Development of a simple one-pot extraction method for various drugs and metabolites of forensic interest in blood by modifying the QuEChERS method

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.

Green Analytical Toxicology for the Determination of Cocaine Metabolites

Brazil is the third largest contributor to Green Analytical Chemistry, and there is significant participation of toxicologists in the development and improvement of environmental techniques. Currently, toxicologists have their own strategies and guidelines to promote the reduction/replacement or elimination of solvents, reduce the impacts of derivatization and save time, among other objectives, due to the peculiarities of toxicological analysis. Thus, this review aims to propose the concept of Green Analytical Toxicology and conduct a discussion about its relevance and applications specifically in forensic toxicology, using the microextraction methods developed for the determination of cocaine and its metabolites as examples.

Successive liquid-phase microextraction of acidic and basic analytes

Practical biological and environmental samples always contain both acidic and basic substances, and the samples are always precious. Thus, separation of analytes with different nature from the same sample was of great significance. Successive liquid phase microextraction (sLPME) of acidic and basic analytes under optimal extraction conditions was therefore proposed for the first time. The concept of sLPME was proved by using three acidic analytes (naproxen, flurbiprofen and diclofenac) and three basic analytes (haloperidol, fluoxetine and sertraline) as model analytes, and using polypropylene glycol with an average molecular weight of 4000 (PPG4000) as SLM. The recoveries of all target analytes by sLPME were similar to that by individual LPME due to good affinity of PPG4000 to both acidic and basic analytes. Under optimal extraction conditions, the recoveries for all analytes by sLPME from urine samples were in the range of 62%-95%. Moreover, combined with LC-MS/MS, such sLPME approach was also evaluated with urine samples. The matrix effect of sLPME-LC-MS/MS at different levels for all analytes ranged from -14.1%-13.2%. The linear ranges with R² > 0.996 were 5-1000 ng mL^-1 for basic analytes, and 20-1000 ng mL^-1 for acidic analytes except diclofenac (1-1000 ng mL^-1). The repeatability and accuracy at four levels were in the range of 3%-10% and 86%-120%, respectively. The limit of detection (LOD, S/N = 3) and limit of quantification (LOQ, S/N = 10) were found to be 0.07-0.49 ng mL^-1 and 0.25-1.63 ng mL^-1, respectively. Finally, the strategy for constructing a sLPME system was further confirmed with urine, plasma and saliva using another two versatile SLM solvents possessing high affinity to both acidic and basic analytes. Successive LPME enabled separation of acidic and basic analytes from the same sample under optimum extraction conditions for all target analytes. Thus, we believe that the sLPME system will become a potent platform for forensic toxicology analysis, food science, environmental analysis and epidemiology study.

Nano-titania modified cupric-based metal–organic frameworks for the on-line pass-through cleanup of phenothiazine drugs and metabolites in human plasma

SEM (A) and TEM (B) images of NTMCu-MOFs.

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.

LC-MS/MS method for determining picogram-level of zolpidem and its main metabolites in hair using a zirconia-based sorbent

Although urine and blood samples have been conventionally used for testing zolpidem (ZPD), a sedative-hypnotic, these matrices have limited application because they have a relatively short detection period and can be used only in case of recent drug exposure. Therefore, it is necessary to use an alternative biological sample to obtain the evidence of ZPD misuse. Herein, a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for the determination of ZPD and its metabolites, zolpidem phenyl-4-carboxylic acid (ZPCA) and zolpidem 6-carboxylic acid (ZCA), in hair to resolve the above-mentioned problems. Mechanical pulverization of hair, methanol extraction with sonication, and the zirconia-based hybrid solid-phase extraction technique were used for obtaining improved extraction efficiency and effective sample purification. The treated hair sample was analyzed using the LC-MS/MS method with the electrospray ionization source in positive and multiple-reaction monitoring modes. The target analytes were separated and detected within 8 min using an Xselect HSS T3 column. Gradient elution was performed using 5 mM ammonium formate and acetonitrile. The lower limit of quantification of ZPD, ZPCA, and ZCA were 1.0, 0.5, and 1.0 pg mg^-1, respectively. The calibration ranges were 1.0-1000.0 pg mg^-1 for ZPD, 0.5-200.0 pg mg^-1 for ZPCA, and 1.0-200.0 pg mg^-1 for ZCA, with the determination coefficients (r² ≥ 0.9986). The intraday accuracy and precision ranged from -7.1 to 9.0% and within 6.5%, respectively, and the interday accuracy and precision ranged from -6.1 to 7.9% and within 5.4%, respectively. The recovery, matrix effect, and process efficiency were 65.2-96.6%, 64.6-106.5%, and 44.3-100.5%, respectively, with the relative standard deviation of 4.0-5.0%. The developed method was successfully applied to analyze 13 forensic hair samples of ZPD abusers, and the concentration ratios of ZPD and its two main metabolites (ZPCA and ZCA) in the ZPD-positive samples were also presented. These results revealed that ZPCA and ZCA were not easily incorporated into hair, and demonstrated that their analysis in hair samples requires the employed method to have picogram-level sensitivity. Therefore, the developed method was suitable for simultaneous analysis of ZPD, ZPCA, and ZCA in hair samples, and it could provide clear evidence for illegal ZPD administration, including ZPD-facilitated sexual assault.

