Trace level determination of selected organophosphorus pesticides and their degradation products in environmental air samples by liquid chromatography-positive ion electrospray tandem mass spectrometry

Spatial and temporal variations of currently used pesticides (CUPs) concentrations in ambient air in Wallonia, Belgium

Pesticides are among the most widely used chemicals thus contributing to a global contamination of the environment. Studies in North America and Europe have reported ambient air concentrations of Currently Used Pesticides in rural and urban locations as well as in remote areas. Monitoring pesticides in air is required for a better understanding of human exposure through inhalation and to assess potential health effects related to this exposure pathway. In this study, 46 pesticides were analyzed in ambient air in sampling stations distributed over Wallonia during a year, from May 2015 to May 2016. Different typologies were defined for sampling sites (remote areas, urban sites, agricultural sites, livestock area, and sites with other professional uses). Ambient air was sampled for 14 days with an active air sampler at a flow rate of 4 m³/h. Quartz filters and PUF/XAD-2/PUF cartridges were used to sample both gas and particulate phase pesticides. On the 46 pesticides studied, 6 insecticides, 18 herbicides and 18 fungicides were detected. Herbicides were measured in 68.3% of samples throughout the year, whereas fungicides and insecticides were measured in 62.6% and 13.2% of the samples, respectively. The highest mean concentrations for all pesticides were measured in spring-summer, whereas few pesticides were measured at low concentrations in winter. Six pesticides were measured in the remote sampling station at lower concentrations than in all other sites highlighting volatility of these pesticides. The highest number of different pesticides and the highest concentrations were measured in agricultural stations, where uses of plant protection products are higher. Finally, less volatile pesticides were only detected near application areas and at low concentrations. Together, these results provide better insight on the spatial and temporal variations of pesticides concentrations in ambient air, which were related to pesticides uses as well to atmospheric volatility and persistence.

Malathion Biodegradation by L. casei (NRRL1922) and L. acidophilus (NRRL 23431) in Fermented Skimmed Milk

The aim of this study was to investigate and trace the biodegradation products of the pesticide malathion in a comparative manner by two different lactobacilli strains; L. casei (NRRL1922) and L. acidophilus (NRRL 23431). The two strains were cultivated separately into skimmed milk supplemented with 5 ng/ml malathion. After incubation under the appropriate conditions, randomized samples were taken at intervals 24, 48, 72 and 120 hours along with control samples and analyzed for the presence of malathion and its degradation products by the GC-MS spectrometry; As well as, analyzed to record the level of phosphatase enzyme which suggested to be involved in the biodegradation process. The results showed a high ability of the two tested strains to degrade malathion with a superiority of L. acidophilus (NRRL 23431) over L. casei (NRRL 1922). The level of phosphatase enzyme was elevated in both strains in the presence of malathion and decreased gradually upon the depletion of malathion from the sample, which reflects the role of the phosphatase enzyme in the biodegradation process.

Screening 89 Pesticides in Fishery Drugs by Ultrahigh Performance Liquid Chromatography Tandem Quadrupole-Orbitrap Mass Spectrometer

Multiclass screening of drugs with high resolution mass spectrometry is of great interest due to its high time-efficiency and excellent accuracy. A high-scale, fast screening method for pesticides in fishery drugs was established based on ultrahigh performance liquid chromatography tandem quadrupole-Orbitrap high-resolution mass spectrometer. The target compounds - were diluted in methanol and extracted by ultrasonic treatment, and the extracts were diluted with MeOH-water (1:1, v/v) and centrifuged to remove impurities. The chromatographic separation was performed on an Accucore aQ-MS column (100 mm × 2.1 mm, 2.6 μm) with gradient elution using 0.1% formic acid in water (containing 5 mmol/L ammonium formate) and 0.1% formic acid in methanol (containing 5 mmol/L ammonium formate) in Full Scan/dd-MS2 (TopN) scan mode. A screening database, including mass spectrometric and chromatographic information, was established for identification of compounds. The screening detection limits of methods ranged between 1–500 mg/kg, the recoveries of real samples spiked with the concentration of 10 mg/kg and 100 mg/kg standard mixture ranged from 70% to 110% for more than sixty compounds, and the relative standard deviations (RSDs) were less than 20%. The application of this method showed that target pesticides were screened out in 10 samples out of 21 practical samples, in which the banned pesticide chlorpyrifos were detected in 3 out of the 10 samples.

