Simultaneous kinetic-potentiometric determination of hydrazine and thiosemicarbazide by partial least squares and principle component regression methods

Simultaneous determination of hydrazine (HZ) and thiosemicarbazide (TSC) by partial least squares (PLS) and principle component regression (PCR) was carried out based on kinetic data of novel potentiometry. The rate of chloride ion production in reaction of HZ and TSC with N-chlorosuccinimide (NCS) was monitored by a chloride ion-selective electrode. The experimental dada shows not only the good ability of ion-selective electrodes (ISEs) as detectors for the direct determination of chloride ions but also for simultaneous kinetic-potentiometric analysis using chemometrics methods. The methods are based on the difference observed in the production rate of chloride ions. The results show that simultaneous determination of HZ and TSC can be performed in their concentration ranges of 0.7-20.0 and 0.5-20.0 mu g mL(-1), respectively. The total relative standard error for applying PLS and PCR methods to 9 synthetic samples in the concentration ranges of 0.8-10 mu g mL(-1) of TSC and 1.0-12.0 mu g mL(-1) of HZ was 4.62 and 4.98, respectively. The effects of certain foreign ions upon the reaction rate were determined for the assessment of the selectivity of the method. Both methods (PLS and PCR) were validated using a set of synthetic sample mixtures and then applied for simultaneous determination of HZ and TSC in water samples.