Determination of sodium monofluoroacetate (compound 1080) in tissues and baits as its benzyl ester by reaction-capillary gas chromatography

A reaction-capillary gas-chromatographic procedure using photo-ionization (PID) or flame-ionization (FID) detection was developed for the determination of sodium monofluoroacetate (compound 1080), a pesticide, in tissues and baits. Fluoroacetic acid from tissue (1 g) and bait (10 g) extracts was first partitioned into ethyl acetate and then into 0.5 M benzyldimethylphenylammonium hydroxide. Benzylation was achieved by pyrolysis of the quaternary ammonium salt in the injection port. Chloroacetic acid was used as the internal standard. A linear relationship (r = 0.999) was observed between the peak area ratio of the substrate/internal standard and the fluoroacetic acid concentration. The detection limit for compound 1080 using the described analytical procedure, was 15 micrograms/kg with PID and 100 micrograms/kg with FID.

High-performance liquid chromatographic strategies for the determination and confirmation of anticoagulant rodenticide residues in animal tissues

A comprehensive approach to the analysis of anticoagulant rodenticide residues in animal tissues based on high-performance liquid chromatography (HPLC) has been developed. Residues of warfarin, coumatetralyl, difenacoum, brodifacoum, bromadiolone, diphacinone and chlorophacinone were extracted with chloroformacetone (1:1, v/v). Extracts were cleaned-up by an integrated gel permeation and adsorption chromatographic procedure which divided the rodenticides into two groups. Residues were then determined and confirmed using normal-phase, ion-pair and weak ion-exchange HPLC techniques. Ion-pair gradient separation resolved all seven rodenticides in a single chromatographic analysis. UV detection methods were employed for all seven rodenticides. Use of a diode array detection system permitted additional confirmation of residues down to 0.1 mg kg-1 by matching UV spectra and derivatives of spectra. Sensitive fluorescence detection was possible for the coumarin-based rodenticides but not for diphacinone and chlorophacinone. Post-column pH-switching fluorescence detection methods were shown to be superior to other methods of fluorescence detection of coumarin-based rodenticides. Recoveries from spiked liver tissue were around 90% at levels from 0.05 to 1 mg kg-1. Detection limits of around 0.002 mg kg-1 for most rodenticides and of 0.01 mg kg-1 for warfarin could be achieved with animal tissue extracts.

Reversed-phase ion-pair liquid chromatographic determination of chlorophacinone residues in animal tissues

A sensitive and specific high-performance liquid chromatographic method for the identification and quantitation of chlorophacinone in animal tissues has been developed. Residues were extracted with chloroform-acetone (1:1, v/v). Clean-up of extracts was accomplished with a combined gel permeation-adsorption chromatographic procedure using Bio-Beads SX-3 and incorporating an on-line Sep-Pak silica cartridge. Residues were determined by ion-pair liquid chromatography, with the tetrabutylammonium ion as counter-ion, using a fixed-wavelength UV detector at 280 nm or a diode array detector at 285 nm. Recoveries from spiked liver tissue were around 90% at levels from 0.05 to 1 mg kg-1. A detection limit of 0.001 mg kg-1 could be achieved in animal tissues. The diode array detector confirmed identification by matching spectra for residues down to 0.1 mg kg-1 and below this level by multi-wavelength monitoring.

Gas chromatographic analysis of coyote and magpie tissues for residues of compound 1080 (sodium fluoroacetate)

Tissues of coyotes and magpies administered known dosages of 1080 were analyzed for residues by an analytical method specifying gas chromatography and electron capture detection. The repeatability of the method was determined for the replicate analyses of coyote muscle tissue samples aged under different storage conditions. The average coefficient of variation (CV) was 6% for quadruplicate determinations of 1080 in fresh tissues, 12-14% for samples stored at - 10 degrees C for 30-60 days, and 24% for samples aged for 7 days at ambient temperatures. The larger CV value obtained for stored samples is attributed more to greater sample variability than to less precision of the analytical method. Residues of 1080 appear to be relatively stable in tissues; there was essentially no change in the concentration of 1080 in samples stored up to 28 days at ambient temperature. Residue levels in the muscle, heart, kidney, and intestine were comparable, slightly lower in the liver, and much higher in the stomach. The concentration of 1080 in the muscle tissue was related to the administered dosages. Correlation analyses of dosages and residue levels in coyote muscle tissue showed a correlation coefficient of 0.99 for 1080 administered by gavage, and 0.88 for 1080 administered by bait. A correlation coefficient of 0.99 was observed between dosages and mean residues in the breast muscle tissues of magpies. The average CV value was 3.5% for duplicate analyses of 1 g samples of magpie tissues.

