Cleaning up blood samples using a modified "QuEChERS" procedure for the determination of drugs of abuse and benzodiazepines by UPLC-MSMS(☆)

Development of a dispersive liquid-liquid microextraction method for the evaluation of maternal-fetal exposure to cocaine employing human umbilical cord tissue

Illicit drug use is a serious and complex public health problem, not only due to the severity of the health damage but also to the social implications, such as marginalization and drug trafficking. Currently, cocaine (COC) is among the most abused drugs worldwide with about 22 million users. Drug abuse has also been found in women during the pregnancy period, which has shed light on a new group for epidemiology. The diagnosis of COC use in these cases usually depends largely on the mother's reports, which in several cases omit or deny consumption. Therefore, considering physical-chemical methods of sample preparation and exposure biomarkers, the development of analytic toxicological methods can help to confirm drug use during pregnancy. Thus, the objective of the present work was to develop an analytical method based on dispersive liquid-liquid microextraction for the determination of COC analytes, using umbilical cord tissue as an alternative biological matrix, and detection by gas chromatography coupled to mass spectrometry. Therefore, after optimization, the dispersive liquid-liquid microextraction method was fully validated for quantification of COC, benzoylecgonine, cocaethylene, ecgonine, ecgonine methyl ester and norcocaine. The limits of detection were between 15 and 25 ng/g, the limits of quantification were 30 ng/g for ecgonine and 25 ng/g for the other analytes. Linearity ranged from the limits of quantification to 1,000 ng/g. Coefficients of variation for intra-assay precision were <18.5%, inter-assay was <8.75% and bias was <16.4% for all controls. The developed method was applied in 10 suspected positive samples, based on the mother's report and maternal urine screening and confirmation. COC, benzoylecgonine, ecgonine and ecgonine methyl ester were quantified in four umbilical cords with concentrations that ranged from 39.6 to 420.5 ng/g.

Validation of a non-targeted method devoted to identification and quantitation of toxicologically relevant compounds in plasma with HRMS

The objective of this study was to develop and validate a simple method using liquid chromatography hyphenated to high resolution mass spectrometry (HRMS) allowing both the performance of a non-targeted screening and the simultaneous quantification of 29 compounds of interest in clinical and forensic toxicology. Extraction was done with QuEChERS salts and acetonitrile, after addition of internal standard to 200 μL of human plasma samples. The mass spectrometer was an Orbitrap, with a heated electrospray ionization (HESI) probe. The analyses were carried out in full scan experiment with a nominal resolving power of 60,000 FWHM within the 125-650 m/z mass range, followed by four cycles of data dependent analysis (DDA) with a mass resolution of 16,000 FWHM. The untargeted screening was evaluated using 132 compounds, mean limit of identification (LOI) was 8.8 ng/mL (min = 0.05 ng/mL, max = 500 ng/mL) and mean limit of detection (LOD) was 0.25 ng/mL (min = 0.05 ng/mL, max = 5 ng/mL). The method was linear in the 5 to 500 ng/mL range (0.5 to 50 ng/mL for cannabinoids, 6-acetylmorphine and buprenorphine) with correlation coefficients > 0.99, intra- and inter-day accuracy and precision were < 15% for all compounds. The method was successfully applied to 31 routine samples.

Development of two fully automated quick, easy, cheap, effective, rugged, and safe pretreatment methods for the extraction of psychotropic drugs from whole blood samples

