Applications of dispersive liquid–liquid micro-extraction in forensic toxicology

Innovative disposable in-tip cellulose paper (DICP) device for facile determination of pesticides in postmortem blood samples: A proof-of-concept study

Accurately identifying and quantifying toxicants is crucial for medico-legal investigations in forensic toxicology; however, low analyte concentrations and the complex samples matrix make this work difficult. Therefore, a simplified sample preparation procedure is crucial to streamline the analysis to minimize sample handling errors, reduce cost and improve the overall efficiency of analysis of toxicants. To address these challenges, an innovative disposable in-tip cellulose paper (DICP) device has been developed for the extraction of three pesticides viz. Chlorpyrifos, Quinalphos and Carbofuran from postmortem blood samples. The DICP device leverages cellulose paper strips housed within a pipette tip to streamline the extraction process, significantly reducing solvent usage, time, and labor while maintaining high analytical accuracy. The extraction of pesticides from postmortem blood using the DICP device involves a streamlined process characterized by adsorption and desorption. The diluted blood samples were processed through the DICP device via repeated aspirating and dispensing calyces to adsorb the pesticides onto the cellulose paper. The adsorbed pesticides are then eluted using acetone, which is collected for GC-MS analysis. The method was meticulously optimized, achieving a limit of quantification in the range of 0.009-0.01 µg mL-1. The intra-day and inter-day precisions were consistently less than 5 % and 10 %, respectively, with accuracy ranging from 94-106 %. Relative recoveries for the analytes were observed to be between 60 % and 93.3 %, and matrix effects were determined to be less than 10 %. The method's sustainability was validated with a whiteness score of 98.8, an AGREE score of 0.64, a BAGI score of 70 and ComplexMoGAPI score of 77. Applicability was demonstrated through successful analysis of real postmortem blood samples and proficiency testing samples, highlighting its potential utility in forensic toxicology.

Solvent-Focused Gas Chromatographic Determination of Thymol and Carvacrol Using Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction through Solidifying Floating Organic Droplets (USA-DLLME-SFO)

An ultrasound-assisted dispersive liquid-liquid microextraction by solidifying floating organic droplets, coupled to a form of temperature-programmed gas chromatography flame ionization detection, has been developed for the extraction and determination of thymol and carvacrol. This method utilizes undecanol as the extraction solvent, offering advantages such as facilitating phase transfer through solidification and enhancing solvent-focusing efficiency. The optimal gas chromatography conditions include a sample injection volume of 0.2 µL, a split ratio of 1:10, and a flow rate of 0.7 mL min-1. The extraction conditions entail an extraction solvent volume of 20 µL, a disperser solvent (acetone) volume of 500 µL, pH 7.0, 7.0% NaCl (3.5 M), a sample volume of 5.0 mL, an ultrasound duration of 10 min, and a centrifuge time of 7.5 min (800 rpm). These conditions enable the achievement of a high and reasonable linear range of 3.5 to 70. 0 μg mL-1 for both thymol and carvacrol. The detection limits are found to be 0.95 and 0.89 μg mL-1, respectively, for thymol and carvacrol. The obtained relative standard deviations, 2.7% for thymol and 2.6% for carvacrol, demonstrate acceptable precision for the purpose of quantitative analysis.

Determination of pesticide residues in urine by chromatography-mass spectrometry: methods and applications

Introduction

Pollution has emerged as a significant threat to humanity, necessitating a thorough evaluation of its impacts. As a result, various methods for human biomonitoring have been proposed as vital tools for assessing, managing, and mitigating exposure risks. Among these methods, urine stands out as the most commonly analyzed biological sample and the primary matrix for biomonitoring studies.

Objectives

This review concentrates on exploring the literature concerning residual pesticide determination in urine, utilizing liquid and gas chromatography coupled with mass spectrometry, and its practical applications.

Method

The examination focused on methods developed since 2010. Additionally, applications reported between 2015 and 2022 were thoroughly reviewed, utilizing Web of Science as a primary resource.

Synthesis

Recent advancements in chromatography-mass spectrometry technology have significantly enhanced the development of multi-residue methods. These determinations are now capable of simultaneously detecting numerous pesticide residues from various chemical and use classes. Furthermore, these methods encompass analytes from a variety of environmental contaminants, offering a comprehensive approach to biomonitoring. These methodologies have been employed across diverse perspectives, including toxicological studies, assessing pesticide exposure in the general population, occupational exposure among farmers, pest control workers, horticulturists, and florists, as well as investigating consequences during pregnancy and childhood, neurodevelopmental impacts, and reproductive disorders.

