[Determination of sodium monofluoroacetate in human blood and food samples by ion chromatography]

A method was developed for the determination of sodium monofluoroacetate in human blood by ion chromatography. The analysis was performed on a Dionex Ion Pac AS11 column (250 mm x 4 mm i.d.) with an AG11 guard column (50 mm x 4 mm i.d.). A conductivity detector, an SRS suppressor and a 25 microL sample loop were used. The eluent was 2.0 mmol/L Na2B4O7 with a flow rate of 1.0 mL/min. A blood sample of 0.2 mL was pipetted into a test tube followed by adding 1.0 mL of pure water. And then acetonitrile was used to dilute it to 3.0 mL. After the protein was settled down from the blood sample, the supernatant layer was filtered through a 0.45 microm filter before injected into the ion chromatographic system. Good linear relationship between the peak area and the concentration of sodium monofluoroacetate was found with correlation coefficient (r2) of 0.9978 within the range from 0.10 to 10.0 mg/L. The detection limit for blood was 2.5 mg/L. This method also can be used for the determination of sodium monofluoroacetate in food samples.

Rat poison and food security in the People's Republic of China: focus on tetramethylene disulfotetramine (tetramine)

The last several years have seen a large number of mass poisonings in mainland China, particularly those caused by illicit rodenticides. One rat poison, tetramine (tetramethylene disulfotetramine) is responsible for a great percentage of death and injury in the People’s Republic of China (PRC). Tetramine is an acutely toxic substance with human oral toxicity estimated as low as 0.1 mg/kg, and is widely available in open markets in mainland China—this despite being prohibited for manufacture or sale in the PRC. Being a GABA antagonist, and having an extremely potent effect on the brain stem, many victims can quickly fall into convulsions and die within hours following ingestion. With no known effective antidote at this time, clinical data from the PRC show that acute cases of tetramine poisoning are extremely difficult to treat. The widespread use of tetramine—including its reported sale at a Malaysian outdoor market in September 2002—could exacerbate its hazard to public health, particularly in those areas having large overseas Chinese populations.

Spatial and temporal analysis of second-generation anticoagulant rodenticide residues in polecats (Mustela putorius) from throughout their range in Britain, 1992-1999

Polecats (Mustela putorius) in Britain are currently expanding their range eastwards from Wales to reoccupy central and eastern areas of England. Second-generation anticoagulant rodenticides (SGARs), to which polecats are exposed by eating contaminated prey, are used more extensively in these central and eastern regions, leading to fears of increased exposure, and possible resultant mortality. We measured bromadiolone, difenacoum, flocoumafen and brodifacoum concentrations in the livers of 50 polecats from areas that included newly recolonised habitats and found that at least one SGAR was detected in the livers of 13 out of 37 (35.1%) male and 5 out of 13 (38.5%) female polecats. Difenacoum and bromadiolone were detected most frequently. We then combined these data with measurements on another 50 individuals from earlier studies to create a dataset for 100 polecats collected throughout the 1990s from across the whole of their current range. Using this dataset, we determined if there was any evidence that contamination in polecats had increased during the 1990s and whether animals from England were more contaminated than those from Wales, as might be expected given regional differences in the patterns of SGAR use. Overall, 31 of the 100 polecats analysed to date contained SGAR residues. The incidence was a little higher (40%) in animals that died between January and June and this probably better reflects the overall proportion of animals that are sub-lethally exposed. There was no statistically significant change during the 1990s in the proportion of polecats exposed to SGARs nor any evidence that greater use of SGARs in England resulted in more contamination of polecats. Contrary to expectation, the proportion of animals that contained difenacoum was marginally higher in Wales than elsewhere.

The effect of particle size reduction by grinding on subsampling variance for explosives residues in soil

Efforts to characterize the surface soil contamination on military training ranges have been compromised by the inability to obtain representative subsamples of soils submitted to analytical laboratories for determination of explosives residues. Two factors affecting subsampling error for explosives residues were examined using soils collected from hand grenade and anti-tank ranges. These factors were increased subsample size and particle size reduction prior to subsampling of soils. Increasing the subsample size from 2 to 50 g did not reduce the soil subsampling error because of the extreme heterogeneous distribution of the solid contaminants. Alternatively, particle size reduction by machine grinding on a ring mill reduced subsampling error to less than 10% relative standard deviation for replicate analyses using 10-g subsamples.

