“Green” nature of the process of derivatization in analytical sample preparation

Derivatization of carboxylic groups prior to their LC analysis - A review

Carboxylic acids (CAs) represent a large group of important molecules participating in various biologically significant processes. Analytical study of these compounds is typically performed by liquid chromatography (LC) combined with various types of detection. However, their analysis is often accompanied by a wide variety of problems depending on used separation system or detection method. The dominant ones are: i) poor chromatographic behavior of the CAs in reversed-phase LC; ii) absence of a chromophore (or fluorophore); iii) weak ionization in mass spectrometry (MS). To overcome these problems, targeted chemical modification, and derivatization, come into play. Therefore, derivatization still plays an important and, in many cases, irreplaceable role in sample preparation, and new derivatization methods of CAs are constantly being developed. The most commonly used type of reaction for CAs derivatization is amidation. In recent years, an increased interest in the isotopic labeling derivatization method has been observed. In this review, we comprehensively summarize the possibilities and actual trends in the derivatization of CAs that have been published over the past decade.

Molecularly imprinted dispersive micro solid-phase extraction and tandem derivatization for the determination of histamine in fermented wines

Histamine causes allergic reactions and can serve as an indicator for assessing food quality. This study designed and developed a dispersive micro solid-phase extraction (D-μSPE) method that combined the advantages of dispersive liquid-liquid extraction and solid-phase extraction (SPE). Molecularly imprinted polymers (MIPs) were employed as the solid phase in the D-μSPE method to extract histamine in wine samples. We used microwave energy to significantly reduce the synthesis time, achieving an 11.1-fold shorter synthesis time compared to the conventional MIP synthetic method. Under optimized D-μSPE conditions, our results showed that the dispersive solvent could effectively increase the adsorption performance of MIPs in wine samples by 97.7%. To improve the sensitivity of histamine detection in gas chromatography-mass spectrometry, we employed the microwave-assisted tandem derivatization method to reuse excess derivatization reagents and reduce energy consumption and reaction time. Calibration curves were constructed for wine samples spiked with 0-400 nmol histamine using the standard addition method, resulting in good linearity with a coefficient of determination of 0.999. The intra- and inter-batch relative standard deviations of the slope and intercept were < 0.7% and < 5.3%, respectively. The limits of quantitation and detection were 0.4 nmol and 0.1 nmol, respectively. The developed method was successfully applied to analyze the histamine concentration in 10 commercial wine samples. In addition, the AGREEprep tool was used to evaluate the greenness performance of the developed method, which obtained a higher score than the other reported methods.

Inline phase transition trapping-selective supercritical fluid extraction-supercritical fluid chromatography: A green and efficient integrated method for determining prohibited substances in cosmetics

BACKGROUND

Developing an environmentally friendly and efficient integrated analytical approach is a cutting-edge topic in current analytical science. Due to the unique properties of supercritical carbon dioxide (sc-CO2), online supercritical fluid extraction-supercritical fluid chromatography (SFE-SFC) is developing rapidly and has been widely applied in many fields. However, it still faces several challenges such as peak broadening and matrix interference. In order to solve the problems, we developed an inline phase transition trapping-selective supercritical fluid extraction-supercritical fluid chromatography (PTT-SSFE-SFC)-tandem mass spectrometry (MS/MS) method in this study.

RESULTS

This method integrated extraction, purification, separation, and detection, which was applied to determine 114 prohibited substances in cosmetics within 33 min, covering ten categories. The PTT strategy trapped the extracts on the head of the column by transforming CO2 from a supercritical state to a gaseous state, preventing peak spreading and improving sensitivity. Several adsorbents were tested when analyzing aqueous samples to reduce matrix interference and absorb water. Compared with conventional online SFE-SFC, this method improved the matrix effects of 93 and 87 target substances in the toner and mask matrix, respectively. Because the integrated method reduced sample loss, it achieved high sensitivity with LODs ranging from 0.00104 μg L-1 to 3.09 μg L-1. Furthermore, compared with other reported green methods, the inline method showed advantages in automation, efficiency, sample amount, and waste volume.

SIGNIFICANCE AND NOVELTY

With the introduction of the PTT strategy and the adsorbent, the system obtained good peak shapes, high sensitivity, low matrix effect, and good recovery. Based on the results, inline PTT-SSFE-SFC-MS/MS as a green and efficient integrated method has great potential for analyzing low abundance and multiple categories of targets in complex samples.

A review of bioanalytical applications of microextraction techniques combined with derivatization

Microextraction techniques have attracted the attention of many researchers working in the field of bioanalysis due to their unique advantages, mainly in downsizing the scale of sample preparation steps. In parallel, analytical derivatization offers a powerful combination in terms of additional sensitivity, selectivity and compatibility with modern separation techniques. The aim of this review is to discuss the most recent advances in bioanalytical sample preparation based on the combination of microextraction and analytical derivatization. Both innovative fundamental reports and analyte-targeted applications are included and discussed. Dispersive liquid-liquid extraction and solid-phase microextraction are the most common techniques that typically combined with derivatization, while the development of novel and greener protocols is receiving substantial consideration in the field of analytical chemistry.

