A novel capillary electrophoresis method with pressure assisted field amplified sample injection in determination of thiol collectors in flotation process waters

Xanthate degradation occurring in flotation process waters of a gold concentrator plant

“…The CE separation method was validated using the initial data from the published method (Sihvonen et al, 2014;Sihvonen, 2012). In the present research, the method, based on sample introduction with a PA-FASI made when the sample is introduced into the capillary with concurrent high voltage and pressure, was optimized for ethyl xanthate, ethyl dixanthogen, ethyl thiocarbonate, ethyl perxanthate, and ethyl xanthyl thiosulfate.…”

“…This translates into 89 pg in the detection. We had previously reported the LOD and LOQ values for some of the ethyl group analytes (Sihvonen et al, 2014;Sihvonen, 2012) in process waters. Ethyl xanthate yielded LOD and LOQ values of 160 lg L À1 and 500 lg/L, respectively.…”

“…All flotation chemicals used in the method development are listed in Table 1. In the processes, the commercial Danafloat™ 507 (50% water solution, Cheminova, Brenntag Nordic Oy, Vantaa, Finland) mineral collector was used; it is an aqueous solution of dialkyl dithiophosphate and thionocarbamate (Sihvonen et al, 2014). The chemical 3-(cyclohexylamino)propane-1-sulfonic acid (CAPS, purity >98%), used for the preparation of the electrolyte solution, was obtained from Sigma-Aldrich (St. Louis, MO, USA).…”

“…The idea of the technique is based on an electro-aided separation of ionic compounds in narrow-bore fused silica capillaries (with a volume below 1 lL) under an applied electric field (100-800 V cm À1 ). Electrical separation of the side-products of thiols is possible due to the ionization of compounds in industrial process waters and the flotation chemicals in water (Kokkonen et al, 2004;Hissner et al, 1999;Sihvonen et al, 2014;Sihvonen, 2012). In the present project, CE was used because it is applicable to on-line measurements due to the low eluent and sample consumption and to the reusability of the separation capillaries (Kokkonen et al, 2004).…”

“…They concluded that on-line concentration by stacking yields the best sensitivity. However, Sihvonen et al (2014) have recently found that pressure-assisted field-amplified sample injection (PA-FASI) is even more effective than stacking when the sample matrices contain high ionic strengths, as is the case for waters of flotation processes. Their research aimed at finding an optimized method for quantification of diisobutyl dithiophosphate (DTP), diisobutyl dithiophosphinate (DTPI), ethyl xanthates (EX) and isobutyl xanthates (IBX), which are all used as thiol collectors in froth flotation.…”