[Advances in the detection method of several forbidden rodenticides]

The progress of detection method of four forbidden rodenticides, including fluoroacetamide, sodium fluoroacetate, gliftor and tetramine is reviewed in this paper. The technique of sample preparation and gas chromatography are emphasized.

[Simultaneous determination of fluoroacetamide and tetramine by gas chromatography]

A simple and fast gas chromatographic method was used for the simultaneous determination of fluoroacetamide and tetramine. The samples were extracted with acetone and the extracts were analyzed by gas chromatography. A megabore capillary column coated with FFAP and a nitrogen-phosphorous detector were used to obtain satisfactory selectivity and sensitivity. The detection limits and average recoveries were 5 ng and 69.1% for fluoroacetamide and 1 ng and 89.8% for tetramine.

Use of liquid chromatography/tandem mass spectrometry to detect distinctive indicators of in situ RDX transformation in contaminated groundwater

An important element of monitored natural attenuation is the detection in groundwater of distinctive products of pollutant degradation or transformation. In this study, three distinctive products of the explosive RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) were detected in contaminated groundwater from the Iowa Army Ammunition Plant; the products were MNX (hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine), DNX (hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine), and TNX (hexahydro-1,3,5-trinitroso-1,3,5-triazine). These compounds are powerful indicators of RDX transformation for several reasons: (a) they have unique chemical features that reveal their origin as RDX daughter products, (b) they have no known commercial, industrial, or natural sources, and (c) they are well documented as anaerobic RDX metabolites in laboratory studies. The products were analyzed by LC/MS/MS (liquid chromatography/mass spectrometry/mass spectrometry) with selected reaction monitoring and internal standard quantification using [ring-U-15N]RDX. Validation tests showed the novel LC/MS/MS method to be of favorable sensitivity (detection limits ca. 0.1 microg/L), accuracy, and precision. The products, which were detected in all groundwater samples with RDX concentrations of > ca. 1 microg/L (25 out of 55 samples analyzed), were present at concentrations ranging from near the detection limit to 430 microg/L. MNX was the typically the most abundant of the three nitroso-substituted products; concentrations of the products seldom exceeded 4 mol % of the RDX concentration, although they ranged as high as 26 mol % (TNX). Geographic and temporal distributions of RDX, MNX, DNX, and TNX were assessed. A degradation product resulting from RDX ring cleavage, methylenedinitramine, was not detected by LC/MS/MS in any sample (detection limit ca. 0.6-4 microg/L). This extensive field characterization of MNX, DNX, and TNX distributions in groundwater by a highly selective analytical method (LC/MS/MS) is significant because very little is known about the occurrence of intrinsic RDX transformation in contaminated aquifers.

Shortfalls using second-generation anticoagulant rodenticides

Second-generation anticoagulant rodenticides can give rise to unexpected casualties in nontarget species in zoos. The first two offspring of a pair of turkey vultures (Cathartes aura) died of brodifacoum toxicosis. The adult birds fed rodenticide-killed mice to their offspring. There are previous case reports of small carnivorous birds (Dacelo novae-guinae and Tockus deckeni) killed eating poisoned (difenacoum and brodifacoum) mice. Even a granivorous species (Rollulus roulroul) died, probably by contamination of its food by cockroaches that transported the rodenticide.