Simple and Effective Derivatization of Amino Acids with 1-Fluoro-2-nitro-4-(trifluoromethyl)benzene in a Microwave Reactor for Determination of Free Amino Acids in Kombucha Beverages

Kombucha is a fermentation product of sweetened tea with a symbiotic culture of acetic acid and yeast bacteria, consumed worldwide for its health-promoting properties. Few reports can be found about free amino acids among the health-promoting compounds found and determined in kombucha. These compounds influence the sensory properties of kombucha, and they are precursors of bioactive compounds, which have a significant role as neurotransmitters and are involved in biological functions. The presented studies proposed a convenient, simple, and "more green" procedure of the synthesis of amino acid derivatives, assisted by microwave energy, followed by chromatographic determination. The structure of 1-Fluoro-2-nitro-4-(trifluoromethyl)benzene was used as a suitable reagent for the derivatization of free amino acids in fermented kombucha beverages prepared from selected dry fruit such as Crataegus L., Morus alba L., Sorbus aucuparia L., Berberis vulgaris L., Rosa canina L., and black tea. The obtained results were discussed regarding the tested beverages' application as a source of amino acids in one's daily diet. The obtained results point out that the proposed microwave-assisted derivatization procedure prior to HPLC analyses allows for a significant time reduction and the limitation of using organic reagents.

Derivatization, an Applicable Asset for Conventional HPLC Systems without MS Detection in Food and Miscellaneous Analysis

One of the most valuable practices for analyzing not-so-analytical-friendly analytes in complex, heterogenous matrices is derivatization. Availability of numerous derivatizing reagents (DRs) makes the modification of analyte more exploitable in terms of an analytical perspective. A wide array of derivatization techniques like pre or post-column, in-situ, enzymatic, ultrasound-assisted, microwave-assisted, photochemical derivatization has added much-needed methodological strength in analyzing intricate analytical matrices (food, water, and soil). In recent years, analytical chemistry has achieved greater heights through the development of new sensitive methods with simple conventional instruments like High-Performance Liquid Chromatography (HPLC) devoid of Mass detectors. The prompt availability of these straightforward instruments also makes it a favorable option for routine analysis in food, environmental, bioanalytical chemistry. Analyzing food, environmental or bioanalytical specimen has some of the most problematic aspects, like the low concentration of the analytes accompanied by not too suitable analytical properties. Even though conventional HPLC lacks the required sensitivity but merger with derivatization can lead to a remarkable increase in sensitivity. In recent years there has been a lot of application of diverse derivatizations to increase the sensitivity and selectivity of the analyte for available instruments, resulting in notable findings. Therefore, this review describes the application of derivatization principles in the analysis of analytes in food and additional matrices using conventional HPLC instruments such as HPLC-UV, HPLC-DAD, and HPLC-FD. In this article, we will briefly review the different modes and multiple types of derivatizing reagents with their mechanisms and importance for encouraging the use of established HPLC instruments.

Recent Applications of Derivatization Techniques for Pharmaceutical and Bioanalytical Analysis through High-performance Liquid Chromatography

Background:

Derivatization of analytes is a quite convenient practice from an analytical perspective. Its vast prevalence is accounted by the availability of distinct reagents, primarily pragmatic for obtaining desired modifications in an analyte structure. Another reason for its handiness is typically to overcome limitations such as lack of sensitive methodology or instrumentation.The past decades have witnessed various new derivatization techniques including in-situ, enzymatic, ultrasound-assisted, microwave-assisted, and photochemical derivatization which have gain popularity recently.

Methods:

The online literature available on the utilization of derivatization as prominent analytical tools in recent years with typical advancements is reviewed. The illustrations of the analytical condition together with the structures of different derivatizing reagents (DRs) are provided to acknowledge the vast capability of derivatization to resolve analytical problems.

Results:

The derivatization techniques have enabled analytical chemists throughout the globe to develop an enhanced sensitivity method with the simplest of the instrument like High-Performance Liquid Chromatography (HPLC). The HPLC, compared to more sensitive Liquid chromatography coupled to tandem mass spectrometer, is readily available and can be readily utilized for routine analysis in fields of pharmaceuticals, bioanalysis, food safety, and environmental contamination. A troublesome aspect of these fields is the presence of a complex matrix with trace concentrations for analyses. Liquid chromatographic methods devoid of MS detectors do not have the desired sensitivity for this. A possible solution for overcoming this is to couple HPLC with derivatization to enable the possibility of detecting trace analytes with a less expensive instrument. Running cost, enhanced sensitivity, low time consumption, and overcoming the inherent problems of analyte are critical parameters for which HPLC is quite useful in high throughput analysis.

