s) is required to extract less volatile solutes. The results presented in this report can help analysts to predict the occurrence of matrix effects when analyzing real samples. They also provide a basis for increasing extraction efficiency to detect low-abundance analytes.

Bubbles, Foam Formation, Stability and Consumer Perception of Carbonated Drinks: A Review of Current, New and Emerging Technologies for Rapid Assessment and Control

Quality control, mainly focused on the assessment of bubble and foam-related parameters, is critical in carbonated beverages, due to their relationship with the chemical components as well as their influence on sensory characteristics such as aroma release, mouthfeel, and perception of tastes and aromas. Consumer assessment and acceptability of carbonated beverages are mainly based on carbonation, foam, and bubbles, as a flat carbonated beverage is usually perceived as low quality. This review focuses on three beverages: beer, sparkling water, and sparkling wine. It explains the characteristics of foam and bubble formation, and the traditional methods, as well as emerging technologies based on robotics and computer vision, to assess bubble and foam-related parameters. Furthermore, it explores the most common methods and the use of advanced techniques using an artificial intelligence approach to assess sensory descriptors both for descriptive analysis and consumers' acceptability. Emerging technologies, based on the combination of robotics, computer vision, and machine learning as an approach to artificial intelligence, have been developed and applied for the assessment of beer and, to a lesser extent, sparkling wine. This, has the objective of assessing the final products quality using more reliable, accurate, affordable, and less time-consuming methods. However, despite carbonated water being an important product, due to its increasing consumption, more research needs to focus on exploring more efficient, repeatable, and accurate methods to assess carbonation and bubble size, distribution and dynamics.

The Effect of Sonication on Bubble Size and Sensory Perception of Carbonated Water to Improve Quality and Consumer Acceptability

Bubbles are important for carbonated beverage quality since smaller bubbles contribute to higher acceptability. Therefore, the effects and acceptability of the application of audible sound in carbonated water were studied using three brands and applying five frequencies for one minute each in ascending order. Six samples, two from each brand, were used for treatments: (i) control and (ii) sonication. Physicochemical measurements consisted of total dissolved solids (TDS), electric conductivity (EC), pH, bubble size, and bubble size distribution. A sensory session (N = 30) was conducted using the Bio-Sensory application to assess acceptability and emotions using self-reported and biometric responses. Statistical analysis included: ANOVA (α = 0.05) and principal component analysis (PCA) for quantitative data and Cochran Q test with pairwise comparisons (p < 0.05) for self-reported emotion responses. Results showed that the sonication effect for the sample with higher TDS, EC, and pH (SPS) reduced bubble size by 46%, while in those with lowest TDS, EC, and pH (IceS) caused an increase of 158% compared to the control. For samples with intermediate values (NuS), there were non-significant differences (p > 0.05) compared to the control. Acceptability was higher for samples with sonication for the three brands. Emotional self-reported responses were more positive for samples with sonication, showing significant differences (p < 0.05) for emotions such as “happy” and “pleased” during both sound and visual assessments. From PCA, a positive relationship between bubble size and liking of bubbles was found as well as for the number of medium bubbles and happy facial expression. The audible sound generated by ubiquitous sound systems may potentially be used by the industry, applying it to the bottled product to modify bubble size and improve quality and acceptability of carbonated beverages.

Automation of mass spectrometric detection of analytes and related workflows: A review

The developments in mass spectrometry (MS) in the past few decades reveal the power and versatility of this technology. MS methods are utilized in routine analyses as well as research activities involving a broad range of analytes (elements and molecules) and countless matrices. However, manual MS analysis is gradually becoming a thing of the past. In this article, the available MS automation strategies are critically evaluated. Automation of analytical workflows culminating with MS detection encompasses involvement of automated operations in any of the steps related to sample handling/treatment before MS detection, sample introduction, MS data acquisition, and MS data processing. Automated MS workflows help to overcome the intrinsic limitations of MS methodology regarding reproducibility, throughput, and the expertise required to operate MS instruments. Such workflows often comprise automated off-line and on-line steps such as sampling, extraction, derivatization, and separation. The most common instrumental tools include autosamplers, multi-axis robots, flow injection systems, and lab-on-a-chip. Prototyping customized automated MS systems is a way to introduce non-standard automated features to MS workflows. The review highlights the enabling role of automated MS procedures in various sectors of academic research and industry. Examples include applications of automated MS workflows in bioscience, environmental studies, and exploration of the outer space.

