Systematic optimization of a pyromellitic acid background electrolyte for capillary electrophoresis with indirect UV-vis detection and online pre-concentration analysis of thiosalt anions in treated mine tailings

Abstract

An indirect CZE method was developed for the simultaneous determination of five thiosalt anions: sulfate (SO42−), thiosulfate (S2O32−), trithionate (S3O62−), tetrathionate (S4O62−) and pentathionate (S5O62−).

Determination of inorganic anions in oilfield water using capillary electrophoresis with indirect fluorescence detection

“…Inorganic anion analysis using capillary electrophoresis (CE) with indirect photometric detection has been widely studied. 35,43,45,49,60 However, most of these applications have dealt with simple water matrices. The high salinity and variable nature of oileld water presents a challenge for anion analysis.…”

“…44,45 Recently, Donkor et al developed a CE-indirect UV detection method for inorganic anion analysis in highly saline oileld water. 46 In general, the sensitivity of indirect UV absorbance (10 À5 to 10 À6 M) [47][48][49] is poor. Indirect conductivity can achieve comparable or lower detection limits (10 À5 to 10 À7 M).…”

Application of Capillary Electrophoresis for Determination of Inorganic Analytes in Waters

“…The presented method has been successfully applied for the determination of 12 metal cations, including alkali, alkaline earth, transition metals, and ammonium in tap and mineral water samples with base-line resolution, in time periods up to 8 min. CE with indirect UV detection and PMA as UV probe were employed for the determination of sulfur-containing anions in pond water [21], while using chromium trioxide (CrO 3 ) as a UV probe capillary coated with polybrene and SDS for determinations of chloride and sulfate in saline oil-field water [22]. In the determinations of phosphate and calcium, Ca 2+ ions were complexed with 2,6-pyridine-dicarboxylic acid (2,6-PDCA) in BGE to form Ca[PDCA] 2 2− complex, and then HPO 4 2− and Ca[PDCA] 2 2− were separated with the direct UV detection used for calcium complex detection, while indirect UV detection was employed for phosphate determination.…”

“…The preconcentration of the analyte as effect of stacking is based on its concentration in narrow segments of the interphase, separating zones of weak and strong electric fields so the stacking effect can be created by introducing a sample solution of much lower conductivity than that one used in BGE. For example, the field amplified sample stacking technique for on-line sample preconcentration was applied in the analysis of five sulfur-containing anions, and the LOD values (from 0.02 to 0.12 μg mL −1 ) were improved by about 4-fold [21]. The CE runs were performed by introducing a water plug prior to the electrokinetic injection of the sample.…”

Reservoir souring: sulfur chemistry in offshore oil and gas reservoir fluids

“…Thiosalts have relatively strong UV absorbance and, therefore, more selective direct detection at 214 nm is used (Padarauskas et al 2000). Thiosulfate, trithionate, tetrathionate, and pentathionate have been detected using indirect UV-Vis detection (Pappoe and Bottaro 2014). Fully ionized pyromellitate ion (PMA) with a high molar absorptivity was used as the chromophoric probe.…”