Ultrasound-assisted dispersive liquid-liquid microextraction for the determination of seven recreational drugs in human whole blood using gas chromatography-mass spectrometry

Simultaneous determination of methadone and tramadol in serum samples by ultrasonic-assisted micro solid phase extraction and gas chromatography-mass spectrometry

Ultrasonic-assisted dispersive micro solid phase extraction (UA-DMSPE) is proposed as a fast and easy technique for the extraction and preconcentration of methadone and tramadol from serum samples. Different sorbents including carbon nanotubes, oxidized carbon nanotubes, and TiO2 nanoparticles were compared to extract methadone and tramadol. The best performance was obtained using oxidized carbon nanotubes due to the strong affinity between the drugs and carbon nanotube adsorbents. Final analysis of drugs performed by using gas chromatography-mass spectrometric detection. Different parameters affecting the extraction efficiency, such as the sample volume, amount of adsorbent, desorption solvent type and volume, centrifugation time, and speed were investigated and optimized. The striking features of this technique are correlated to its speed and the small volumes of sample (about 1 mL), desorption solvent (about 50 μL), and adsorbent (about 0.001 g) for analysis of drugs, and finally, milder centrifugation conditions relative to the previously reported adsorbent. The optimal parameters were achieved as follows: pH value was set at 9, the sample volume was adjusted to 1200 µL, the amount of adsorbent used was 1 mg, the extraction time was set at 5 min, and the volume of the desorption solvent was adjusted to 50 µL. The limits of detections (0.5 and 0.8 ng mL-1) and quantifications (1.5 and 2.5 ng mL-1) were obtained for methadone and tramadol, respectively. The developed method also showed good repeatability, relative standard deviation (RSD) of 9.49 % and 7.47 % (n = 5), for the spiked aqueous solution at the concentration level of 10, 50, and 100 ng mL-1 for analytes, and linearity, R ≥ 0.9809. The results showed that UA-DMSPE is a quick, relatively inexpensive, and environmentally friendly alternative technique for the extraction of opiate drugs from serum samples.

Green Analytical Toxicology procedure for determination of ketamine, its metabolites and analogues in oral fluid samples using dispersive liquid-liquid microextraction (DLLME)

New psychoactive substances (NPS) are often synthesized via small changes in the molecular structure, producing drugs whose effect and potency are not yet fully known. Ketamine is one of the oldest NPS, with therapeutic use in human and veterinary medicine authorized in several countries, being metabolized mainly into norketamine and 6-hydroxy-norketamine. Furthermore, two structural analogues of ketamine have recently been identified, deschloroketamine and 2-fluorodeschloroketamine, marketed as drugs of abuse. To comply with Green Analytical Toxicology (GAT) fundamentals, miniaturized techniques such as dispersive liquid-liquid microextraction (DLLME) were employed to determine toxicants in biological fluids. An analytical method for determining ketamine, its metabolites and its analogues in oral fluid was fully developed and validated by using DLLME and liquid chromatography-tandem mass spectrometry (LC-MS-MS). The extraction parameters were optimized by multivariate analysis, obtaining the best conditions with 200 μL of sample, 100 μL of methanol as dispersive solvent and 50 μL of chloroform as extractor solvent. Linearity was obtained from 10 to 1,000 ng/mL, with limit of detection (LOD) and lower limit of quantification (LLOQ) at 10 ng/mL. Imprecision (% relative standard deviation) and bias (%) were less than 8.2% and 9.5%, respectively. The matrix effect did not exceed 10.6%, and the recovery values varied from 24% to 42%. No matrix interference and good selectivity in the evaluation of 10 different sources of oral fluid and 42 drugs at 500 ng/mL, respectively, were observed. The method was applied in the analysis of 29 authentic oral fluid samples and had its green characteristic evaluated by three different tools: the Green Analytical Procedure Index (GAPI), the Analytical Eco-Scale and the Analytical GREEnness (AGREE) metrics.