Risk assessment of airborne pesticides in a Mediterranean region of Spain

A risk assessment strategy based on the quantitative target analysis and semi-quantitative retrospective screening determination of pesticides in PM10 has been developed. The proposed methodology was applied to 345 real samples from nine stations of a Mediterranean area in Spain, and the risk was assessed for adult, children and infants. Forty pesticides were detected with average concentrations ranging from 8 to 30,000pgm^-3. Each station showed its specific pesticide profile, which is linked to the different types of crops around each station. For adults, children and infants the estimated chronic inhalation risk, expressed as Hazard Quotient (HQ), was <1 for all pesticides. The cumulative exposure for organophosphates, neonicotinoids, benzimidazoles, carbamates, micro-organism and triazoles pesticides (HI, Hazard Index) were <1 for the three groups of populations assessed. For infants, the cancer risk estimated for the detected pesticides classified as possible and potential carcinogens were lower than 1.0 E-06, except for carbendazim and hexythiazox.

Determination of neonicotinoid insecticides and strobilurin fungicides in particle phase atmospheric samples by liquid chromatography-tandem mass spectrometry

A liquid chromatography-tandem mass spectrometry method has been developed for the determination of neonicotinoids and strobilurin fungicides in the particle phase fraction of atmosphere samples. Filter samples were extracted with pressurized solvent extraction, followed by a cleanup step with solid phase extraction. Method detection limits for the seven neonicotinoid insecticides and six strobilurin fungicides were in the range of 1.0-4.0 pg/m(3). Samples were collected from June to September 2013 at two locations (Osoyoos and Oliver) in the southern Okanagan Valley Agricultural Region of British Columbia, where these insecticides and fungicides are recommended for use on tree fruit crops (apples, pears, cherries, peaches, apricots) and vineyards. This work represents the first detection of acetamiprid, imidacloprid, clothianidin, kresoxim-methyl, pyraclostrobin, and trifloxystrobin in particle phase atmospheric samples collected in the Okanagan Valley in Canada. The highest particle phase atmospheric concentrations were observed for imidacloprid, pyraclostrobin, and trifloxystrobin at 360.0, 655.6, and 1908.2 pg/m(3), respectively.

Environmental exposure to organophosphorus and pyrethroid pesticides in South Australian preschool children: a cross sectional study

Organophosphorus (OP) and pyrethroid (PYR) compounds are the most widely used insecticides. OPs and PYRs are developmental neurotoxicants. Understanding the extent of exposure in the general population and especially in young children is important for the development of public health policy on regulation and use of these chemicals. Presented here are the results of the first investigation into the extent of environmental exposure to neurotoxic insecticides in preschool children in South Australia (SA). Children were enrolled from different areas of SA and assigned into urban, periurban and rural groups according to their residential address. Residential proximity to agricultural activity, parental occupational contact to insecticides and use of insecticides within the household were investigated as potential indirect measures of exposure. We used liquid chromatography/tandem mass spectrometry to measure the following metabolites of OPs and PYRs in urine samples as direct indicators of exposure: dialkylphosphates, p-nitrophenol, 3-methyl-4-nitrophenol, 3,5,6-trichloro-2-pyridinol, cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropane-1-carboxylic acid, cis-3-(2,2-dibromovinyl)-2,2-dimethyl-cyclopropane-1-carboxylic acid, 2-methyl-3phenylbenzoic acid and 3-phenoxybenzoic acid. Results were analysed to assess factors affecting the risk and level of exposure. Results were also compared to the published data in similar age groups from US and German studies. The results of this study demonstrate that there was widespread chronic exposure to OPs and and PYRs in SA children. OP metabolites were detected more commonly than PYR. Exposure to more than one chemical and contemporaneous exposure to chemicals from both OP and PYR groups was common in the study population. There were some differences in risks and levels of exposure between the study groups. Exposure to some restricted use of chemicals, for example, fenitrothion, was higher in periurban and rural children. There was no difference among the study groups in exposure to chlorpyrifos, used commonly in agriculture and in domestic settings and most frequently found OP pesticide in food in Australia. South Australian children appear to have higher levels of exposure compared their peers in US and Germany.

