Chromatography-positive Electrospray Tandem Mass Spectrometry Research Articles

Dried Blood Spot Technique-Based Liquid Chromatography-Tandem Mass Spectrometry Method as a Simple Alternative for Benznidazole Pharmacokinetic Assessment.

Chagas disease (CD) is recognized as one of the major neglected global tropical diseases. Benznidazole (BNZ) is the drug of choice for the treatment of adults, young infants, and newborns with CD. However, the pharmacokinetics (PK) of BNZ have been poorly evaluated in all age groups, with consequent gaps in knowledge about PK-pharmacodynamic relationships in CD. The purpose of this study was to develop and validate a bioanalytical method to quantify BNZ levels in small-volume whole-blood samples collected as dried blood spots (DBS). The analysis was performed using high-performance liquid chromatography-positive electrospray tandem mass spectrometry. PK evaluation in healthy male volunteers was conducted to verify the correlation between DBS and plasma BNZ concentrations. The calibration curve was linear from 50 to 20,000 ng · ml-1 Intra- and interday precision and bias values were less than 14.87% (n = 9) and 9.81% (n = 27), respectively. The recovery rates ranged from 94 to 100% with no matrix effect. There was no hematocrit level effect in a range of 20 to 70%. The PK results obtained from DBS and plasma were comparable (r2 = 0.8295) and equivalent to previously published information on BNZ. BNZ in DBS was stable at room temperature for more than one year. This article describes the first microsampling method for measuring BNZ levels in DBS that has the potential to facilitate broad implementation of PK in clinical trials involving adult and pediatric patients in remote areas and helps to address existing knowledge gaps in the treatment of CD.

A novel approach for concurrent quantitation of glutathione, glutathione disulfide, and 2‐hydroxyethylated glutathione in lungs of mice exposed to ethylene oxide, using liquid chromatography–positive electrospray tandem mass spectrometry

Glutathione (GSH), glutathione disulfide (GSSG) and 2-hydroxyethylated glutathione (HESG) are important biomarkers for exploring the genotoxicity mechanism of ethylene oxide (EO) or ethylene in vivo. A liquid chromatography-tandem mass spectrometry method was developed for simultaneous determination of GSH, GSSG and HESG in mouse lung tissues after inhalation exposure to EO. The lower limit of quantitation for all these biomarkers was 0.002 µg/mL. The linearity of the calibration curves for all analytes was >0.998. The intra-day assay precision relative standard deviation (RSD) values for quality control samples for all analytes were ≤12.8% with accuracy values ranging from 87.2 to 113%. The inter-day assay precision (RSD) values for all analytes were ≤13.1% with accuracy values ranging from 86.9 to 103%. This method was applied to concurrently determine the levels of GSH, GSSG and HESG in lung samples isolated from mouse after 4-week inhalation exposure to EO at 0, 10, 50, 100 and 200 ppm.

A sensitive high performance liquid chromatography–positive electrospray tandem mass spectrometry method for N7-[2-[(2-hydroxyethyl)thio]-ethyl]guanine determination

A simple, fast, sensitive and robust method for the determination of the sulfur mustard (SM) exposure biomarker– N 7-[2-[(2-hydroxyethyl)thio]-ethyl]guanine (HETEG) was reported using high-performance liquid chromatography–positive electrospray tandem mass spectrometry (HPLC–ESI-MS/MS), working in multiple reaction monitor (MRM) mode. The method provided limit of detection of 0.330 ng/mL and lower limit of quantitation of 0.940 ng/mL. The method was linearly calibrated from 0.940 ng/mL to 587 ng/mL with precisions of 3.5–14.5%, and accuracies of 88–112%. The recovery varied from 102% to 118%. HETEG spiked in DNA hydrolytes isolated from the human whole blood was stable after five freeze/thaw cycles and 35-day frozen at −20 °C. For the exposed biological samples, alkylated DNA was isolated from SM-treated human whole blood, followed by DNA digestion and adducts enrichment, the resulting alkylation base was determined. By the procedure, the HETEG level in DNA hydrolytes isolated from the human whole blood exposure to 312 ng/mL SM was detected successfully.

Multi-residue method for the determination of basic/neutral pharmaceuticals and illicit drugs in surface water by solid-phase extraction and ultra performance liquid chromatography–positive electrospray ionisation tandem mass spectrometry

The paper presents the development and validation of a new multi-residue method for the determination of 28 basic/neutral pharmaceuticals (antiepileptics, antibacterial drugs, β-blockers, analgesics, lipid-regulating agents, bronchodilators, histamine-2-blockers, anti-inflammatory agents, calcium channel blockers, angiotensin-II antagonists and antidepressants) and illicit drugs in surface water with the usage of a new technique: ultra performance liquid chromatography–positive electrospray tandem mass spectrometry (UPLC–MS/MS). The usage of the novel UPLC system with 1.7 μm particle size and 1 mm internal diameter column allowed for low mobile phase flow rates (0.07 mL min −1) and short retention times (from 1.3 to 15.5 min) for all compounds analysed. As a result, a fast and cost-effective method was developed. SPE with the usage of Oasis MCX strong cation-exchange mixed-mode polymeric sorbent was chosen for pharmaceuticals extraction from environmental samples. The influence of matrix-assisted ion suppression and low SPE recovery on the sensitivity of the method was studied. The instrumental limits of quantification varied from 0.2 to 10 μg L −1. The method limits of quantification were at low nanogram per litre levels and ranged from 0.3 to 50 ng L −1. The instrumental and method intra- and inter-day repeatabilities were on average less than 10%. The method was applied for the determination of pharmaceuticals in Rivers Taff (UK) and Warta (Poland). Fifteen compounds were determined in river water at levels ranging from single nanograms to single micrograms per litre.