Future directions

Such strategies were essential in examining the health risks associated with exposure to complex mixtures, including pesticides and other relevant compounds, thereby painting a broader and more accurate picture of human exposure. Moreover, the implementation of integrated strategies, involving international research initiatives and biomonitoring programs, is crucial to optimize resource utilization, enhancing efficiency in health risk assessment.

A validated dilute-and-shoot LC-MS-MS urine screening for the analysis of 95 illicit drugs and medicines: Insights from clinical and forensic Brazilian cases

Urine toxicological analysis is a relevant tool in both clinical and forensic scenarios, enabling the diagnosis of acute poisonings, elucidation of deaths, verification of substance use in the workplace and identification of drug-facilitated crimes. For these analyses, the dilute-and-shoot technique associated with liquid chromatography coupled with tandem mass spectrometry (LC-MS-MS) is a promising alternative since it has demonstrated satisfactory results and broad applicability. This study developed and validated a comprehensive LC-MS-MS screening method to analyze 95 illicit drugs and medicines in urine samples and application to clinical and forensic Brazilian cases. The dilute-and-shoot protocol was defined through multivariate optimization studies and was set using 100 µL of sample and 300 µL of solvent. The total chromatographic run time was 7.5 min. The method was validated following the recommendations of the ANSI/ASB Standard 036 Guideline. The lower limits of quantification varied from 20 to 100 ng/mL. Within-run and between-run precision coefficient of variations% were <20%, and bias was within ± 20%. Only 4 of the 95 analytes presented significant ionization suppression or enhancement (>25%). As proof of applicability, 839 urine samples from in vivo and postmortem cases were analyzed. In total, 90.9% of the analyzed samples were positive for at least one substance, and 78 of the 95 analytes were detected. The most prevalent substances were lidocaine (40.2%), acetaminophen (38.0%) and benzoylecgonine (31.5%). The developed method proved to be an efficient and simplified alternative for analyzing 95 therapeutic and illicit drugs in urine samples. Additionally, the results obtained from sample analysis are essential for understanding the profile of Brazilian substance use, serving as a valuable database for the promotion of health and safety public policies.

Utilization of a pH-switchable hydrophilicity solvent for the microextraction of clomipramine from human urine samples

Clomipramine (CLP) is a tricyclic antidepressant drug, and its determination in biological samples is of high importance in clinical and forensic evaluations to assure appropriate drug concentrations. In the present study, benzoic acid was employed as a pH-switchable hydrophilicity solvent (SHS) for the microextraction of CLP from authentic human urine samples prior to its determination by high performance liquid chromatography-ultraviolet detection (HPLC-UV). The microextraction protocol was based on the phase transition of the SHS through pH alteration that resulted in its rapid dispersion and simultaneous phase separation. The obtained solid was collected in a syringe filter, dissolved in methanol, and analyzed. The main parameters that affected the efficiency of the microextraction procedure were studied and optimized to ensure high extraction efficiency for CLP and the analytical method was validated. Under optimum conditions, good linearity was observed between 0.05 and 5.0 μg mL-1. The limit of detection and limit of quantification were found to be 0.015 and 0.05 μg mL-1, respectively. The RSD values for intra-day repeatability and inter-day precision were 2.4-8.9 % and 1.7-9.1 %, respectively. The relative recovery values were within 90.0 and 110.0 % in all cases, demonstrating good method accuracy. The proposed SHS microextraction showed cost-efficiency, handling simplicity, and rapidity resulting in enhanced sample throughput. Moreover, the proposed method exhibited a green character and good applicability based on its evaluation by Green Analytical Procedure Index and Blue Applicability Grade Index.

Standardization of the analytical procedure based on deep eutectic solvent for the extraction and measurement of tricyclic antidepressants drugs in post-mortem blood samples

Measuring drugs in post-mortem blood samples is one of the most important challenges in forensic medicine. The development of sensitive analytical techniques for the measurement of drugs in biological samples is of great use in forensic medicine. In this research an easy, safe and environmental friendly vortex-assisted liquid phase microextraction (VA-LPME) based on deep eutectic solvent (DES) followed by high performance liquid chromatography-ultraviolet detector (HPLC-UV) was developed for the extraction, preconcentration and analysis of tricyclic antidepressants drugs (TCAs) in post-mortem blood samples. DES synthesized from thymol as hydrogen bond acceptor (HBA) and ethylene glycol (EG) as hydrogen bond donor (HBD) with a molar ratio of 2:1 was used as an extractant. After adding DES to the sample solution, the resulting mixture was vortexed in order to increase the contact surface and increase the extraction efficiency. Next, phase separation was done using centrifugation. Some effective parameters on the extraction were studied and optimized. Under the optimum conditions, intra- and inter-day %RSDs of the method based on 7 replicate measurements of 100 μg L-1 of TCAs in blood samples were in the range of 2.4-5.1 and 3.7-6.8 %, respectively. The analytical performance of the method showed linearity over the concentration of 3-500 μg L-1 with the detection limits ranging from 1.0-2.0 μg L-1. The trueness of the method was confirmed by spiking different concentrations of TCAs in real blood samples and obtaining relative recoveries in the range of 91.2-108 %.