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.

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.

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.

Quantitation of Fentanyl and Metabolites from Liver Tissue Using a Validated QuEChERS Extraction and LC-MS-MS Analysis

According to the National Institute on Drug Abuse (NIDA), more than one hundred people die every day from opioid overdose. Overdose fatalities have risen as the availability of potent synthetic opioids, such as fentanyl, has increased. A forensic postmortem toxicological specimen is often in various stages of decomposition, experiencing autolysis and putrefaction, which complicates the extraction, creating a difficult challenge for toxicologists. Isolating the target drug, while creating an efficient and simplified analytical scheme, is a goal for most toxicology laboratories. The validation of a quick, easy, cheap, effective, rugged and safe extraction protocol is presented in this study as an alternative analytical method for efficient extraction and detection of fentanyl and its major metabolites: norfentanyl and despropionyl fentanyl (4-ANPP). The liquid Chromatography with tandem mass spectrometry analysis was validated following the American Academy of Forensic Sciences Standards Board (ASB) standard 036 proposed requirements. Evaluated parameters include selectivity, matrix effects (MEs), linearity, processed sample stability, bias, precision and proof of applicability using liver samples from authentic postmortem cases. MEs (represented as percent ionization suppression or enhancement) at low and high concentrations were -10.0% and 1.4% for fentanyl, -2.1% and -0.3% for 4-ANPP and 3.1% and 2.8% for norfentanyl, respectively. Bias for the three analytes ranged from -8.5% to -19.9% for the low concentrations, -3.6% to -14.7% for the medium concentrations and 1.5% to -16.1% for the high concentrations with all being within the ±20% guideline. Precision for the three analytes ranged from 2.2% to 15.1%. The linear range for the fentanyl and norfentanyl was 0.5-100 and 4-ANPP had a linear range of 0.4-80 μg/kg. The authentic postmortem liver samples ranged in fentanyl concentrations from 56.6 to 462.3 μg/kg with a mean of 149.2 μg/kg (n = 10). The range of norfentanyl concentrations were 1.9 to 50.0 μg/kg with a mean of 14.1 μg/kg (n = 10). The range of 4-ANPP concentrations were 3.2 to 23.7 μg/kg with a mean of 7.5 μg/kg (n = 7).

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.

Development of a UHPLC-MS/MS method for the determination of 84 pharmaceuticals and drugs of abuse in human liver

Analysis of post-mortem liver for toxicological reasons is a considerable option when blood is unavailable. The development of analytical methods for tissue specimens is not as straightforward as for biological fluids as tissue presents challenges to the analytical chemist. The present study reports the development of a UHPLC-MS/MS method for the detection and quantification of 84 drugs and pharmaceuticals in human liver. The selected target drugs include pharmaceutical drugs and drugs of abuse. Sample preparation was studied using QuEChERS and different ratios of solvent volume and sample mass. Best results were attained by homogenizing 1 g of liver with acetonitrile K2CO3 buffer (pH = 10), QuEChERS salts MgSO4/ NaCl (1st purification step) and PSA/ 150 mg MgSO4 (2nd purification step). The extracted sample was analysed on UHPLC-MS/MS in multiple reaction monitoring mode (MRM) on a reversed-phase (Acquity BEH C18) column. Elution was accomplished by gradient program of mobile phase A: water, 0.1% formic acid and B: methanol, 0.1% formic acid that lasted 17 min. The method was specific, without interferences from the complex matrix. Sensitivity was satisfactory with limit of detection (LOD) ranging from 0.01 ng/g to 4.94 ng/g. Validation study was based on the guidelines of international bodies and included evaluation of recovery, carry-over, matrix effect, accuracy, stability, and precision of the method. The method performed satisfactory in relation to established bioanalytical criteria and was therefore applied to the analysis of liver tissue obtained post-mortem from chronic drug abusers, offering unambiguous identification and quantitative determination of drugs in postmortem blood.