Quick, easy, cheap, effective, rugged, and safe extraction strategies are becoming increasingly adopted in various analytical fields to determine drugs in biological specimens. In the present study, we developed two fully automated quick, easy, cheap, effective, rugged, and safe extraction methods based on acetonitrile salting-out assisted liquid-liquid extraction (method 1) and acetonitrile salting-out assisted liquid-liquid extraction followed by dispersive solid-phase extraction (method 2) using a commercially available automated liquid-liquid extraction system. We applied these methods to the extraction of 14 psychotropic drugs (11 benzodiazepines and carbamazepine, quetiapine, and zolpidem) from whole blood samples. Both methods prior to liquid chromatography-tandem mass spectrometry analysis exhibited high linearity of calibration curves (correlation coefficients, > 0.9997), ppt level detection sensitivities, and satisfactory precisions (< 8.6% relative standard deviation), accuracies (within ± 16% relative error), and matrix effects (81-111%). Method 1 provided higher recovery rates (80-91%) than method 2 (72-86%), whereas method 2 provided higher detection sensitivities (limits of detection, 0.003-0.094 ng/mL) than method 1 (0.025-0.47 ng/mL) owing to the effectiveness of its dispersive solid-phase extraction cleanup step. These fully automated extraction methods realize reliable, labor-saving, user-friendly, and hygienic extraction of target analytes from whole blood samples.

Microextraction Techniques for Sample Preparation of Amphetamines in Urine: A Comprehensive Review

Psychological disorders and dramatic social problems are serious concerns regarding the abuse of amphetamine and its stimulant derivatives worldwide. Consumers of such drugs experience great euphoria along with serious health problems. Determination and quantification of amphetamine-type stimulants are indispensable skills for clinical and forensic laboratories. Analysis of low drug doses in bio-matrices necessitates applications of simple and also effective preparation steps. The preparation procedures not only eliminate adverse matrix effects, but also provide reasonable clean-up and pre-concentration benefits. The current review presents different methods used for sample preparation of amphetamines from urine as the most frequently used biological matrix. The advantages and limitations of various sample preparation methods were discussed focusing on the miniaturized methods.

Recent Update on Pretreatment and Analysis Methods of Buprenorphine in Different Matrix

Buprenorphine is one of the most commonly used pain-killing drugs due to its lengthy duration of action and high potency. However, excessive usage of buprenorphine can be harmful to one's health and prolonged use might result in addiction. Additionally, an increasing number of cases have been documented involving the illegal use of buprenorphine. Therefore, a variety of effective and reliable methods for pretreatment and determination of buprenorphine and its main metabolite norbuprenorphine have been established. This review aims to update the current state of pretreatment and detection techniques for buprenorphine and norbuprenorphine from January 2010 to March 2022. Pretreatment methods include several traditional extraction methods, solid-phase extraction, QuECHERS, various micro-extraction techniques, etc. while analytical methods include LC-MS, LC coupled with other detectors, GC-MS, capillary electrophoresis, electrochemical sensors, etc. The pros and cons of various techniques were compared and summarized, and the prospects were provided. HIGHLIGHTSProgress in pretreatment and detection methods for buprenorphine is demonstrated.Pros and cons of different pretreatment and analysis methods are compared.New materials (such as nanomaterials and magnetic materials) used in buprenorphine pretreatment are summarized.Newly emerged environmental-friendly methods are discussed.

The direct immersion solid phase microextraction coupled with the LC–MS method for ex vivo determination of selected date-rape drugs in the human blood samples

Nowadays, solid phase microextraction is developing rapidly. The use of this extraction technique allowed for the reduction of toxic solvents usage, easy automatization, and integration with other techniques. In this study, the use of DI-SPME/LC–MS to determine selected date-rape drugs (benzodiazepines, ketamine, and cocaine) is presented. The determined values of validation parameters: limits of detection (LOD = 0.6–4.9 ng cm−3), and quantification (LOQ = 25 or 50 ng cm−3), intra-day and inter-day precision (CV = 0.87–10.7% and 4.96–16.1%, respectively), recovery (RE = 94.6–106.7%) and matrix effect (81.7–116.5%) indicated that the tested method could be used to determine the concentration of date-rape drugs in blood samples. The evaluation of the method according to the principles of White Analytical Chemistry showed that the DI-SPME/LC–MS method was characterized by satisfactory analytical quality, greenness, and economical use. The use of this method met the requirements of Green Chemistry. The significant advantages of this method were the quick analytical procedure, partial automation of the extraction stages, high sensitivity, lower sample, and reagent consumption.