Magnetic ionic liquid-based liquid-liquid microextraction followed by ultra-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry for simultaneous determination of neurotransmitters in human cerebrospinal fluid and plasma

A green, efficient and easy sample pretreatment method of magnetic ionic liquid-based liquid-liquid microextraction (MIL-based LLME) combined with a sensitive, rapid and precise analytical method of ultra-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UPLC-QqQ/MS²) was developed to simultaneously - determining of neurotransmitters (NTs) in biosamples. Two magnetic ionic liquids (MILs), [P_6,6,6,14]₃[GdCl₆] and [P_6,6,6,14]₂[CoCl₄] tested, and the latter was selected as the extraction solvent due to its advantages of visual recognition, paramagnetic behavior and higher extraction efficiency. Facile magnetic separation of MIL containing analytes from matrix was realized by applying external magnetic field without rather than centrifugation. Experimental parameters that would influence the extraction efficiency, including type and amount of MIL, extraction time, speed of the vortex process, salt concentration, and environmental pH, were optimized obtained. The proposed method was successfully applied to the simultaneous extraction and determination of 20 NTs in human cerebrospinal fluid and plasma samples. Excellent analytical performance indicates the broad potential of this method for clinical diagnosis and therapy of neurological diseases.

Fabric phase sorptive extraction-gas chromatography-mass spectrometry for the determination of favipiravir in biological and forensic samples

Favipiravir, a pyrazine analog, is proposed as providential antiviral agent against the COVID-19 infection during 2020 pandemic emergency. For the first time, a fabric phase sorptive extraction (FPSE) combined with gas chromatography-mass spectrometry (GC-MS) has been developed and applied for the determination of favipiravir (FAV) in biological samples (human plasma, blood and urine), pharmaceutical and forensic samples. The method comprises of extraction of FAV by FPSE followed by its derivatization with N, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA) and GC-MS analysis. Design of experiment-based optimization was performed using Placket-Burman Design (PBD) and Central Composite Design (CCD) for the screening of significant factors of FPSE and their optimization, respectively. Among all tested membranes, sol-gel polyethylene glycol (PEG) has offered the best extraction efficiency for FAV. Under optimum conditions, the proposed method was found to be linear in the range of 0.01–10 µg mL⁻¹ by GC-MS. The LODs and LOQs were as low as 0.001-0.0026 μg mL⁻¹ and 0.003-0.0086 μg mL⁻¹, respectively by GC-MS. Intra-day and inter-day precisions were less than 5 and 10 %, respectively, showing good method precision. The proposed method has been successfully applied to detect and quantify FAV in human urine, whole blood and plasma samples along with seized forensic samples. In addition, the proposed method has been evaluated for its green character by ComplexGAPI index.

Simple determination of dichlorvos in cases of fatal intoxication by gas Chromatography-Mass spectrometry

Dichlorvos (DDVP) is an organophosphorous insecticide which is classified as "highly hazardous" Class 1B chemical by World Health Organization (WHO) and largely misused for the purpose of self-poisoning in developing countries. Forensic toxicology laboratories are routinely encountering cases of pesticide poisoning due to their fatal intoxication. Herein; a method is described based on vortex-assisted dispersive liquid-liquid microextraction (VA-DLLME) coupled with Gas Chromatography-Mass Spectrometry (GC-MS) for the determination of an organophosphorous insecticide; dichlorvos (DDVP) in human autopsy samples (blood, stomach content and liver). Under the optimum conditions, the method was found to be linear in the range of 0.5-10 µg mL^-1 and 1.5-10 µg g^-1 for blood and tissue samples, respectively. Limit of quantification was set at 0.55 µg mL^-1 and 1.1 µg g^-1 for blood and tissue samples, respectively. Intraday and inter-day precisions were less than 8 and 12 %, respectively. Good recoveries in the range of 86-95 % were obtained for the proposed procedure. The method has been satisfactorily applied for the determination of DDVP in autopsy samples from two different cases received in our laboratory. In comparison to previous methods; the proposed method is relatively short, high sample throughput, inexpensive and adheres to the principles of green analytical chemistry (GAC) for determination of DDVP in human autopsy samples. The method can be adopted in forensic toxicological laboratories for analysis of DDVP in autopsy samples. In addition, the green character of the proposed method was evaluated using ComplexGAPI procedure.