Application of a membrane bioreactor for treating explosives process wastewater

A bench-scale anoxic membrane bioreactor (MBR) system, consisting of a bioreactor coupled to a ceramic cross-flow ultrafiltration module, was evaluated to treat a synthetic wastewater containing alkaline hydrolysis byproducts (hydrolysates) of RDX. The wastewater was formulated the same as hydrolysis wastewater and consisted of acetate, formate and formaldehyde as carbon sources and nitrite and nitrate electron acceptors. The MBR system removed 80-90% of the carbon sources, and approximately 90% of the stoichiometric amount of nitrate, 60% of nitrite. The reactor was also operated over a range of transmembrane pressure, temperature, suspended solids concentration, and organic loading rate to maximize treatment efficiency and permeate flux. Increasing the transmembrane pressure and temperature did not improve flux significantly. Increasing mixed liquor volatile suspended solids (MLVSS) concentration in the bioreactor decreased the permeate flux significantly. The maximum volumetric organic loading rate was 0.72 kg COD/m3/day. The maximum food-to-mass ratio was 0.50 kg N/kg MLVSS/day and 1.82 kg COD/kg MLVSS/day. Membrane permeate was clear and essentially free of bacteria, as indicated by heterotrophic plate count. Permeate flux ranged between 0.15 and 2.0 m3/m2 day and was maintained by routine backwashing every three days. Backwashing with tap water containing chlorine bleach every fourth or fifth backwashing was able to restore membrane flux to its original value.

Identification of hydroxylamino-dinitroso-1,3,5-triazine as a transient intermediate formed during the anaerobic biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine

The metabolic fate of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in a mixed culture incubated under methanogenic conditions was studied. Analysis by high-performance liquid chromatography (HPLC) confirmed the loss of RDX and the formation of mono-, di-, and trinitroso-RDX as transient biodegradation intermediates. An additional peak observed in the HPLC chromatograms was identified by liquid chromatography-mass spectrometry as hydroxylamino-dinitroso-1,3,5-triazine. This is the first report identifying hydroxylamino-dinitroso-1,3,5-triazine as a transient intermediate produced during the anaerobic biodegradation of RDX.

[New applications of FTIR micro-spectroscopy in the field of forensic science]

The new applications of FTIR micro-spectroscopy in the field of forensic science are presented, and the process and results of infrared spectra measurements of many kinds of samples, such as paint, fiber, dye, plastic, rubber, ink and drug have been discussed in detail, including two real cases. Various sampling accessories (Diamond cell, Attenuated total reflection and Micro manipulator system) and different determination modes (transmission and reflectance) are used according to the properties of samples.

[Study of diphacinone in biological samples by high performance liquid chromatography/diode array detector]

An analytical approach has been developed for high performance liquid chromatographic determination of diphacinone extracted from liver, blood, urine and kidney of rabbit by solid phase extraction (SPE) cartridges (using SAX, CN or SILICA GEL) with coumarin as the internal standard. Diphacinone was separated by reversed-phase gradient chromatography with DAD detection at 286 nm. The Analytical column was Hypersil BDS C18(150 mm x 4.6 mm i.d., 5 microns) and the guard column was Phenomenex ODS(4 mm x 3.0 mm i.d.). The mobile phase was a gradient mixture of aqueous solution (A) and methanol solution (B) both containing 0.5% ion pair A. There was a good linear relationship between the concentration of diphacinone and the ratio of peak areas of diphacinone and coumarin (internal standard) (r = 0.9999). The linear range was 1 mg/L-100 mg/L, and the lower detection limit was 5 ng (S/N = 3). The average recoveries of diphacinone in urine, blood and liver were 88.4% (n = 3, RSD = 1.25%, SPE by CN column), 82.2% (n = 3, RSD = 1.67%, SPE by SAX column), 91.0% (n = 3, RSD = 2.77%, SPE by SILICA GEL column), respectively.

Determination of bromethalin in commercial rodenticides found in consumer product samples by HPLC-UV-vis spectrophotometry and HPLC-negative-ion APCI-MS

A small amount of green particulate material is encountered in a consumer complaint sample. The green particulates in the sample are identified as a bromethalin-containing rodenticide using high-performance liquid chromatographic (HPLC)-UV-vis spectrophotometric and HPLC-negative-ion atmospheric pressure chemical ionization (APCI)-mass spectrometric (MS) approaches, which are commonly used for the detection and confirmation of bromethalin in grain-based rodenticides. The selective and sensitive nature of the MS detector makes it possible to determine bromethalin without extensive sample cleanup and preconcentration. The estimated detection limit with the UV-vis detector is 500 pg of bromethalin injected into the column. The extensive fragmentation of the bromethalin molecule under APCI conditions provides sufficient structural information for positive identification.

