Waldman J.M.,Environmental Health Laboratory |
Gavin Q.,Environmental Health Laboratory |
Anderson M.,Environmental Health Investigations Branch |
Hoover S.,Safer Alternatives Assessment and Biomonitoring Section |
And 11 more authors.
Environment International | Year: 2016
Firefighters are at increased risk for exposure to toxic chemicals compared to the general population, but few studies of this occupational group have included biomonitoring. We measured selected phenolic chemicals in urine collected from 101 Southern California firefighters. The analytes included bisphenol A (BPA), triclosan, benzophenone-3 (BP-3), and parabens, which are common ingredients in a range of consumer products. BP-3, BPA, triclosan, and methyl paraben were detected in almost all study subjects (94-100%). The BP-3 geometric mean for firefighters was approximately five times higher than for a comparable National Health and Nutrition Examination Survey (NHANES) subgroup. Demographic and exposure data were collected from medical records and via a questionnaire, and covariates were examined to assess associations with BP-3 levels. BP-3 levels were elevated across all firefighter age groups, with the highest levels observed in the 35 to 39 year old group. Body fat percentage had a significant inverse association with BP-3 concentrations. Our results indicate pervasive exposure to BP-3, BPA, triclosan, and methyl paraben in this population of firefighters, consistent with studies of other populations. Further research is needed to investigate possible explanations for the higher observed BP-3 levels, such as occupational or California-specific exposures. © 2015 Elsevier Ltd.
Draper W.M.,Drinking Water and Radiation Laboratory |
Xu D.,Drinking Water and Radiation Laboratory |
Behniwal P.,Drinking Water and Radiation Laboratory |
Behniwal P.,Environmental Health Laboratory |
And 4 more authors.
Analytical Methods | Year: 2013
The performance of a solid phase extraction (SPE) LC-MS-MS procedure for determining microcystins (MC) in water was investigated. Six MC, MCRR, MCYR, MCLR, MCLA, MCLF and MCLW, were determined using positive ion electrospray (+ESI) with separation on a C8 column eluted with a methanol-water gradient containing 15 mM ammonium formate and 0.006% acetic acid. Each MC, as well as the internal standard and surrogate, were detected by two transitions. Isocratic and gradient separations were examined to increase the resolution of MCRR and MCLF as all known naturally occurring MC elute between these two variants. Analysis of fortified laboratory reagent water as well as bloom samples from northern California provided performance information. Cell lysis, accomplished by freeze-thawing samples, was required to determine total sample toxins as 93 to 99% of the toxins were intracellular. Up to 98% of dissolved MC were lost by sorption in filter cartridges, but satisfactory recoveries were obtained with polypropylene filters after the filtrate was combined with a methanol rinse. C18 SPE required elution with trifluoroacetic acid (TFA) for acceptable recoveries of the arginine-containing MC. Freezing was required to preserve MC which degraded rapidly by microbial metabolism at 4°C after an approximate 10 day lag period. With the optimized method the experimental Method Detection Limits (MDL) for both quantitation and confirmation transitions for the arginine-containing MC ranged from 0.03 to 0.04 μg L-1. Laboratory reporting limits (or LOQ) of 0.1 and 0.2 μg L-1 were confirmed by analyzing surface water samples where accuracy averaged 65 to 70%. Measurement of total MC in bloom samples was reproducible with relative standard deviations of 8.3 to 12%. The study demonstrates the importance of sample preservation, sample workup and quality control procedures in reliable MC determination using modern LC-MS-MS instruments. © 2013 The Royal Society of Chemistry.
Liao W.,Drinking Water and Radiation Laboratory |
Draper W.M.,Drinking Water and Radiation Laboratory
Analyst | Year: 2013
The mass-to-structure or MTS Search Engine is an Access 2010 database containing theoretical molecular mass information for 19438 compounds assembled from common sources such as the Merck Index, pesticide and pharmaceutical compilations, and chemical catalogues. This database, which contains no experimental mass spectral data, was developed as an aid to identification of compounds in atmospheric pressure ionization (API)-LC-MS. This paper describes a powerful upgrade to this database, a fully integrated utility for filtering or ranking candidates based on isotope ratios and patterns. The new MTS Search Engine is applied here to the identification of volatile and semivolatile compounds including pesticides, nitrosoamines and other pollutants. Methane and isobutane chemical ionization (CI) GC-MS spectra were obtained from unit mass resolution mass spectrometers to determine MH+ masses and isotope ratios. Isotopes were measured accurately with errors of <4% and <6%, respectively, for A + 1 and A + 2 peaks. Deconvolution of interfering isotope clusters (e.g., M+ and [M - H]+) was required for accurate determination of the A + 1 isotope in halogenated compounds. Integrating the isotope data greatly improved the speed and accuracy of the database identifications. The database accurately identified unknowns from isobutane CI spectra in 100% of cases where as many as 40 candidates satisfied the mass tolerance. The paper describes the development and basic operation of the new MTS Search Engine and details performance testing with over 50 model compounds. This journal is © 2013 The Royal Society of Chemistry.