Gas Chromatography-negative Chemical Ionization Mass Research Articles

Estimates of the Effect of Feeding on Whole-Body Protein Degradation in Women Vary with the Amino Acid Used as Tracer

We measured how feeding status affects the kinetics of multiple indispensable amino acids in four adult female subjects studied both in fed and fasted state. The subjects ingested one dose of uniformly 13C-labeled algae (Spirulina platensis). The isotopic enrichments (measured with negative chemical ionization gas chromatography-mass spectrometry) of the branched chain amino acids, phenylalanine, lysine and threonine were followed for 24 h in both the plasma and in VLDL-apolipoprotein B-100 (apoB-100). Fasting lowered body protein degradation when measured with the branched chain amino acids, increased it when measured with phenylalanine and had no statistically significant effect when determined from the kinetics of lysine and threonine. These apparent differences challenge the adequacy of current models of whole-body protein turnover. The ratio of the peak labeling of amino acids in plasma and apoB-100 was used as an estimate of the isotopic dilution in the hepatic pool. In contrast to our earlier observations during intravenous tracer amino acid administration, in the present study fasting lowered the ratio of the peak isotopic enrichments of apoB-100 and plasma amino acids. This supports our contention that feeding increases the use of hepatic portal amino acids for hepatic secretory protein synthesis.

Association between serum concentrations of perfluoroalkyl substances and global DNA methylation levels in peripheral blood leukocytes of Japanese women: A cross-sectional study

Global DNA methylation levels in peripheral blood leukocytes can be a biomarker for cancer risk; however, levels can be changed by various factors such as environmental pollutants. We investigated the association between serum concentrations of perfluoroalkyl substances (PFASs) and global DNA methylation levels of leukocytes in a cross-sectional study using the control group of a Japanese breast cancer case-control study [397 women with a mean age of 54.1 (SD 10.1) years]. Importantly, our analysis distinguished branched PFAS isomers as different from linear isomers. The serum concentrations of 20 PFASs were measured by in-port arylation gas-chromatography negative chemical ionization mass spectrometry. Global DNA methylation levels in peripheral blood leukocytes were measured using a luminometric methylation assay. Associations between log10-transformed serum PFAS concentrations and global DNA methylation levels were evaluated by regression coefficients in multivariable robust linear regression analyses. Serum concentrations of 13 PFASs were significantly associated with increased global DNA methylation levels in leukocytes. Global DNA methylation was significantly increased by 1.45 %–3.96 % per log10-unit increase of serum PFAS concentration. Our results indicate that exposure to PFASs may increase global DNA methylation levels in peripheral blood leukocytes of Japanese women.

Compound-Specific Chlorine Isotope Analysis of Organochlorine Pesticides by Gas Chromatography-Negative Chemical Ionization Mass Spectrometry.

Compound-specific stable chlorine isotope analysis (CSIA-Cl) is an important method for identifying sources of organochlorine contaminants and helping assess their quantification of transformation processes. However, the present CSIA-Cl is challenged by either redundant conversion pretreatment or complicated mathematical correction. To overcome the mentioned problems, a novel method has been developed for the CSIA-Cl of eight organochlorine pesticides using gas chromatography-negative chemical ionization mass spectrometry (GC-NCI-qMS) in this study. The instrument parameters, acquisition mode, and required injection amounts were optimized in terms of the precision of GC-NCI-qMS. An ionization energy of 90 eV and emission current of 90 μA were selected, and the precisions for eight organochlorine pesticides were in the range of 0.37‰–2.15‰ in single ion monitoring (SIM) mode when the injected amount was 0.50 mg L−1 (viz. 0.5 ng on column). Furthermore, when standards from Supelco and O2si were calibrated using standards from AccuStandard regarded as external isotope standard, chlorine isotope composition of α-hexachlorocyclohexane (α-HCH) and 2, 2-dichloro−1, 1-bis (4-chlorophenyl) ethylene (p, p′-DDE) in Supelco and O2si was confidently differentiated. The provenance identification method was validated by three organochlorine contaminated groundwater samples and showed a prospect in identifying the source of organochlorine pesticides.