Graphical abstract

Novel extraction method using an ISOLUTE PLD+ protein and phospholipid removal column for liquid chromatography-tandem mass spectrometry analysis of 20 psychoactive drugs in postmortem whole blood samples

A novel sample extraction method using an ISOLUTE PLD+ protein and phospholipid removal column was developed for simultaneous quantification of 20 psychoactive drugs, including antidepressants, antipsychotics, sedative-hypnotics, and amphetamines, in postmortem whole blood samples by liquid chromatography-tandem mass spectrometry. The method showed improvement in extract cleanliness compared with traditional protein precipitation and the QuEChERS extraction method. The method was validated for all analytes; the calibration curves showed good linearity, with r² values exceeding 0.991. The intra- and interday accuracies and precisions were 87.6-117.5% and 1.0-18.6%, respectively. The recovery efficiencies were in the range of 64.6-96.8%. Matrix effects were observed in the range of 82.6-116.0%. All analytes were stable under different storage conditions. This method was successfully applied in postmortem forensic sample analysis to quantify psychoactive drugs. The method described in the current study will be useful for forensic toxicological investigations.

Development and Validation of a Method for Quantification of 28 Psychotropic Drugs in Postmortem Blood Samples by Modified Micro-QuEChERS and LC-MS-MS

The development of new sample preparation alternatives in analytical toxicology leading to quick, effective, automated and environmentally friendly procedures is growing in importance. One of these alternatives is the QuEChERS, originally developed for the analysis of pesticide residues, producing cleaner extracts than liquid-liquid extraction, and easier separation of aqueous and organic phases. However, there are few published studies on the miniaturization of this technique for forensic toxicology, especially in postmortem analysis. We developed and validated a modified micro-QuEChERS and LC-MS-MS assay to quantify 16 antidepressants, 7 antipsychotics and 3 metabolites and semi-quantify norfluoxetine and norsertraline in postmortem blood. The calibration curve was linear from 1 to 500 ng/mL, achieved an r > 0.99, with all standards quantifying within ±15% of target except ±20% at the limit of quantification of 1 ng/mL for 26 substances. The F test was applied to evaluate if the variance between replicates remained constant for all calibrators. Six weighting factors were analyzed (1/x, 1/x2, 1/x0,5, 1/y, 1/y2 and 1/y0,5), with the weighting factor with the lowest sum of residual regression errors (1/x2) selected. No endogenous or exogenous interferences were observed. Method imprecision and bias were <19.0% and 19.7%, respectively. Advantages of this method include a low sample volume of 100 µL, simple but effective sample preparation and a rapid 8.5-min run time. The validated analytical method was successfully applied to the analysis of 100 authentic postmortem samples.

Improved liquid-liquid extraction by modified magnetic nanoparticles for the detection of eight drugs in human blood by HPLC-MS

Magnetic nanoparticles modified with porous titanium dioxide were used as clean-up nanospheres for the detection of eight drug poisons in human blood by high-performance liquid chromatography-mass spectrometry. The magnetic clean-up nanospheres (Fe₃O₄@mTiO₂) with a mesoporous structure were successfully synthesized and characterized by scanning electron microscopy/energy dispersive spectroscopy, transmission electron microscopy, X-ray diffractometry, vibrating sample magnetometry, infrared spectroscopy, and Brunauer–Emmett–Teller techniques. Lipid co-extractives, such as phosphatidic acid and fatty acids, which are major interferences in HPLC-MS analysis causing ion suppression in the MS spectra of blood, could be efficiently removed by Fe₃O₄@mTiO₂ based on the Lewis acid–Lewis base interactions. Following the optimization of the quantities of Fe₃O₄@mTiO₂, the method was applied to the determination of eight drugs in spiked blood. The analytical ranges typically extended from 2 to 500 ng mL⁻¹, and the recoveries ranged from 79.5–99.9% at different concentrations of blood. The limits of quantitation for drug poisons were 0.14–1.03 ng mL⁻¹, which makes the method a viable tool for drug poison monitoring in blood.

