Derivatization Step Research Articles

Simultaneous direct determination of Glyphosate and AMPA in the ambient air and inhalation risk assessment in a Mediterranean Region (Spain)

A new analytical strategy for the direct determination in ambient air by LC-MS/MS of glyphosate (Gly) and aminomethylphosphonic acid (AMPA) without a derivatization step was developed and validated. Sample treatment was performed using ultrasonic assisted extraction (UAE) and HCl: CH3OH (90:10, v/v)) as a solvent extractor. The developed methodology showed recoveries ranging from 93.3 % to 103.9 % for Gly and from 101.0 % to 109.4 % for AMPA with LOQs of 8.2 pg m−3 for both compounds when 730 m3 of air was sampled. The strategy was applied to the analysis of 35 air samples collected in four different areas. This is the first study which investigates the presence of Gly and AMPA in ambient air in Spain. The obtained results showed that Gly was detected in 94 % of the analysed samples, whereas AMPA was not detected. Gly concentrations oscillated from 20.23 pg m−3 to 629.95 pg m−3 with a median of 83.09 pg m−3.This work is also pioneering in performing Gly inhalation risk assessment in Spain. Daily inhalation exposure (DIE) and hazard quotient (HQ) were calculated to assess the obtained data. Using maximum concentrations, obtained DIE was 1.07 E−07 mg kg−1 b. w. day−1 in adults and 5.04 E−07 mg kg−1 b. w. day−1 in children. The obtained HQ values were lower than 1 in all cases, indicating that low health risk due to Gly inhalation exposure was expected for the assessed population. Furthermore, cancer risk for Gly was also lower than the concern level (1.0 E−06).

A global LC-MS2 -based methodology to identify and quantify anionic phospholipids in plant samples.

Anionic phospholipids (PS, PA, PI, PIPs) are low-abundant phospholipids with impactful functions in cell signaling, membrane trafficking and cell differentiation processes. They can be quickly metabolized and can transiently accumulate at defined spots within the cell or an organ to respond to physiological or environmental stimuli. As even a small change in their composition profile will produce a significant effect on biological processes, it is crucial to develop a sensitive and optimized analytical method to accurately detect and quantify them. While thin-layer chromatography (TLC) separation coupled with gas chromatography (GC) detection methods already exist, they do not allow for precise, sensitive, and accurate quantification of all anionic phospholipid species. Here we developed a method based on high-performance liquid chromatography (HPLC) combined with two-dimensional mass spectrometry (MS2 ) by MRM mode to detect and quantify all molecular species and classes of anionic phospholipids in one shot. This method is based on a derivatization step by methylation that greatly enhances the ionization, the separation of each peak, the peak resolution as well as the limit of detection and quantification for each individual molecular species, and more particularly for PA and PS. Our method universally works in various plant samples. Remarkably, we identified that PS is enriched with very long chain fatty acids in the roots but not in aerial organs of Arabidopsis thaliana. Our work thus paves the way for new studies on how the composition of anionic lipids is finely tuned during plant development and environmental responses.

Production of poly (3-hydroxybutyrate) and extracellular polymeric substances from glycerol by the acidophile Acidiphilium cryptum.

Acidiphilium cryptum is an acidophilic, heterotrophic, and metallotolerant bacteria able to use dissolved oxygen or Fe(III) as an electron sink. The ability of this extremophile to accumulate poly(3-hydroxybutyrate) (PHB) and secrete extracellular polymeric substances (EPS) has also been reported. Hence, the aim of this work is to characterize the production of PHB and EPS by the wild strain DSM2389 using glycerol in shaken flasks and bioreactor. Results showed that maximum PHB accumulation (37-42% w/w) was obtained using glycerol concentrations of 9 and 15gL-1, where maximum dry cell weight titers reached 3.6 and 3.9gL-1, respectively. The culture in the bioreactor showed that PHB accumulation takes place under oxygen limitation, while the redox potential of the culture medium could be used for online monitoring of the PHB production. Recovered EPS was analyzed by Fourier-transform infrared spectroscopy and subjected to gas chromatography-mass spectrometry after cleavage and derivatization steps. These analyses showed the presence of sugars which were identified as mannose, rhamnose and glucose, in a proportion near to 3.2:2.3:1, respectively. Since glycerol had not been used in previous works, these findings suggest the potential of A. cryptum to produce biopolymers from this compound at a large scale with a low risk of microbial contamination due to the low pH of the fermentation process.