Effect of fasting status and other pre-analytical variables on quantitation of long-chain fatty acids in red blood cells

Long-chain fatty acids (LCFAs), including omega-3 and omega-6 fatty acids, play essential roles in health maintenance and outcomes. Insufficient intake or the inability to absorb LCFAs from the diet can cause a number of health problems. Evaluation of fatty acid profiles in plasma, serum or red blood cells (RBCs) is routinely used to monitor patients at risk of developing deficiency. Quantitation of LCFAs in RBCs offers advantages over serum/plasma due to low intra-individual variability. Fatty acid composition in RBCs also reflects long-term dietary intake, providing additional information about the patient's nutritional status. However, the literature does not currently address the impact of pre-analytical factors (conditions of RBC collection, sample handling and short-term storage) on LCFA measurements. This study evaluated the effect of several anticoagulants, interferents, different storage conditions and fasting status on quantitation of the twenty-one most abundant LCFAs in RBCs by gas chromatography negative chemical ionization-mass spectrometry (GCNCI-MS). LCFA results were assessed quantitatively (nmol/mL) or as a percent of total. Most common tube types (containing citrate, sodium heparin or EDTA) were all appropriate for blood collection. Whole blood and lysed RBCs were stable at least 24 h at room temperature and up to 7 days refrigerated. Lysed RBCs were also stable for up to three freeze/thaw cycles. The presence of icterus or lipemia did not affect results. LCFAs concentrations in RBCs did not change ~4 h after high-fat intake when the lipid concentration in circulation reaches a peak, while plasma levels of most fatty acids increased up to 40% in response. In summary, RBCs are a reliable sample type for LCFA quantitation in the clinical laboratory. In contrast to plasma or serum, RBCs isolated from non-fasting, hemolyzed or lipemic whole blood specimens are all acceptable for testing. Therefore, RBCs might be a preferable sample type for evaluation of nutritional status of young pediatric patients and in patients with conditions associated with hemolytic anemia or hyperlipidemia.

Umbilical cord serum PBDE concentrations and child adiposity measures at 7 years

BackgroundPolybrominated diphenyl ethers (PBDEs) exist extensively in the environment. Toxicological studies suggested PBDEs may interfere with adipogenic pathways. However, few human evidence addressed PBDE exposures in utero related to childhood adiposity. ObjectiveWe assessed associations between PBDEs concentrations in cord serum and childhood adiposity measures at 7 years. MethodsAmong 318 mother-child pairs from Sheyang Mini Birth Cohort Study (SMBCS) in China, nine PBDE congener concentrations were quantified in umbilical cord serum using gas chromatography-negative chemical ionization mass spectrometry (GC-NCI-MS). Anthropometric indicators of children aged 7 years were measured, including weight, height and waist circumference. Age and sex-specific body mass index (BMI) z scores were calculated based on World Health Organization (WHO)'s child growth standards. Multivariate linear and logistic regression models adjusted for putative confounders were performed to examine associations between PBDE congeners and adiposity parameters. ResultsBDE-209 was the most abundant congener of PBDEs with a median value of 19.5 ng/g lipid. The geometric mean values of nine PBDE congeners ranged from below limit of detection (LOD) to 18.1 ng/g lipid, and the detection rates were 46.5%~96.5%. Cord serum BDE-153 and BDE-154 concentrations were associated with lower childhood BMI z score (regression coefficient, β=-0.15, 95% confidence interval: -0.29, −0.02; p=0.02; β=-0.23, 95%CI: -0.43, −0.03; p=0.03, respectively) and lower waist circumference (β=-0.75 cm, 95%CI: -1.43, −0.06; p=0.03; β=-1.22 cm, 95%CI: -2.23, −0.21; p=0.02, respectively), after controlling for potential confounders. Moreover, prenatal BDE-154 exposure was related to a decreased obesity risk of children aged 7 years (odds ratio, OR=0.46, 95%CI: 0.22, 0.94; p=0.03). These effects were only observed among boys in sex-straitified analyses. ConclusionsCord serum BDE-153 and BDE-154 concentrations were related to reduced adiposity measures at 7 years of age. Further evidence regarding the impacts of prenatal PBDE exposures on childhood development is warranted.

