SNaP-C: Validation of a novel, selective silver nanoparticle antioxidant capacity assay for Vitamin C content in beverages.

A validated silver nanoparticle assay (SNaP-C) for quantitation of Vitamin C, as ascorbic acid (AA) and total AA (TAA), was applied to 31 beverages. SNaP-C assay results (LOD of 2.2 mg/L AA) were compared to AA and TAA determined by high-performance liquid chromatography with UV/Vis (LOD = 0.4 mg/L AA), and two well-known assays. All approaches were calibrated using meta-phosphoric acid stabilized AA, where the reducing agent tris(2-carboxyethyl) phosphine hydrochloride was added to convert dehydroascorbic acid to AA for determination of TAA. Statistical comparisons of these four resulting datasets were completed. SNaP-C and HPLC were not statistically significantly different (P > 0.05) for comparison of AA and TAA (mg/L) in these samples, whereas the CUPRAC and Folin-Ciocalteu assays statistically significantly overestimated values of AA and TAA content, respectively. The SNaP-C method is a novel assay that has high specificity for AA capable of quantifying TAA with addition of TCEP.

Micro-extraction method for the analysis of flame retardants in dust collected from air filters from HVAC systems.

Dust is a sink for many semi-volatile compounds including flame retardants of the organophosphate ester (OPE) and brominated flame-retardant (BFR) classes. Given the large amount of time that we spend indoors, our exposure to these compounds via dust is of significant interest. Here, we present a novel microextraction approach to determine quantitative levels of selected OPEs and BFRs sampled from residential air filters from HVAC systems using a small volume of solvent. Dust samples (25 mg) is extracted with 1 mL of hexane/acetone (50/50, v/v). Upon solvent extraction of these HVAC dust samples, the analytes (TCPP, TDCPP, TPHP, T24DtBPP, TBBPA, and TriBBPA) were quantified via gas chromatography-mass spectrometry (GC/MS) or liquid chromatography-mass spectrometry (LC/MS). The methods for extracting these compounds from HVAC dust samples are detailed here with extensive method validation data to demonstrate accuracy and precision of these methods. •Dust is a sink for many semi-volatile compounds, including novel or emerging indoor pollutants like the organophosphate ester flame retardant T24DtBPP.•Here, a small amount of dust (25 mg) is extracted with a small volume of solvent (1 mL hexane and acetone) prior to analysis via chromatographic separation and mass spectrometric detection.

Exploring the residential exposome: Determination of hazardous flame retardants in air filter dust from HVAC systems.

Dust is a sink for flame retardants, which are added to a myriad of consumer products in residential spaces. Organophosphate esters (OPEs) and brominated flame retardants (BFRs) are two classes of flame retardants that are frequently used in consumer products and consequently found in dust. In this present work, a novel solvent-limited microextraction technique, which we detailed in a companion study, was applied for the determination of four OPEs and two BFRs with limits of quantitation at the ng/g level by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry from n = 47 air filter dust samples collected from forced air HVAC systems. Levels of the BFRs, including tetrabromobisphenol-A and its derivative tribromobisphenol-A, were found at levels <4 µg/g and not frequently detected. Conversely, all four OPEs were detected in all air filter dust samples. Total OPE load was dominated by tris(2,4-di-tert-butylphenyl) phosphate, T24DtBPP, a novel OPE not widely examined in the literature. Comparison of individual and total OPE concentrations to residential characteristics revealed statistically significant relationships to location of the home and dominant flooring type. Overall, this study motivates future work in examining the whole house exposome using air filter dust as a passive sampling regime with more examination of T24DtBPP loads within other indoor spaces.

Headspace versus direct injection for the quantitation of methanol, ethyl acetate, and fusel oils in distilled spirits by gas chromatography - Flame ionization detection.

Distilled spirits can be very complex in their sensory or organoleptic compounds. Of significant interest is determination of the concentration of methanol, ethyl acetate, and fusel oils, which include n-propanol, isobutanol, n-butanol, active amyl (2-methyl-1-butanol) and isoamyl (3-methyl-1-butanol) alcohols. Here, we describe a validated method for the analysis of these analytes using a headspace (HS) sampling unit coupled with a gas chromatograph fitted with a flame ionization detector (GC/FID) for profiling these analytes in distilled spirits (n = 26) obtained from local retailers. HS results were compared to the direct injection (DI) GC/FID protocol made available by the US Alcohol and Tobacco Tax and Trade Bureau (TTB), method SSD:TM:200 via correlation and Bland-Altman difference plots to demonstrate that HS-GC/FID is a valid alternative to the direct injection protocols described elsewhere. •A method for the analysis of methanol, ethyl acetate, and fusel oils via headspace sampling coupled to a gas chromatograph fitted with a flame ionization detector (HS-GC/FID) is described.•Samples required no pre-treatment beyond diluting 1 mL of distilled spirit in 4 mL water containing table salt, which resulted in a method with minimal inlet or column maintenance, little sample prepration, and a rapid run time with retention times under 7 min.•Validation by comparing to established protocols using direct injection made available by the US Federal Tax and Trade Bureau (TTB).