Recent Advances in Dispersive Liquid-Liquid Microextraction for Pharmaceutical Analysis

Sample clean-up and pre-concentration are critical components of pharmaceutical analysis. The dispersive liquid-liquid microextraction (DLLME) technique is widely recognized as the most effective approach for enhancing overall detection sensitivity. While various DLLME modes have been advanced in pharmaceutical analysis, there need to be more discussions on pre-concentration techniques specifically developed for this field. This review presents a comprehensive overview of the different DLLME modes used in pharmaceutical analysis from 2017 to May 2023. The review covers the principles of DLLME, the factors affecting microextraction, the selected applications of different DLLME modes, and their advantages and disadvantages. Additionally, it focuses on multi-extraction strategies employed for pharmaceutical analysis.

Detection, quantification and degradation kinetic for five benzodiazepines using VAUS-ME-SFO/LC-MS/MS method for water, alcoholic and non-alcoholic beverages

Benzodiazepines can make victims more docile, they are frequently used in drug-facilitated crimes, such as robberies and sexual assaults. Therefore, it is essential to develop techniques for determining whether these chemicals are present in relation with illegal activity is crucial. Therefore, to determine the presence of five benzodiazepines (alprazolam, clonazepam, diazepam, lorazepam, and oxazepam) in water, alcoholic beverages, and non-alcoholic beverages, a simple and direct, miniaturized, and effective vortex assisted ultrasound based microextraction using solidification of floating organic droplets (VAUS-ME-SFO) in combination with LC-MS/MS was developed. 1-Undecanol and acetonitrile, respectively, served as the extractant and disperser solvents. Many other parameters affect the efficiency of the developed analytical procedure VAUS-ME-SFO/LC-MS/MS. These parameters were optimized using Plackett Burman Design and Central Composite Design to obtain reliable results. The optimum conditions for the extraction were: 10.0 mL of sample; 180 μL acetonitrile, as a dispersive solvent; 200 μL of 1-undecanol, as an extraction solvent; pH 7; 105 s of vortex agitation; 120 s of ultrasonication application and 3 min of centrifugation at 7000 rpm. The benzodiazepines were separated by a chromatographic separation technique carried out by a UPLC system consisting of a binary mobile phase. The solvent system comprises of 0.1% Formic acid in Milli-Q (Solvent A) and 0.1% Formic acid in ACN (Solvent B) with a gradient flow of 3.5 min total analysis time. Under the optimized conditions, the calibration curve was studied in the range of 0.124-7.810 ng mL^-1. The regression correlation coefficient (R²) value of all targeted analytes ranges from 0.993 to 0.999. The LOD and LOQ of VAUS-ME-SFO methods using LC-MS/MS analysis range from 0.316 to 0.968 ng mL^-1 and 1.055-3.277 ng mL^-1 respectively. The repeatability within a day varied from 0.6 to 3.5%, and the reproducibility across days varied from 2.2 to 6.3%. The recoveries ranges for water, alcoholic and non-alcoholic beverages from 70.77 to 114.53%, 63.20-102.21% and 66.23-113.28% respectively. Further, the degradation kinetics was studied to establish the half-life of each targeted analyte in the matrix undertaken in the study. The water samples were classified based on their BDZs residues. This implies that the more health care and anthropogenic activity, the more the BDZs residue will be in water samples.

Competitive fluorescence immunoassay for the rapid qualitative screening and accurate quantitative analysis of ketamine

In this paper, a sensitive and specific competitive fluorescence immunoassay (CFIA) method was developed for the qualitative and quantitative analysis of ketamine (KET). A novel competitive model in which ketamine hapten (KET-BSA), coated on microporous plates, competed with ketamine antigen (KET-Ag) in actual samples to bind fluorescein isothiocyanate-labeled antibody (KET-Ab) could be used for rapid and indirect quantitative analysis of KET in human urine, blood, or sewage. In the CFIA method, KET concentration in the sample negatively correlated with the detected fluorescence intensity. The linear correlation coefficient of the competitive quantitative equation was 0.992, the linear range was 0.01-0.5 μg mL^-1, and the limit of detection (LOD) was 0.1 pg mL^-1. The specificity results showed that the cross-reaction rate of norketamine was less than 10%. Recoveries of spiked samples at low, medium, and high concentrations ranged from 96% to 117%. The CFIA method and classical gas chromatography-tandem mass spectrometry (GC-MS/MS) were used to detect the actual samples simultaneously. The relative deviation of the quantitative results was less than 10%. The LOD value of KET by CFIA was four orders of magnitude lower than that by GC-MS/MS. Additionally, CFIA had great advantages over GC-MS/MS in terms of sample pretreatment and economic investment. In conclusion, this study provided a targeting detection platform for KET, which achieved a rapid, portable, and sensitive analysis of trace KET in various materials.

