[Development and validation of an assay method of the paraphenylene diamine by gas chromatography-mass spectrometry]. / Développement et validation d'une méthode de dosage de la paraphénylène diamine par chromatographie gazeuse couplée à la spectrométrie de masse.

Paraphenylenediamine is an aromatic amine used as a hair dye; it is responsible for poisoning characterized by respiratory distress involving life-threatening. The objective of this work is the development and validation of an assay of para-phenylenediamine in the whole blood. The method is based on the determination of paraphenylene diamine in whole blood by gas chromatography-mass spectrometry after liquid-liquid extraction and derivatization. The validation protocol has included the study of the recovery factor of extraction, the measurement range, accurency, repetability and intermediate precision. The calibration curve was linear between 98 and 1350 µg/L (r = 0.999), the limit of detection and quantification were 37 µg/L and 63 µg/L respectively. The accuracy were 94.7%. Coefficients of variation were (2.3/6.8/9.7%) for repeatability and (4.4/8.7/9.8%) for intermediate precision. The method is suitable for quantification of PPD in acute poisoning situations. A method for the determination of the paraphenylene diamine in the whole blood by gas chromatography coupled to mass spectrometry was developed. The validation of the method showed good linearity, good accuracy and low limit of quantification.

HPLC MS/MS method for quantification of meprobamate in human plasma: application to 24/7 clinical toxicology.

We described the development and full validation of rapid and accurate liquid chromatography method, coupled with tandem mass spectrometry detection, for quantification of meprobamate in human plasma with [(13)C-(2)H(3)]-meprobamate as internal standard. Plasma pretreatment involved a one-step protein precipitation with acetonitrile. Separation was performed by reversed-phase chromatography on a Luna MercuryMS C18 (20 mm×4 mm×3 µm) column using a gradient elution mode. The mobile phase was a mix of distilled water containing 0.1% formic acid and acetonitrile containing 0.1% formic acid. The selected reaction monitoring transitions, in electrospray positive ionization, used for quantification were 219.2→158.2 m/z and 223.1→161.1m/z for meprobamate and internal standard, respectively. Qualification transitions were 219.2→97.0 and 223.1→101.1 m/z for meprobamate and internal standard, respectively. The method was linear over the concentration range of 1-300 mg/L. The intra- and inter-day precision values were below 6.4% and accuracy was within 95.3% and 103.6% for all QC levels (5, 75 and 200 mg/L). The lower limit of quantification was 1 mg/L. Total analysis time was reduced to 6 min including sample preparation. The present method is successfully applied to 24/7 clinical toxicology and demonstrated its usefulness to detect meprobamate poisoning.