Determination of t,t-muconic acid in urine samples using a molecular imprinted polymer combined with simultaneous ethyl chloroformate derivatization and pre-concentration by dispersive liquid–liquid microextraction

Microextraction techniques for occupational biological monitoring: Basic principles, current applications and future perspectives

The application of green microextraction techniques (METs) is constantly being developed in different areas including pharmaceutical, forensic, food and environmental analysis. However, they are less used in biological monitoring of workers in occupational settings. Developing valid extraction methods and analytical techniques for the determination of occupational indicators plays a critical role in the management of workers' exposure to chemicals in workplaces. Microextraction techniques have become increasingly important because they are inexpensive, robust and environmentally friendly. This study aimed to provide a comprehensive review and interpret the applications of METs and novel sorbents and liquids in biological monitoring. Future perspectives and occupational indicators that METs have not yet been developed for are also discussed.

Recent molecularly imprinted polymers applications in bioanalysis

Molecular imprinted polymers (MIPs) as extraordinary compounds with unique features have presented a wide range of applications and benefits to researchers. In particular when used as a sorbent in sample preparation methods for the analysis of biological samples and complex matrices. Its application in the extraction of medicinal species has attracted much attention and a growing interest. This review focus on articles and research that deals with the application of MIPs in the analysis of components such as biomarkers, drugs, hormones, blockers and inhibitors, especially in biological matrices. The studies based on MIP applications in bioanalysis and the deployment of MIPs in high-throughput settings and optimization of extraction methods are presented. A review of more than 200 articles and research works clearly shows that the superiority of MIP techniques lies in high accuracy, reproducibility, sensitivity, speed and cost effectiveness which make them suitable for clinical usage. Furthermore, this review present MIP-based extraction techniques and MIP-biosensors which are categorized on their classes based on common properties of target components. Extraction methods, studied sample matrices, target analytes, analytical techniques and their results for each study are described. Investigations indicate satisfactory results using MIP-based bioanalysis. According to the increasing number of studies on method development over the last decade, the use of MIPs in bioanalysis is growing and will further expand the scope of MIP applications for less studied samples and analytes.

Solidified floating organic droplet microextraction coupled with HPLC for rapid determination of trans, trans muconic acid in benzene biomonitoring

Benzene is one of the carcinogenic compounds in the work environments. Exposure assessment of benzene through biological monitoring is an acceptable way to accurately measure the real exposure in order to conducting the health risk assessment, but it is always complicated, laborious, time consuming and costly process. A new sensitive, simple, fast and environmental friendly method was developed for the determination of urinary metabolite of benzene, trans trans muconic acid (t,t-MA) by dispersive liquid-liquid micro extraction based on solidification of floating organic droplet coupled with high-performance liquid chromatography with ultra violet detector. Central composite design methodology was utilized to evaluate the effective factors on the extraction output of the target metabolite. The calibration curve was plotted in the concentration ranges of 0.02-5 µg mL^-1. The precision and accuracy of the method were assayed via the relative standard deviation (RSD%) and relative recovery (RR%) using spiked samples with three replications. The RR% and RSD% of the optimized method were 86.9-91.3% and 4.3-6.3% respectively. The limit of detection (LOD) of the method was 0.006 µg mL^-1. The level of t,t-MA in real samples was ranged from 0.54 to 1.64 mg/g creatinine. We demonstrated that t,t-MA can be extracted and determined by an inexpensive, simple and fast method.

A new approach for microextraction of trace albendazole sulfoxide drug from the samples of human plasma and urine, and water by the molecularly imprinted polymer nanoparticles combined with HPLC

In this research study, a method of dispersive-micro-solid phase extraction (D-µ-SPE) combined with molecularly imprinted polymer nanoparticles (MIP-NPs) with HPLC-UV was developed for the fast and selective detection of the trace amount of albendazole sulfoxide (ABZSO) in the biological samples. To investigate the effective factors on ABZSO microextraction by the method, central composite design (CCD) was utilized, and the optimum conditions for ABZSO microextraction were sample pH of 8.0, MIP-mass of 15 mg, sonication time of 12 min, and eluent (methanol) volume of 0.25 mL. Under the obtained optimal extraction conditions, the value for the limit of detection (LOD) and limit of quantification (LOQ) was respectively showed to be 0.074 and 0.246 ng mL^-1. In addition, the calculated peak areas exhibited a linear relationship with the ABZSO concentration ranging from 0.4 to 4200 ng mL^-1. The analyses of the samples including human plasma and urine, and water were successfully performed by the usage of the D-µ-SPE method, which was a simple and sensitive technique and a suitable alternative for the analysis of ABZSO. In the analysis of ABZSO in various samples, the recoveries at various levels of ABZSO concentrations (50, 300, and 500 ng mL^-1) were in the range of 95.7-103.0 %, and the relative standard deviations (RSDs; n = 3) varied from 2.2 to 4.4%.