Analytical Approaches for the Determination of Buprenorphine, Methadone and Their Metabolites in Biological Matrices

The abuse of buprenorphine and methadone has grown into a rising worldwide issue. After their consumption, buprenorphine, methadone and their metabolites can be found in the human organism. Due to the difficulty in the assessment of these compounds by routine drug screening, the importance of developing highly sensitive analytical approaches is undeniable. Liquid chromatography tandem mass spectrometry is the preferable technique for the determination of buprenorphine, methadone and their metabolites in biological matrices including urine, plasma, nails or oral fluids. This research aims to review a critical discussion of the latest trends for the monitoring of buprenorphine, methadone and their metabolites in various biological specimens.

Green bioanalysis: an innovative and eco-friendly approach for analyzing drugs in biological matrices

Green bioanalytical techniques aim to reduce or eliminate the hazardous waste produced by bioanalytical technologies. A well-organized and practical approach towards bioanalytical method development has an enormous contribution to the green analysis. The selection of the appropriate sample extraction process, organic mobile phase components and separation technique makes the bioanalytical method green. UHPLC-MS is the best option, whereas supercritical fluid chromatography is one of the most effective green bioanalytical procedures. Nevertheless, there remains excellent scope for further research on green bioanalytical methods. This review details the various sample preparation techniques that follow green analytical chemistry principles. Furthermore, it presents green solvents as a replacement for conventional organic solvents and highlights the strategies to convert modern analytical techniques to green methods.

Novel Applications of Microextraction Techniques Focused on Biological and Forensic Analyses

In recent years, major attention has been focused on microextraction procedures that allow high recovery of target analytes, regardless of the complexity of the sample matrices. The most used techniques included liquid-liquid extraction (LLE), solid-phase extraction (SPE), solid-phase microextraction (SPME), dispersive liquid-liquid microextraction (DLLME), microextraction by packed sorbent (MEPS), and fabric-phase sorptive extraction (FPSE). These techniques manifest a rapid development of sample preparation techniques in different fields, such as biological, environmental, food sciences, natural products, forensic medicine, and toxicology. In the biological and forensic fields, where a wide variety of drugs with different chemical properties are analyzed, the sample preparation is required to make the sample suitable for the instrumental analysis, which often includes gas chromatography (GC) and liquid chromatography (LC) coupled with mass detectors or tandem mass detectors (MS/MS). In this review, we have focused our attention on the biological and forensic application of these innovative procedures, highlighting the major advantages and results that have been accomplished in laboratory and clinical practice.

Dispersive liquid-liquid microextraction of 11-nor-Δ9-tetrahydrocannabinol-carboxylic acid applied to urine testing

Aim: THC-COOH is the major metabolite of Δ⁹-tetrahydrocannabinol commonly tested in urine to determine cannabis intake. In this study, a method based on dispersive liquid-liquid microextraction was developed for testing THC-COOH in urine. Materials & methods: Hydrolyzed urine specimens were extracted via dispersive liquid-liquid microextraction with acetonitrile (disperser solvent) and chloroform (extraction solvent). Derivatization was performed with N,O-Bis(trimethylsilyl)trifluoroacetamide with 1% trichloro(chloromethyl)silane. Analysis was performed by GC-MS/MS. Results: The method showed acceptable linearity (5-500 ng/ml), imprecision (<10.5%) and bias (<4.9%). Limits of detection and quantitation were 1 and 5 ng/ml, respectively. Twenty-four authentic samples were analyzed, with 22 samples being positive for THC-COOH. Conclusion: The proposed method is more environmentally friendly and provided good sensitivity, selectivity and reproducibility.

