The effect of experimental conditions on the formation of dixanthogen by triiodide oxidation in the determination of ethyl xanthate by HPLC-ICP-MS/MS

The rising concern over the environmental impact of xanthates, especially in the arctic region, has increased the need to study these traditional flotation reagents in greater detail. The environmental concern relates mostly to the formation of carbon disulfide (CS₂) and the heavy metal complexes of xanthates. Due to the unstable nature and multiple reaction mechanisms of xanthates, their reliable determination at low concentration levels is difficult. In this study, a xanthate pretreatment method was optimized and applied for the determination of ethyl xanthate (EX^-) by high performance liquid chromatography-inductively coupled plasma tandem mass spectrometry (HPLC-ICP-MS/MS). Ethyl xanthate was oxidized to diethyl dixanthogen ((EX)₂) by triiodide (I₃^-) in aqueous solution and the formed (EX)₂ was extracted into n-hexane. Important experimental parameters, including pH, I₃^- amount, and oxidation time, were optimized and the detection limit of 0.29 mg L^-1 for potassium ethyl xanthate was obtained. During the optimization experiments, it was found that the oxidation reaction resulted in multiple products, decreasing the efficiency of (EX)₂ formation and, therefore, the sensitivity of the method. The proposed method was applied to wastewater samples with recoveries of 105-106%. This study provides a selective method for the determination of ethyl xanthate and introduces novel information on the parameters affecting the oxidation of xanthates.