Ion-imprinted electrospun nanofibers of chitosan/1-butyl-3-methylimidazolium tetrafluoroborate for the dynamic expulsion of thorium (IV) ions from mimicked effluents

The present study explores the innocuous, biocompatible, and extremely competent molecularly imprinted chitosan/RTIL electrospun nanofibers having average diameter of 30 nm for the expulsion of thorium (IV) ions from the mimicked effluent waste. The extended Flory-Huggins theory and three-dimensional molecular modeling have been effectively premeditated via Materials Studio software for enumerating the inter-miscibility and compatibility (Chi parameter (χ) = 1.019, mixing energy (E_mix) = 0.603 kcal/mol) of the chitosan/RTIL (1-butyl-3-methylimidazolium tetrafluoroborate). The maximum adsorption efficiency is found to be 90% at a neutral pH of 7, and a temperature of 298 K within 120 min. The adsorption process was extensively studied by two-parameter adsorption isotherms like Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D-R) and three-parameter models like Redlich-Paterson and Sips isotherm. Pseudo-second-order kinetics model (R² = 0.982) and Langmuir isotherm (R² = 0.994) bestowed the best fitting on chitosan/RTIL nanofibers for the adsorption of Th (IV) ions. The thermodynamic study reveals the spontaneity and exothermic nature of the reaction. The experimental analysis conjoint with isotherm and kinetic models, and simulation study establish the applicability of chitosan/RTIL nanofibers for the expulsion of Th (IV) and other toxic metal ions from the effluents. Graphical abstract Ion-imprinted electrospun nanofiber for expulsion of thorium (IV) ion.

Molecular imprinting: perspectives and applications

This critical review presents a survey of recent developments in technologies and strategies for the preparation of MIPs, followed by the application of MIPs in sample pretreatment, chromatographic separation and chemical sensing.

Microextraction in urine samples for gas chromatography: a review

Since the complexity origin of biological samples, the research trends have been directed to the development of new miniaturized sample preparation techniques. This review provides a comprehensive survey of past and present microextraction methods followed by GC analysis for preconcentration and determination of various analytes in urine samples. These techniques have been classified in three general groups, including liquid-, solid- and membrane-based techniques. The principal of different microextraction methods that are located in each general group as well as their various extraction modes and the recent developments introduced for them has been presented. Subsequently, a comparison survey has been carried out among different microextraction techniques and finally a future perspective has been predicted based on the existing literature.

Ultra sound assisted one step rapid derivatization and dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometric determination of amino acids in complex matrices

A rapid and economical method for the simultaneous determination of 20 amino acids in complex biological and food matrices (hair, urine and soybean seed samples) has been developed using ultrasound assisted dispersive liquid-liquid micro extraction (UA-DLLME). The method involves simultaneous derivatization and extraction followed by gas chromatography-mass spectrometric (GC-MS) analysis of amino acids. The parameters of UA-DLLME were optimized with the aid of design of experiments approach. The procedure involves the rapid injection of mixture of acetonitrile (disperser solvent), trichloroethylene (TCE) (extraction solvent) and ethylchloroformate (derivatization reagent) into the aqueous phase of sample extract containing pyridine. The Plackett-Burman design has indicated that, the factors such as volume of disperser and extraction solvents and pH were found to be significantly affects the extraction efficiency of the method. The optimum conditions of these factors based on central composite design were found to be 250μL of acetonitrile, 80μL of TCE and pH of 10. The limit of detection and limit of quantification were found to be in the range of 0.36-3.68μgL(-1) and 1.26-12.01μgL(-1) respectively. This is the first application of DLLME for the analysis of amino acids in any matrices. The advantages like (i) in situ derivatization and extraction of amino acids without any prior lyophilization and cleanup of sample, (ii) low consumption of extraction solvent, (iii) fast and simple, (iv) cost-effective and (iv) good repeatability make the method amenable for the routine analysis of amino acids in clinical, toxicological, nutritional and quality control laboratories.

Molecularly imprinted SPE combined with dispersive liquid–liquid microextraction for selective analysis of telmisartan in biological and formulation samples

Background: The present communication describes the combination of molecularly imprinted SPE and dispersive liquid–liquid microextraction for the selective preconcentration and determination of telmisartan (TEL) in rat urine, plasma and pharmaceutical formulation by HPLC. Results: Various factors that can affect the extraction efficiency of molecularly imprinted SPE and dispersive liquid–liquid microextraction were optimized. The LOD and LOQ were found to be 0.19 and 0.63 µg ml-1 in urine, while in plasma it was found to be 0.28 and 0.87 µg ml-1, respectively. The percentage recovery of TEL in different matrices was found to be in the range of 81–97%. Conclusion: The proposed method may find wide applications in clinical, toxicological and QC laboratories for the routine analysis of TEL.