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

Rapid screening procedures for a variety of complex forensic samples using laser diode thermal desorption (LDTD) coupled to different mass spectrometers

RATIONALE

The applications shared in this paper demonstrate the wide variety of samples that can be analyzed when Laser Diode Thermal Desorption (LDTD) is interfaced with a high-resolution mass spectrometer and show the speed at which high quality data can be generated from complex matrices.

METHODS

Samples are solvent extracted and spotted in a 96-well plate. In the case of biological fluids, hydrolysis followed by solid-phase extraction is required. The solvent in the 96-well plate is evaporated followed by mass spectrometric (MS) analysis with atmospheric pressure chemical ionization. Where applicable, the instrument is operated in data-dependent mode, with a full-scan mass spectrum followed by MS/MS spectra of the top 10 ions with a total runtime of 0.4 min.

RESULTS

Four applications (MAAQ and Tear Gas, twelve rodenticides, seven explosives, and 40 drugs of abuse) are reported in this paper. MAAQ, tear gas, and rodenticides were identified by full-scan, followed by MS/MS experiments at levels of 125 μg/L, 125 μg/L, and 500 μg/L, respectively. Explosives were all identified at 102 μg/L by full-scan experiments. The drugs of abuse were identified by multiple reaction monitoring (MRM) experiments at defined cutoff levels from 2 to 1000 μg/L.

CONCLUSIONS

Interfacing LDTD with a mass spectrometer allows for rapid screening of a wide range of samples, with either minimal or complex sample preparation. Using a high-resolution mass spectrometer with the combination to perform full-scan and MS/MS experiments adds a high level of specificity.

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.

Method for the detection of desmethylbromethalin in animal tissue samples for the determination of bromethalin exposure

Bromethalin, a potent neurotoxin, is widely available for use as a rodenticide. As access to other rodenticides is reduced due to regulatory pressure, the use of bromethalin is likely to increase with a concomitant increase in poisonings in nontarget animals. Analytical methods for the detection of bromethalin residues in animals suspected to have been exposed to this rodenticide are needed to support post-mortem diagnosis of toxicosis. This paper describes a novel method for the analysis of desmethylbromethalin (DMB), bromethalin's toxic metabolite, in tissue samples such as liver, brain, and adipose. Samples were extracted with 5% ethanol in ethyl acetate, and an aliquot of the extract was evaporated dry, reconstituted, and analyzed by reverse phase ultrahigh-performance liquid chromatography-mass spectrometry. The mass spectrometer utilized electrospray ionization in negative ion mode with multiple reaction monitoring. This method was qualitatively validated at a level of 1.0 ng/g in liver tissue. The quantitative potential of the method was also evaluated, and a method detection limit of 0.35 ng/g wet weight was determined in fat tissue. DMB was detected in tissue samples from animals suspected to have been poisoned by this compound. To the authors' knowledge, there have been no other methods reported for analysis of DMB in tissue samples using LC-MS/MS.

Mass spectrometric detection in chromatography. Trends and perspectives

The newest results in the use of miscellaneous mass spectrometric detection methods in various chromatographic techniques are compiled and critically evaluated. Examples of application in clinical chemistry, health care, and in the analysis of pharmaceuticals, environmental pollutants, foods and food products are given. The benefits and drawbacks of MS detection are discussed, and future trends are briefly discussed.