High-performance magnetic Fe₃O₄@TiO₂, nanospheres with mesoporous structures was synthesized for cleanup phosphatidic acid and fatty acids in blood sample for 8 drugs test with HPLC-MS.

Quantitative analysis of 20 fentanyl analogues by modified QuEChERS-LC-MS/MS in health products and transdermal patches

The spreading of narcotics especially illicit novel psychoactive substances is a continuing problem in recent years. In response to reduce the morbidity and crime related to fentanyl analogues, the accurate measurement of fentanyl analogues concentrations is significantly important in the analytical laboratories for customs checks and clinical application. In this work, ethyl acetate was selected as extraction solvent, 50 mg of PSA, 100 mg of C18, and 10 mg of GCB were optimized for purification. A modified QuEChERS extraction method followed by high performance liquid chromatography-tandem mass spectrometry with the mode of multiple reaction monitoring has been developed for the simultaneous determination of 20 fentanyl analogues in collagen peptides, slimming capsules and fentanyl transdermal patches. The limits of detection (LODs) varied from 0.004 to 0.02 μg L^-1 with relative standard deviations of 4.89-11.4 % and showed good linearity in the range of 0.02-10 μg L^-1 and 0.01-1.00 mg L^-1, respectively. The recoveries for 20 fentanyl analogues in the low (at μg L^-1 level) and high (at mg L^-1 level) concentration spiked samples were in the range of 77.7-114 % and 83.9-116 %, which demonstrated the application potential of the proposed method for the determination of fentanyl analogues with low and high concentration in real case samples. In addition, the matrix effect and the cross-reactivity were also proved to not interfere with quantitation of targeted fentanyl analogues. Thus, the developed method showed high sensitivity and good accuracy, which makes it suitable for the rapid detection of fentanyl analogues for customs and border service as well as pharmaceuticals.

Simple extraction of toxicologically relevant psychotropic compounds and metabolites from whole blood using mini-QuEChERS followed by UPLC-MS/MS analysis

The determination of psychotropic drugs and metabolites in blood is relevant in the context of both therapeutic drug monitoring and clinical and forensic toxicology. LC-MS/MS is the preferred method for these assays. However, LC-MS/MS is particularly susceptible to matrix ionization effects and appropriate sample preparation is required to minimize these effects. In this study, a simple, single-step, mini-QuEchERS extraction procedure, coupled to UPLC-MS/MS, was developed and validated for the determination of 15 toxicologically relevant compounds in whole blood, including psychoactive drugs and some metabolites. The assay was linear in the range of 25-1,000 ng ml^-1 , fulfilling criteria for accuracy and precision. Extraction yields (71.9-87.7%) and matrix effects (-3.3 to +4.4%, with the exception of codeine, which had matrix effects of -35.36 to -28.14%) were acceptable for the majority of the evaluated compounds, using a single internal standard. The assay was applied to 238 clinical specimens from patients admitted to an emergency service, with 22 samples presenting quantifiable concentrations of 11 different compounds. The developed assay is a simple and efficient strategy for determination of target psychotropic drugs and metabolites in forensic and clinical toxicology.