High throughput analysis of alendronate in human samples with derivatization-free hydrophilic-interactive chromatography mass spectrometry

A derivatization-free hydrophilic-interactive chromatography-mass spectrometry (HILIC-MS/MS) method was developed for quantifying low levels of alendronate in human plasma. Alendronate was separated and concentrated using calcium co-precipitation and analyzed by HILIC-MS/MS, requiring only a 300 μL plasma sample for each analysis. The method is simpler, safer, and more environmentally friendly than the conventional LC-MS/MS method that requires solid-phase extraction and derivatization steps during sample pretreatment. The method was validated for selectivity, linearity, precision, accuracy, extraction recovery, matrix effect and limit of quantification. The between-run precisions were no more than 7.1 % with accuracy ranging from − 1.7–6.3 %; extraction recovery was determined to be 85.3 %; while validation results indicated that the method was suitable for accurately quantifying alendronate concentrations in the range from 0.2 to 50 ng/mL. The approach was used successfully for high throughput analysis of alendronate in more than 3700 plasma samples from 120 subjects in a bioequivalence study.

Electrophoretic Determination of L-Carnosine in Health Supplements Using an Integrated Lab-on-a-Chip Platform with Contactless Conductivity Detection.

The health supplement industry is one of the fastest growing industries in the world, but there is a lack of suitable analytical methods for the determination of active compounds in health supplements such as peptides. The present work describes an implementation of contactless conductivity detection on microchip technology as a new strategy for the electrophoretic determination of L-carnosine in complex health supplement formulations without pre-concentration and derivatization steps. The best results were obtained in the case of +1.00 kV applied for 20 s for injection and +2.75 kV applied for 260 s for the separation step. Under the selected conditions, a linear detector response of 5 × 10-6 to 5 × 10-5 M was achieved. L-carnosine retention time was 61 s. The excellent reproducibility of both migration time and detector response confirmed the high precision of the method. The applicability of the method was demonstrated by the determination of L-carnosine in three different samples of health supplements. The recoveries ranged from 91 to 105%. Subsequent analysis of the samples by CE-UV-VIS and HPLC-DAD confirmed the accuracy of the obtained results.

Potential application of a chromatographic method in the accurate simultaneous determination of amikacin sulfate and its preservation additives in different pharmaceutical dosage forms

Aminoglycosides are antibiotics with high clinical importance that face a great challenge of detection in the UV range. This study aimed to develop an accurate, simple, and sensitive validated high-performance liquid chromatographic (HPLC) method for the determination of amikacin sulfate, one of the widely used aminoglycoside antibiotics in the pharmaceutical formulations, as the target analyte without interference from its preservation additive sodium metabisulfite in the pharmaceutical dosage forms without the usage of any derivatization reactions. The developed method is based on direct UV detection at 205 nm using a gradient mobile phase consisting of acetonitrile as an organic solvent and buffered solution; pH 3.0. This method was developed on a reversed-phase ZORBAX ECLIPSE XDB-C8 (4.6 × 250 mm, 5-μm) analytical column with a flow rate of 1.5 mL min−1 at a column temperature of 35 °C. The separation of amikacin sulfate and sodium metabisulfite was achieved at 3.7, and 1.5 min, respectively. The developed method validation was performed as prescribed by the International Conference on Harmonization (ICH) guidelines to confirm its linearity, precision, and accuracy. Finally, using simple, commonly available analytical tools, safe buffer concentration on the HPLC system, and without any complicated equipment or challenging derivatization steps, our validated HPLC method was applied for the simultaneous determination of amikacin and sodium metabisulfite in commercially available pharmaceutical formulations in a single method of analysis.

