Determination of xanthates as Cu(II) complexes by high-performance liquid chromatography - Inductively coupled plasma tandem mass spectrometry.

The present study provides a novel, selective analysis method for the determination of low xanthate concentrations. The rising concern over the environmental effects of xanthates demands the development of analysis methods which this study answers. Complex formation in aqueous solution between xanthates and an excess of Co(II), Ni(II), Pb(II), Cd(II), Cu(II), and Zn(II) ions was utilized to selectively determine xanthates by high-performance liquid chromatography-inductively coupled plasma tandem mass spectrometry for the first time. The complexes that were formed were extracted to ethyl acetate using liquid-liquid extraction and separated by high-performance liquid chromatography technique before the quantitative determination of metal ions and sulfur in the xanthate complexes. Good separation and high measurement sensitivity were achieved using Cu(II) as the complex metal ion. The analysis method was optimized for the determination of sodium isopropyl xanthate and sodium isobutyl xanthate with detection limits of 24.7 and 13.3 µg/L, respectively. With a linear calibration range of 0.1-15 mg/L and a total analysis time of 4-5 min, the present method is a fast and sensitive option for selective xanthate determination.

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.

Response of wheat and barley seedlings on soil contamination with bromides.

Environmental pollution is becoming one of the most important global problems. Understanding the main factors affecting accumulation of toxic trace elements in consumed crops is of particular value. Unfortunately, possible toxicity of many trace elements is still poorly studied. The development of measures on identification of new potentially toxic trace elements is critical for high quality and safety of food. In the research, we performed greenhouse pot experiments with two major crops, wheat and barley, that were grown in the soil contaminated with bromides of ammonium and neodymium. The concentrations of elements in the plants and soil were determined by ICP-MS/ICP-OES after leaching the samples with tetramethyl ammonium hydroxide. Additionally, variations in the biomasses and concentrations of pigments in the plant leaves were studied. Although wheat and barley are botanically similar and were grown under the same conditions, concentrations of several elements in the plants were rather different. Both wheat and barley were capable of accumulating high concentrations of bromine (Br) when the plants grow in the soil contaminated with this trace element, but demonstrated different response on the soil contamination. The Br concentrations were always higher in barley, while the concentrations of pigments in barley leaves were lower than in leaves of wheat. During first days, biomass of the plants grown in the soil contaminated with bromides was slightly lower than biomass of the wheat and barley grown in uncontaminated soil. However, with time the bromides exhibited positive effect on the plant biomass.