Development of a simple HPLC-DAD multi-analyte procedure and its application in cases evaluated by the Poison Control Center of São Paulo, Brazil

This work describes a simple approach to overcome challenges in emergency toxicological analysis, using liquid-liquid extraction and high-performance liquid chromatography coupled with a diode-array detector (HPLC-DAD). A rapid procedure has been developed, for the extraction and detection of 19 analytes from the following drug classes: analgesics, benzodiazepines, antidepressants, anticonvulsants and drugs of abuse. These substances are relevant in the context of emergency toxicology in Brazil. The method has been validated according to international guidelines by establishing parameters such as lower limit of quantification, sensitivity, linearity, accuracy and precision. The intra and inter-day precision values, at the lowest concentration levels, have always been less than 20% considering its relative standard deviation. As for accuracy values, these have also been satisfactory (above 81.3%). This method was successfully applied in 201 blood samples from patients with suspected poisoning of the Poison Control Center of São Paulo (PCC-SP), Brazil. Finally, the developed method has shown to be relevant for emergency toxicology due to its high sensitivity and it could be also very useful in both fields of clinical and forensic toxicology.

Determination of 12 commonly found compounds in DUID cases in whole blood using fully automated supported liquid extraction and UHPLC-MS/MS

A high-throughput UHPLC-MS/MS method for the most frequently found compounds; tetrahydrocannabinol (THC), amphetamine, methamphetamine, MDMA, clonazepam, diazepam, nordiazepam, oxazepam, alprazolam, nitrazepam, morphine, and codeine, in driving under the influence of drugs (DUID) cases in whole blood, is presented. Automated sample preparation by 96-well supported liquid extraction (SLE) plates with ethyl acetate + heptane (80 + 20, v/v) as organic solvent was carried out on a Freedom Evo 200 platform from Tecan. An aliquot of 100 μL whole blood was used. Sample preparation time for 96 samples was 1.5 h. Compounds were separated with gradient elution on a C₁₈ column (50 × 2.1 mm, 1.7 μm) with a mobile phase consisting of 5 mM pH 10.2 ammonium formate and methanol. The run time was 4.5 min and 1 μL was injected on an Acquity UPLC I-Class system with a Xevo TQS tandem-quadrupole mass spectrometer in multiple-reaction monitoring mode (MRM) from Waters. Isotope labelled, ¹³C, internal standards (ISs) were used for all compounds except for alprazolam and morphine, which had deuterated analogs. Quantification was carried out with calibrators without whole blood matrix. Full validation was carried out according to international guidelines, and a new approach for evaluation of process efficiency (PE) has been presented. Linear or quadratic weighted (1/x) calibration curves were used with R² ≥ 0.999. The method showed satisfactory deviations ±16% when compared to the existing methods, and satisfactory agreement with proficiency testing control samples (z-score -1.6 to 1.8, n = 16 samples). The precision, estimated as the relative standard deviation (RSD) of the concentration difference between results from two independent analyses of authentic whole blood samples, was ≤7.2% in antemortem and ≤9.3% in postmortem samples. Recovery was ≥85% for all the compounds, except morphine ≥62% and THC ≥ 50%. PE was satisfactory for all the compounds with low variation in IS response, RSD ≤ 16% (THC 27%) in antemortem samples and ≤34% (THC 66%) in postmortem samples. To the best of our knowledge, this is the first automated 96-well SLE UHPLC-MS/MS method developed for the simultaneous determination of these 12 compounds in whole blood covering the concentration ranges found in forensic samples. The method has been used in routine work during the last ten months, analysing about 9900 antemortem and 1000 postmortem whole blood samples, and has proven to be robust and reliable.