Analytical methods based on liquid chromatography for the analysis of albumin adducts involved in retrospective biomonitoring of exposure to mustard agents.

The objective of the present review is to list, describe, compare, and critically analyze the main procedures developed in the last 20years for the analysis of digested alkylated peptides, resulting from the adduction of albumin by different mustard agents, and that can be used as biomarkers of exposure to these chemical agents. While many biomarkers of sulfur mustard, its analogues, and nitrogen mustards can easily be collected in urine such as their hydrolysis products, albumin adducts require blood or plasma collection to be analyzed. Nonetheless, albumin adducts offer a wider period of detectability in human exposed patients than urine found biomarkers with detection up to 25days after exposure to the chemical agent. The detection of these digested alkylated peptides of adducted albumin constitutes unambiguous proof of exposure. However, their determination, especially when they are present at very low concentration levels, can be very difficult due to the complexity of the biological matrices. Therefore, numerous sample preparation procedures to extract albumin and to recover alkylated peptides after a digestion step using enzymes have been proposed prior to the analysis of the targeted peptides by liquid chromatography coupled to mass spectrometry method with or without derivatization step. This review describes and compares the numerous procedures including a number of different steps for the extraction and purification of adducted albumin and its digested peptides described in the literature to achieve detection limits for biological samples exposed to sulfur mustard, its analogues, and nitrogen mustards in the ng/mL range.

Automated sample preparation with 6-Aminoquinolyl-N-hydroxysuccinimidyl carbamate and iodoacetamide derivatization reagents for enantioselective liquid chromatography tandem mass spectrometry amino acid analysis

Enantioselective amino acid analysis is gaining increasing importance in pharmaceutical, biomedical and food sciences. While there are many methods available for enantiomer separation of amino acids, the simultaneous analysis of all chiral proteinogenic amino acids by a single method with one column and a single condition is still challenging. Herein, we report an enantioselective high-performance liquid chromatography-tandem mass spectrometry (LC-MS) assay using Chiralpak QN-AX as chiral column. With 6-aminoquinolyl-N-hydrosysuccinimidyl carbamate (AQC) as derivatization reagent, efficient enantioselective separation of D- and L-amino acids using HPLC has become possible. Thiol-containing amino acids like Cys are alkylated prior to AQC-labelling. A protocol for automated sample preparation including both derivatization step and calibrator preparation is presented. For compensating matrix effects, u-13C15N-labelled internal standards (IS) were employed. The method was validated and applied to the enantioselective analysis of amino acids in a bacterial fermentation broth.

Solid Phase Photothermo-Induced Chemical Vapor Generation: A New Desorption Method for Mercury Analysis by High-Throughput 20-Fiber Direct Immersion Solid Phase Microextraction.

A simple solid phase photothermo-induced chemical vapor generation (SP-PT-CVG) is described and used as an environmentally friendly desorption method for the sensitive determination of mercury in water by direct immersion solid phase microextraction (DI-SPME) atomic fluorescence spectrometry (AFS). A DI-SPME array equipped with 20 nano-TiO2-coated tungsten fibers was employed to simultaneously preconcentrate mercury from 20 samples, enabling an extraction throughput of 40 samples per hour. Subsequently, the fibers were drawn from the sample solutions and inserted into an inner tube sealed in a specially designed UV lamp in turn for SP-PT-CVG to generate Hg0, which was swept to an AFS detector for its detection. It is worth noting that the tube served as both a vapor generator and a desorption chamber. This proof-of-concept study confirms the feasibility of solid phase CVG. Compared to conventional CVG carried out in the liquid phase, solid phase CVG not only retains the advantages of conventional CVG but also alleviates the matrix interference on vapor generation and preconcentrates analyte prior to vapor generation, improving analytical performance for liquid state samples. DI-SPME-SP-PT-CVG-AFS provides a limit of detection of 2.3 ng L-1 for mercury determination by AFS. In the proposed method, the combination of DI-SPME and SP-PT-CVG eliminates the tedious derivatization steps required in conventional headspace SPME, thus minimizing toxic reagent consumption and improving extraction throughput. The practicality of DI-SPME-SP-PT-CVG-AFS was evaluated by analyzing two different certified reference materials and river water samples with good spike recoveries (98-107%).