A Non-Instrumental Green Analytical Method Based on Surfactant-Assisted Dispersive Liquid-Liquid Microextraction-Thin-Layer Chromatography-Smartphone-Based Digital Image Colorimetry(SA-DLLME-TLC-SDIC) for Determining Favipiravir in Biological Samples

Favipiravir (FAV) has become a promising antiviral agent for the treatment of COVID-19. Herein, a green, fast, high-sample-throughput, non-instrumental, and affordable analytical method is proposed based on surfactant-assisted dispersive liquid-liquid microextraction (SA-DLLME) combined with thin-layer chromatography-digital image colourimetry (TLC-DIC) for determining favipiravir in biological and pharmaceutical samples. Triton X-100 and dichloromethane (DCM) were used as the disperser and extraction solvents, respectively. The extract obtained after DLLME procedure was spotted on a TLC plate and allowed to develop with a mobile phase of chloroform:methanol (8:2, v/v). The developed plate was photographed using a smartphone under UV irradiation at 254 nm. The quantification of FAV was performed by analysing the digital images' spots with open-source ImageJ software. Multivariate optimisation using Plackett-Burman design (PBD) and central composite design (CCD) was performed for the screening and optimisation of significant factors. Under the optimised conditions, the method was found to be linear, ranging from 5 to 100 µg/spot, with a correlation coefficient (R2) ranging from 0.991 to 0.994. The limit of detection (LOD) and limit of quantification (LOQ) were in the ranges of 1.2-1.5 µg/spot and 3.96-4.29 µg/spot, respectively. The developed approach was successfully applied for the determination of FAV in biological (i.e., human urine and plasma) and pharmaceutical samples. The results obtained using the proposed methodology were compared to those obtained using HPLC-UV analysis and found to be in close agreement with one another. Additionally, the green character of the developed method with previously reported protocols was evaluated using the ComplexGAPI, AGREE, and Eco-Scale greenness assessment tools. The proposed method is green in nature and does not require any sophisticated high-end analytical instruments, and it can therefore be routinely applied for the analysis of FAV in various resource-limited laboratories during the COVID-19 pandemic.

Cellulose paper sorptive extraction (CPSE): A simple and affordable microextraction method for analysis of basic drugs in blood as a proof of concept

Aiming towards simplifying sample preparation procedure, the present work explores use of unmodified laboratory filter paper as sorbent for extraction of nine basic drugs (five antidepressants, four benzodiazepines, and ketamine) from human blood samples and their analysis by gas chromatography-mass spectrometry (GC-MS). The procedure termed as cellulose paper sorptive extraction (CPSE) is straightforward. It involves adsorption of target analytes from deproteinized diluted blood samples on the unmodified cellulose paper followed by elution into 2 mL of methanol. Multivariate optimization, consisting of Placket-Burman design (PBD) and central composite design (CCD), was used to screen and optimize significant factors for CPSE. The proposed method follows the principles of green analytical chemistry (GAC), as the unmodified filter paper used as the sorbent is inexpensive and biodegradable. The technique is easy to perform and requires only 2 mL of MeOH during the entire extraction procedure. Under the optimized conditions, the limit of detection and quantification for the target analytes were estimated to be in the range of 0.003-0.035 and 0.010-0.117 µg mL^-1, respectively. In contrast, the relative standard deviations were consistently below 10 %. The calibration curves were linear in the range of 0.015-2 µg mL^-1 with a coefficient of determination (R²) in the range of 0.995-0.999.Satisfactory recoveries ranging from 87 to 99 % was achieved. As proof of concept, the analysis of nine drugs in blood samples from the patients was performed to demonstrate the potential application of the proposed method.

Rapid Determination of Non-Steroidal Anti-Inflammatory Drugs in Urine Samples after In-Matrix Derivatization and Fabric Phase Sorptive Extraction-Gas Chromatography-Mass Spectrometry Analysis