Automation of fizzy extraction enabled by inexpensive open-source modules

The implementation of most instrumental analysis methods requires a considerable amount of human effort at every step, including sample preparation, detection, and data processing. Automated analytical workflows decrease the amount of required work. However, commercial automated platforms are mainly available for well-established sample processing methods. In contrast, newly developed prototypes of analytical instruments are often operated manually, what limits their performance and decreases the chance of their adoption by the broader community. Open-source electronic modules facilitate the prototyping of complex analytical instruments and enable the incorporation of automated functions at the early stage of technique development. Here, we exemplify this advantage of open-source electronics while prototyping an automated analytical device. Fizzy extraction takes advantage of the effervescence phenomenon to extract semi-volatile solutes from the liquid to the gas phase. The entire fizzy extraction process has been automated by using three Arduino-related microcontrollers. The functions of the developed autonomous fizzy extraction device include triggering the analysis by a smartphone app, control of carrier gas pressure in the headspace of the sample chamber, displaying experimental conditions on an LCD screen, acquiring mass spectrometry data in real time, filtering electronic noise, integrating peaks, calculating the analyte concentration in the extracted sample, printing the analysis report, storing the acquired data in non-volatile memory, monitoring the condition of the motor by counting the number of extraction cycles, and cleaning the elements exposed to the sample (to minimize carryover). The performance of this automated system has been evaluated using standards and real samples.

On-line coupling of fizzy extraction with gas chromatography

Fizzy extraction (FE) is carried out by first dissolving a carrier gas (typically, carbon dioxide) in a liquid sample at a moderate pressure (typically, 150 kPa) and then rapidly depressurizing the sample. The depressurization leads to instant release of numerous microbubbles in the liquid matrix. The abruptly released gas extracts the volatile solutes and elutes them toward a detector in a short period of time. Here, we describe on-line coupling of FE with gas chromatography (GC). The two platforms are highly compatible and could be combined following several modifications of the interface and adjustments of the extraction sequence. The analytes are released within a short period of time (1.5 s). Thus, the chromatographic peaks are satisfactorily narrow. There is no need to trap the extracted analytes in a loop or on a sorbent, as it is done in standard headspace and microextraction methods. The approach requires only minor sample pretreatment. The main parameters of the FE-GC-mass spectrometry (MS) method were optimized. The results of FE were compared with those of headspace flushing (scavenging headspace vapors), and the enhancement factors were in the order of ~ 2 to 13 (for various analytes). The limits of detection for some of the tested analytes were lower in the proposed FE-GC-MS method than in FE combined with atmospheric pressure chemical ionization MS. The method was further tested in analyses of selected real samples (apple flavor milk, mixed fruit and vegetable juice drink, mango flavored drink, pineapple green tea, toothpaste, and yogurt). Graphical abstract.