Conclusion:

The review critically highlights various kinds of derivatization applications in different fields of analytical chemistry. The information primarily focuses on pharmaceutical and bioanalytical applications in recent years. The various modes, types, and derivatizing reagents with brief mechanisms have been ascribed briefly Additionally, the importance of HPLC coupled to fluorescence and UV detection is presented as an overview through examples accompanied by their analytical conditions.

One step derivatization and dispersive liquid-liquid microextraction of hydroxychloroquine sulfate for its sensitive and accurate determination using GC-MS

In the present study, a novel analytical method for the determination of hydroxychloroquine sulfate in human serum and urine samples was established. One step derivatization and dispersive liquid-liquid microextraction (DLLME) was developed for quantitative determination of hydroxychloroquine sulfate in aqueous samples. Hydroxychloroquine sulfate was first hydrolyzed and converted to its benzoate derivative by adding benzoyl chloride in chloroform which also served as extraction solvent. Significant parameters such as type/volume of extraction and dispersive solvents, concentration/volume of sodium hydroxide, type/period of mixing and concentration of derivatizing agent were carefully optimized by one variable at a time approach. Under the optimum DLLME conditions, limit of detection (LOD), quantitation (LOQ) and dynamic range were calculated as 35.2, 117.2 and 96-1980 μg/kg (ppb), respectively. Recovery studies were conducted by spiked human serum and urine samples and the results were ranged between 93 and 107% with low standard deviations. Developed method can be easily used in hydroxychloroquine sulfate based SARS-CoV-2 and malaria treatment studies.

Analytical Methods for Determination of Non-Nutritive Sweeteners in Foodstuffs

Sweeteners have been used in food for centuries to increase both taste and appearance. However, the consumption of sweeteners, mainly sugars, has an adverse effect on human health when consumed in excessive doses for a certain period, including alteration in gut microbiota, obesity, and diabetes. Therefore, the application of non-nutritive sweeteners in foodstuffs has risen dramatically in the last decade to substitute sugars. These sweeteners are commonly recognized as high-intensity sweeteners because, in a lower amount, they could achieve the same sweetness of sugar. Regulatory authorities and supervisory agencies around the globe have established the maximum amount of these high-intensity sweeteners used in food products. While the regulation is getting tighter on the market to ensure food safety, reliable analytical methods are required to assist the surveillance in monitoring the use of high-intensity sweeteners. Hence, it is also necessary to comprehend the most appropriate method for rapid and effective analyses applied for quality control in food industries, surveillance and monitoring on the market, etc. Apart from various analytical methods discussed here, extraction techniques, as an essential step of sample preparation, are also highlighted. The proper procedure, efficiency, and the use of solvents are discussed in this review to assist in selecting a suitable extraction method for a food matrix. Single- and multianalyte analyses of sweeteners are also described, employing various regular techniques, such as HPLC, and advanced techniques. Furthermore, to support on-site surveillance of sweeteners’ usage in food products on the market, non-destructive analytical methods that provide practical, fast, and relatively low-cost analysis are widely implemented.

Hydrophilic carboxyl supported immobilization of UiO-66 for novel bar sorptive extraction of non-steroidal anti-inflammatory drugs in food samples

Herein, the preparation of UiO-66 on frosted glass rod (FGR) was proposed through the coordination interaction of Zr-OH groups and carboxyl sites on FGR. The relative standard deviations (RSDs) of intra-batch and inter-batch were below 8.0% (n = 7). UiO-66-modified FGR (UiO-66@FGR) was applied to the extraction and monitoring of five non-steroidal anti-inflammatory drugs (NSAIDs) by coupling to novel bar sorptive extraction (BSE) with ultra-high performance liquid chromatography (UPLC). Sample volume, stirring rate, extraction time, sample pH value, desorption solvent, and desorption time were investigated. NSAIDs (ketoprofen, flurbiprofen, ibuprofen, naproxen, and diclofenac sodium) were determined at a low limit of detection (0.92 ng/mL) over a wide linear range (10-1500 ng/mL). The developed method was used to analyze NSAIDs in sheep muscle, chicken wing, and milk with recoveries of 80.8%-117.2%, RSDs < 6.5%. Fabricated UiO-66@FGR exhibited excellent reproducibility, stability, and good adsorption property towards NSAIDs in food samples.