The reliability of using urinary biomarkers to estimate children's exposures to chlorpyrifos and diazinon

A few studies have reported concurrent levels of chlorpyrifos (CPF) and diazinon (DZN) and their environmentally occurring metabolites, 3,5,6-trichloro-2-pyridinol (TCP) and 2-isopropyl-6-methyl-4-pyrimidinol (IMP), in food and in environmental media. This information raises questions regarding the reliability of using these same metabolites, TCP and IMP, as urinary biomarkers to quantitatively assess the everyday exposures of children to CPF and DZN, respectively. In this study, we quantified the distributions of CPF, DZN, TCP, and IMP in several environmental and personal media at the homes and day-care centers of 127 Ohio preschool children and identified the important sources and routes of their exposures. The children were exposed to concurrent levels of these four chemicals from several sources and routes at these locations. DZN and IMP were both detected above 50% in the air and dust samples. CPF and TCP were both detected in greater than 50% of the air, dust (solid), food, and hand wipe samples. TCP was detected in 100% of the urine samples. Results from our regression models showed that creatinine levels (<0.001), and dietary (P<0.001) and inhalation (P<0.10) doses of TCP were each significant predictors of urinary TCP, collectively explaining 27% of the urinary TCP variability. This information suggests that measurement of urinary TCP did not reliably allow quantitative estimation of the children's everyday environmental exposures to CPF.

A novel immunochromatographic electrochemical biosensor for highly sensitive and selective detection of trichloropyridinol, a biomarker of exposure to chlorpyrifos

We present a novel portable immunochromatographic electrochemical biosensor (IEB) for simple, rapid, and sensitive biomonitoring of trichloropyridinol (TCP), a metabolite biomarker of exposure to organophosphorus insecticides. Our new approach takes the advantage of immunochromatographic test strip for a rapid competitive immunoreaction and a disposable screen-printed carbon electrode for a rapid and sensitive electrochemical analysis of captured HRP labeling. Several key experimental parameters (e.g. immunoreaction time, the amount of HRP labeled TCP, concentration of the substrate for electrochemical measurements, and the blocking agents for the nitrocellulose membrane) were optimized to achieve a high sensitivity, selectivity and stability. Under optimal conditions, the IEB has demonstrated a wide linear range (0.1-100 ng/ml) with a detection limit as low as 0.1 ng/ml TCP. Furthermore, the IEB has been successfully applied for biomonitoring of TCP in the rat plasma samples with in vivo exposure to organophosphorus insecticides like Chlorpyrifos-oxon (CPF-oxon). The IEB thus opens up new pathways for designing a simple, rapid, clinically accurate, and quantitative tool for TCP detection, as well as holds a great promise for in-field screening of metabolite biomarkers, e.g., TCP, for humans exposed to organophosphorus insecticides.

Occurrence and relationship of organophosphorus insecticides and their degradation products in the atmosphere in Western Canada agricultural regions

This paper presents the atmospheric occurrence and seasonal variations of the most frequently detected organophosphorus insecticides (OPs) and their OP oxon degradation products at Bratt's Lake, Saskatchewan in the Canadian Prairies (April 2003 to March 2004, January-December, 2005) and at Abbotsford in the Lower Frazer Valley (LFV) of British Columbia from May 2004 to December, 2005. During 2005 there were 10 OPs, 8 OP oxons, and 6 other OP degradation products measured. The most frequently detected OPs were chlorpyrifos, malathion, and diazinon. At Bratt's Lake the highest atmospheric concentrations were observed for chlorpyrifos, with maximum concentrations observed during July and August in 2003 showing much higher concentrations than those from 2005. This was related to its usage for grasshopper control in the province. At Abbotsford, diazinon and malathion were observed in much higher atmospheric concentrations than chlorpyrifos. Concentrations reached maximum in spring for diazinon and summer for malathion. This study is the first reported study of seasonal variations of OP oxons with their parent OP. Chlorpyrifos oxon concentrations during July were generally low, indicating strong local source contributions. The chlorpyrifos oxon/chlorpyrifos ratio and diazinon oxon/diazinon ratio showed a strong seasonal variation with increasing ratio from spring to summer which was attributed to increasing sunlight hours. Malathion oxon/mathion at both sites was similar and relatively constant throughout the year. The oxon/thion ratio represents a good indicator of age of source or contributions from local versus regional atmospheric sources.

Simple analytical method for determination of pesticide residues in human serum by liquid chromatography tandem mass spectrometry

The aim of this study was to develop an analytical method for the determination of residues of organophosphorus and carbamate pesticides which are widely used in Tunisia. This method involves a liquid-liquid extraction procedure followed by liquid chromatography tandem mass spectrometry (LC/MS/MS) for the identification and quantification of compounds. Ionization of molecules was performed by the electrospray mode. Multiple reactions monitoring (MRM) was the acquisition mode used for the monitoring of two MS/MS transitions for each compound. The average recoveries obtained, at three different fortification levels, ranged between 65% and 106% for most of the pesticides studied, except for methamidophos (lower than 25%).The linearity of the method was in the range of 5 to 50 micro g/L with a correlation coefficient from 0.995 to 0.999, depending on the analyte. The estimated limit of detection and limit of quantification were 2 micro g/L and 5 micro g/L, respectively. The precision of the analytical procedure was satisfactory and the coefficients of variation, evaluated at three concentration levels were lower than 15% for most pesticides studied. The application of the method was investigated in a population of agricultural workers chronically exposed to various pesticides some of which, such as carbofuran, carbendazim, methomyl and pirimicarb, were detected in some serum samples.