Fabric phase sorptive extraction (FPSE) has become a popular sorptive-based microextraction technique for the rapid analysis of a wide variety of analytes in complex matrices. The present study describes a simple and green analytical protocol based on in-matrix methyl chloroformate (MCF) derivatization of non-steroidal anti-inflammatory (NSAID) drugs in urine samples followed by FPSE and gas chromatography-mass spectrometry (GC-MS) analysis. Use of MCF as derivatizing reagent saves substantial amounts of time, reagent and energy, and can be directly performed in aqueous samples without any sample pre-treatment. The derivatized analytes were extracted using sol−gel Carbowax 20M coated FPSE membrane and eluted in 0.5 mL of MeOH for GC-MS analysis. A chemometric design of experiment-based approach was utilized comprising a Placket−Burman design (PBD) and central composite design (CCD) for screening and optimization of significant variables of derivatization and FPSE protocol, respectively. Under optimized conditions, the proposed FPSE-GC-MS method exhibited good linearity in the range of 0.1−10 µg mL−1 with coefficients of determination (R2) in the range of 0.998−0.999. The intra-day and inter-day precisions for the proposed method were lower than <7% and <10%, respectively. The developed method has been successfully applied to the determination of NSAIDs in urine samples of patients under their medication. Finally, the green character of the proposed method was evaluated using ComplexGAPI tool. The proposed method will pave the way for simper analysis of polar drugs by FPSE-GC-MS.

Overview of Different Modes and Applications of Liquid Phase-Based Microextraction Techniques

Liquid phase-based microextraction techniques (LPµETs) have attracted great attention from the scientific community since their invention and implementation mainly due to their high efficiency, low solvent and sample amount, enhanced selectivity and precision, and good reproducibility for a wide range of analytes. This review explores the different possibilities and applications of LPμETs including dispersive liquid–liquid microextraction (DLLME) and single-drop microextraction (SDME), highlighting its two main approaches, direct immersion-SDME and headspace-SDME, hollow-fiber liquid-phase microextraction (HF-LPME) in its two- and three-phase device modes using the donor–acceptor interactions, and electro membrane extraction (EME). Currently, these LPμETs are used in very different areas of interest, from the environment to food and beverages, pharmaceutical, clinical, and forensic analysis. Several important potential applications of each technique will be reported, highlighting its advantages and drawbacks. Moreover, the use of alternative and efficient “green” extraction solvents including nanostructured supramolecular solvents (SUPRASs, deep eutectic solvents (DES), and ionic liquids (ILs)) will be discussed.

Vortex-assisted dispersive liquid-liquid microextraction-gas chromatography (VADLLME-GC) determination of residual ketamine, nimetazepam, and xylazine from drug-spiked beverages appearing in liquid, droplet, and dry forms

Presently, investigations of drug-facilitated crimes (DFCs) rely on the detection of substances extracted from biological samples following intake by the victim. However, such detection requires rapid sampling and analysis prior to metabolism and elimination of the drugs from the body. In cases of suspected DFCs, drug-spiked beverage samples, whether in liquid, droplet, or even dried form, can be tested for the presence of spike drugs and used as evidence for the occurrence of DFCs. This study aimed to quantitatively determine three sedative-hypnotics (ketamine, nimetazepam, and xylazine) from drug-spiked beverages using a vortex-assisted dispersive liquid-liquid microextraction-gas chromatography (VADLLME-GC) approach. In this study, a GC method was first developed and validated, followed by the optimization of the VADLLME protocol, which was then applied to quantify the target substances in simulated forensic case scenarios. The developed GC method was selective, sensitive (limit of detection: 0.08 μg/ml [ketamine]; 0.16 μg/ml [nimetazepam]; 0.08 μg/ml [xylazine]), linear (R²  > 0.99), precise (%RSD <7.2%), and accurate (% recovery: 92.8%-103.5%). Higher recoveries were achieved for the three drugs from beverage samples in liquid form (51%-97%) as compared to droplet (48%-96%) and dried (44%-93%) residues. The recovery was not hindered by very low volumes of spiked beverage and dried residues. In conclusion, the developed VADLLME-GC method successfully recovered ketamine, nimetazepam, and xylazine from spiked beverages that are likely to be encountered during forensic investigation of DFCs.

A rapid and cost-effective method based on dispersive liquid-liquid microextraction coupled to injection port silylation-gas chromatography-mass spectrometry for determination of morphine in illicit opium

A simple, rapid, cost-effective and environment friendly analytical method based on dispersive liquid-liquid microextraction (DLLME) coupled to injection port silylation (IPS)-gas chromatography-mass spectrometry is described for the determination of morphine in illicit opium samples. Raw opium was dispersed in ultrapure water and 5 mL of aqueous sample was subjected to DLLME by rapidly injecting a mixture of chloroform and acetone (extraction and disperser solvent, respectively) followed by ultrasonication for 1 min and subsequent centrifugation for 3 min at 5000 rpm. The sedimented phase thus obtained was reconstituted in acetonitrile and 1 µL along with 1 µL of N,O-Bis(trimethylsilyl)acetamide (BSA) was injected manually into GC-MS injection port at a temperature of 250°C. The derivatization reaction was completed instantaneously inside the heated GC-MS injection port without any side product. Various parameters associated with IPS and DLLME have been thoroughly optimized. Under the optimized conditions, the method has been found linear in the range of 5-50 µg/mL with a correlation coefficient (R 2) of 0.997. The limit of detection (LOD) and limit of quantification (LOQ) for morphine-diTMS were found to be 1.6 and 4.8 µg/mL. The method has been successfully applied for the quantitative analysis of morphine in illicit opium samples. In conclusion, the proposed method has completely eliminated the time consuming and laborious steps of LLE and in-vial silylation and can be routinely used for analysis of opium and other polar analytes in forensic science laboratories.