Rapid simultaneous determination of ketamine and midazolam in biological samples using ion mobility spectrometry combined by headspace solid-phase microextraction

Ketamine (Ket) and midazolam (Mdz) are among well-known anesthetic agents which frequently coadministered in surgical procedures and emergency department. Only a few reports have been published for the simultaneous analysis of these compounds. In the present study, we reported a simple, sensitive, and rapid method for simultaneous determination of Ket and Mdz based on headspace solid-phase microextraction coupled with ion mobility spectrometry (HS-SPME-IMS). Ion mobility spectrometer operated under positive mode of a corona discharge ionization source using ammonia as a dopant. The effective parameters on the extraction process consisting of pH of the sample, extraction temperature, extraction time, salt concentration were optimized. The calibration plots exhibited good linearity over the concentration ranges of 10-800 and 100-1500 µg L^-1 and detection limit of 8.9 and 52 µg L^-1 for Ket and Mdz respectively with correlation coefficients greater than 0.99. The relative standard deviation (RSD) for five replicate measurements was determined to be less than 8%. Finally, the applicability of the proposed method was tested in human plasma and serum samples. These tests showed that the matrix in serum samples interfere with midazolam determination but quantitative recoveries from 85 to 95 % were obtained for both drugs in the human plasma samples. The method herein provides simple and suitable approach while minimizing sample preparation and the overall complexity of the analysis in comparison to existing methodologies.

Review of LC techniques for determination of methadone and its metabolite in the biological samples

Methadone (MTD) is a synthetic analgesic drug used for treating opioid dependence and effectively used clinically for patients with severe pain. The abuse of MTD may lead to poisoning, disorder in the central nervous system and even death. The regular monitoring of MTD in biological matrices including serum, plasma and urine samples is an effective way to control abuse of MTD. In this manner, the selection of analytical monitoring of MTD in biological matrices is of paramount importance. This study was conducted to review high-performance liquid chromatography (HPLC) techniques carried out on MTD and its main metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in the biological samples during 2015-June 2021.

Application of Microextraction-Based Techniques for Screening-Controlled Drugs in Forensic Context-A Review

The analysis of controlled drugs in forensic matrices, i.e., urine, blood, plasma, saliva, and hair, is one of the current hot topics in the clinical and toxicological context. The use of microextraction-based approaches has gained considerable notoriety, mainly due to the great simplicity, cost-benefit, and environmental sustainability. For this reason, the application of these innovative techniques has become more relevant than ever in programs for monitoring priority substances such as the main illicit drugs, e.g., opioids, stimulants, cannabinoids, hallucinogens, dissociative drugs, and related compounds. The present contribution aims to make a comprehensive review on the state-of-the art advantages and future trends on the application of microextraction-based techniques for screening-controlled drugs in the forensic context.

Recent applications of microextraction sample preparation techniques in biological samples analysis

Analysis of biological samples is affected by interfering substances with chemical properties similar to those of the target analytes, such as drugs. Biological samples such as whole blood, plasma, serum, urine and saliva must be properly processed for separation, purification, enrichment and chemical modification to meet the requirements of the analytical instruments. This causes the sample preparation stage to be of undeniable importance in the analysis of such samples through methods such as microextraction techniques. The scope of this review will cover a comprehensive summary of available literature data on microextraction techniques playing a key role for analytical purposes, methods of their implementation in common biological samples, and finally, the most recent examples of application of microextraction techniques in preconcentration of analytes from urine, blood and saliva samples. The objectives and merits of each microextration technique are carefully described in detail with respect to the nature of the biological samples. This review presents the most recent and innovative work published on microextraction application in common biological samples, mostly focused on original studies reported from 2017 to date. The main sections of this review comprise an introduction to the microextraction techniques supported by recent application studies involving quantitative and qualitative results and summaries of the most significant, recently published applications of microextracion methods in biological samples. This article considers recent applications of several microextraction techniques in the field of sample preparation for biological samples including urine, blood and saliva, with consideration for extraction techniques, sample preparation and instrumental detection systems.

