Rapid method for the detection of rodenticides in contaminated foods.

Rodenticides are toxic chemicals used to control rodent populations and are among the most common household toxicants. Ingestion of foods contaminated with rodenticides may cause severe illness or death in humans and animals. A rapid analytical method was developed for the identification of nine common rodenticides in foods using solid-liquid extraction followed by dispersive-solid phase extraction prior to the analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and UV detection. The method validation on a variety of food matrices including cornmeal, peanut, whole wheat flour and pork liver produced average recoveries between 91.2 and 107% with relative standard deviations between 2.6 and 14% for all studied rodenticides. The method detection limits ranged from 2.7 to 8.2 µg/kg (ppb) for eight rodenticides analyzed by LC-MS/MS and between 0.10 and 0.21 mg/kg (ppm) for bromethalin which was analyzed by LC with UV detection. This method could be useful in preparedness for emergency response situations involving widespread food contamination, terrorist acts or for forensic studies.

Simultaneous determination of nine anticoagulant rodenticides by ultra-performance liquid chromatography-tandem mass spectrometry with ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction.

A sensitive determination method is developed for nine anticoagulant rodenticides (ARs) in urine samples by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction (UA-LDS-DLLME) pretreatment. The target analytes are brodifacoum, bromadiolone, warfarin, coumachlor, coumatetralyl, difenacoum, pindone, diphacinone and chlorophacinone. The parameters that influence the extraction recovery in the UA-LDS-DLLME were systematically investigated and optimized. With the optimized extraction parameters, recoveries ranging from 64.6%-124.2% were obtained for the target analytes. The linear range for all analytes was 0.1-100 ng/mL with correlation coefficients higher than 0.99. Very low LODs ranging in 0.003-0.03 ng/mL were obtained. LOQs were in the range of 0.01-0.1 ng/mL for the nine target analytes. The accuracy that was expressed as mean relative error was within ±5.8% while the precision expressed as relative standard error was less than 5.9%. The combination of UA-LDS-DLLME with UPLC-MS/MS is a feasible, sensitive and rapid analytical approach for the determination of ARs in urine matrix, which is particularly suitable for clinical and forensic purposes.

Determination of Rodenticide Tetramethylenedisulfotetramine (Tetramine) in Processed Foods by Gas Chromatography-Tandem Mass Spectrometry.

A GC-MS/MS method for determination of the rodenticide tetramethylenedisulfotetramine was developed. Tetramethylenedisulfotetramine was extracted from the sample with ethyl acetate in the presence of anhydrous sodium sulfate. Then, an aliquot of the extract was evaporated under vacuum, followed by acetonitrile/hexane partitioning, and cleanup with a tandem graphitized carbon/primary secondary amine (PSA) column, prior to GC-MS/MS analysis. The recoveries from 10 processed foods, all of which were fortified at 0.1 mg/kg, were in the range of 85-96%, and the relative standard deviations were less than 7%. The proposed method effectively removed co-extracted matrix components, and matrix effects were negligible in the GC-MS/MS analysis. In addition, no interfering peaks were found in the chromatograms of the blank samples at the retention time of tetramethylenedisulfotetramine, indicating that the method is highly selective. Overall results suggest that the proposed method is suitable for determining tetramethylenedisulfotetramine contained in processed foods.

In vitro selection of DNA aptamers binding pesticide fluoroacetamide.

Fluoroacetamide (Mw = 77.06) is a lethal rodenticide to humans and animals which is still frequently abused in food storage somewhere in China. The production of antibodies for fluoroacetamide is difficult due to its high toxicity to animals, which limits the application of immunoassay method in poison detection. In this work, aptamers targeting N-fluoroacetyl glycine as an analog of fluoroacetamide were selected by a specific systematic evolution of ligands by exponential enrichment (SELEX) strategy. The binding ability of the selected aptamers to fluoroacetamide was identified using surface plasmon resonance (SPR)-based assay. The estimated KD values in the low micromolar range showed a good affinity of these aptamers to the target. Our work verified that the SELEX strategy has the potential for developing aptamers targeted to small molecular toxicants and aptamers can be employed as new recognition elements instead of antibodies for poison detection.

Comprehensive characterization of rodenticides in wastewater by liquid chromatography-tandem mass spectrometry.

Rodenticides are used as pest control to eradicate rodents and have emerged as new environmental contaminants due to their widespread use in domestic and urban infrastructures. In this study, we have developed and validated an analytical methodology based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of 13 anticoagulant rodenticides in wastewater. In a first step, ionization conditions were tested in electrospray mode, and positive ionization gave the highest sensitivity. Fragmentation patterns were determined and two selected reaction monitoring (SRM) transitions were selected for each compound. Using a Zorbax Eclipse XDB-C18 column and specific SRM transitions, 13 compounds were resolved. The LC-MS/MS method provided good linearity, sensitivity, intra- and inter-day precision, and good identification capabilities for these compounds in wastewaters. Thereafter miniaturized liquid-liquid extraction (LLE) and solid-phase extraction (SPE) were optimized. Oasis HLB and Strata WA SPE cartridges with methanol/dichloromethane as eluting solvents provided good recoveries and limits of detection ranged between 0.34 and 20 ng L(-1), whereas LLE failed to recover some compounds. Finally, the performance of both LLE and SPE methods was evaluated by analyzing rodenticides in a set of wastewaters. Warfarin was the only detected compound at nanogram per liter level, and good agreement was observed between LLE and SPE.

Analysis of multiple anticoagulant rodenticides in animal blood and liver tissue using principles of QuEChERS method.