Determination of coumarin anticoagulant rodenticide residues in animal tissue by high-performance liquid chromatography. I. Fluorescence detection using post-column techniques

A multi-residue method was developed for the determination of the rodenticides warfarin, coumatetralyl, bromadiolone, difenacoum and brodifacoum in animal tissues by high-performance liquid chromatography with fluorescence detection. Extracts were cleaned-up by gel permeation chromatography on Bio-Beads SX-3 and residues determined by normal and reversed-phase high-performance liquid chromatography using post-column pH-switching, with chloroform -sec.-butylamine and borate buffer (pH 10.4) respectively, to maximise the native fluorimetric responses. Confirmation of identification was possible by re-chromatographing extracts in the absence of the post-column reagent. Chloroform-acetone (1:1) was significantly better than chloroform for the extraction of residues of these rodenticides from liver tissues. Recoveries from spiked liver tissue were generally greater than 90% at levels of 0.05-1 mg kg-1. Detection limits in animal tissues of 0.002 mg kg-1 for coumatetratyl, difenacoum and brodifacoum, 0.01 mg kg-1 for bromadiolone and 0.02 mg kg-1 for warfarin and could be routinely achieved.

Determination of coumarin anticoagulant rodenticide residues in animal tissue by high-performance liquid chromatography. II. fluorescence detection using ion-pair chromatography

A high-performance liquid chromatographic method was developed for the determination of warfarin, coumatetralyl, bromadiolone, difenacoum and brodifacoum in animal tissues using fluorescence detection. Ion-pair chromatography, with the tetrabutylammmonium ion as counter-ion, was used to take full advantage of their native fluorescence. Detection limits in liver tissue after gel permeation clean-up were 0.002 mg kg-1 for coumatetralyl, difenacoum and bromdifacoum, 0.008 mg kg-1 for bromadiolone, and 0.01 mg kg-1 for warfarin.

The stability of ergocalciferol in rodenticidal baits

Concentrations of the rodenticide ergocalciferol (vitamin D2) in samples of rodent baits laid in foodstores and in the laboratory were monitored over several months. Bait samples were solvent extracted and ergocalciferol concentration determined by high pressure liquid chromatography (HPLC). Ergocalciferol levels were constant for more than 21 days in dry samples and did not fall by more than 30% in 100 days. When water (10% w/w) was added to the baits in the laboratory the ergocalciferol concentration fell by approximately 30% in 30 days. In these wet laboratory samples there was a rapid visible growth of fungus and in normal rodent control use baits should have been replaced when such deterioration became evident.

Improved method for high pressure liquid chromatographic determination of chlorophacinone in mouse tissue

A simplified method is described for the determination of chlorophacinone, 2-[(p-chlorophenyl)-phenylacetyl]-1,3-indandione, in homogenized mice. Chlorophacinone is extracted with acetonitrile. After Florisil cleanup, the extract is injected into a high pressure liquid chromatograph for reverse phase chromatography on a polar Lichrosorb NH2 (10 micron) column, with a mobile phase of acetonitrile-water (80 + 20). An injection containing 70 ng chlorophacinone produces 1/2 scale peaks at 254 nm with a full scale absorbance of 0.1 unit, an order of magnitude improvement over the sensitivity reported earlier with a 280 nm detector. Six homogenized mice samples and six spiked homogenized mice samples were quantitatively analyzed for trace levels of chlorophacinone by this method. Recoveries from spiked samples, as determined by peak height measurement, were greater than 95%. Mean retention time for the chlorophacinone peaks in all samples was 6.05 +/- 0.05 min. Chlorophacinone levels determined in homogenized whole mouse samples ranged from 0 to 63 ppm.

