Janel E. Owens

Quantitative analysis of chemical warfare agent degradation products in beverages by liquid chromatography tandem mass spectrometry.

Though chemical warfare agents (CWAs) have been banned by the Chemical Weapons Convention, the threat that such chemicals may be used, including their deliberate addition to food, remains. In such matrixes, CWAs may hydrolyze to phosphonic acids, which are good surrogate markers of CWA contamination. The method described here details the extraction of five CWA degradation products, including methylphosphonic acid (MPA), ethyl-MPA, isopropyl-MPA, cyclohexyl-MPA, and pinacolyl-MPA, from five different beverages by strata-X solid phase extraction cartridges. Samples were analyzed by liquid chromatography tandem mass spectrometry (LC/MS/MS) with multiple reaction monitoring. The limit of quantitation ranged from 0.05 to 0.5 ng on-column, and the limit of detection was >0.02 ng on-column. Beverages were fortified with the five phosphonic acids at 1 microg/mL and 0.25 microg/mL and quantitated using both an internally standardized method and matrix-matched standards. Reasonable recoveries (>50%) were achieved for ethyl, isopropyl, cyclohexyl, and pinacolyl-MPA for most matrixes.

Quantitation of abrine, an indole alkaloid marker of the toxic glycoproteins abrin, by liquid chromatography/tandem mass spectrometry when spiked into various beverages.

Abrine is an alkaloid chemical marker and surrogate analyte of abrin, a group of highly toxic glycoproteins. These toxins can be easily isolated from the seed of the rosary pea plant and distributed in a variety of matrices, including food. A procedure for the cleanup of abrine from various beverages, including milk, cola, juice drink, tea, and water, by C18 Strata-X solid-phase extraction (SPE) cartridges is described with comparison to a previously developed liquid-liquid extraction protocol utilizing acetonitrile and water. Analysis was by liquid chromatography/tandem mass spectrometry. Abrine quantitation was based on fragmentation of m/z 219.2 to product ion m/z 188.2. The method detection limit was 0.025 microg/mL, and the quantitation limit was 0.05 microg/mL. Fortifications of the five beverages at 0.5 and 0.05 microg/mL were recovered ranging from 88 to 111% [relative standard deviation (RSD) < 16%] by SPE and from 48 to 101% (RSD < 19%) by liquid-liquid extraction.

Quantitative Analysis of Tetramethylenedisulfotetramine (Tetramine) Spiked into Beverages by Liquid Chromatography−Tandem Mass Spectrometry with Validation by Gas Chromatography−Mass Spectrometry

Tetramethylenedisulfotetramine, commonly known as tetramine, is a highly neurotoxic rodenticide (human oral LD(50) = 0.1 mg/kg) used in hundreds of deliberate and accidental food poisoning events in China. This paper describes a method for the quantitation of tetramine spiked into beverages, including milk, juice, tea, cola, and water, with cleanup by C8 solid phase extraction and liquid-liquid extraction. Quantitation by high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) was based upon fragmentation of m/z 347 to m/z 268. The method was validated by gas chromatography-mass spectrometry (GC-MS) operated in selected ion monitoring mode for ions m/z 212, 240, and 360. The limit of quantitation was 0.10 μg/mL by LC-MS/MS versus 0.15 μg/mL for GC-MS. Fortifications of the beverages at 2.5 and 0.25 μg/mL were recovered ranging from 73 to 128% by liquid-liquid extraction for GC-MS analysis, from 13 to 96% by SPE, and from 10 to 101% by liquid-liquid extraction for LC-MS/MS analysis.

Single nucleotide polymorphisms in CETP, SLC46A1, SLC19A1, CD36, BCMO1, APOA5, and ABCA1 are significant predictors of plasma HDL in healthy adults

BackgroundIn a marker-trait association study we estimated the statistical significance of 65 single nucleotide polymorphisms (SNP) in 23 candidate genes on HDL levels of two independent Caucasian populations. Each population consisted of men and women and their HDL levels were adjusted for gender and body weight. We used a linear regression model. Selected genes corresponded to folate metabolism, vitamins B-12, A, and E, and cholesterol pathways or lipid metabolism.MethodsExtracted DNA from both the Sacramento and Beltsville populations was analyzed using an allele discrimination assay with a MALDI-TOF mass spectrometry platform. The adjusted phenotype, y, was HDL levels adjusted for gender and body weight only statistical analyses were performed using the genotype association and regression modules from the SNP Variation Suite v7.ResultsStatistically significant SNP (where P values were adjusted for false discovery rate) included: CETP (rs7499892 and rs5882); SLC46A1 (rs37514694; rs739439); SLC19A1 (rs3788199); CD36 (rs3211956); BCMO1 (rs6564851), APOA5 (rs662799), and ABCA1 (rs4149267). Many prior association trends of the SNP with HDL were replicated in our cross-validation study. Significantly, the association of SNP in folate transporters (SLC46A1 rs37514694 and rs739439; SLC19A1 rs3788199) with HDL was identified in our study.ConclusionsGiven recent literature on the role of niacin in the biogenesis of HDL, focus on status and metabolism of B-vitamins and metabolites of eccentric cleavage of β-carotene with lipid metabolism is exciting for future study.