Quantification of 54 Benzodiazepines and Z-Drugs, Including 20 Designer Ones, in Plasma

Benzodiazepines are widely used in the treatment of sleep and anxiety disorders, as well as epileptic seizures and alcohol withdrawal because of their broad therapeutic index and low cost. Due to their central nervous system depressant effects they are also often implicated in traffic accidents and drug-related intoxications. With an increasing number of designer benzodiazepines used in a recreational setting, there is a need for analytical methods to be able to quantify both the prescribed and designer benzodiazepines. A liquid chromatography-triple quadrupole mass spectrometry method was developed for the quantification of 34 prescribed and 20 designer benzodiazepines in plasma. Different sample preparation strategies, including protein precipitation, liquid-liquid extraction, solid-phase extraction and mini-QuEChERS, were tested. The best recoveries for all compounds of interest were obtained with a liquid-liquid extraction using methyl-tertiary-butyl-ether and 500 μL plasma. The method was fully validated according to the European Medicines Agency guidelines for all compounds, except pivoxazepam, which is included for qualitative purposes only. In-sample stability issues were observed for cloxazolam, both at ambient temperature and during long-term storage at -20°C. Due to the large number of compounds included, the simple and time-efficient sample preparation and the relatively inexpensive instrumentation used, the presented method can be readily implemented in both therapeutic drug monitoring and forensic analyses.

A UHPLC-MS-MS Method for the Determination of 84 Drugs of Abuse and Pharmaceuticals in Blood

The analysis of blood samples for forensic or clinical intoxication cases is a daily routine in an analytical laboratory. The list of 'suspect' drugs of abuse and pharmaceuticals that should be ideally screened is large, so multi-targeted methods for comprehensive detection and quantification are a useful tool in the hands of a toxicologist. In this study, the development of an ultra-high performance liquid chromatography (LC)-tandem mass spectrometry (MS-MS) method is described for the detection and quantification of 84 drugs and pharmaceuticals in postmortem blood. The target compounds comprise pharmaceutical drugs (antipsychotics, antidepressants, etc.), some of the most important groups of drugs of abuse: opiates, cocaine, cannabinoids, amphetamines, benzodiazepines and new psychoactive substances. Sample pretreatment was studied applying a modified Mini-QuEChERS single step, and the best results were obtained after adding a mixture of 20 mg MgSO4, 5 mg K2CO3 and 5 mg NaCl together with 600 μL of cold acetonitrile in 200 μL of sample. After centrifugation, the supernatant was collected for direct injection. LC-MS analysis took place on a C18 column with a gradient elution over 17 min. The method was found to be selective and sensitive, offering limits of detection ranging from 0.01 to 9.07 ng/mL. Validation included evaluation of limit of quantification, recovery, carryover, matrix effect, accuracy and precision of the method. The method performed satisfactorily in relation to established bioanalytical criteria and was therefore applied to the analysis of blood obtained postmortem from chronic drug abusers, offering unambiguous identification and quantitative determination of drugs in postmortem blood.

High-Performance Liquid Chromatography-Tandem Mass Spectrometry for Buprenorphine Evaluation in Plasma-Application to Pharmacokinetic Studies in Rabbits

The precise and reliable determination of buprenorphine concentration is fundamental in certain medical or research applications, particularly in pharmacokinetic studies of this opioid. The main challenge is, however, the development of an analytical method that is sensitive enough, as the detected in vivo concentrations often fall in very low ranges. Thus, in this study we aimed at developing a sensitive, repeatable, cost-efficient, and easy HPLC analytical protocol for buprenorphine in rabbit plasma. In order to obtain this, the HPLC-MS² system was used to elaborate and validate the method for samples purified with liquid-liquid extraction. Fragment ions 468.6→396.2 and 468.6→414.2 were monitored, and the method resulted in a high repeatability and reproducibility and a limit of quantification of 0.25 µg/L with a recovery of 98.7–109.0%. The method was linear in a range of 0.25–2000 µg/L. The suitability of the analytical procedure was tested in rabbits in a pilot pharmacokinetic study, and it was revealed that the method was suitable for comprehensively describing the pharmacokinetic profile after buprenorphine intravenous administration at a dose of 300 µg/kg. Thus, the method suitability for pharmacokinetic application was confirmed by both the good validation results of the method and successful in vivo tests in rabbits.