Development of a new method for the determination of 4-hydroxyproline as a measurement of collagen content in meat products and dietary supplements by cyclodextrin-assisted electrokinetic chromatography

The rise in consumption of ultra-processed meat and dietary collagen supplements challenges food quality control. 4-hydroxyproline stands out as collagen signature amino acid, and its determination is a well-known way to estimate collagen content, although for this measurement, the majority of the methods require a mandatory derivatization step. Therefore, this study aimed to develop an innovative method using cyclodextrin-assisted electrokinetic chromatography with indirect UV detection to determine 4-hydroxyproline for collagen monitoring in dietary supplements and meat products. Separations were performed in fused silica capillaries, at 12.5 °C, detection at 220 nm, 30 kV voltage, and hydrodynamic injection. Background electrolyte consisted of histidine 25 mmol L-1, butylamine 180 mmol L-1, and β-cyclodextrin 10 mmol L-1 at pH 11.4. Samples were hydrolyzed with sulfuric acid, and their removal was accomplished by simultaneous neutralization/precipitation reactions using strontium carbonate. Validation assured method detectability, accuracy (recoveries 88% - 102%), and precision (CV < 7%). Dietary supplements and meat products were successfully evaluated, indicating that this method is a feasible quality control alternative.

Determination of methionine and selenomethionine in food matrices by gas chromatography mass spectrometry after aqueous derivatization with triethyloxonium salts

A novel analytical method for the simultaneous gas chromatography–mass spectrometry (GC–MS) determination of methionine and selenomethionine in food samples is described. Samples were digested with methanesulfonic acid in a closed vessel without the need for reflux. A single step derivatization using triethyloxonium tetrafluoroborate was optimized for the conversion of the analytes into their ethyl derivatives, followed by their extraction with hexane and GC–MS analysis.. This derivatization approach was simpler and/or safer with respect to current methods based on alkyl chloroformate or silylating reagents and it yielded very clean chromatography. A design of experiment approach, based on an open source chemometric software, was used to optimize the experimental conditions. When analysis of a 1 mL volume of aqueous standard was performed, detection limits of 1 ng/g methionine and 10 ng/g for selenomethionine were obtained.The method was validated by analysis of a selenized yeast Certified Reference Material NRC SELM-1.

Optimization of bioactive compounds by ultrasound extraction and gas chromatography - mass spectrometry in fast-growing leaves

Fast-growing crops are of great economic importance in the production of paper pulp and energy. The commercialization of the bioactive components from underutilized parts could provide additional value to these crops. In the present study, chromatography gas coupled to mass spectrometry triple quadrupole (GC–MS/MS) and ultrasound extraction technique was used in the bioactive compounds determination in fast-growing crops leaves. Twenty-one terpenes and eight polyphenolic bioactive compounds were studied. Prior to GC–MS/MS, polydimethylsiloxane (PDMS) - stir bars preconcentration and trimethylsilane (TMS) derivatization steps were used for terpenes and polyphenolic compounds, respectively. Several parameters (pH, temperature, ethanol–water mixtures, ultrasound power, and ultrasound time) of the extraction step were optimized by central composite experimental design. Ethanol content, ultrasound power, and ultrasound time were the parameters that most influence the extraction efficiency of terpenes in biomass residues, while for polyphenolic compounds it was temperature and ultrasound time.The optimal ultrasound extraction conditions for terpenes were 60% ethanol, pH 4, 80 W, 40 °C, and 15 min, whereas for polyphenolic compounds they were 60% ethanol, pH 4, 120 W, 50 °C, and 15 min. The detection limits (LOD) were in the range of 0.200–3.02 µg kg−1 and 7.9–540 µg kg−1 for terpenes and polyphenolic compounds, respectively.The developed analytical method was applied to twelve fast-growing leaves (Leucaene (diversifolia and leucocephala), Eucalyptus (globulus and urograndis), Populus (I214 and AF2), Prosopis (alba and juliflora), Robinia, Tagasaste, Ulmus pumila, and Paulownia). Eucalyptol was the mayor terpene present in all the plants studied, while chlorogenic and quinic acid were the mayor phenolic compounds.