Gender and Single Nucleotide Polymorphisms in MTHFR, BHMT, SPTLC1, CRBP2, CETP, and SCARB1 Are Significant Predictors of Plasma Homocysteine Normalized by RBC Folate in Healthy Adults

Using linear regression models, we studied the main and 2-way interaction effects of the predictor variables gender, age, BMI, and 64 folate/vitamin B-12/homocysteine (Hcy)/lipid/cholesterol-related single nucleotide polymorphisms (SNP) on log-transformed plasma Hcy normalized by RBC folate measurements (nHcy) in 373 healthy Caucasian adults (50% women). Variable selection was conducted by stepwise Akaike information criterion or least angle regression and both methods led to the same final model. Significant predictors (where P values were adjusted for false discovery rate) included type of blood sample [whole blood (WB) vs. plasma-depleted WB; P < 0.001] used for folate analysis, gender (P < 0.001), and SNP in genes SPTLC1 (rs11790991; P = 0.040), CRBP2 (rs2118981; P < 0.001), BHMT (rs3733890; P = 0.019), and CETP (rs5882; P = 0.017). Significant 2-way interaction effects included gender × MTHFR (rs1801131; P = 0.012), gender × CRBP2 (rs2118981; P = 0.011), and gender × SCARB1 (rs83882; P = 0.003). The relation of nHcy concentrations with the significant SNP (SPTLC1, BHMT, CETP, CRBP2, MTHFR, and SCARB1) is of interest, especially because we surveyed the main and interaction effects in healthy adults, but it is an important area for future study. As discussed, understanding Hcy and genetic regulation is important, because Hcy may be related to inflammation, obesity, cardiovascular disease, and diabetes mellitus. We conclude that gender and SNP significantly affect nHcy.

Analysis of Fentanyl in Urine by DLLME–GC-MS

Fentanyl is a synthetic narcotic anesthetic ∼80-100 times more potent than morphine. Owing to the potential for its abuse, the drug may be included in a forensic toxicology work-up, which requires fast, precise and accurate measurements. Here, the stability of fentanyl was assessed when stored at three different temperatures (-20, 4 and 25°C) in synthetic urine. Stability at those three temperatures was demonstrated over 12 weeks upon analysis by gas chromatography-mass spectrometry with a deuterated internal standard (fentanyl-D5) utilizing three different extraction techniques: liquid-liquid extraction (LLE), solid-phase extraction and dispersed liquid-liquid microextraction (DLLME). The DLLME method was then optimized before use in the analysis of fentanyl in urine samples obtained from autopsy cases at the El Paso County Coroners Office. Accuracy of the DLLME method was assessed by completing spike and recovery studies at three different fortification levels (10, 100 and 250 ng/mL) with excellent recovery (89.9-102.6%). The excellent comparability between DLLME and LLE is demonstrated (Bland-Altman difference plot with a mean difference of 4.9 ng/mL) and the use of this methodology in the analysis of forensically relevant samples is discussed.

Development of a low‐density‐solvent dispersive liquid–liquid microextraction with gas chromatography and mass spectrometry method for the quantitation of tetrabromobisphenol‐A from dust

The development of an alternative dispersive liquid-liquid microextraction protocol utilizing a low-density extraction solvent, toluene, is described here for the extraction of the brominated flame retardant, tetrabromobisphenol-A, from dust prior to selected ion monitoring analysis by gas chromatography with mass spectrometry. Method parameters of dispersive solvent type and extraction solvent type were optimized. Excellent recovery (88.9%; n = 5 spike replicates) with good precision was achieved in a spike and recovery study. This developed method was utilized to survey tetrabromobisphenol-A concentrations in dust sampled from a local electronics recycling facility from the ambient environment and 20 computer towers undergoing recycling. Concentrations of tetrabromobisphenol-A from dust in computer towers ranged from not detected (n = 2) up to 64 μg/g with a mean value of 11 μg/g and median of 4.1 μg/g tetrabromobisphenol-A. A composite sample of dust collected from the ambient indoor environment was analyzed with a resulting concentration of 36 μg/g. This is the first application of this novel green method for pre-concentrating flame retardants from dust and the first report of tetrabromobisphenol-A concentrations at a U.S.-based electronics recycling facility.