Recent developments in sample preparation techniques combined with high-performance liquid chromatography: A critical review

This review article compares and contrasts sample preparation techniques coupled with high-performance liquid chromatography (HPLC) and describes applications developed in biomedical, forensics, and environmental/industrial hygiene in the last two decades. The proper sample preparation technique can offer valued data for a targeted application when coupled to HPLC and a suitable detector. Improvements in sample preparation techniques in the last two decades have resulted in efficient extraction, cleanup, and preconcentration in a single step, thus providing a pathway to tackle complex matrix applications. Applications such as biological therapeutics, proteomics, lipidomics, metabolomics, environmental/industrial hygiene, forensics, glycan cleanup, etc., have been significantly enhanced due to improved sample preparation techniques. This review looks at the early sample preparation techniques. Further, it describes eight sample preparation technique coupled to HPLC that has gained prominence in the last two decades. They are (1) solid-phase extraction (SPE), (2) liquid-liquid extraction (LLE), (3) gel permeation chromatography (GPC), (4) Quick Easy Cheap Effective Rugged, Safe (QuEChERS), (5) solid-phase microextraction (SPME), (6) ultrasonic-assisted solvent extraction (UASE), and (7) microwave-assisted solvent extraction (MWASE). SPE, LLE, GPC, QuEChERS, and SPME can be used offline and online with HPLC. UASE and MWASE can be used offline with HPLC but have also been combined with the online automated techniques of SPE, LLE, GPC, or QuEChERS for targeted analysis. Three application areas of biomedical, forensics, and environmental/industrial hygiene are reviewed for the eight sample preparation techniques. Three hundred and twenty references on the eight sample preparation techniques published over the last two decades (2001-2021) are provided. Other older references were included to illustrate the historical development of sample preparation techniques.

Essential oil-based dispersive liquid-liquid microextraction for the determination of N,N-dimethyltryptamine and β-carbolines in human plasma: A novel solvent-free alternative

The present study describes the development of a novel solvent-free vortex-assisted dispersive liquid-liquid microextraction alternative based on a natural essential oil as extracting solvent (VA-EO-DLLME) for the determination of N,N-dimethyltryptamine (DMT), harmine (HRM), harmaline (HRL) and tetrahydroarmine (THH) (compounds found in the ayahuasca tea, a psychedelic plant preparation) in human plasma. After optimization through full factorial and Box-Behnken experimental designs, this VA-EO-DLLME followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was completely validated and applied to authentic plasma specimens. Sample preparation consisted in the addition of 60 mg of NaCl, 100 μL of borate buffer and 100 μL of Eucalyptus globulus essential oil to a 200 μL aliquot of human plasma. After 30 s of vortex agitation followed by 5 min of centrifugation (10,000 rpm), 80 μL of the oil supernatant was dried and resuspended in mobile phase prior to injection into the UHPLC-MS/MS system. Once optimized, the validated method yielded LoDs ≤1.0 ng mL^-1 for all analytes. LoQ was 1.0 ng mL^-1 for DMT, HRL and HRM and 2.0 ng mL^-1 for THH. The method has shown to be linear over the range of LoQ up to 150 ng mL^-1 (r² ≥ 0.9926). Intra/inter-day precision and accuracy met the acceptance criteria at three quality control (QC) levels. An additional intermediate precision study demonstrated that, except for THH and HRL at low and medium QCs, the overall method performance was similar for the three different oil sources. Matrix effect evaluation showed predominant ion suppression, ranging from 56% to 83%. Recovery varied from 33 up to 101% with an average of 50 ± 15.8%. Selectivity studies showed no interferences. Analysis of 13 authentic samples proved method feasibility. Finally, we believe that our novel VA-EO-DLLME approach offers a very simple, fast, cost-effective and eco-friendly alternative based on the use of an easily accessible and entirely green material as an extracting solvent. This may represent an incentive for researchers to investigate novel and creative alternatives, such as essential oils, as substitutes of organic solvents for microextraction methods in forensic and clinical contexts.