Dataset of surveyed PFAS in water, sediment, and soil of Fountain Creek Watershed, Colorado, USA.

Per- and polyfluoroalkyl substances (PFAS) are widespread and highly persistent organic chemicals with adverse health effects. The US Environmental Protection Agency has issued health advisory limits of 70 ng/L for aqueous concentrations of PFOA + PFOS. In the Colorado Springs, Colorado (USA), metro area, the Widefield Aquifer (groundwater) and Fountain Creek Watershed (surface water) have been contaminated by PFAS from aqueous film-forming foams. Here we present the concentrations of selected linear and branched isomers of legacy PFAS found in surface water (n = 95), soil (n = 83), and sediment (n = 34) samples collected from several creeks of the Fountain Creek Watershed. Collected samples were prepared for high-performance liquid chromatography tandem mass spectrometry (LC/MS/MS) analysis via liquid/liquid extraction and/or solid phase extraction (SPE). This dataset includes the geographic locations of sampled creeks, LC/MS/MS instrumental conditions, method verification data including percent recovery to assess method accuracy and background contamination of PFAS in laboratory reagents and supplies, and determined concentrations of PFAS in water, soil, and sediment samples. These locations were surveyed monthly for a full year and provide a rich dataset to assess influence of sampling location, temporal variability in concentration, and overall contaminant persistence.

Analysis of sugars and amino acids in aphid honeydew by hydrophilic interaction liquid chromatography - Mass spectrometry.

Past analyses of sugar and amino acid composition of aphid honeydews have been completed using diverse instrumentation. Here we report the use of hydrophilic interaction liquid chromatography (HILIC) coupled with a triple quadrupole mass spectrometric (MS/MS) detector for the analysis of seven saccharides (xylose, fructose, glucose, sucrose, trehalose, melezitose and raffinose) and five amino acids (glutamic acid, glutamine, aspartic acid, serine, and asparagine). Limits of quantitation ranged from 0.05 mg/L (melezitose) to 1.0 mg/L (fructose) for sugars and from 0.10 mg/L (glutamic acid) to 3.66 mg/L (asparagine) for amino acids. Sample preparation was fast and simple, requiring only the washing of foils used to collect aphid honeydew with hot (80 °C) water and sonication of samples prior to HILIC/MS/MS analysis for both classes of analytes. No analyte derivatization was required and excellent chromatographic characteristics were observed. For those studying honeydew-mediated interactions in the field, this technique allows for rapid characterization of ecologically important amino acids and sugars.•Composition of seven saccharides in Aphis asclepiadis honeydew including xylose, fructose, glucose, sucrose, trehalose, melezitose,and raffinose, and five standard amino acids including glutamic acid, glutamine, aspartic acid, serine, and asparagine, were analyzed using hydrophilic interaction liquid chromatography-mass spectrometry.•All polar analytes were analyzed without derivatization using HILIC-MS with chromatographic run times of 7 min (sugars) and 10 min (amino acids).

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.

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 Coroner's 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.

Quantitation of tetrabromobisphenol-A from dust sampled on consumer electronics by dispersed liquid-liquid microextraction.

Tetrabromobisphenol-A (TBBPA) is a brominated flame retardant used worldwide. Despite its widespread use, there are few data concerning environmental concentrations of TBBPA. Thus, the objective of this work was to optimize an ultrasound-assisted dispersed liquid-liquid microextraction (DLLME) method to analyze swabbed surfaces of consumer electronics to determine TBBPA concentrations. Upon sample preparation with DLLME, TBBPA was derivatized with acetic anhydride and then analyzed by gas chromatography-mass spectrometry (GC/MS). Using a (13)C12-TBBPA internal standard to improve precision and quantitation, a recovery study was performed. At concentrations of 250-1000 ng/mL, recoveries were 104-106%. Sample preparation with solid phase extraction had comparable recoveries, although overall, improved analyte recovery and precision were achieved with DLLME. In a small survey study, TBBPA concentrations in dust collected from 100 cm(2) areas on electronic surfaces (monitor, microwave, refrigerator, and TV) were determined to range from less than the LOQ to 523 ng/mL.

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

BACKGROUND: In 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. METHODS: Extracted 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. RESULTS: Statistically 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. CONCLUSIONS: Given 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 ß-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.

High-throughput method for the quantitation of total folate in whole blood using LC-MS/MS.

