Determination of sulphur compounds by fully automated molecular emission cavity analysis

Abstract

The performance of an automated molecular emission cavity analysis (MECA) instrument for the determination of sulphur compounds was investigated. Thiourea, sulphuric acid, ammonium thiocyanate and promethazine were chosen as model compounds. The control of the time required for the various sectors of the MECA operation (time spent in flame, cooling time before sample injection and solvent pre-evaporation time) allows conditions of greatest sensitivity or reproducibility to be established. If complete solvent evaporation is possible before cavity introduction into the flame, sensitivity and calibration linearity are greatly improved. The automated instrument also allows an assessment to be made of the simultaneous determination of thiocyanate and sulphate.