Quantification of modified nucleotides and nucleosides by isotope dilution mass spectrometry.

Epigenetic modifications are closely related to certain disorders of the organism, including the development of tumors. One of the main epigenetic modifications is the methylation of DNA cytosines, 5-methyl-2'-deoxycycytidine. Furthermore, 5-mdC can be oxidized to form three new modifications, 5-(hydroxymethyl)-2'-deoxycytidine, 5-formyl-2'-deoxycytidine,and 5-carboxy-2'-deoxycytidine. The coupling of liquid chromatography with tandem mass spectrometry has been widely used for the total determination of methylated DNA cytosines in samples of biological and clinical interest. These methods are based on the measurement of the free compounds (e.g., urine) or after complete hydrolysis of the DNA (e.g., tissues) followed by a preconcentration, derivatization, and/or clean-up step. This review highlights the main advances in the quantification of modified nucleotides and nucleosides by isotope dilution using isotopically labeled analogs combined with liquid or gas chromatography coupled to mass spectrometry reported in the last 20 years. The different possible sources of labeled compounds are indicated. Special emphasis has been placed on the different types of chromatography commonly used (reverse phase and hydrophilic interaction liquid chromatography) and the derivatization methods developed to enhance chromatographic resolution and ionization efficiency. We have also revised the application of bidimensional chromatography and indicated significant biological and clinical applications of these determinations.

Determination of Bisphenol A (BPA) in the Port of Gdynia Waters Using Gas Chromatography Coupled with Mass Spectrometry (GC-MS)

This paper presents a procedure for the determination of bisphenol A (BPA) in seawater. Gas chromatography coupled with mass spectrometry (GC-MS) was used as the analytical method, preceded by analyte isolation via solid-phase extraction (SPE). Initially, the best conditions for extraction, derivatization, and GC-MS analysis were established. The need for derivatization in the determination of BPA was investigated, and for this reason, two methods of sample preparation were compared: with and without the derivatization step. The parameters of the two methods of sample preparation were compared with each other, and a more efficient method was chosen for the analysis of marine water samples. Afterwards, the validation process was carried out and the following parameters were determined: limit of detection (LOD), limit of quantification (LOQ), linearity, precision, reproducibility, and repeatability. Finally, the results of the determination of bisphenol A in water samples collected from five harbor basins of the Port of Gdynia using an unmanned mobile research unit, HydroDron-1, were presented. The identified concentrations ranged from 0.01 µg/L to 0.03 µg/L, depending on the investigated area.

Simultaneous analysis of degradation products of Novichok agents and conventional nerve agents in human urine by ion chromatography-tandem mass spectrometry using ammonium regeneration solution

An ion chromatography (IC)-tandem mass spectrometry (MS/MS) method to analyze nerve agent degradation products in human urine was developed. Six degradation products of conventional nerve agents and six Novichok agent degradation products were analyzed simultaneously despite their differences in hydrophilicity and acidity. Using ammonium regeneration solution improved the peak shapes greatly compared with the results obtained with the ordinary IC-MS/MS configuration. For urine samples, a simple pretreatment method of dilution with water and ultrafiltration was used. The detection limits of the nerve agent degradation products were sufficiently low (10–250 ng/mL) and the calibration curves showed acceptable linearity. Due to the absence of a derivatization step, throughput was higher than for our previous derivatization-liquid chromatography-MS/MS method.

Identification and synthesis of (Z)-3'-hydroxy clomiphene as a new potential doping-relevant metabolite of clomiphene.

