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Declining snow cover is reshaping ecological communities. Early loss of snow cover initiates changes in key interactions that mediate herbivore abundance, i.e., top-down and bottom-up effects. In this study, we used a field experiment to test the effects of host plant water stress and phenology on the multitrophic interactions that determine aphid abundance. The aphid, Aphis asclepiadis, in our study system colonizes the flowering stalks of the host plant Ligusticum porteri and relies on a protection mutualism with ants. We added snow and water to replicate host plants and tested for a variety of phenological and physiological responses to these treatments. Relative to host plants in ambient conditions, both water and snow addition reduced key signals of water stress (senescence and abscisic acid levels) and increased seed set. While aphid colonies were generally larger with reduced host plant water stress, the ant–aphid mutualism interacted with plant quality in complex ways. Without ant tending, we did not detect differences in aphid colony growth with host plant treatment. When tended by ants, aphid colony growth was greatest on host plants with snow addition. Host plant quality also altered the benefits exchanged in this mutualism. Ant-tended colonies hosted by plants with snow addition produced honeydew enriched in trehalose, which may have decreased both ant and natural enemy abundance. Our results suggest that early loss of snow reduces aphid abundance by creating low-quality, water-stressed host plants, and this effect may be exacerbated by natural enemies and the costs of ant attendance.

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)., Graphical abstract Image, graphical abstract

Ligusticum porteri (osha) is an important wild-harvested medicinal plant. Populations of this plant occur in meadows and forest understories in the subalpine and montane zones of the Rocky Mountains. We examined variation in the bioactive compounds of 44 methanolic extracts of L. porteri roots harvested from eleven populations in Colorado, USA during 2012 and 2015. Populations were found in two distinct regions of Colorado, the Front Range and Western Slope. We also classified population light environment as either meadow or understory based on the mean percent of full-sun photosynthetically active radiation above plants. We used high performance liquid chromatography (HPLC) to quantify variation in five secondary metabolites: Z-ligustilide, trans-ferulic acid, (Z/E)-3-butylidenephthalide, isovanillin and elemicin. Variation between sampling years was found for trans-ferulic acid, elemicin and (E)-3-butylidenephthalide. Root extracts from the Front Range had more than double the mean relative concentrations of (Z)-ligustilide than root extracts from plants on the Western Slope of Colorado. Our results demonstrate distinct chemotypes in L. porteri, and this could have therapeutic effects because (Z)-ligustilide is the major bioactive compound in this species.

Analysis of whiskey samples prepared by a green microextraction technique, dispersive liquid–liquid microextraction (DLLME), before analysis by a qualitative gas chromatography–mass spectrometry (GC/MS) method, is described as a laboratory experiment for an upper division instrumental methods of analysis laboratory course. Here, aroma compounds in whiskey samples (n = 11) were extracted using ultrasound-assisted DLLME with chloroform (as extraction solvent). The chloroform extract was analyzed by GC/MS with data manipulation by AMDIS (automated mass spectral deconvolution and identification system) to allow for comparisons between whiskey samples. Aroma compounds commonly reported in the literature (furfural, isoamyl acetate, 5-methyl furfural, ethyl esters, phenylethyl alcohol, whiskeylactone, and vanillin) were tentatively identified based upon the match to the MS library. This unique laboratory allows students to engage in a real-world analysis of a high-value product and to explore the use of AMDIS to...

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.

The objective of this study was to assess the antibacterial activity and inhibition of biofilm formation of silver nanoparticles (AgNPs) against Escherichia coli (MG1655), Bacillus subtilis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Janthinobacterium lividum. The AgNPs utilized in this study were prepared through one-pot microwave-assisted syntheses guided by principles of green chemistry. The AgNPs were synthesized in three different schemes by reducing Ag+ ions (from AgNO3) with reducing agents dextrose, arabinose, and soluble starch. Formation of AgNPs occurred in less than 15 min, and nanoparticles had diameters of 30 nm or less. Successful synthesis of AgNPs was confirmed using multiple orthogonal approaches, including UV–visible spectroscopy, fluorescence emission spectroscopy, powder X-ray diffraction, and transmission electron microscopy, while size analysis was gathered from transmission electron microscopy images and dynamic light scattering. All AgNPs prepared in...

This paper discusses a K–12/university collaboration in which students participated in a four-day scenario-based summer STEM (science, technology, engineering, and mathematics) camp aimed at making difficult scientific concepts salient. This scenario, Jumpstart STEM–CSI: Chocolate Science Investigation (JSCSI), used open- and guided-inquiry methods to generate meaningful student engagement for 33 rising 8th through 12th graders. This paper presents curriculum for the scenario; reports results from postevent survey data regarding students’ self-reported gains in science motivation, science confidence, science knowledge, and students’ associations with scientifically-minded social niches; and illustrates how a scenario can incorporate the use of skills and knowledge from many disciplines and make them relevant to student learning, providing a context for STEM literacy. Implications for science educators are discussed.

Silver nanoparticles (AgNPs) were prepared in a one-step microwave-assisted synthesis guided by the principles of green chemistry. Microwave parameters were optimized using the Box–Benhken design for three factors (time, temperature, and pressure). Aqueous extracts from the peels of citrus fruits (orange, grapefruit, tangelo, lemon, and lime) were used for the synthesis of AgNPs using microwave technology, though the synthesis of AgNPs was only successful using the orange peel extract. Nanospheres of TEM mean diameter (with standard deviation) of 7.36 ± 8.06 nm were successfully synthesized in 15 min by reducing Ag+ ions (from AgNO3) with orange peel extract, which also served as a capping agent. Creation of AgNPs was confirmed using UV–visible spectroscopy, fluorescence emission spectroscopy, powder X-ray diffraction, and transmission electron microscopy, while size analysis was gathered from both transmission electron microscopy as well as dynamic light scattering. Analysis of all citrus peel extracts b...

J. Inst. Brew. 113(3), 243–248, 2007 Folate levels in a range of beers and other beverages have been measured using high-performance liquid chromatography with fluorescence detection (HPLC-FLD) and by liquid chromatog-raphy tandem mass spectrometry (LC-MS/MS). The data from the LC-MS/MS study was revealed to be unreliable, through the masquerading of polyphenol degradation products as folates. Using the HPLC-FLD procedure most beers ranged between 2.2 and 24.2 µg per bottle, or up to 6.1% of the recommended daily allowance. Some imported beers contained no detectable folate and we believe that this is due to the folate decreasing in level during storage and transportation. Wine, vodka and whiskey contained no detectable folate, while orange juice contained folate at a comparable level to that found in the beer with the highest folate. Key words: Beer, folate, high-performance liquid chromatog-raphy with fluorescence detection, liquid chromatography–mass spectrometry. INTRODUCTION

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.

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.

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 β-carotene with lipid metabolism is exciting for future study.

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 13C12-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 cm2 areas on electronic surfaces (monitor, microwave, refrigerator, and TV) were determined to range from less than the LOQ to 523 ng/mL.

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.

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.

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.

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.

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, p0.01), but the intake instruments were highly correlated for total folate intake (r=0.608, p0.01). Correlations between instruments and RBC folate were low (r0.35) but strong (p0.01). 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.

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

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 (>104 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.