Determination of low concentrations of the quaternary ammonium compound thiazinamium methylsulphate in plasma and urine

Abstract
A sensitive and selective method for the quantitative determination of the quaternary ammonium antiacetylcholine-compound thiazinamium methylsulphate (Multergan) in plasma and urine is described. The procedure is based on ion pair extraction of the compound with iodide as the counter ion. This is followed by gas chromatography using an alkali flame ionization detector. The detection limit is 2 ng ml−1 with a recovery of 88·0 ± 6·2% from plasma, 91·4 ± 4·6% from urine. The described method can also be applied to other quaternary ammonium compounds.