IoT-Enabled Fluorescence Sensor for Quantitative KET Detection and Anti-Drug Situational Awareness

Recently, drug abuse has become a worldwide concern. Among varieties of drugs, KET is found to be favorite in drug addicts, especially teenagers, for recreational purposes. KET is a kind of analgesic and anesthetic drug which can induce hallucinogenic and dissociative effects after high-dose abuse. Hence, it is critical to develop a rapid and sensitive detection method for strict drug control. In this study, we proposed a cloud-enabled smartphone based fluorescence sensor for quantitative detection of KET from human hair sample. The lateral flow immunoassay (LFIA) was used as the detecting strategy where UCNPs were introduced as fluorescent labels. The sensor was capable of identifying the up-converted fluorescence and calculating the signal intensities on TL and CL to obtain a T/C value, which was corresponding to the KET concentration. The sensor transmitted the test data to the cloud-enabled smartphone through Type-C interface, and the data were further uploaded to the edge of the network for cloud-edge computing and storage. The entire detection took only 5 minutes with high stability and reliability. The detection limit of KET was 1 ng/mL and a quantitative detection range from 1 to 150 ng/mL. Furthermore, based on the huge development of Internet of Things (IoT), an App was developed on the smartphone for anti-drug situational awareness. Based on this system, it was convenient for Police Department to perform on-site KET detection. Moreover, it was critical for prediction of the development trend of future events, benefiting much to constructing a harmonious society.

Dispersive liquid-liquid microextraction (DLLME) and external real matrix calibration for the determination of the UV absorber 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV 328) and its metabolites in human blood

2-(2H-Benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV 328; CAS: 25973-55-1) is a benzotriazole ultraviolet light (BUV) absorber which is applied to plastics and other organic substances to prevent discoloration and enhance product stability. Therefore, UV 328 is frequently used as a plastic additive and may lead to an exposure of consumers. For a reliable assessment of UV 328 metabolism, an analytical method applying dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography tandem mass spectrometry and advanced electron ionization was developed which allows the determination of UV 328 and six of its metabolites in human whole blood. Sample preparation was optimized with respect to DLLME parameters. A critical aspect of the procedure was the application of spiked human blood for calibration, which proved to be essential for achieving accurate results. Validation of the method resulted in limits of detection of 0.1 μg/L for all analytes. Variation coefficients ranged from 2 to 9% for intraday precision and from 3 to 11% for interday precision. Furthermore, relative recovery rates between 80 and 100% were calculated. Afterwards, the procedure was successfully applied to blood samples collected from a volunteer orally exposed to a single dose of UV 328. The method proved to be highly sensitive, repeatable and robust for all compounds and may further be used for studies to elucidate the human metabolism and kinetics of UV 328 and for biomonitoring of specific, environmental and occupational exposure to this UV stabilizer.

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.

Targeted mass spectrometry of ketamine and its metabolites cis-6-hydroxynorketamine and norketamine in human blood serum

Ketamine (KET) was originally developed as an anesthetic agent but has also attracted attention for further clinical applications such as medical treatment of depression or pain. The use of KET induces dissociation and emergence delirium. Due to these effects, KET has a high potential for abuse. In order to investigate metabolization of KET or to confirm misuse of KET, highly sensitive analytical methods that cover KET and its metabolites are necessary. A new analytical approach for simultaneous analysis of KET and its metabolites cis-6-hydroxynorketamine (HNK) and norketamine (NK) was established. The compounds were extracted from human blood serum by ultrafiltration and solid phase extraction with subsequent vacuum evaporation. The compounds were analyzed by non-enantioselective ultra-high performance micro-flow liquid chromatography (Waters ACQUITY UPLC® M-Class HSS T3 column, 0.1% formic acid and acetonitrile with 0.1% formic acid, 14 µL/min flow rate) coupled with tandem mass spectrometry in positive scheduled multiple reaction monitoring mode. Validation parameters such as linearity, precision, recovery, accuracy, stability, limit of detection (LOD), and limit of quantification (LOQ) were proven. LOD for KET and NK was 0.08 ng/mL and LOQ were 0.5 ng/mL and 0.6 ng/mL, respectively. For HNK, LOD was 0.1 ng/mL and LOQ 0.8 ng/mL. The method was then successfully applied to quantify KET, HNK, and NK in blood serum samples from subjects who received KET intravenously. A novel method for the simultaneous analysis of KET, NK, and HNK was established. This new method could now be used for clinical trials investigating KET and its metabolites HNK and NK or for forensic analysis in order to confirm KET abuse.