Optimization of QuEChERS extraction for detection and quantification of 20 antidepressants in postmortem blood samples by LC-MS/MS

In this study, a comprehensively optimization of QuEChERS (quick, easy, cheap, effective, rugged and safe) method using design of experiments (DOE) was conducted to evaluate the best conditions to obtain the most effective extraction. Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis was performed to identify and quantify the antidepressants, with electrospray ionization acquired in positive mode. The method was validated for all analytes; the calibration curves were linear from 10-1000ng/mL, with R²>0.98, and with LOD and LOQ defined as 10ng/mL. Method imprecision and bias were less than 14.3% and 18.9%, respectively. Neither carryover nor interferences were observed. Overall, the optimized method was applied in postmortem real sample analysis to quantify the antidepressants. This study showed a viable method that can be applied for routine forensic analysis, with a quick and easy sample preparation and a rapid total run time of 8min for each analysis.

Determination of morphine and its metabolites in the biological samples: an updated review

Morphine (MO) as an opioid analgesic is used for the treatment of moderate-to-severe pains, particularly cancer-related pains. Pharmacologic studies on MO are complicated due to drugs binding to the protein or metabolization to active metabolites, and even inter-individual variability. This necessitates the selection of a reliable analytical method for monitoring MO and the concentrations of its metabolites in the biological samples for the pharmacokinetic or pharmacodynamic investigations. Therefore, this study was conducted to review all the analytical research carried out on MO and its metabolites in the biological samples during 2007-2019 as an update to the study by Bosch et al. (2007).

A case report positive for synthetic cannabinoids: are cardiovascular effects related to their protracted use?

The use of synthetic cannabinoids is being increasingly recognised worldwide, but the chemical compositions and physiological effects of these drugs are poorly characterised and are continually changing. New substances are constantly being added to the content of synthetic cannabinoids and they are rarely identified on toxicological screening tests. Due to their structures synthetic cannabinoids and their effects have been compared to the psychoactive compound, Δ-9-tetrahydrocannabinol (THC), found in marijuana. On the molecular level, they are potent cannabinoid receptor agonists that also may have affinity for other types of receptors such as those on platelets. Reported symptoms of toxicity include anxiety, agitation, paranoia, hallucinations, tachycardia, hypertension, excessive sweating, nausea, and vomiting. They can also be linked to serious adverse cardiovascular events and can affect the cardiovascular system causing hypotension and bradycardia, myocardial infarction, atrial fibrillation, prolonged QTc, and Mobitz type II atrioventricular block, as well as interfere with the aggregation of platelets. We present a case report of a cardiac tamponade with toxicological findings positive for synthetic cannabinoids. This case highlights the importance of testing routinely for novel psychoactive compounds, and recognising their potential to cause life-threatening conditions.

Psychoactive substances in mussels: Analysis and occurrence assessment

This work presents an analytical methodology based on a "Quick, easy, cheap, effective, rugged, and safe" (QuEChERS) extraction and liquid chromatography-tandem mass spectrometry detection (LC-MS/MS) for the simultaneous determination of 35 psychoactive substances in fresh mussel samples. The compounds investigated include illicit drugs, new psychoactive substances, commonly prescribed psychiatric pharmaceuticals, and caffeine. The methodology was validated in terms of recovery (relative recoveries 77-118%), repeatability (relative standard deviation values <20%), and sensitivity (limits of detection and quantification <2 ng/g fresh weight (f.w.) and <6.7 ng/g f.w., respectively, for most compounds). The method was applied to the analysis of 15 samples, covering both commercially available mussels purchased from local food markets and wild fresh mussels collected in the Northeast coast of Spain in the Mediterranean Sea. Only one sample corresponding to wild mussels was found to contain 2 of the target analytes, namely, sertraline (1.5 ng/g f.w.) and caffeine, (12.8 ng/g f.w.).

