Liquid-phase microextraction in 96-well plates - calibration and accurate quantification of pharmaceuticals in human plasma samples

Solvent-free parallel artificial liquid membrane extraction for drugs of abuse in plasma samples using LC-MS/MS

BACKGROUND

Parallel artificial liquid membrane extraction (PALME) is a 96-well plate setup variant of liquid-phase microextraction. Basic or acidic analytes are extracted in neutral form from the sample, through a supported liquid membrane (SLM), and into aqueous acceptor. PALME is already considered a green extraction technique, but in the current conceptual work, we sought to make it even greener by replacing the use of organic solvents with essential oils (EO). PALME was combined with LC-MS/MS for analysis of plasma samples and multiple drugs of abuse with toxicological relevance (amphetamines, phenethylamines, synthetic cathinones, designer benzodiazepines, ayahuasca alkaloids, lysergic acid diethylamide, and ketamine).

RESULTS

Fourteen EO were compared to organic solvents frequently used in PALME. The EO termed smart & sassy yielded the best analyte recovery for all drugs studied and was thus selected as SLM. Then, factorial screening and Box-Behnken were employed to optimize the technique. The extraction time, concentration of base, sample volume, and percentage of trioctylamine significantly impacted analyte recovery. The optimum values were defined as 120 min, 10 mmol/L of NaOH, 150 μL, and 0%, respectively. Once optimized, validation parameters were 1-100 ng mL-1 as linear range, accuracy ±16.4%, precision >83%, 1 ng mL-1 as limit of quantitation, 0.1-0.75 ng mL-1 as limit of detection, matrix effect <20%, and recovery 20-106%. Additionally, EO purchased from different production batches were tested and achieved acceptable reproducibility. Data were in compliance with requirements set by internationally accepted validation guidelines and the applicability of the technique was proven using authentic samples.

SIGNIFICANCE

In this study, the use of an EO provided a solvent-free sample preparation technique suited to extract different classes of drugs of abuse from plasma samples, dismissing the use of hazardous organic solvents. The method also provided excellent sample clean-up, thus being a simple and efficient tool for toxicological applications that is in agreement with the principles of sustainable chemistry.

Parallel artificial liquid membrane extraction coupled with UPLC-ESI-MS/MS method for high-throughput quantitation of repaglinide in diabetic patients

A high-throughput therapeutic monitoring method was developed for repaglinide (RPG) in diabetic patients, combining parallel artificial liquid membrane extraction (PALME) with ultraperformance liquid chromatography electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). PALME was performed using a 96-well donor plate comprising a donor solution containing a plasma sample, 50 mM phosphate buffer (pH = 8.0), and cetirizine (CTZ) as internal standard. A polypropylene (PP) porous membrane served as a selective support for the liquid membrane (SLM), preventing nonspecific binding produced by other membranes. The extraction was accomplished across SLM made of PP membrane with dodecyl acetate and 1 % trioctylamine (w/w), and the acceptor solution comprised DMSO and 200 mM formic acid (50:50, v/v). The simple workflow for PALME provided analyte enrichment, highly efficient sample cleanup, high throughput analysis, and excellent reproducibility. Method validation met FDA criteria, with a linear plasma calibration range (0.1-100 ng mL-1, r = 0.9995) and a lower limit of quantitation (LLOQ) of 0.1 ng mL-1. Recovery results at 98.9 % affirmed method reliability. The ability to analyze 198 samples per hour, coupled with a reduced amount of solvents, underscores the method's high throughput and eco-friendly profile. The PALME-UPLC-ESI-MS/MS method was successfully applied to therapeutic drug monitoring of RPG in diabetic patients following 2 mg RPG tablet administration, establishing its effectiveness.

High-throughput quantification of emerging "nitazene" benzimidazole opioid analogs by microextraction and UHPLC-MS-MS