(E/Z)-3'-HC and (E/Z)-4'-HC were synthesized involving the McMurry reaction. An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and optimized after a derivatization step with dansyl chloride to separate eight HC isomers. Using this method, urine samples from a controlled clomiphene administration study were analyzed, in which male study participants received therapeutic doses of clomiphene for 30 days and collected urine samples for up to 8months. Thus, isomer-specific HC elimination profiles could be monitored. The metabolite previously found in doping-control samples was identified as (Z)-3'-HC. The elimination profiles of the different HCs confirmed previous results, with (Z)-3-HC being the most abundant urinary hydroxy metabolite shortly after administration. A new finding was that the data suggest that (Z)-3'-HC is excreted at higher relative concentrations only several weeks after drug intake. These findings might be of particular importance in sport drug testing as they can assist in the decision-making process to distinguish between intentional doping and inadvertent exposure to clomiphene via food contamination.

An approach to quantify ortho-phthalaldehyde contamination on work surfaces.

Ortho-phthalaldehyde (OPA) is used as a high-level disinfectant for reusable medical devices in healthcare settings. The ACGIH recently adopted a Threshold Limit Value-Surface Limit (TLV-SL; 25 µg/100 cm2) for OPA surface contamination to prevent induction of dermal and respiratory sensitization following dermal exposure. However, there is no current validated method to measure OPA surface contamination. This study aimed to develop a standardized approach for sample collection and quantitative determination of OPA from work surfaces for use in risk assessment practices. The reported method utilises readily available commercial wipes to collect surface samples coupled with direct detection of OPA via liquid chromatography time of flight mass spectrometry (LC-ToF-MS). This approach avoided complex derivatization steps commonly required for the analysis of aldehydes. Method evaluation was conducted in accordance with the Occupational Safety and Health Administration (OSHA) surface sampling guidelines. Overall recoveries of 25 µg/100 cm2 of OPA from stainless steel and glass surfaces were 70% and 72%, respectively. The reported LOD for this method was 1.1 µg/sample and the LOQ was 3.7 µg/sample. OPA remained stable on the sampling medium for up to 10 days, when stored at 4 °C. The method was demonstrated in a workplace surface assessment at a local hospital sterilising unit, successfully detecting OPA on work surfaces. This method is intended to supplement airborne exposure assessment and provide a quantitative assessment tool for potential dermal exposure. When used in conjunction with a thorough occupational hygiene program that includes hazard communication, engineering controls, and personal protective equipment, skin exposure and consequent sensitization risks in the workplace can be minimized.

An innovative method for the extraction and HPLC analysis of bioactive policosanols from non-psychoactive Cannabis sativa L.

Policosanols (PCs) refer to a mixture of long-chain aliphatic alcohols. Sugar cane is the main industrial source of PCs, but others, including beeswax and Cannabis sativa L., are also known. In the raw material PCs are bonded to fatty acids to form long-chain esters, known as waxes.PCs are mainly used as a cholesterol-lowering product, even though their efficacy is controversial. More recently, the pharmacological interest in PCs has increased, as they have been investigated as antioxidant, anti-inflammatory and anti-proliferative agents.Given their promising biological implications, the development of efficient extraction and analytical methodologies for the determination of PCs is extremely important to identify new potential sources of these compounds and to ensure the reproducibility of biological data. Conventional techniques used for the extraction of PCs involve time-consuming approaches leading to low yields, while analytical methods for their quantification are based on gas-chromatographic (GC) techniques, which require an additional derivatization step during the sample preparation to increase their volatility.In the light of all the above, this work was aimed at the development of an innovative method for the extraction of PCs from non-psychoactive C. sativa (hemp) inflorescences, taking advantage of the microwave-assisted technology. In addition, a new analytical method based on high-performance liquid chromatography (HPLC) coupled with an evaporative light scattering detector (ELSD) was developed for the first time for both the qualitative and quantitative analysis of these compounds in the extracts. The method was validated according to ICH guidelines, and it was applied to the analysis of PCs in hemp inflorescences belonging to different varieties. The results were analyzed using Principal Component Analysis (PCA) and hierarchical clustering analysis to rapidly identify samples with the highest content of PCs, which might find an application as alternative sources of these bioactive compounds in both the pharmaceutical and nutraceutical fields.