Dry ice fog extraction of volatile organic compounds

Extraction of volatile organic compounds (VOCs) into a condensed phase requires maximizing the surface-to-volume ratio of the extracting medium. In the case of the solid-phase extracting media, the surface-to-volume ratio can be increased by implementing porous monoliths or particles with different size. In the case of the liquid-phase extracting media, the surface-to-volume ratio can be increased by generating microbubbles or aerosol microdroplets. Here, we propose dry ice fog extraction (DIFE) approach. Briefly, aerosol microdroplets are generated by inserting dry ice into the extraction solvent. The produced fog, containing high-density microdroplets, is directed toward the sample headspace, where the gas-liquid extraction occurs. The microdroplets, containing the extracted VOCs, subsequently coalesce on a cold surface. The movement of the microdroplets is facilitated by a small pressure difference between the fog generator and the extract collector. Within several minutes, a few hundred microliters of the extract are collected, which is sufficient for chromatographic and mass spectrometric analyses. In this proof-of-concept study, the DIFE approach was characterized by using gas chromatography coupled with electron ionization mass spectrometry (MS), as well as direct infusion atmospheric pressure chemical ionization MS. The limits of detection for linalool and menthol were 2.0 × 10^-6 and 4.7 × 10^-5 M, respectively. The method was further applied in analyses of VOCs emanating from a variety of liquid and solid matrices (e-cigarette "vapor", cinnamon branch, curly spearmint leaves, lily petal, garlic bulb, ginger root, mouthwash, shampoo, spoiled seafood, toothpaste, and red wine). DIFE effectively isolated the VOCs associated with these complex matrices.

Kinetic study of continuous liquid-liquid extraction of wine with real-time detection

Kinetic optimization of continuous liquid-liquid extraction (CLLE) can shorten sample preparation times and reduce losses of labile or volatile analytes. Here, we coupled a downscaled CLLE apparatus with atmospheric pressure chemical ionization interface of triple quadrupole mass spectrometer. Real-time sampling was guided by an Arduino-based programmable logic controller. The recorded datasets were processed to compute the extraction rate constants for the target analytes. The extraction time in subsequent on-line experiments was set to 180 min as a compromise between the reduction of the analysis time and maximizing its yield. Interestingly, off-line analysis of the extract produced different results than on-line analysis pointing to the immanent degradation of the collected extract aliquots. Next, we implemented this hyphenated system in the analysis of red wine samples, which were stored during different periods of time after opening the bottle. The results reveal differences in the depletion of the volatile wine components during storage.

Fizzy Extraction of Volatile Organic Compounds Combined with Atmospheric Pressure Chemical Ionization Quadrupole Mass Spectrometry

Chemical analysis of volatile and semivolatile compounds dissolved in liquid samples can be challenging. The dissolved components need to be brought to the gas phase, and efficiently transferred to a detection system. Fizzy extraction takes advantage of the effervescence phenomenon. First, a carrier gas (here, carbon dioxide) is dissolved in the sample by applying overpressure and stirring the sample. Second, the sample chamber is decompressed abruptly. Decompression leads to the formation of numerous carrier gas bubbles in the sample liquid. These bubbles assist the release of the dissolved analyte species from the liquid to the gas phase. The released analytes are immediately transferred to the atmospheric pressure chemical ionization interface of a triple quadrupole mass spectrometer. The ionizable analyte species give rise to mass spectrometric signals in the time domain. Because the release of the analyte species occurs over short periods of time (a few seconds), the temporal signals have high amplitudes and high signal-to-noise ratios. The amplitudes and areas of the temporal peaks can then be correlated with concentrations of the analytes in the liquid samples subjected to fizzy extraction, which enables quantitative analysis. The advantages of fizzy extraction include: simplicity, speed, and limited use of chemicals (solvents).

Analysis of volatile compounds by open-air ionization mass spectrometry

This study demonstrates a simple method for rapid and in situ identification of volatile and endogenous compounds in culinary spice samples through mass spectrometry (MS). This method only requires a holder for solid spice sample (2-3 mm) that is placed close to a mass spectrometer inlet, which is applied with a high voltage. Volatile species responsible for the aroma of the spice samples can be readily detected by the mass spectrometer. Sample pretreatment is not required prior to MS analysis, and no solvent was used during MS analysis. The high voltage applied to the inlet of the mass spectrometer induces the ionization of volatile compounds released from the solid spice samples. Furthermore, moisture in the air also contributes to the ionization of volatile compounds. Dried spices including cinnamon and cloves are used as the model sample to demonstrate this straightforward MS analysis, which can be completed within few seconds. Furthermore, we also demonstrate the suitability of the current method for rapid screening of cinnamon quality through detection of the presence of a hepatotoxic agent, i.e. coumarin.