Benzimidazole opioids, often referred to as nitazenes, represent a subgroup of new psychoactive substances with a recent increase in fatal overdoses in the USA and Europe. With a variety of analogs emerging on the illicit drug market, forensic laboratories are challenged to identify these potent drugs. We here present a simple quantitative approach for the determination of nine nitazene analogs, namely, clonitazene, etodesnitazene, etonitazene, etonitazepyne, flunitazene, isotonitazene, metodesnitazene, metonitazene and protonitazene in whole blood using liquid-phase microextraction and electromembrane extraction in a 96-well format and liquid chromatography-tandem mass spectrometry. Green and efficient sample preparation was accomplished by liquid-phase microextraction in a 96-well format and resulted in high extraction yields for all analytes (>81%). Here, blood diluted with buffer (1:1, %v) was extracted from a donor compartment across a thin organic liquid membrane and into an aqueous acceptor solution. The acceptor solution was collected and directly injected into the analysis platform. Chromatographic separation was accomplished with a biphenyl column, allowing for a baseline separation of the structural isomers isotonitazene and protonitazene before detection by multiple reaction monitoring. Validation was performed according to Scientific Working Group of Forensic Toxicology guidelines. The calibration range was from 0.5 to 50 nM (except for protonitazene and clonitazene from 0.1 nM) with good linearity and limits of detection down to 0.01 nM. An AGREEprep assessment was performed to evaluate sample preparation greenness, with a final score of 0.71. Nitazenes represent a current threat to public health, and analytical methods that cover a wide range of these analogs are limited. Here, the described method may assist in the detection of nitazenes in whole blood and prevent these substances from being missed in postmortem investigations.

Solid supports and supported liquid membranes for different liquid phase microextraction and electromembrane extraction configurations. A review

Liquid phase microextraction (LPME) and electromembrane microextraction (EME) can be considered as two of the most popular techniques in sample treatment today. Both techniques can be configurated as membrane-assisted techniques to carry out the extraction. These supports provide the required geometry and stability on the contact surface between two phases (donor and acceptor) and improve the reproducibility of sample treatment techniques. These solid support pore space, once is filled with organic solvents, act as a selective barrier acting as a supported liquid membrane (SLM). The SLM nature is a fundamental parameter, and its selection is critical to carry out successful extractions. There are numerous SLMs that have been successfully employed in a wide variety of application fields. The latter is due to the specificity of the selected organic solvents, which allows the extraction of compounds of a very different nature. In the last decade, solid supports and SLM have evolved towards "green" and environmentally friendly materials and solvents. In this review, solid supports implemented in LPME and EME will be discussed and summarized, as well as their applications. Moreover, the advances and modifications of the solid supports and the SLMs to improve the extraction efficiencies, recoveries and enrichment factors are discussed. Hollow fiber and flat membranes, including microfluidic systems, will be considered depending on the technique, configuration, or device used.

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.

Current development of bioanalytical sample preparation techniques in pharmaceuticals

Sample preparation is considered as the bottleneck step in bioanalysis because each biological matrix has its own unique challenges and complexity. Competent sample preparation to extract the desired analytes and remove redundant components is a crucial step in each bioanalytical approach. The matrix effect is a key hurdle in bioanalytical sample preparation, which has gained extensive consideration. Novel sample preparation techniques have advantages over classical techniques in terms of accuracy, automation, ease of sample preparation, storage, and shipment and have become increasingly popular over the past decade. Our objective is to provide a broad outline of current developments in various bioanalytical sample preparation techniques in chromatographic and spectroscopic examinations. In addition, how these techniques have gained considerable attention over the past decade in bioanalytical research is mentioned with preferred examples. Modern trends in bioanalytical sample preparation techniques, including sorbent-based microextraction techniques, are primarily emphasized.

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Bioanalytical sampling techniques are described with suitable applications in pharmaceuticals.

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The pros and cons of each bioanalytical sampling techniques are described.

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Relevant biological matrices are outlined.

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.

Parallel artificial liquid membrane extraction of organophosphorus nerve agent degradation products from environmental samples

An emerging miniaturized high-throughput microextraction technique named Parallel artificial liquid membrane extraction (PALME) was, for the first time, investigated for the extraction of polar alkyl methylphosphonic acids (AMPAs) that are the degradation products of organophosphorus nerve agents. The effect of the key-parameters of the extraction method (nature of the membrane, of the extraction solvent, of the pH values of both donor and acceptor phases, agitation speed, extraction time, temperature and ionic strength) on the extraction recoveries was studied in spiked pure water samples. This led to extraction recoveries in the range of 25-102% for the 5 targeted analytes from water with enrichment factors in the range of 4.50-42.75. The developed PALME-LC-MS/MS method was first evaluated with spiked pure water. LOQs (S/N ≥ 10) were in the range of 0.009-1.141 ng mL^-1, linearity above 0.9973 for all the AMPAs and with RSD values below 11%. This method was then applied on simulated waste water, river water and aqueous soil extracts. The achieved LOQs were in the range of 0.011-1.210, 0.013-1.196 and 0.016-6.810 ng mL^-1, respectively. A detailed comparison of the performances of this PALME method with those of a previously developed hollow fiber liquid-phase microextraction methods already applied to AMPAs was done thus allowing to demonstrate the easy transfer of methods from HF-LPME to PALME. Moreover, the high-throughput potential of PALME was revealed since 192 samples were processed in parallel during 120 min (37.5 s/sample).