Analysis of Perfluorooctanesulfonate Isomers and Other Perfluorinated Alkyl Acids in Serum by In-Port Arylation Gas Chromatography Negative Chemical Ionization–Mass Spectrometry

Perfluorooctanesulfonate (PFOS) is a common environmental pollutant and has been detected in various environmental media. Several major isomers have been identified, and their profiles provide important signatures from the source of contamination. Gas chromatography has a significant resolving power for the isomers. However, methods for derivatizing sulfonates for a sensitive analysis are limited. In this study, in-port derivatization with diaryl iodonium salts into aryl sulfonates was used. A technical mixture of PFOS was separated on gas chromatography to afford 11 isomers. In electron-capture negative ionization, the PFOS derivatives form specific fragmented anions (sulfinate anions). The derivatization was also applied to other per- or polyfluoroalkyl acids (PFASs; 13 perfluoroalkyl carboxylic acids and 10 sulfonates). Analysis of human serum samples was achieved with as little as 50 μL of sample and indicated the presence of PFOS isomers and PFASs. The detection limits of PFOS isomers were 0.02–0.09 ng mL–¹ with sufficient recoveries (85%–98%), and those for other PFASs ranged from 0.01–1 ng mL–¹ (recoveries, 80%–100%), which are suitable for the analysis of human serum samples.

Determination of organochlorine pesticides (OCPs) in breast milk from Rio Grande do Sul, Brazil, using a modified QuEChERS method and gas chromatography-negative chemical ionisation-mass spectrometry

ABSTRACTThe food chain is the main source of exposure to humans by organochlorine pesticides (OCPs) due to the bioaccumulation. Breast milk can accumulate OCPs, so this matrix is often used as an environmental bioindicator. The currently available methods for the determination of several OCPs and metabolites in breast milk involve, in general, multi-step sample preparation and quantification techniques with low selectivity, high cost and much time and labour. Thus, a fast and efficient method based on sample preparation using the quick, easy, cheap, effective, rugged and safe (QuEChERS) method combined with gas chromatography coupled to mass spectrometry with negative chemical ionisation (GC-NCI-MS) was developed, validated and applied for determination of 16 OCPs and metabolites in breast milk samples. The extract was cleaned by dispersive solid-phase extraction (d-SPE) using MgSO4 and C18, evaporated in a Turbovap® system, redissolved and analysed by GC-NCI-MS. The method was validated showing acceptable recoveries (72–118%) and precision (RSD <19%). Method limits of detection (LODs) and quantification (LOQs) ranged from 0.75 to 7.5 ng g−1 and from 2.5 to 25 ng g−1 lipid, respectively. The method was successfully applied to 20 samples of breast milk from different regions of the Rio Grande do Sul state, Brazil, of which 75% contained residues below the LOQs.

Simultaneous determination of cis-permethrin and trans-permethrin in rat plasma and brain tissue using gas chromatography-negative chemical ionization mass spectrometry.