Identification of molecular species of simple lipids by normal phase liquid chromatography–positive electrospray tandem mass spectrometry, and application of developed methods in comprehensive analysis of low erucic acid rapeseed oil lipids

Mono-, di- and triacylglycerol (MAG, DAG, TAG), sterol ester (SE), free sterol (S) and free fatty acid (FFA) standards were analyzed in the presence of ammonium ions and ammonia by flow injection MS 2 and MS 3, and by normal phase-liquid chromatography (NP-LC) MS 2 positive electrospray ionization (ESI) mass spectrometry (MS). The MS data recorded for ammonium adducts ([ M + NH 4] +) of TAGs, DAGs, and MAGs were consistent with stepwise fragmentation mechanisms. In the first step, ammonium ion in [ M + NH 4] + donates proton to acylglycerol and ammonia is released. In the second step, FFA is cleaved from protonated TAG, water from protonated 1,3-DAG and MAG, both FFA and water from protonated 1,2-DAG, hence leading to formation of [DAG] + ion from TAG and 1,3-DAG, [DAG] + and [MAG] + ions from 1,2-DAG, and [MAG] + ion from MAG. In the third step, [DAG] + ion of TAG is fragmented to yield [Acyl] +, [Acyl + 74] +, [DAG − 74] + ions, [DAG] ion of 1,3-DAG to [Acyl] + ions, and [MAG] + ion of MAG to protonated FAs, which are decomposed to water and [Acyl] + ions in the fourth step. A stepwise mechanism for fragmentation of FFA was also evident from MS 2 and MS 3 data. Molecular species of low erucic acid rapeseed oil simple lipids were identified from characteristic ions produced in the NP-LC–ESI-MS 2 of [ M + NH 4] + ions. The percentage composition of the molecular species of each lipid class was calculated from integrated extracted ion chromatograms of [( M + NH 4)] + ions of SE, TAG, MAG, and FFA, of the sum of [( M + NH 4)] + and [( M + NH 4) − NH 3 − H 2O] + ions of both regioisomers of DAGs, and of sterol fragment ions of S.

Simultaneous quantitation of 7-methyl- and O6-methylguanine adducts in DNA by liquid chromatography–positive electrospray tandem mass spectrometry

A methodology has been developed and validated for the simultaneous quantitation of O6-methyl- and 7-methylguanine in DNA isolated from in vitro exposure to the model alkylating agents: N-methyl-N-nitrosourea (MNU) and methyl methane sulfonate (MMS). After exposure, DNA was isolated and directly hydrolyzed under acid conditions to hydrolytes containing DNA bases (modified and unmodified). The hydrolytes were used for direct O6- and 7-methylguanine quantitation using a rapid and selective liquid chromatography-electrospray tandem mass spectrometry (LC/ESI-MS/MS). The lower limits of quantitation for O6-methyl- and 7-methylguanine were 75.8 and 151.5 fmol, respectively. Linearity of the calibration curve was greater than 0.999 from 75.8 to 151,600.0 fmol for O6-methylguanine and 0.999 from 151.5 to 303,200.0 fmol for 7-methylguanine. The intra-day assay precision relative standard deviation (R.S.D.) values for O6-methylguanine for quality control (QC) samples were < or =9.2% with accuracy values ranging from 90.8 to 118%, and for 7-methylguanine the R.S.D. values for QC samples were < or =11%, with accuracy values ranging from 92.9 to 119%. The inter-day assay precision (R.S.D.) values for O6-methylguanine QC samples were < or =7.9% with accuracy values ranging from 94.5 to 116%, and for 7-methylguanine QC samples were < or =7.1% with accuracy values ranging from 95.2 to 110.2%. This method was used for simultaneous determination of the levels of 7-methyl- and O6-methylguanine in DNA acidic hydrolytes present in a series of incubations from salmon testis DNA treated with either MNU or MMS.

Identification of ractopamine residues in tissue and urine samples at ultra-trace level using liquid chromatography–positive electrospray tandem mass spectrometry

Beta-agonist compounds are widely used in human therapeutics because of bronchodilator or heart tonic properties; they are also used as growth promoters in food-producing animals. Ractopamine is a forbidden molecule in the EU, but is registered as an additive in other countries such as in the USA for pigs. Consequently, efficient analytical methods were developed to survey residues in edible tissue and urine samples. This paper describes a protocol based on a powerful extraction and purification process and a liquid chromatography–positive electrospray mass spectrometry identification method. A validation was performed according to the “DG SANCO 1805/2000” European decision. The obtained decision limit (CC α) and detection capability (CC β) were as low as 10 and 30 ng/kg (ppt), respectively. This method appeared very efficient on incurred samples, including porcine edible tissues (meat, liver, kidney), tissues enriched in β-agonist receptors (lung, retina), and finally bovine urine samples.