High pressure liquid chromatographic determination of sodium fluoroacetate (compound 1080) in canine gastric content

A sensitive high pressure liquid chromatographic method was developed for the determination of sodium fluoroacetate (compound 1080) in canine gastric content. The procedure involves extraction of 1080 with water, methyl ethyl ketone, and dilute base, followed by sample cleanup using octadecylsilane bonded phase cartridges and derivatization in ethyl acetate sodium with O-p-nitrobenzyl-N-N'-diisopropylisourea (PNBDI). The compound was chromatographed on a 10 micrometer silica column, and ultraviolet absorbance at 254 and 280 nm was measured. Recovery was greater than 95% for standard 1080 and in the 70-90% range for spiked samples (1-50 ppm).

[Method of toxicological research of anticoagulant rodenticides (author's transl)]

The analytical method which is described enables to detect principal anticoagulants presently used in France as rodenticides. Its particularity lies in using a mixture of iso octane and dichloromethane 95/5 (V/V) in the extractive part whose output varies according to the compounds from 80 to 25 per cent in supplemented liver. Besides thin layer chromatography which is used to achieve identification and semi quantitative evaluation, spectrometric measurement can be carried through to confirm identity and precise quantity with more accuracy. Sensitivity varying according to compounds, it is possible to detect products whose minimum concentration in biological materials is between 1 and 5 ppm.

[Detection of rodenticidal preparations - urea derivatives (Dirax, Vacor) in biological materials using thin layer chromatography]

The methods of toxicological detection of the rodenticides Dirax and Vacor (urea derivates) in biological material were worked out and tested. The new chromatographic methods using a thin silica gel layer can be of help in laboratory toxicological diagnostics.

Determination of the rodenticide difenacoum in biological materials by high-pressure liquid chromatography with confirmation of identity by mass spectrometry

A method for determining difenacoum in liver, plasma, urine and feedingstuffs by high-pressure liquid chromatography is described. Samples are cleaned up by molecular exclusion chromatography on porous glass. In some cases this also serves for determination; if not, the separated difenacoum is determined on an adsorption column. Identity is confirmed by chemical ionisation mass spectrometry. Recoveries at levels of 0.025-5 ppm from plasma were 101-113% by exclusion chromatography alone and 93-101% after adsorption chromatography. Recoveries from liver after both chromatographic steps were 62-86%. Reasons for the lower recoveries from liver are suggested.

Gas-liquid chromatographic determination of strychnine in grain baits

A simple and rapid gas-liquid chromatographic procedure, using a 6' times 1/4'' glass column packed with 5% SE-30 on Chromosorb W (DMCS) and a flame ionization detector, is described. Grain baits containing strychnine alkaloid are ground, mixed, and extracted by shaking with chloroform containing an internal standard, 1,3,5-triphenylbenzene. Without further cleanup, extract filtrates are injected directly into a gas chromatograph. Peak height ratios are used for quantitation of strychnine. The analysis of commercial samples shows that the method compares well with a commonly employed ultraviolet spectrophotometric method; good precision, with recoveries ranging from 89.9 to 91.7%, is obtained in the analysis of prepared samples. The method is sensitive to 2 mug strychnine.

High-performance liquid chromatographic determination of strychnine in grain baits.l

A simple and rapid high-performance liquid chromatographic procedure is described for the determination of strychnine. Grain baits containing strychnine alkaloid are ground, mixed, and extracted by shaking with chloroform. Without further cleanup, extract filtrates are injected directly into a liquid chromatograph. Chromatography is complete within 7 min and peak heights are used for quantitation. Separations were made on a 30 cm times 4 mm id stainless steel column packed with mu Porasil (8-12 mum silica). The eluting solvent was methanol-chloroform (10+90) at a flow rate of 2.0 ml/min. Recovery of spiked samples ranged from 91.5 to 95.2%. Confirmation of strychnine from a commercial sample was made by high resolution mass spectrometry with mass agreement to 1.2 ppm.