Liquid chromatography with post-column reagent addition of ammonia in methanol coupled to negative ion electrospray ionization tandem mass spectrometry for determination of phenoxyacid herbicides and their degradation products in surface water

A new liquid chromatography (LC)-negative ion electrospray ionization (ESI(-))-tandem mass spectrometry (MS/MS) method with post-column addition of ammonia in methanol has been developed for the analysis of acid herbicides: 2,4-dichlorophenoxy acetic acid, 4-chloro-o-tolyloxyacetic acid, 2-(2-methyl-4-chlorophenoxy)butyric acid, mecoprop, dichlorprop, 4-(2,4-dichlorophenoxy) butyric acid, 2,4,5-trichlorophenoxy propionic acid, dicamba and bromoxynil, along with their degradation products: 4-chloro-2-methylphenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and 3,5-dibromo-4-hydroxybenzoic acid. The samples were extracted from the surface water matrix using solid-phase extraction (SPE) with a polymeric sorbent and analyzed with LC ESI(-) with selected reaction monitoring (SRM) using a three-point confirmation approach. Chromatography was performed on a Zorbax Eclipse XDB-C18 (50 x 4.6 mm i.d., 1.8 mum) with a gradient elution using water-methanol with 2 mM ammonium acetate mobile phase at a flow rate of 0.15 mL/min. Ammonia in methanol (0.8 M) was added post-column at a flow rate of 0.05 mL/min to enhance ionization of the degradation products in the MS source. One SRM transition was used for quantitative analysis while the second SRM along with the ratio of SRM1/SRM2 within the relative standard deviation determined by standards for each individual pesticide and retention time match were used for confirmation. The standard deviation of ratio of SRM1/SRM2 obtained from standards run on the day of analysis for different phenoxyacid herbicides ranged from 3.9 to 18.5%. Limits of detection (LOD) were between 1 and 15 ng L(-1) and method detection limits (MDL) with strict criteria requiring <25% deviation of peak area from best-fit line for both SRM1 and SRM2 ranged from 5 to 10 ng L(-1) for acid ingredients (except dicamba at 30 ng L(-1)) and from 2 to 30 ng L(-1) for degradation products. The SPE-LC-ESI(-) MS/MS method permitted low nanogram-per-liter determination of pesticides and degradation products for surface water samples.

Comparison of gas chromatography-mass spectrometry and gas chromatography-tandem mass spectrometry with electron ionization and negative-ion chemical ionization for analyses of pesticides at trace levels in atmospheric samples

A comparison of detection limits of gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) with gas chromatography-tandem mass spectrometry (GC-MS/MS) in selected reaction monitoring (SRM) mode with both electron ionization (EI) and negative-ion chemical ionization (NCI) are presented for over 50 pesticides ranging from organochlorines (OCs), organophosphorus pesticides (OPs) and pre-emergent herbicides used in the Canadian prairies (triallate, trifluralin, ethalfluralin). The developed GC-EI/SIM, GC-NCI/SIM, and GC-NCI/SRM are suitable for the determination of pesticides in air sample extracts at concentrations <100 pg μL⁻¹ (<100 pg m⁻³ in air). No one method could be used to analyze the range of pre-emergent herbicides, OPs, and OCs investigated. In general GC-NCI/SIM provided the lowest method detection limits (MDLs commonly 2.5–10 pg μL⁻¹) along with best confirmation (<25% RSD of ion ratio), while GC-NCI/SRM is recommended for use where added selectivity or confirmation is required (such as parathion-ethyl, tokuthion, carbofenothion). GC-EI/SRM at concentration <100 pg μL⁻¹ was not suitable for most pesticides. GC-EI/SIM was more prone to interference issues than NCI methods, but gave good sensitivity (MDLs 1–10 pg μL⁻¹) for pesticides with poor NCI response (OPs: sulfotep, phorate, aspon, ethion, and OCs: alachlor, aldrin, perthane, and DDE, DDD, DDT).