Greenness of magnetic nanomaterials in miniaturized extraction techniques: A review

Green analytical chemistry principles should be followed, as much as possible, and particularly during the development of analytical sample preparation methods. In the past few years, outstanding materials such as ionic liquids, metal-organic frameworks, carbonaceous materials, molecularly imprinted materials, and many others, have been introduced in a wide variety of miniaturized techniques in order to reduce the amount of solvents and sorbents required during the analytical sample preparation step while pursuing more efficient extraction methods. Among them, magnetic nanomaterials (MNMs) have gained special attention due to their versatile properties. Mainly, their ability to be separated from the sample matrix using an external magnetic field (thus enormously simplifying the entire process) and their easy combination with other materials, which implies the inclusion of a countless number of different functionalities, highly specific in some cases. Therefore, MNMs can be used as sorbents or as magnetic support for other materials which do not have magnetic properties, the latter permiting their combination with novel materials. The greenness of these magnetic sorbents in miniaturized extractions techniques is generally demonstrated in terms of their ease of separation and amount of sorbent required, while the nature of the material itself is left unnoticed. However, the synthesis of MNMs is not always as green as their applications, and the resulting MNMs are not always as safe as desired. Is the analytical sample preparation field ready for using green magnetic nanomaterials? This review offers an overview, from a green analytical chemistry perspective, of the current state of the use of MNMs as sorbents in microextraction strategies, their preparation, and the analytical performance offered, together with a critical discussion on where efforts should go.

Direct immersion single-drop microextraction of semi-volatile organic compounds in environmental samples: A review

Single-drop microextraction (SDME) techniques are efficient approaches to pretreatment of aqueous samples. The main advantage of SDME lies in the miniaturization of the solvent extraction process, minimizing the hazards associated with the use of toxic organic solvents. Thus, SDME techniques are cost-effective, and represent less harm to the environment, subscribing to green analytical chemistry principles. In practice, two main approaches can be used to perform SDME - direct immersion (DI)-SDME and headspace (HS)-SDME. Even though the DI-SDME has been shown to be quite effective for extraction and enrichment of various organic compounds, applications of DI-SDME are normally more suitable for moderately polar and non-polar semi-volatile organic compounds (SVOCs) using organic solvents which are immiscible with water. In this review, we present a historical overview and current advances in DI-SDME, including the common analytical tools which are usually coupled with DI-SDME. The review also focuses on applications concerning SVOCs in environmental samples. Currents trends in DI-SDME and possible future direction of the procedure are discussed.

A sieve-conducted two-syringe-based pressurized liquid-phase microextraction for the determination of indium by slotted quartz tube-flame atomic absorption spectrometry

In this study, a new liquid-phase microextraction method termed sieve-conducted two-syringe-based pressurized liquid-phase microextraction (SCTS-PLPME) was developed as a preconcentration tool for indium. Here, two syringes were connected to each other by an apparatus to produce an environment subject to pressure. The pressure created between the two syringes by simultaneous movements of the syringe plungers (to and fro) generated an efficient dispersion and this eliminated the need for dispersive solvents. Determination of indium after preconcentration was carried out with a slotted quartz tube attached flame atomic absorption spectrometer (SQT-FAAS). The detection limit (LOD) and quantification limit (LOQ) of the developed method were calculated as 19.2 and 72.2 μg L^-1, respectively. The reliability and accuracy of the developed method was tested by performing recovery studies on lake water spiked at different concentrations and the obtained percent recoveries were between 101.2 and 106.9%.

3D cryogel composites as adsorbent for isolation of protein and small molecules

A green and promising sample pretreatment method was successfully established, which efficiently isolated proteins and small molecules in human serum. This method was achieved based on the multifunctional polymer, cryogel, as a solid phase extraction (SPE) monolith easily equipped in a syringe. The cryogel (pDC/GO-DE) was composed of diallyldimethyl ammonium chloride (DC) and 2-hydroxyethyl methacrylate (HE), which was further modified with graphene oxide (GO) and N-diethylethanamine hydrobromide (DE). Various proteins, including bovine serum albumin (BSA), lysozyme (Lys), γ-globulins, immunoglobulin G (IgG), transferrin, small molecules (ribavirin, adenosine, ofloxacin, estriol, rutin, amoxicillin, ibuprofen, 1-methyl-3-phenyl-propylamine, and benzylamine) and their mixtures were successively studied as model analytes to evaluate the new material and demonstrate the isolation mechanism, which was mainly dependent on mixed-mode ion-exchange and the hybrid hydrophobicity-hydrophilicity property of pDC/GO-DE cryogel. Moreover, the three-dimensional macroporous structure contributed to the underlying size-selective isolation. When 10 times diluted human serum was used as the sample, more than 95% of proteins were adsorbed within 10 min under physiological conditions, and the interference matrix in serum was also efficiently reduced. After recycling three times, the extraction ratio of proteins in human serum was still higher than 90%. When four small molecules (camptothecin, ribavirin, 1-methyl-3-phenylpropylamine and ofloxacin) were added to blank human serum, their recoveries were within 65.6-81.8%, and were comparable to those obtained by protein precipitation method (63.7-83.2%).