Quantification of amphetamine and derivatives in oral fluid by dispersive liquid-liquid microextraction and liquid chromatography-tandem mass spectrometry

The abuse of stimulants such as amphetamine, methamphetamine, ecstasy (MDMA), and their analogues (MDEA and MDA) has been increasing considerably worldwide since 2009. In this work, an analytical method using dispersive liquid-liquid microextraction (DLLME) to determine amphetamine and derivatives in oral fluid samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and validated. Linearity was achieved between 20 to 5000 ng/mL (r>0.992, 1/x² weighted linear regression), with a limit of quantification (LOQ) of 20 ng/mL. Imprecision (%relative standard deviation) and bias (%) were not higher than 9.1 and -12.3%, respectively. The matrix effect was lower than 14.6%, with no carryover observed up to 5000 ng/mL and no interference with 10 different oral fluid matrix sources and against 14 pharmaceuticals and other common drugs of abuse. MDMA, MDA, and MDEA in processed samples were stable up to 24 h at autosampler (10°C); and amphetamine and methamphetamine up to 18 h. The developed method was successfully applied to authentic oral fluid analyses (n = 140). The proposed method is an example of the Green Analytical Toxicology, since it reduces both the amount of solvent required in samples preparation and the quantity of solvents and reagents used in analytical-instrumental stage, as well as requires a minimal sample volume, being a cheaper, quicker and more ecological alternative to conventional methods. Obtained results showed that DLLME extraction combined with LC-MS/MS is a fast and simple method to quantify amphetamine derivatives in oral fluid samples.

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).

Application of microextraction techniques in alternative biological matrices with focus on forensic toxicology: a review

The interest in alternative biological matrices (e.g., hair and saliva) for forensic toxicology analysis has increased, and recent developments in sample preparation have targeted rapid, cheap, efficient and eco-friendly methods, including microextraction techniques. For this review, we have gathered information about these two hot topics. We discuss the composition, incorporation of analytes and advantages and disadvantages of different biological matrices, and also present the operation principles of the most reported microextraction procedures and their application in forensic toxicology. The outcome of this review may encourage future forensic researches into alternative samples and microextraction techniques.

MASS SPECTROMETRY ANALYSIS OF DRUGS OF ABUSE: CHALLENGES AND EMERGING STRATEGIES

Mass spectrometry has been the "gold standard" for drugs of abuse (DoA) analysis for many decades because of the selectivity and sensitivity it affords. Recent progress in all aspects of mass spectrometry has seen significant developments in the field of DoA analysis. Mass spectrometry is particularly well suited to address the rapidly proliferating number of very high potency, novel psychoactive substances that are causing an alarming number of fatalities worldwide. This review surveys advancements in the areas of sample preparation, gas and liquid chromatography-mass spectrometry, as well as the rapidly emerging field of ambient ionization mass spectrometry. We have predominantly targeted literature progress over the past ten years and present our outlook for the future. © 2020 Periodicals, Inc. Mass Spec Rev.

A simple, cost-effective and rapid method for simultaneous determination of Strychnos nux-vomica alkaloids in blood and Ayurvedic medicines based on ultrasound-assisted dispersive liquid-liquid microextraction-thin-layer chromatography-image analysis

A simple, rapid, cost-effective and green analytical method is developed based on ultrasound-assisted dispersive liquid-liquid microextraction (US-DLLME) coupled to thin-layer chromatography (TLC)-image analysis for the simultaneous determination of two major alkaloids of Strychnos nux-vomica L i.e., strychnine and brucine. The method is composed of three steps, namely (i) US-DLLME by injecting a mixture of 100-μL chloroform (extraction solvent) and 1-mL methanol (disperser solvent) in 5 mL of aqueous sample, followed by ultrasonication and centrifugation, (ii) TLC of 20 μL of sedimented phase with methanol: ammonia (100:1.5, v/v) as the mobile phase and visualization under ultraviolet radiation (254 nm) and (iii) photography of TLC plate and quantification of spots by image analysis using freely available imageJ software (National Institute of Health, Bethesda, MD, USA). The limit of detection and limit of quantification for both alkaloids were found to be in the range of 0.12-0.15 and 0.36-0.48 μg/spot, respectively. The method was found to be linear in the range of 0.5-5 μg/spot with correlation coefficient (R2) of 0.995 and 0.997 for strychnine and brucine, respectively. The developed method was successfully applied for the determination of strychnine and brucine in Ayurvedic formulations and blood samples. The method does not require any sophisticated instrument and handling skills and can be adopted for rapid analysis of strychnine and brucine in forensic toxicological laboratories.

