Automated polarographic determination of sulfide as contaminant in parenteral amino acid solutions

A method for the automated polarographic determination of sulfide in a gas-diffusion flow system was developed, The volatile sulfide, existing as a contamination parenteral amino acid solutions, was measured after gas diffusion using 0.1 mol l(-1) NaOH Solution as acceptor, The linear range of calibration, for measurements at a dropping-mercury electrode (DME), was from 5 to 100 mu g of sulfide with r = 0.999 and RSD = 7.5% (n = 5) for 10 mu g of sulfide, For measurements at the hanging mercury-drop electrode (HMDE), with a preconcentration time of 30 s, the linear range of calibration was from 0.9 to 20 mu g of sulfide with r = 0.998 and RSD = 5.8% (n = 5) for 2 mu g of sulfide, Detection limits of 59 and II mu g l(-1) at the DME and HMDE, respectively, were calculated and the recoveries of sulfide from spiked samples were 91.5-104.5%, Parameters that affect the sulfide determination using this method, such as the organic content of the matrix, pH, flow rate and sample size, were investigated.