Interpol review of toxicology 2016-2019

This review paper covers the forensic-relevant literature in toxicology from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20.Papers%202019.pdf.

Rapid Analysis of Four Amphetamines in Urine by Self-Made Pipette-Tip Solid-Phase Extraction Followed by GC-MS/MS

A simple and rapid pipette-tip solid-phase extraction (PT-SPE) procedure with derivatization prior to gas chromatography triple quadrupole mass spectrometry analysis is developed for the simultaneous determination of amphetamine (AMP), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA) in urine samples. The PT-SPE procedure using self-made sorbent could extract drugs within 6 min from 100-μL urine samples, requiring low solvent-consumption (&lt;2.0 mL). Besides, the self-made pipette tip could be reused at least five times. Under optimized conditions, the recoveries of four amphetamines at spiked levels (low, medium and high) ranged from 87.7 to 110.4%, with relative standard deviations &lt; 9.5%. The limit of detections and limit of quantifications for AMP, MA, MDA and MDMA were in the range of 2.52–8.25 ng⋅mL−1 and 8.4–27.5 ng⋅mL−1, respectively. Validation results show that the proposed method is suitable for the quantitation of amphetamines and has been successfully applied in the urine samples of suspected drug abusers.

Validation and Optimization of Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction as a Preparation Method for Detection of Methadone in Saliva with Gas Chromatography-Mass Spectrometry Technique

Purpose: We investigated validation and optimization of ultrasound-assisted dispersive liquidliquid microextraction (UADLLME) as a preparation method for detection of methadone in saliva samples.

Methods: We used blank and methadone-containing saliva samples and also standard methadone solution. Sodium hydroxide and chloroform were added to samples and they were held in ultrasonic bath. Then preparations were centrifuged and extracted analyte was analyzed by gas chromatography-mass spectrometry (GC-MS). Accuracy was measured by Intra and between-day mean relative errors (RE). Precision was assessed by coefficient of variation (CV). Recovery, specificity, linearity and limits of detection and quantification were also determined. Optimization was conducted for ultrasound duration, pH and extraction phase volume. Efficiency of dispersive liquid-liquid microextraction (DLLME) and UADLLME were compared.

Results: Intra and between-day accuracies (2.3 -7.5%), recovery (89.4-115.5%) and precision (5.2-11.3%) were all acceptable. Calibration curve was linear in the concentration range of 150 ng/mL-10 µL/mL with R² >0.9995 and equation of y=86.901x-5342.5. Limits of detection and quantification were 50 and 150 ng/mL, respectively. Specificity was measured by comparing retention times of saliva samples (containing methadone metabolites and other commonly used drugs) during UADLLME/GC-MS analysis and no interference was observed. Recovery of UADLLME was 1.4 of DLLME. Solvent and sample volumes required for UADLLME were 1/200 and 1/20 of DLLME. The greatest efficiency obtained at pH of 10, with ultrasound treatment duration of 5 minutes and extraction phase volume of 1000 µL.

Conclusion: Study found that UADLLME/GC-MS is a valid and efficient method for detection of methadone in oral fluid.

Recent advances in microextraction procedures for determination of amphetamines in biological samples

Amphetamine and its related derivatives have stimulant and hallucinogenic properties. Illegal use of these drugs is an increasing global problem resulting in significant public health and legal problems. Deaths have been reported after intake of these drugs due to overdose. It is important to determine the type and concentration of illicit drugs in biological samples. These compounds are found in complex matrices at low concentration levels. The microextraction techniques are dominant sample preparation procedure and they are widely accepted as the most labor-intensive part of the bioanalytical process. For this purpose, a survey of recent published advances in microextraction procedures for quantification of amphetamines in biological samples found in the different databases from 2008 to date will be conducted.