Determination of benzodiazepines in pericardial fluid by gas chromatography-mass spectrometry

In Forensic Toxicology it is sometimes impossible to obtain a valid blood sample to perform toxicological analysis due to several factors like advanced state of decomposition, severe burns, bleed to death…. Pericardial Fluid has already been studied during the last years and has been proposed as a valid specimen for toxicological tests. Over the years, the consumption of benzodiazepines spread among the drug dependent population and became noticeable in drug facilitated assault cases and road accidents. Improvement of the analytical methodology required for detecting the presence of these drugs in biological samples is of great importance for forensic toxicology, in order to correctly diagnose an exposure or a poisoning. In this study, 9 benzodiazepines (diazepam, nordiazepam, midazolam, bromazepam, oxazepam, temazepam, lorazepam, clonazepam and alprazolam) have been determined in pericardial fluid. For this purpose a solid phase extraction (SPE) was carried out using Bond Elut Certify cartridges. After the derivatization of six of the nine benzodiazepines, gas chromatography coupled to a selective mass detector was used as the technique for the separation of the analytes. The method developed was fully validated for the 9 analytes and was applied to real samples of pericardial fluid received at the Forensic Toxicology Service of the University of Santiago de Compostela. Finally, they were compared with blood results looking for the existence of a possible correlation between both biological samples.

High-throughput determination of valproate in human samples by modified QuEChERS extraction and GC-MS/MS

A new high-throughput method was developed for analysis of valproate in human plasma samples by QuEChERS extraction and gas chromatography-tandem mass spectrometry (GC-MS/MS). Plasma samples (0.2 ml) spiked with valproate and secobarbital-d₅ (internal standard) were diluted with 1.3 ml of distilled water. Acetonitrile (1 ml) was added followed by 0.4 g MgSO₄ and 0.1 g NaOAC. After a centrifugation step (2000 g for 10 min), 1 ml of the supernatant was transferred to a dispersive-solid phase extraction (dSPE) tube containing 150 mg MgSO₄ and 50 mg C₁₈. This mixture was vortexed and centrifuged at 3000 g for 5 min, and then the upper layer was evaporated to dryness under a stream of nitrogen. The residue was dissolved in 40 μl ethyl acetate, and a 1-μl aliquot was injected into the GC-MS/MS. The GC separation of the compounds was achieved on a fused-silica capillary column Rxi-5Sil MS (30 m × 0.25 mm i.d.; 0.25-µm film thickness) and detected by MS/MS operating in electron ionization ion source mode. The regression equations showed excellent linearity (r > 0.9997) from 50 to 5000 ng/ml for plasma, with limit of detection of 10 ng/ml. The extraction efficiency of valproate for plasma ranged between 71.2%-103.5%. The coefficient of variation was <18.5%. The method was successfully applied to actual analyses of an autopsy case. This method can be useful for simple and reliable measurements of valproate in clinical and toxicological analyses; it can be integrated in screening and simultaneous determination methods for multiple drugs and poisons in the further studies.

UPLC-MS/MS analysis of ochratoxin A metabolites produced by Caco-2 and HepG2 cells in a co-culture system

Ochatoxin A (OTA) is one of the most important mycotoxins based on its toxicity. The oral route is the main gateway of entry of OTA into the human body, and specialized epithelial cells constitute the first barrier. The present study investigated the in vitro cytotoxic effect of OTA (5, 15 and 45 μM) and production of OTA metabolities in Caco-2 and HepG2 cells using a co-culture Transwell System to mimic the passage through the intestinal epithelium and hepatic metabolism. The results derived from MTS cell viability assays and transepithelial electrical resistance measurements showed that OTA was slightly cytotoxic at the lowest concentration at 3 h, but significant toxicity was observed at all concentrations at 24 h. OTA metabolites generated in this co-culture were ochratoxin B (OTB), OTA methyl ester, OTA ethyl ester and the OTA glutathione conjugate (OTA-GSH). OTA methyl ester was the major metabolite found in both Caco-2 and HepG2 cells after all treatments. Our results showed that OTA can cause cell damage through several mechanisms and that the OTA exposure time is more important that the dosage in in vitro studies. OTA methyl ester is proposed as an OTA exposure biomarker, although future studies should be conducted.