Effect-based approach for screening of chemical mixtures in whole blood of green turtles from the Great Barrier Reef

Organisms are exposed to mixtures of both known and unknown chemicals which are diverse and variable, and thus difficult and costly to characterise and monitor using traditional target analyses. The objective of this study was to validate and apply in vitro effect-based methods by which whole blood can be used to screen internal exposure to such complex chemical mixtures. For this study, we used whole blood of green sea turtles (Chelonia mydas). To ensure the chemical mixture in blood is transferred with minimal losses or bias, we tested a modified QuEChERS extraction method specifically developed for multi- and non-target instrument analysis. The extracts were dosed to a battery of in vitro bioassays (AhR-CAFLUX, AREc32, NFκB-bla, VM7Luc4E2, Microtox), each with a different mode of action (e.g., AhR receptor mediated xenobiotics, NrF2-mediated oxidative stress, NFκB mediated response to inflammation, estrogen activity and baseline toxicity oxidative stress, respectively) in order to cover a wide spectrum of chemicals. Results confirmed the absence of interferences of the blood extract with the responses of the different assays, thus indicating the methods' compatibility with effect-based screening approaches. To apply this approach, whole blood samples were collected from green turtles foraging in agricultural, urban and remote areas of the Australian Great Barrier Reef. The effect-based screening revealed significant differences in exposure, with higher induction of AhR-CAFLUX, AREc32 and Microtox assays in turtles from the agricultural foraging ground. Overall, these results corroborated with concurrent health, target and non-target analyses in the same animals performed as part of a larger program. This study provides evidence that the proposed effect-based approach is suitable for screening and evaluating internal exposure of organisms to chemical mixtures. The approach could be valuable for advancing understanding on multiple levels ranging from identification of priority chemicals in effect-directed investigations to exploring relationships between exposure and disease, not only in sea turtles, but in any organism.

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.

Recent advances in salt-assisted LLE for analyzing biological samples

Salt-assisted LLE (SALLE) has been attracting growing interest in bioanalysis. The technique is particularly advantageous due to its simple and fast experimental execution using conventional laboratory equipment. Besides, SALLE uses water-miscible organic solvents making the extracts readily compatible with various analytical separation and detection techniques. This article presents a brief overview of the extraction technique and its role in bioanalysis. Some of the most relevant achievements on SALLE application to biological samples are discussed - namely the study of the main extraction parameters, the combination with other extraction techniques and the instrumental analysis of the extracts. Developments on automation, miniaturization and microextraction for SALLE procedures are also discussed as a perspective for future applications even more attractive for the analysis of biological samples.

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.

Sample preparation with solid phase microextraction and exhaustive extraction approaches: Comparison for challenging cases

In chemical analysis, sample preparation is frequently considered the bottleneck of the entire analytical method. The success of the final method strongly depends on understanding the entire process of analysis of a particular type of analyte in a sample, namely: the physicochemical properties of the analytes (solubility, volatility, polarity etc.), the environmental conditions, and the matrix components of the sample. Various sample preparation strategies have been developed based on exhaustive or non-exhaustive extraction of analytes from matrices. Undoubtedly, amongst all sample preparation approaches, liquid extraction, including liquid-liquid (LLE) and solid phase extraction (SPE), are the most well-known, widely used, and commonly accepted methods by many international organizations and accredited laboratories. Both methods are well documented and there are many well defined procedures, which make them, at first sight, the methods of choice. However, many challenging tasks, such as complex matrix applications, on-site and in vivo applications, and determination of matrix-bound and free concentrations of analytes, are not easily attainable with these classical approaches for sample preparation. In the last two decades, the introduction of solid phase microextraction (SPME) has brought significant progress in the sample preparation area by facilitating on-site and in vivo applications, time weighted average (TWA) and instantaneous concentration determinations. Recently introduced matrix compatible coatings for SPME facilitate direct extraction from complex matrices and fill the gap in direct sampling from challenging matrices. Following introduction of SPME, numerous other microextraction approaches evolved to address limitations of the above mentioned techniques. There is not a single method that can be considered as a universal solution for sample preparation. This review aims to show the main advantages and limitations of the above mentioned sample preparation approaches and the applicability and capability of each technique for challenging cases such as complex matrices, on-site applications and automation.

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

The "QuEChERS" (quick, easy, cheap, effective, rugged, and safe) dispersive SPE (dSPE) method is an emerging sample preparation technique that is becoming increasingly popular in the area of multi-residue pesticide analysis in food and agricultural products. A simplified QuEChERS extraction method followed by ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) has been developed for the simultaneous determination of forensically relevant drugs of abuse (opiates including buprenorphine, methadone and fentanyl and analogues, cocaine and metabolites, amphetamines, LSD) and benzodiazepines and analogues (Z-drugs) in 1mL of human whole blood performing a sole extraction. The method was validated showing good repeatability, accuracy and linearity; LODs were 0.5ng/mL for all benzodiazepines tested while for drugs of abuse LODs varied from 0.05 to 2ng/mL. The method showed high throughput capabilities and was applied on various forensic cases for determination of pharmaceuticals and drugs of abuse.