A high-throughput liquid chromatography tandem mass spectrometry (HT LC-MS/MS) method for red blood cell (RBC) folate analysis was developed from a previously described manual (M) LC-MS/MS method. The HT LC-MS/MS method used 96-well plates in which RBC folates were hydrolyzed with concentrated HCl in the presence of the [13C6]pABA internal standard (IS). The pH of the hydrolysate was adjusted to 5.0 before cleanup using 96-well plate OASIS HLB SPE cartridges. The analyte and IS were eluted with ethyl acetate/hexane (95:5, v/v) and methylated with methanol and trimethylsilyldiazomethane. The methylated analyte and IS were quantified with LC-MS/MS as previously described. The HT LC-MS/MS method was validated by determining the recovery of six different folate vitamers, which were quantitatively recovered (84-105% with CV<9.0%). RBC folate concentrations in whole blood samples correlated between HT and M LC-MS/MS methods (r=0.922, p<0.0001 for n=43 samples) and between the HT LC-MS/MS method and a chemiluminescence assay (r=0.664, p<0.001 for n=325 samples). Comparison of the results between HT LC-MS/MS and chemiluminescence methods with Bland-Altman difference plots and by ROC curve analysis indicates that the chemiluminescence assay underreports RBC folate concentrations. The HT LC-MS/MS method allows for high-throughput sample preparation for the analysis of RBC folate.

Comparison of two dietary folate intake instruments and their validation by RBC folate.

An optimal folate nutritional status is important in minimizing developmental and degenerative disease. Therefore, constant monitoring of folate intake and of biomarkers of folate nutritional status is essential. The objective of this research was to compare two folate intake instruments and validate each one against RBC folate measured by a high-throughput liquid chromatography tandem mass spectrometry (HT LC-MS/MS) method described in the companion paper (Owens, J. E.; Holstege, D. M.; Clifford, A. J. J. Agric. Food Chem. 2007, 55, 3292-3297). A food frequency questionnaire (FFQ) and a folate-targeted semiquantitative Block dietary folate equivalents (DFE) screener were compared and individually validated against an HT LC-MS/MS method. RBC folate was 1178 +/- 259 nmol/L (mean +/- SD) in a population of 337 normal adult subjects. Folate intakes were 556 +/- 265 microg/day by the FFQ and 524 +/- 276 microg/day by the DFE screener. Folate intakes by the DFE screener were approximately 34 microg less than by the FFQ (paired t test, p<0.01), but the intake instruments were highly correlated for total folate intake (r=0.608, p<0.01). Correlations between instruments and RBC folate were low (r<0.35) but strong (p<0.01). ROC curve analysis indicates that the measurement of RBC folate by the HT LC-MS/MS method is a better predictive tool than are intake instruments for the evaluation of marginal folate status.

Analysis of chemical contamination within a canal in a Mexican border colonia.

This study examines urban pollution within Derechos Humanos, a colonia popular in Matamoros, Tamaulipas, Mexico. General water quality indicators (coliform bacteria, total dissolved solids, ecologically relevant cations and anions), heavy metals (copper, lead, nickel, zinc, iron and cadmium), and volatile organic compounds (benzene, toluene, ethylbenzene, styrene, and dichlorobenzene and xylene isomers) were quantified within a wastewater canal running adjacent to the community. Water samples were collected at multiple sites along the banks of the canal and evidence of anthropogenic emissions existed at each sampling location. Sample site 2, approximately 10 m upstream of the colonia, contained both the widest range of hazardous pollutants and the greatest number exceeding US Environmental Protection Agency surface water standards. At each sampling location, high concentrations of total coliform (> 10(4) colonies/100 mL sample), lead (ranging from 0.05 to 0.40 mg/L), nickel (levels from 0.21 to 1.45 mg/L), and benzene (up to 9.80 mg/L) were noted.

Quantitation of total folate in whole blood using LC-MS/MS.

An accurate method for measuring whole blood total folate using liquid chromatography with tandem mass spectrometry is described and compared to GC/MS and a chemiluminescence assay. Whole blood from normal adults (n = 15) was fortified with a [(13)C(6)]para-aminobenzoic acid (pABA) internal standard and treated with 12.1 N hydrochloric acid at 110 degrees C for 4 h to hydrolyze all folates to pABA. Contaminants in the hydrolysate were adsorbed onto a C18 SPE cartridge. The eluate containing the folate catabolite pABA was partitioned into ethyl acetate and methylesterified with trimethylsilyldiazomethane. The methyl-pABA derivatives were quantified by positive-ion atmospheric pressure chemical ionization (APCI)LC-MS/MS. An isocratic mobile phase of acetonitrile-water (70:30) (v/v) on a C18 analytical column was used with a postcolumn reagent of 0.025% formic acid. The limit of quantitation for folate was 56.6 nmol/L RBC, and the limit of detection was 22.6 nmol/L RBC. Folate levels as determined by LC-MS/MS correlated well with the chemiluminescence assay and a GC/MS method. This new LC-MS/MS method provides enhanced sample throughput (n = 36 per day) as compared to GC/MS methods. LC-MS/MS will enable accurate measurements of red blood cell (RBC) folate in nutrition surveys and clinical trials.