A quick and easy method for the analysis of anticoagulant rodenticides in blood or tissue using principles of dispersive solid-phase extraction (dSPE), commonly known as QuEChERS (short for quick, easy, cheap, effective, rugged, and safe), was developed. Briefly, a combination of magnesium sulfate, PSA, florisil, and basic alumina was used to cleanup blood samples. Further, to cleanup liver tissue samples, C(18) sorbent was included along with the previously mentioned. The samples were analyzed using high-performance liquid chromatography equipped with a reversed-phase C(18) column (150 x 4.6 mm, 5-microm particle size) and a UV and fluorescence detector. The mobile phase consisted of 0.03 M tetrabutylammonium hydroxide (TBA) adjusted to pH 7/methanol (1:1, v/v) as solvent A and methanol as solvent B in a gradient run. The method detection limit was as low as 10 ng/mL for brodifacoum and difenacoum in blood and 10 ng/g in liver; 50 ng/mL for bromadiolone, difethialone, and chlorphacinone in blood and similarly 50 ng/g in liver; and 100 ng/mL for coumafuryl, pindone, warfarin, and diphacinone in blood and 100 ng/g in liver samples. A number of clinical samples of both blood and liver were analyzed; the comparison of this modified QuEChERS and traditional solid-phase extraction data was found to be in close agreement. This method resulted in drastic reduction in processing time and solvent cost both in terms of consumption and disposal, thus making it an attractive alternative to the traditional solid-phase extraction.

Simultaneous measurement of indandione-type rodenticides in human serum by liquid chromatography-electrospray ionization- tandem mass spectrometry.

Measurement of indandione rodenticides is important in the diagnosis and treatment of accidental rodenticide ingestion. Current assays lack effective measurements for simultaneous analysis of the indandiones, especially the isomers. The intent of this study was to establish a novel and selective method for the simultaneous determination of indandione-type rodenticides (diphacinone, chlorophacinone, valone, and pindone) in human serum by liquid chromatography-electrospray ionization-tandem mass spectrometry. After addition of internal standard, the sample was extracted with 10% methanol in acetonitrile and cleaned by solid-phase extraction (SPE). The analytes were separated on a C(18) rapid column and infused into an ion trap mass spectrometer in the negative electrospray ionization mode. The multiple-reaction monitoring ion pairs were m/z 339 --> 167, m/z 373 --> 201, m/z 229 --> 145, m/z 229 --> 172, and m/z 307 --> 161 for diphacinone, chlorophacinone, valone, pindone, and IS, respectively. Recoveries were between 81.5 and 94.6%, and the limits of quantification were 0.2 to 0.5 ng/mL. Intra- and interday RSDs were less than 7.9 and 11.5%, respectively. The assay was linear in the range of 0.5-100.0 ng/mL with coefficients of determination (r(2) > 0.99) for all analytes. The proposed method enables the unambiguous confirmation and quantification of the indandiones in both clinical and forensic specimens.

Remediating munitions-contaminated soil with zerovalent iron and cationic surfactants.

Soils contaminated from military operations often contain mixtures of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), and TNT (2,4,6-trinitrotoluene) rather than a single explosive. Differences among explosives in solubility and reactivity make developing a single remediation treatment difficult. When Fe(0) was used to treat a munitions-contaminated soil, we observed high rates of destruction for RDX and TNT (98%) but not HMX. Our objective was to determine if HMX destruction by Fe(0) could be enhanced by increasing HMX solubility by physical (temperature) or chemical (surfactants) means. To determine electron acceptor preference, we treated RDX and HMX with Fe(0) in homogeneous solutions and binary mixtures. Increasing aqueous temperature (20 to 55 degrees C) increased HMX solubility (2 to 22 mg L(-1)) but did not increase destruction by Fe(0) in a contaminated soil slurry that also contained RDX and TNT. Batch experiments using equal molar concentrations of RDX and HMX demonstrated that RDX was preferentially reduced over HMX by Fe(0). By testing various surfactants, we found that the cationic surfactants (HDTMA [hexadecyltrimethylammonium bromide], didecyl, and didodecyl) were most effective in increasing HMX concentration in solution. Didecyl and HDTMA were also found to be highly effective in facilitating the transformation of HMX by Fe(0). Using HDTMA or didecyl solutions (3%, w/v) containing solid-phase HMX, we observed that 100% of the added HMX was transformed by Fe(0) in the didecyl matrix and 60% in the HDTMA matrix. These results indicate that cationic surfactants can increase HMX solubility and facilitate Fe(0)-mediated transformation kinetics but HMX destruction rates will be slowed when RDX is present.

Separation of estrogens and rodenticides using capillary electrophoresis with aqueous-methanolic buffers.

Capillary electrophoresis (CE) has proven to be an efficient method for the separation of various charged and neutral analytes. For analytes having limited solubility in water, the CE mode of separation has been micellar electrokinetic capillary chromatography (MECC). However, another approach is the direct addition of an organic solvent to a non-MECC CE separation system. Walbroehl and Jorgenson and also Balchunas and Sepaniak have reported on the use of organics in CE but the focus of their work was using MECC to separate small organic compounds. This work examines the use of aqueous-methanolic buffers in non-MECC CE separations of estrogens and rodenticides.

TLC-spectrophotometric assay of the main glycosides of red squill, a specific rodenticide.

Red squill bulbs, with reported specific rodenticidal properties, have been assayed for their content of the two main glycosides, scilliroside and scillaren A, by a method depending on the separation of the glycosides from purified plant extracts by tlc followed by spectrophotometric (uv and visible) determination of the individual glycosides in the eluates. The method was found convenient for assessment of the potency of red squill bulbs.