Green sample preparations for the bioanalysis of drugs of abuse in complex matrices

The sample preparation is the most critical step involved in the bioanalytical process. When dealing with green analytical chemistry, sample preparation can be even more challenging. To fit the green analytical chemistry principles, efforts should be made toward the elimination or reduction of the use of toxic reagents and solvents, minimization of energy consumption and increased operator safety. The simplest sample preparations are more appropriate for liquid biological matrices with little interfering compounds such as urine, plasma and oral fluid. The same does not usually occur with complex matrices that require more laborious procedures. The present review discusses green analytical approaches for the analyses of drugs of abuse in complex biological matrices, such as whole blood, breast milk, meconium and hair.

Rapid liquid-phase microextraction of analytes from complex samples on superwetting porous silicon for onsite SALDI-MS analysis

To simplify the pretreatment process of complex samples is a key step for rapid detection. Herein, we report a single-step method to rapidly extract analytes with liquid-phase microextraction (LPME) from complex samples on a superwetting porous silicon (PSi) for onsite detection with surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). The operation time is less than 3 min with this simple method. The limit of detection (LOD) of malachite green in lake water is lowered to 10^-13 M, that of verapamil and methadone in whole blood is down to 10^-11 M and 10^-13 M, in urine is 10^-13 M and 10^-14 M, respectively; and the ranges of quantification is up to 8 or 9 orders of magnitude with high precision (coefficients of determination (R²) > 0.98) for the complex samples. This method could provide an approach to directly extract target compounds from complex samples on substrate for SALDI-MS analysis.

Ultrasound-assisted dispersive liquid-liquid microextraction followed by ion mobility spectrometry for the simultaneous determination of bendiocarb and azinphos-ethyl in water, soil, food and beverage samples

A sensitive and fast ultrasound-assisted dispersive liquid-liquid microextraction procedure combined with ion mobility spectrometry has been developed for the simultaneous extraction and determination of bendiocarb and azinphos-ethyl. Experimental parameters affecting the analytical performance of the method were optimized: type and volume of extraction solvent (chloroform, 150 µL), pH (9.0), type and volume of buffer (ammonium buffer pH = 9.0, 4.5 mL) and extraction time (3.0 min). Under optimum conditions, the linearity was found to be in the range of 2-40 and 6-100 ng/mL and the limits of detection (LOD) were 1.04 and 1.31 ng/mL for bendiocarb and azinphos-ethyl, respectively. The method was successfully validated for the analysis of bendiocarb and azinphos-ethyl in different samples such as waters, soil, food and beverage samples.

Theoretical and experimental approach to hydrophilic interaction dispersive solid-phase extraction of 2-aminothiazoline-4-carboxylic acid from human post-mortem blood

In this paper, we proposed an innovative hydrophilic interaction dispersive solid-phase extraction (HI-d-SPE) protocol suitable for the isolation of the potential cyanide intoxication marker, 2-aminothiazoline-4-carboxylic acid (ATCA), from such complicated matrix as post-mortem blood. To create an optimal HI-d-SPE protocol, two sorbents were used: a molecularly imprinted polymer (MIP) and commercially available Oasis-MCX^®. The latter sorbent was identified as more recovery-efficient with higher clean-up abilities in a carefully optimized process. Computational analysis was employed to provide insight into the adsorption mechanism of the two selected sorbents. The theoretical results were in agreement with the experiment regarding the efficiency of the sorbent. HI-d-SPE was successfully applied to the analysis of ATCA in 20 post-mortem blood samples using LC-MS/MS. The analytical performance of the method was finally compared to prior existing methods, in turn revealing its superiority.

Solvent-terminated dispersive liquid-liquid microextraction: a tutorial

Solvent-terminated dispersive liquid-liquid microextraction (ST-DLLME) is a special mode of DLLME in which a demulsifying solvent is injected into the cloudy mixture of sample/extractant to break the emulsion and induce phase separation. The demulsification process starts by flocculation of the dispersed microdroplets by Ostwald ripening or coalescence to form larger droplets. Then, the extractant either floats or sinks depending on its density as compared with that for the aqueous sample. The demulsifier should have high surface activity and low surface tension in order to be capable of inducing phase separation. The extraction efficiency in ST-DLLME is controlled by the same experimental variables of normal DLLME (n-DLLME) such as the type and volume of the extractant as well as the disperser. Other parameters such as pH and the temperature of the sample, the stirring rate, the time of extraction and the addition of salt are also important to consider. Along with these factors, the demulsifier type and volume and the demulsification time have to be optimized. By using solvents to terminate the dispersion step in DLLME, the centrifugation process is not necessary. This in turn improves precision, increases throughput, decreases the risk of contamination through human intervention and minimizes the overall analysis time. ST-DLLME has been successfully applied for determination of both inorganic and organic analytes including pesticides and pharmaceuticals in water and biological fluids. Demulsification via solvent injection rather than centrifugation saves energy and makes ST-DLLME easier to automate. These characteristics in addition to the low solvent consumption, the reduced organic waste and the possibility of using water in demulsification bestow green features on ST-DLLME. This tutorial discusses the principle, the practical aspects and the different applications of ST-DLLME.