Protocells self-assembled by hydroxyapatite nanoparticles: Highly efficient and selective enrichment of chlorophenols in an aqueous environment

In this paper, amphiphilic hydroxyapatite (HAP) nanoparticles were modified by dibutyl phosphate (DBP) via covalent bonding. The modified HAP particles (m-HAP) were employed as building blocks to construct oil-in-water (O/W) Pickering emulsion, that displayed an excellent performance on the enrichment of organic pollutants dissolved in wastewater by extracting the organic molecules into the oil phase. Environment-friendly organic solvent hexanol was selected as oil phase and three types of monochlorophenol (2-chlorophenol, 3-chlorophenol, 4-chlorophenol) were chosen as model pollutants in simulated wastewater. Two types of natural water were also tested as a proof of principle. The enrichment percentage of chlorophenols was up to 98% in 140 s, following first order kinetics. Thermodynamic study suggested that the enrichment process is spontaneous and exothermic. The external environment of the protocells, such as pH, ionic strength and the natural organic matter have been investigated. This study provides a novel, convenient and environment-friendly approach for enrichment and removal of trace organic pollutants in wastewater.

Determination of cadmium in bread and biscuit samples using ultrasound-assisted temperature-controlled ionic liquid microextraction

BACKGROUND

In the present work, a simple and rapid method was proposed for the preconcentration of cadmium using ultrasound-assisted temperature-controlled ionic liquid microextraction (TC-IL-LPME). The dispersion of the ionic liquid (1-Hmim[PF₆ ]) in the aqueous phase was performed by heating it in an ultrasonic bath, followed by cooling in an ice bath. After centrifugation, the enriched phase was dissolved in 45% (w/w) nitric acid solution to reduce viscosity, and the cadmium content was measured employing electrothermal atomic absorption spectrometry (ET-AAS). The 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol reagent (Br-PADAP) was used as a complexing agent.

RESULTS

Under optimized conditions, the method had a detection limit of 2.0 ng L^-1 and an enrichment factor of 24. The accuracy of the method was evaluated through the analysis of the certified reference material of brown bread (BCR-191). The method was applied to the determination of cadmium in samples of bread and biscuit. The limit of detection of the solid samples was 0.10 μg kg^-1 . The recovery of cadmium in the samples varied between 93% and 107%.

CONCLUSION

The proposed method is presented as a simple, cheap, ecological and a sensitive alternative for the determination of cadmium in bread and biscuit samples. © 2019 Society of Chemical Industry.

State-of-the-art on the technique of dispersive liquid-liquid microextraction

Dispersive liquid-liquid microextraction is a new sample pretreatment technology based on traditional liquid liquid extraction. In this paper, the application of low-toxicity extractants such as low-density extractants, auxiliary extractants, stripping agents and ionic liquids in this technology and the extraction modes such as solvent de-emulsification, suspension extractant curing, auxiliary extraction, back extraction, and ionic liquid-dispersion liquid microextraction, are summarized. In addition, the synergism of this technique with other sample preparation techniques, such as liquid-liquid extraction, solid-phase extraction, solid-phase microextraction, dispersive solid phase extraction, matrix solid-phase dispersion extraction, supercritical fluid extraction and ultrasound-assisted dispersive liquid-liquid microextraction is discussed.

High-throughput screening of toxic substances by extractive electrospray ionization mass spectrometry and their identification via databank construction

More than 200 toxic substances (including narcotic drugs, psychotropic drugs, organic phosphorus compounds, carbamates, pyrethroids and other pesticides, veterinary drugs, rodenticides, natural toxins, and other drugs) were identified and quantified using an ion-trap mass spectrometer. The advantages of this technique-its selectivity, accuracy, precision, utilization of only small amounts of the sample, and short analysis time for a single sample (less than 30s)-render it a rapid and accurate methodology for toxin screening. Subsequently, an extractive electrospray ionization (EESI) mass spectrometry database was established by combining the Xcalibur data processing system with NIST database software. This allowed unknown toxicants in urine and blood samples, stomach contents, and liver samples, as provided by the Jiangxi Provincial Public Security Department, to be analyzed and identified. This EESI methodology and databank has the potential for widespread application to the large-scale analysis of practical samples. Graphical abstract ᅟ.

Methods of liquid phase microextraction for the determination of cadmium in environmental samples

Liquid phase microextraction (LPME) has been widely used in extraction and preconcentration systems as an excellent alternative to conventional liquid phase extraction. In this work, a critical review is presented on liquid phase microextraction techniques used in the determination of cadmium in environmental samples. LPME techniques are classified into three main groups: single-drop liquid phase microextraction (SDME), hollow fiber liquid phase microextraction (HF-LPME), and dispersive liquid-liquid microextraction (DLLME). Methods involving these liquid phase microextraction techniques are described, addressing advantages and disadvantages, samples, figures of merit, and trends.