Assessing cocaine abuse using LC-MS/MS measurements in biological specimens

Cocaine use is still a problem in today's world, and this has several implications on human activities. Indeed, important problems related to cocaine derive from its use in situations where concentration and focus skills are necessary, namely while driving and/or working. The need of analytical methods for drug analysis in specimens of biological origin for proper documentation of human exposure is increasing. While GC-MS-based procedures represented the state-of-the-art of analytical techniques a few years ago, there is a growing trend for their replacement by LC-MS/MS, which can be justified by the increased sensitivity presented by these new technologies. This paper will review recently published papers on the use of LC-MS/MS-based procedures for cocaine measurement in biological specimens.

QuEChERS sample preparation prior to LC-MS/MS determination of opiates, amphetamines, and cocaine metabolites in whole blood

Modern LC-MS/MS instruments have sensitivity and scanning velocity high enough to analyze many different compounds in single runs. Consequently, the sample preparation procedure has become the bottleneck for developing efficient, rapid, and cheap multi-compound methods. Here, we examined one-step sample preparation based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) salts to set up and validate a LC-MS/MS method for the simultaneous determination of 35 drugs of abuse and their metabolites in whole blood. Despite large differences in physicochemical properties, this simplified QuEChERS extraction method yielded satisfactory recoveries (until 96%) for the 35 molecules. The amounts of QuEChERS salts had no influence on extraction yield. Chromatographic separation was obtained in less than 6 min. LLOD and LLOQ were 3 and 5 ng/mL, respectively. The procedure was successfully validated and then applied to 253 cases of driving under the influence of drugs (DUID), collected over a 6-month period.

Highly sensitive analysis of polyphenols and their metabolites in human blood cells using dispersive SPE extraction and LC-MS/MS

Blood cells, particularly erythrocytes, present a significant compartment for distribution of drugs and endogenous compounds and have been suggested to be factored in pharmacokinetic and pharmacodynamic evaluations. We previously detected the binding of polyphenols to red blood cells and found indications for a facilitated uptake of the bioactive procyanidin metabolite δ-(3,4-dihydroxy-phenyl)-γ-valerolactone (M1) into human erythrocytes. The purpose of the present investigation was to develop an effective, sensitive and robust liquid chromatography tandem mass spectrometry (LC-MS/MS) method to quantify low concentrations of polyphenols in human blood cells. Various sample preparation methods including classic sample clean-up techniques and variations of the QuEChERS (quick, easy, cheap, effective, rugged and safe) approach were compared regarding compound recovery, matrix effects and overall process efficiency. The QuEChERS technique which involves a liquid-liquid extraction and clean-up by dispersive solid-phase extraction yielded best results. The method was fully validated for the six analytes: (+)-catechin, ferulic acid, M1, taxifolin, caffeic acid and δ-3-methoxy-4-hydroxy-phenyl- γ-valerolactone (M2) in human blood cells with an optimised QuEChERS sample preparation and prior enzymatic hydrolysis of analyte conjugates. The lower limits of quantification for the analytes ranged from 0.12 ng/mL for M1, M2 and taxifolin to 48.40 ng/mL for caffeic acid. The application of the method to a blood cell sample of a volunteer ingesting 100 mg/day of the standardised pine bark extract Pycnogenol(®) over the course of 3 weeks revealed measurable steady-state concentrations of catechin, M1, taxifolin, ferulic acid and M2. To our knowledge, this is the first report of using the QuEChERS approach for detection and quantification of plant-derived compounds in human blood cells. The method can be applied in pharmacokinetic studies to determine the distribution of polyphenols and their metabolites in human whole blood, blood cells or erythrocytes. This might contribute in gaining deeper insights into the in vivo distribution of polyphenols and their metabolites.