A sensitive method for the simultaneous determination of cis-permethrin (cis-PERM) and trans-permethrin (trans-PERM) in small volumes (100μL) of rat plasma and brain homogenate was developed, using a liquid-liquid extraction for sample preparation and gas chromatography-negative chemical ionization mass spectrometry (GCNCI-MS) for detection. Quantitation of trace levels of the insecticide in small volumes of biological samples is essential to support toxicokinetic studies in small animals. There are currently no validated methods in the literature for determining cis-PERM and trans- PERM in volumes as low as 100μL of rat plasma or brain homogenate. The method provided a linear range of 0.2-150.0ng/mL for analytes in both matrices. The intra- and inter-batch precision (as% relative standard deviation, RSD) and accuracy (as relative error, RE) of the method were better than 20% at the limit of quantitation and better than 15% across the remaining linear range. The validated method was applied in a toxicokinetic study in adult rats with oral dosing of 10mg/kg (cis-PERM) and 100mg/kg (trans-PERM) in corn oil. cis-PERM and trans- PERM were monitored in rat plasma and brain tissue samples for 6h following dosing, and both analytes were detected in all plasma and brain samples.

Peanut butter increases the bioavailability and bioconversion of kale β-carotene to vitamin A.

Kale is a rich source of provitamin A- β-carotene. This study used intrinsically labeled kale [2H9] β-carotene to determine the effect of peanut butter on the bioconversion of kale β-carotene to vitamin A in preschool children. Preschool children (n=37; age 12-36 mo) were randomly assigned to 50 g cooked kale (1.5 mg β-carotene content) with either 33 g peanut butter (PBG) or with 16 g lard (LG) and a reference dose of 1 mg [13C10] retinyl acetate capsule. Blood samples were processed to serum and analyzed by Negative Chemical Ionization-Gas Chromatography Mass Spectrometry (NCI-GCMS) for the enrichments of [2H] retinol from kale [2H9] β-carotene and [13C10] retinol from reference dose. The area under curves (AUCs) of molar enrichment at days 1, 2, 3, 6, 15, and 21 after the labeled doses was 56.3±10.5 and 84.8±16.2 (nmole) for [2H] retinol from LG and PBG kale [2H9] β-carotene, respectively. The AUC of [13C10] retinol from reference dose was 432.6±54.9 (LG) and 560.3±156.7 (nmole) (PBG), respectively. The calculated β-carotene conversion factors were 13.4±3.1 and 11.0±3.9 to 1 (p>0.05) by weight for LG and PBG, respectively. This study showed that peanut butter enhances the vitamin A value of kale.

Novel brominated flame retardants in food composites and human milk from the Chinese Total Diet Study in 2011: Concentrations and a dietary exposure assessment

On the basis of the fifth Chinese total diet study (TDS) performed in 2011, the dietary exposure of the Chinese population to novel brominated flame retardants (NBFRs) was assessed. Six NBFRs were determined in 80 composite samples from four animal origin food groups and 29 pooled human milk samples. Based on gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS) analysis, the levels of the total NBFRs ranged from <LOD to 70.2ng/g lipid weight (lw) in food composites and from 2.48 to 23.9ng/g lw in human milk samples. Decabromodiphenyl ethane (DBDPE), with mean levels of 9.03ng/g lw in food composites and 8.06ng/g lw in human milk, was the most abundant compound in the total NBFRs. No obvious spatial distribution patterns in China were observed in food samples or human milk. The average estimated daily intake (EDI) of total NBFRs via food consumption for a “standard Chinese man” was 4.77ng/kg bodyweight (bw)/day, with a range of 0.681 to 18.9ng/kgbw/day. Meat and meat products were the main dietary source of NBFRs, although levels of NBFRs in aquatic food were found to be the highest among the four food groups. The average EDI of total NBFRs for nursing infants was 38.4ng/kgbw/day, with a range of 17.4 to 113ng/kgbw/day, which was approximately eight-fold higher than the EDI for adults, suggesting the heavy body burden of NBFRs on nursing infants. The levels and EDI of DBDPE in the present study were similar to or higher than those of legacy BFRs (i.e., PBDEs and HBCD) in the TDS 2007, indicating that DBDPE, as a main alternative to PBDEs, might have become the primary BFR used in China.