Membrane-based liquid-phase microextraction of basic pharmaceuticals - A study on the optimal extraction window

The present paper defines the optimal extraction window (OEW) for three-phase membrane-based liquid-phase microextraction (MP-LPME) in terms of analyte polarity (log P), and anchors this to existing theories for equilibrium partitioning and kinetics. Using deep eutectic solvents (DES) as supported liquid membranes (SLM), we investigated how the OEW was affected by ionic-, hydrogen bond and π-π interactions between the SLM and analyte. Eleven basic model analytes in the range -0.4 < log P < 5.0 were extracted by MB-LPME in a 96-well format. Extraction was performed from 250 µL standard solution in 25 mM phosphate buffer (pH 7.0) into 50 µL of 10 mM HCl acceptor solution (pH 2.0) with mixtures of coumarin, camphor, DL-menthol, and thymol, with and without the ionic carrier di(2-ethylhexyl) phosphate (DEHP), as the SLM. The OEW with pure DES was in the range 2 < log P < 5, and low SLM aromaticity was favorable for the extraction of non-polar analytes. Here, extraction recoveries up to 98% were obtained. Upon addition of DEHP to the SLMs, the OEW shifted to the range -0.5 < log P < 2, and a combination of 5% DEHP and moderate aromaticity resulted in extraction recoveries up to 80% for the polar analytes. Extraction with ionic carrier was inefficient for the non-polar analytes, due to excessive trapping in the SLM. The results from our study show that LPME performs optimally in a relatively narrow log P-window of ≈ 2-3 units and that the OEW is primarily affected by ionic carrier and aromaticity.

New Method for the Monitoring of Antidepressants in Oral Fluid Using Dried Spot Sampling

The increase in the consumption of antidepressants is a public health problem worldwide, as these are a class of compounds widely used in the treatment of several illnesses, such as depression and anxiety. This work aimed to develop and optimize a method for the quantification of a number of antidepressants and their metabolites (fluoxetine, venlafaxine, O-desmethylvenlafaxine, citalopram, sertraline, and paroxetine) in 100 µL of oral fluid using the dried saliva spots (DSS) sampling approach and gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). The method was validated, presenting linearity within the studied range, with detection and quantification limits ranging between 10 and 100 ng/mL, and coefficients of determination (R²) of at least 0.99 for all analytes. Recoveries were between approximately 13 and 46%. The analysis of precision and accuracy presented acceptable coefficients of variation and relative errors, considering the criteria usually accepted in the validation of bioanalytical procedures. The method herein described is the first to be reported using DSS for the extraction of antidepressants, proving to be a sensitive, simple, and fast alternative to conventional techniques, and capable of being routinely applied in clinical and forensic toxicology scenarios.

High-throughput subzero-temperature assisted homogenous liquid-liquid extraction for the fast sample preparation of multiple phenolic compounds in propolis

In the present study, a high-throughput homogenous liquid-liquid extraction method was developed for fast sample preparation of multiple phenolic compounds in propolis. This method was proposed based on cooling samples array in subzero temperature to induce phase separation of ACN-H₂O extractant. Due to the high-throughput ability, optimization of extraction parameters was rapidly achieved by using a 5 × 4 × 3 samples array. In addition, multiple arrays were investigated for evaluating the analytical performance of the high-throughput method, which indicated that limits of detection and quantification were ranged from 0.04 to 0.35 µg/mL and 0.12 to 1.05 µg/mL, respectively. Recoveries and precisions in inter-day high-throughput studies were in the range of 90.55-105.50% and 2.58-4.30%, respectively. Comparing with the conventional liquid extraction method, this ecofriendly high-throughput method presented remarkable advantages in reducing sample and chemical consumption, as well as saving labor and time cost. The proposed method might provide a valuable strategy for the design of high-throughput extraction procedures.

