Spectrophotometric determination of hydrogen sulfide in environmental samples using sodium 1,2-naphthoquinone-4-sulfonate and response surface methodology

A simple spectrophotometric method for determination of hydrogen sulfide in wastewater and hot spring samples was developed. The method is based on the reaction between hydrogen sulfide and sodium 1,2-naphthoquinone-4-sulfonate (NQS). The effect of various experimental factors on the reaction between hydrogen sulfide and NQS was investigated and optimized using central composite design. The optimal values of the factors were 5.00 x 10(-4) mol L-1 for concentration of NQS and 1.00 x 10(-2) mol L-1 for concentration of hydrochloric acid. The wavelength of the maximum absorption of the reaction product was 320 nm. Constructed calibration curve for hydrogen sulfide determination was linear in the range of 0.5-20.0 mg L-1 with the detection limit of 0.16 mg L-1. The method was free from interferences. Percent relative errors below 2 % were obtained for determination of hydrogen sulfide in environmental samples.