Determination of novel brominated flame retardants and polybrominated diphenyl ethers in serum using gas chromatography-mass spectrometry with two simplified sample preparation procedures.

Two simple and efficient pretreatment procedures have been developed for the simultaneous extraction and cleanup of six novel brominated flame retardants (NBFRs) and eight common polybrominated diphenyl ethers (PBDEs) in human serum. The first sample pretreatment procedure was a quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based approach. An acetone/hexane mixture was employed to isolate the lipid and analytes from the serum with a combination of MgSO4 and NaCl, followed by a dispersive solid-phase extraction (d-SPE) step using C18 particles as a sorbent. The second sample pretreatment procedure was based on solid-phase extraction. The sample extraction and cleanup were conducted directly on an Oasis HLB SPE column using 5% aqueous isopropanol, concentrated sulfuric acid, and 10% aqueous methanol, followed by elution with dichloromethane. The NBFRs and PBDEs were then detected using gas chromatography-negative chemical ionization mass spectrometry (GC-NCIMS). The methods were assessed for repeatability, accuracy, selectivity, limits of detection (LODs), and linearity. The results of spike recovery experiments in fetal bovine serum showed that average recoveries ranged from 77.9% to 128.8% with relative standard deviations (RSDs) from 0.73% to 12.37% for most of the analytes. The LODs for the analytes in fetal bovine serum ranged from 0.3 to 50.8pg/mL except for decabromodiphenyl ethane. The proposed method was successfully applied to the determination of the 14 brominated flame retardants in human serum. The two pretreatment procedures described here are simple, accurate, and precise, and are suitable for the routine analysis of human serum. Graphical Abstract Workflow of a QuEChERS-based approach (top) and an SPE-based approach (bottom) for the detection of PBDEs and NBFRs in serum.

Simultaneous determination of trace polybrominated diphenyl ethers in serum using gas chromatography-negative chemical ionization mass spectrometry with simplified sample preparation

We have developed a simple and sensitive method which has good application value in the determination of trace PBDEs in serum.

Novel Approach to Stable Chlorine Isotope Analysis using Gas Chromatography-Negative Chemical Ionization Mass Spectrometry

A novel approach to compound-specific stable chlorine isotope analysis is presented to overcome many of the major drawbacks of existing methods. Contemporary methods often require either several laborious off-line procedures prior to isotope analysis or complicated mathematical data calculations and evaluation schemes to derive the chlorine isotope ratios from the mass spectra. In contrast to previous methods, our on-line setup was based on the use of gas chromatography-negative chemical ionization mass spectrometry. The ion traces of 35Cl−(m/z 35) and 37Cl−(m/z 37) were recorded to directly determine the isotopic ratios of chlorine. The chlorine fragments were obtained from each specific chlorinated compound using the appropriate energy and an optimized acquisition mode, and the method completely avoided isobaric interferences. The principle and the mechanism of this approach were presented and explained using trichloroethene. Optimization of the gas chromatography-negative chemical ionization mass spectrometry parameters and method validation were achieved using chlorinated alkenes, chlorinated benzenes, and organochlorine pesticides. The sensitivity of the method over previous methods was significantly improved, and the ultra-trace injection amounts of 0.4–473.5 pmol resulted in standard deviations (1σ) ranging from 0.55‰–2.15‰. The present study suggested that the gas chromatography-negative chemical ionization mass spectrometry method offered an innovative approach to compound-specific chlorine isotope analysis, and it could facilitate the application of compound-specific stable chlorine isotope analysis in environmental fields.