Accurate Quantification of Nervous System Drugs in Aqueous Samples at Trace Levels by Binary Solvent Dispersive Liquid-Liquid Microextraction-Gas Chromatography Mass Spectrometry

Pharmaceutical products are widely consumed globally and are commonly found in wastewaters as a result of constant excretion and disposal into sewers. The present study proposes an efficient binary solvent dispersive liquid-liquid microextraction (BS-DLLME) method that was developed for preconcentration of 7 nervous system drug active compounds from aqueous media for their determination at trace levels by gas chromatography-mass spectrometry. The drug analytes included 3 antidepressants, 2 antipsychotics, 1 antiepileptic, and 1 antidementia. Optimum conditions of the BS-DLLME method were acquired by univariate optimization of parameters including type of binary solvents, ratio of binary solvents, type of disperser solvent, volume of binary solvents, and volume of disperser solvent. Detection and quantification limits were calculated in the range of 0.28 to 6.5 µg/L. Municipal wastewater, medical wastewater, synthetic domestic wastewater, and lake water were utilized as real samples in spike recovery experiments; and the results (94-106%) indicated the method's applicability and accuracy at quantifying the analytes in complex matrices. Environ Toxicol Chem 2021;40:1570-1575. © 2021 SETAC.

Quantifying Precision Loss in Targeted Metabolomics Based on Mass Spectrometry and Nonmatching Internal Standards

In mass spectrometry, reliable quantification requires correction for variations in ionization efficiency between samples. The preferred method is the addition of a stable isotope-labeled internal standard (SIL-IS). In targeted metabolomics, a dedicated SIL-IS for each metabolite of interest may not always be realized due to high cost or limited availability. We recently completed the analysis of more than 70 biomarkers, each with a matching SIL-IS, across four mass spectrometry-based platforms (one GC-MS/MS and three LC-MS/MS). Using data from calibrator and quality control samples added to 60 96-well trays (analytical runs), we calculated analytical precision (CV) retrospectively. The use of integrated peak areas for all metabolites and internal standards allowed us to calculate precision for all matching analyte (A)/SIL-IS (IS) pairs as well as for all nonmatching A/IS pairs within each platform (total n = 1442). The median between-run precision for matching A/IS across the four platforms was 2.7-5.9%. The median CV for nonmatching A/IS (corresponding to pairing analytes with a non-SIL-IS) was 2.9-10.7 percentage points higher. Across all platforms, CVs for nonmatching A/IS increased with increasing difference in retention time (Spearman's rho of 0.17-0.93). The CV difference for nonmatching vs matching A/IS was often, but not always, smaller when analytes and internal standards were close structural analogs.

Bioanalysis of pharmaceuticals using liquid-phase microextraction combined with liquid chromatography-mass spectrometry

In this paper, we review recent research articles on liquid-phase microextraction of drug substances from biological fluids, such as plasma, serum, urine, and saliva. We focus on papers where liquid-phase microextraction is combined with liquid chromatography coupled with mass spectrometry (LC-MS), published in the period 2019-2020. First, we discuss different configurations of liquid-phase microextraction, including dispersive liquid-liquid microextraction (DLLME), dispersive liquid-liquid microextraction based on solidified floating organic droplet (DLLME-SFO), single-drop microextraction (SDME), hollow-fibre liquid-phase microextraction (HF-LPME), solvent bar microextraction (SBME), and electromembrane extraction (EME). Second, we discuss new types of solvents used in liquid-phase microextraction, including ionic liquids, deep eutectic solvents, and nanostructured supramolecular solvents. Especially, we focus on the potential for implementation in routine laboratories, which we consider as the next step for liquid-phase microextraction.

Combination of ultrasound-assisted ethyl chloroformate derivatization and switchable solvent liquid-phase microextraction for the sensitive determination of l-methionine in human plasma by GC-MS

A green and fast analytical method for the determination of l-methionine in human plasma is presented in this study. Preconcentration of the analyte was carried out by switchable solvent liquid phase microextraction after ethyl chloroformate derivatization reaction. Instrumental detection of the analyte was performed by means of gas chromatography-mass spectrometry. N,N-Dimethyl benzylamine was used in the synthesis of switchable solvent. Protonated N,N-dimethyl benzylamine volume, volume/concentration of sodium hydroxide, and vortex period were meticulously fixed to their optimum values. Besides, ethyl chloroformate, pyridine, and ethanol volumes were optimized in order to get high derivatization yield. After the optimization studies, limit of detection and quantitation values were attained as 3.30 and 11.0 ng/g, respectively, by the developed switchable solvent liquid phase microextraction gas chromatography-mass spectrometry method that corresponding to 76.7-folds enhancement in detection power of the gas chromatography-mass spectrometry system. Applicability and accuracy of the switchable solvent liquid phase microextraction-gas chromatography-mass spectrometry method were also checked by spiking experiments. Percent recovery results were ranged from 97.8 to 100.5% showing that human plasma samples could be analyzed for its l-methionine level by the proposed method.