Ultrahigh-performance liquid chromatography-tandem mass spectrometry quantitation of o-cresol in hydrolyzed human urine to assess toluene exposure.

Toluene is a volatile organic compound used in domestic and industrial applications. The main routes of workplace exposure to toluene are inhalation and dermal contact. As toluene exposure can cause severe nervous system damage, its quantification is crucial to prevent occupational illness. Toluene is metabolized mainly as hippuric acid, S-benzylmercapturic acid and epoxides. These are rapidly converted to o-/p-cresol, which is then excreted in the urine as conjugated glucuronides and sulfates. o-Cresol and its conjugates can be chemically hydrolyzed to form free o-cresol, which can then serve as a urinary biomarker of toluene exposure. Current analytical methods for quantifying o-cresol in hydrolyzed urine are, however, either weakened by interference, are not sensitive enough or require water-sensitive sample preparation. Development of a liquid chromatography-tandem mass spectrometry method for assessing exposure to toluene is thus required. Urine samples were acidified and heated to form free o-cresol and then derivatized with dansyl chloride and diluted. Extracts were separated by reverse-phase chromatography on a BEH phenyl column and then analyzed using a triple quadrupole instrument in selected reaction monitoring mode. The dansyl chloride derivatization step was optimized to produce the derivative within a reaction time of 3min. Hydrolysis efficiency in forming free o-cresol from conjugated metabolites was evaluated using o-cresol-β-d-glucuronidespiked human urine: complete hydrolysis occurred in 45 min. Dynamic range was 0.4 to 40 μM, and the method was useful for toluene monitoring in non-occupational (0.1μmol/mmol creatinine) as well as occupational (0.3μmol/mmol creatinine) exposure. The calculated limit of detection and limit of quantitation of the method were 0.06 and 0.21 μM, respectively. Intraday and interday precisions were 3.2% and 4.4%, respectively. Method accuracy was established as 99% using ClinChek® urine controls. An ultrahigh-performance liquid chromatography-tandem mass spectrometry method for analysis of o-cresol was developed for biological monitoring of toluene exposure in human urine. This is the method of choice used by occupational health and safety practitioners in the province of Québec, Canada.

Determination of cannabinoids in 50 μL whole blood samples by online extraction using turbulent flow chromatography and LC-HRAM-Orbitrap-MS: Application on driving under the influence of drugs cases.

The analysis of cannabinoids in whole blood is usually done by traditional mass spectrometry (MS) techniques, after offline cleanup or derivatization steps which can be lengthy, laborious, and expensive. We present a simple, fast, highly specific, and sensitive method for the determination of Δ9 -tetrahydrocannabinol (THC), cannabidiol (CBD), cannabinol (CBN), 11-hydroxy-Δ9 -tetrahydrocannabinol (11-OH-THC), and 11-nor-9-carboxy-Δ9 -tetrahydrocannabinol (THC-COOH) in 50 μL whole blood samples. After the addition of deuterated internal standards (IS) and a simple protein precipitation step, an online extraction of sample supernatants using turbulent flow chromatography (TurboFlow-Thermo Scientific) was carried out. Analytes were separated on a C18 analytical column and detected by LC-HRAM-Orbitrap-MS using a Thermo Scientific Q Exactive Focus MS system. MS detection was performed in polarity switching and selected ion monitoring (SIM) modes using five specific acquisition windows, at a resolution of 70,000 (FWHM). Total run time was about 10min including preanalytical steps. Method validation was carried out by determining limit of detection (LOD), lower limit of quantitation (LLOQ), linearity range, analytical accuracy, intra-assay and interassay precision, carry-over, matrix effect, extraction recovery, and selectivity, for all analytes. Measurement uncertainties were also evaluated, and a decision rule was set with confidence for forensic purposes. The method may become suitable for clinical and forensic toxicology applications, taking advantage of the small matrix volume required, the simple and cost-effective sample preparation procedure, and the fast analytical run time. Performances were monitored over a long-term period and tested on 7620 driving under the influence of drugs (DUID) samples, including 641 positive samples.