Determination of 2-, 3-, 4-methylpentanoic and cyclohexanecarboxylic acids in wine: Development of a selective method based on solid phase extraction and gas chromatography-negative chemical ionization mass spectrometry and its application to different wines and alcoholic beverages

A method to analyse 2-methylpentanoic, 3-methylpentanoic and 4-methylpentanoic acids as well as cyclohexanecarboxylic acid has been developed and applied to wine and other alcoholic beverages. Selective isolation with solid phase extraction, derivatization with 2,3,4,5,6-pentafluorobenzyl bromide at room temperature for 30minutes, and further analysis by gas chromatography-mass spectrometry in negative chemical ionization mode provides detection limits between 0.4 and 2.4ng/L. Good linearity up to 3.6μg/L, satisfactory reproducibility (RSD<10%) and signal recovery of around 100% represent a robust method of analysis. Concentration data of these analytes in wine and other alcoholic beverages are reported for the first time. The levels found ranged from the method detection limits to 2630ng/L, 2040ng/L and 3810ng/L for 2-, 3- and 4-methylpentanoic acids, respectively, and to 1780ng/L for cyclohexanecarboxylic acid. There are significant differences depending on the type of wine or beverage. Distilled beverages, beer and aged wines have higher contents in methylpentanoic and cyclohexanecarboxylic acids.

Levels of polybrominated diphenyl ethers in settled house dust from urban dwellings with resident preschool-aged children in Nanjing, China.

We investigated the levels and possible determinants of polybrominated diphenyl ethers (PBDEs) in the settled house-dust (SHD) of urban dwellings with resident preschool-aged children in Nanjing, China. The possible neurodevelopmental effects of house-dust PBDEs were also explored. SHD was collected from 216 urban houses. Levels of 8 PBDEs were measured by gas chromatography-negative chemical ionization mass spectrometry. The Child Behavior Checklist and the Gesell Development Inventory were used to evaluate the child's development. BDE47, BDE99, BDE153, BDE18, and BDE209 were detected in the SHD of >90 % of houses, of which BDE209 predominated. Most PBDEs were found at significantly greater levels in indoor than in outdoor dust (P < 0.05). Levels of BDE28 and BDE154 in houses with solid-wood floors were significantly greater than those in houses with plywood floors (P < 0.05). BDE154 levels in houses with wallpaper were significantly greater than those without wallpaper (P < 0.05). Greater BDE47 concentrations were found in houses with less natural ventilation time (linear trend P < 0.05). After dichotomization at the geometric mean concentration, BDE209 and total BDEs showed significant risks for depressed behavior problems and lower personal social developmental quotients (DQs); BDE99 and BDE153 indicated a risk for lower personal social DQs. In conclusion, PBDEs (especially BDE209) are ubiquitous in urban SHD in Nanjing residences. Natural ventilation and floor materials potentially influence PBDE levels in SHD. The potential adverse effect of postnatal exposure to PBDEs on the behavior and neurodevelopment of preschool-age children requires follow-up in larger studies.

Analysis of 7 Dinitroaniline Residues in Complex Food Matrices by GC–NCI/MS

A modified quick, easy, cheap, effective, rugged, and safe sample preparation method combined with gas chromatography–negative chemical ionization–mass spectrometry (GC–NCI/MS) has been developed for the determination of 7 dinitroaniline herbicide residues in complex matrices (garlic, olive oil, scallion, leek and chili). Dinitroaniline residues were extracted with hexane-saturated acetonitrile. After the cleanup with the dispersive solid-phase extraction, the extract was analyzed by GC–NCI/MS in selected ion monitoring mode. Two isotope internal standards (trifluralin-d 14 and pendimethalin-d 5) were employed for quantification. Compared with electron ionization (EI) mode, the superiorities of NCI in sensitivity and selectivity were investigated. Limits of the detection of 7 dinitroanilines were in the range of 0.014–0.096 μg kg−1, and there were no interfering peaks (unlike in EI) in the complex matrices. Recoveries of 7 dinitroanilines in five matrices at three spiked levels (10, 20 and 40 μg kg−1) ranged from 61 to 126 % and the relative standard deviations were all below 12 %.