Simultaneous quantitation of meperidine, normeperidine, tramadol, propoxyphene and norpropoxyphene in human plasma using solid-phase extraction and gas chromatography/mass spectrometry: Method validation and application to cardiovascular safety of therapeutic doses

RATIONALE

Several opioid analgesics have been related to the prolongation of cardiac repolarization, a condition which can be fatal. In order to establish a correct estimation of the risk/benefit balance of therapeutic doses of meperidine, normeperidine, tramadol, propoxyphene and norpropoxyphene, it was necessary to develop an analytical method to determinate plasma concentrations of these opioids.

METHODS

Here we describe a method which incorporates strong alkaline treatment to obtain norpropoxyphene amide followed by a one-elution step solid-phase extraction, and without further derivatization. Separation and quantification were achieved by gas chromatography/electron ionization mass spectrometry (GC/EI-MS) in selected-ion monitoring mode. Quantification was performed with 500 μL of plasma by the addition of deuterated analogues as internal standards.

RESULTS

The proposed method has been validated in the linearity range of 25-1000 ng/mL for all the analytes, with correlation coefficients higher than 0.990. The lower limit of quantification was 25 ng/mL. The intra- and inter-day precision, calculated in terms of relative standard deviation, were 2.0-12.0% and 6.0-15.0%, respectively. The accuracy, in terms of relative error, was within a ± 10% interval. The absolute recovery and extraction efficiency ranged from 81.0 to 111.0% and 81.0 to 105.0%, respectively.

CONCLUSIONS

A GC/MS method for the rapid and simultaneous determination of meperidine, normeperidine, tramadol, propoxyphene and norpropoxyphene in human plasma was developed, optimized and validated. This procedure was shown to be sensitive and specific using small specimen amounts, suitable for application in routine analysis for forensic purposes and therapeutic monitoring. To our knowledge, this is the first full validation of the simultaneous determination of these opioids and their metabolites in plasma samples.

Application of gas chromatography-tandem mass spectrometry for the determination of amphetamine-type stimulants in blood and urine

Amphetamine, methamphetamine, phentermine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), and 3,4-methylenedioxy-N-ethylamphetamine (MDEA) are the most popular amphetamine-type stimulants. The use of these substances is a serious societal problem worldwide. In this study, a method based on gas chromatography-tandem mass spectrometry (GC-MS/MS) with simple and rapid liquid-liquid extraction (LLE) and derivatization was developed and validated for the simultaneous determination of the six aforementioned amphetamine derivatives in blood and urine. The detection of all compounds was based on multiple reaction monitoring (MRM) transitions. The most important advantage of the method is the minimal sample volume (as low as 200μL) required for the extraction procedure. The validation parameters, i.e., the recovery (90.5-104%), inter-day accuracy (94.2-109.1%) and precision (0.5-5.8%), showed the repeatability and sensitivity of the method for both matrices and indicated that the proposed procedure fulfils internationally established acceptance criteria for bioanalytical methods The procedure was successfully applied to the analysis of real blood and urine samples examined in 22 forensic toxicological cases. To the best of our knowledge, this is the first work presenting the use of GC-MS/MS for the determination of amphetamine-type stimulants in blood and urine. In view of the low limits of detection (0.09-0.81ng/mL), limits of quantification (0.26-2.4ng/mL), and high selectivity, the procedure can be applied for drug monitoring in both fatal and non-fatal intoxication cases in routine toxicology analysis.