Investigation of biological samples for monofluoroacetate and Dichapetalum cymosum poisoning in southern Africa

A need has existed for the accurate identification of monofluoroacetate (MFA) poisoning in southern Africa. The development of a new method for the determination of MFA has made the analysis of a variety of biological samples (n = 50) feasible. The method has been used in the laboratory over 24 months. Monofluoroacetate was present in 66% of samples from cases of suspected poisoning, reflecting the extent of the problem. Stability of MFA in samples was also determined so as to have a time-bound baseline for the acceptance of samples submitted. It was found that there was a decrease in the level of MFA and, after 14 days at room temperature, only 50% of the spiked dose could be identified. It is suggested that samples be analyzed within 7 days of mortality if they not kept frozen.

Cyclodextrin-based optosensor for the determination of warfarin in waters

A flow-through optosensor for warfarin is described. The sensor is developed in conjunction with flow analysis systems and uses a commercial bound beta-cyclodextrin material as the sensing phase. A strong fluorescence signal was observed as a result of the formation of an inclusion complex between warfarin and beta-cyclodextrin. The analytical performance characteristics of the proposed sensor for analysis of low levels of warfarin were as follows: the detection limits for continuous and flow injection analysis systems were 2 and 19 ppb, respectively; the observed relative standard deviations at 0. 5 ppm warfarin level were less than 2.3%. A study of the interference of other naphthalenic toxic substances was carried out. The continuous flow method was satisfactorily applied to the determination of the rodenticide in natural waters.

Use of an ion-pairing reagent for high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry determination of anionic anticoagulant rodenticides in body fluids

The on-line combination of high-performance liquid chromatography with mass spectrometry (HPLC-MS) has become a powerful tool for trace analysis thanks to the developments in interface techniques. However, non-volatile salts such as ion-pairing reagents are considered to be incompatible with HPLC-MS systems; they cause drops in analyte signals because of contamination of mass analyzers and also because of blocking of the capillary transferring ions from atmospheric pressure to the vacuum manifold. In this work, a new type of ion-pairing reagent, di-n-butylammonium acetate (DBA), was evaluated for use in HPLC-MS. DBA did not cause these problems to HPLC-MS systems; a possible explanation might be that DBA decomposed to volatile compounds under APCI conditions. In addition, DBA was very useful for obtaining sharp peaks, which resulted in high sensitivity. With this ion-pairing reagent, we developed a procedure for the measurement of five (including internal standard) anticoagulant rodenticides in whole blood and urine samples by SIM detection of [M-H]- ions. Calibration range, recoveries and precision of the method were examined; detection limits as low as 1-5 ng/ml blood sample or 0.5-2.5 ng/ml urine sample were achieved.

[SPE analysis of 4 rodenticides in whole blood and liver by HPLC]

A solid phase extraction (SPE) method has been developed for the analysis of 4 rodenticides: warfarin, couatetralyl, bromadiolone and brodifacoum, using reverse phase high performance liquid chromatograph (HPLC) as determination system. The recovery is 62.6-90.0% (RSD5.1-7.8%) and 37.5-67.7% (RSD5.4%-12.8%) in whole blood and liver sample respectively. The procedure is simple and stable. And the method was confirmed to be effective in the animal experiment.

GC and GC-MS determination of fluoroacetic acid and phenoxy acid herbicides via triphasal extractive pentafluorobenzylation using a polymer-bound phase-transfer catalyst

A simple and sensitive gas chromatography and gas chromatography-mass spectrometry (GC-MS) procedure has been developed for fluoroacetic acid (FA) and phenoxy acid herbicides (PAHs) via triphasal extractive pentafluorobenzylation. The triphasal system consisted of an aqueous sample, the extraction solvent toluene containing pentafluorobenzyl bromide as the derivatization reagent, and polymer-bound tri-n-butyl-methylphosphonium bromide as a phase-transfer catalyst, FA spiked in beverages, such as orange juice and milk, was extracted as its pentafluorobenzyl (PFB) derivative under moderate conditions (i.e., at a pH value of 6.5 at 60 degrees C). The detection limits were 0.10-0.20 microgram/mL by GC with electron-capture detection (GC-ECD), and 0.42-0.50 microgram/mL by full-scan GC-MS. PAHs were also detectable in the same manner within the detection limits of 0.05-0.10 microgram/mL by GC-ECD and 0.13-0.25 microgram/mL by full-scan GC-MS. Urine and serum which both contained 2,4-dichlorophenoxyacetic acid could also be analyzed by GC-MS after the triphasal pentafluorobenzylation. The detection limit was 0.20 microgram/mL in the full-scan mode and 10 ng/mL in the selected ion monitoring mode both for the urine and serum.

Identification of zinc phosphide in a falsely labeled rodenticide bait

"Kela" is a commercial rodenticide bait commonly used in Israel, made of wheat grains, which, according to its label, contains chlorophacinone. This product was involved in the death case of a man in which the victim's female companion was accused of assisting in this suicide and was subsequently convicted. Analysis of the wheat grains revealed zinc phosphide, whose use is restricted to authorized exterminators only, instead of chlorophacinone. Zinc phosphide was identified using microscopic examination, scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) and X-ray powder diffraction (XRD).

Reversed-phase ion-pair liquid chromatographic determination of chlorophacinone and diphacinone in steam-rolled oat baits and steam-rolled oat/wax baits

A reversed-phase ion-pair liquid chromatographic (LC) method was developed for analysis of steam-rolled oat (SRO) baits fortified with either chlorophacinone or diphacinone. Baits were prepared with and without paraffin wax. Chlorophacinone or diphacinone was extracted from wax-free SRO baits with 5 mM tetrabutylammonium phosphate methanolic ion-pairing solution. Wax baits were initially extracted with petroleum ether and then cleaned up by liquid extraction into methanolic ion-pairing solution containing 20% water. SRO extracts were analyzed with reversed-phase ion-pair LC. Chlorophacinone and diphacinone were quantified by UV absorption at 325 nm. Recoveries from SRO fortified with chlorophacinone at 25 and 150 micrograms/g were 90.7 and 90.8%, respectively, whereas for diphacinone at the same levels, recoveries were 93.5 and 92.3%, respectively. Recoveries from wax baits fortified at 25 and 75 micrograms/g chlorophacinone were 98.5 and 100%, respectively, whereas for diphacinone at the same levels, recoveries were 93.6 and 98.0%, respectively. Method limits of detection for chlorophacinone and diphacinone in SRO baits were estimated to be 1.0 and 0.76 micrograms/g, respectively. Method limits of detection for chlorophacinone and diphacinone in wax baits were estimated to be 4.2 and 2.8 micrograms/g, respectively.

Development of a soil extraction procedure for ecotoxicity characterization of energetic compounds

The acetonitrile-sonication extraction method (US EPA Method 8330) associated with aquatic-based toxicity tests was examined to study the ecotoxicity of energetic substances in soil. Three studies were carried out: (1) toxicological characterization of different energetic substances to select a representative toxicant and to validate the choice of bioassays; (2) choice of an appropriate solvent to transfer acetonitrile extracts to the bioassay incubation media; and (3) optimization of Method 8330 using soil samples spiked with the toxicant. Initial studies indicated that pure 2,4,6-trinitrotoluene (TNT) was toxic to Vibrio fischeri [Microtox; IC50 (15 min) of 4.2 microM], whereas RDX was less toxic (IC20 = 181 microM) and HMX was not toxic up to its limit of water solubility (< 22 microM). Selected pure TNT metabolites were less toxic than TNT. Similar results were found using the 96-h Selenastrum capricornutum growth inhibition test. The toxicity of pure TNT in different solvents (acetonitrile, acetone, and DMSO) and that from Method 8330-extracted TNT-spiked soil samples were compared to TNT dissolved in water. Data indicated that DMSO was the most appropriate solvent to transfer the acetonitrile extracts. A modified Method 8330 may be used in conjunction with bioassays and chemical analyses to examine the ecotoxicity of soils contaminated with energetic substances.