Determination of four insecticide residues in honey and royal jelly by gas chromatography-negative chemical ionization mass spectrometry

A method was developed for the determination of four insecticide residues in honey and royal jelly by gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS). The honey and royal jelly samples were treated with different preparation methods as the result of the different components. The honey sample was extracted with ethyl acetate and cleaned up with primary second amine, and the royal jelly sample was extracted with acetonitrile-water (1:1, v/v), and cleaned up with a C18 solid-phase extraction column. Finally, the extracts of the honey and royal jelly were analyzed by GC-NCI/MS in selected ion monitoring (SIM) mode separately. External standard calibration method was used for quantification. The linearities of calibration curves of the four insecticides were good with the correlation coefficients greater than 0.99 in the range of 50-500 microg/L. The limits of the detection (LODs) of the four insecticides were in the range of 0.12- 5.0 microg/kg, and the limits of the quantification (LOQs) were in the range of 0.40-16.5 microg/kg. The recoveries of the four insecticides spiked in honey and royal jelly at three spiked levels (10, 15 and 20 microg/kg) were in the range of 78.2 -110.0%, and the relative standard deviations (RSDs) were all below 14%. The sensitivity and selectivity of this method were good with no interfering peaks. The proposed method is simple quick and effective to analyze the four insecticide residues in honey and royal jelly.

Determination of trifluralin residue in aquatic products and edible oils by gas chromatography-negative chemical ionization mass spectrometry

A confirmatory method was established for the determination of trifluralin residue in aquatic products and edible oils with the technique of offline disperse solid phase extraction and gas chromatography-negative chemical ionization mass spectrometry (DSPE-GC-MS/NCI). Trifluralin was extracted from aquatic products and edible oils with acetonitrile, and liquid-liquid partitioning formed by adding anhydrous magnesium sulfate followed by a simple cleanup step known as dispersive solid-phase extraction. The aliquot was analyzed by GC-MS/NCI using isotope internal standard method. The method was reliable and stable. The recoveries of trifluralin were in the range from 80% to 100% at three spiked levels of 1.0, 2.0, and 3.0 microg/kg, and the RSDs were not more than 10.3%. The linearity of method was good from 1 to 40 microg/L, and the LOD was 0.02 microg/kg. This method can be used as a conclusive evidence method for the determination of trifluralin residue in aquatic products and edible oils.

Determination of Phenols in Water by Modified Polymer Extraction-Fluorine Derivative Gas Chromatography-Negative Chemical Ionization Mass Spectrometry

Determination of Phenols in Water by Modified Polymer Extraction-Fluorine Derivative Gas Chromatography-Negative Chemical Ionization Mass Spectrometry

Washoff of cypermethrin residues from slabs of external building material surfaces using simulated rainfall

The use of pesticides by homeowners or pest-control operators in urban settings is common, yet contributions of washoff from these materials are not easily understood. In the present study, cypermethrin, formulated as Cynoff EC (emulsifiable concentrate) and Cynoff WP (wettable powder) insecticides, was applied at typical rates to 10 different building material surfaces to examine its washoff potential from each surface. Using an indoor rainfall simulator, a 1-h rainfall event was generated and washoff samples were collected from 3 replicates of each surface type. Washoff was analyzed for cypermethrin using gas chromatography-negative chemical ionization mass spectrometry. An analysis of variance for a split-plot design was performed. Many building materials had similar water runoff masses, but asphalt resulted in significantly reduced average water runoff masses (73% less). The Cynoff WP formulation generally produced greater cypermethrin washoff than the Cynoff EC formulation. In addition, results for both the WP and EC formulations indicated that smoother surfaces such as vinyl and aluminum siding had higher washoff (1.0–14.1% mean percentage of applied mass). Cypermethrin washoff from rough absorptive surfaces like concrete and stucco was lower and ranged from 0.1 to 1.3% and from 0 to 0.2%, respectively, mean percentage of applied mass. Both building material surface and formulation play a significant role in cypermethrin washoff. Environ Toxicol Chem 2014;33:302–307. © 2013 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited.