Determination of tetrafluoroborate in wastewaters by ion chromatography after ion pair liquid-liquid dispersive microextraction

The ion chromatographic method was developed to determine tetrafluoroborate ion (BF4-) in different types of water using ion pair liquid-liquid dispersive microextraction. Tetrafluoroborate was extracted into an organic phase (1,2-dichloroethane) as an ion pair with a tetrabutylammonium cation (TBA+). The most complete formation of [(ТBА+)(BF4-)] was observed at ion-pair reagent concentration of at least 5 mmol L-1 (C(BF4-) ≤ 1mg L-1). Ultrasonic irradiation was used to disperse the extractant. The achieved concentration factor (K) was 29±3, and the degree of extraction (R) was 50±5%. The limit of detection of tetrafluoroborate using the microextraction technique was 7×10-3 mg L-1. The method applies to the analysis of different water origins. The presence of the main contained anions does not interfere with the microextraction and chromatographic determination of tetrafluoroborate. The maximum molar ratio of BF4- to diverse ions is 1:104 for fluoride, chloride, bromide,  nitrate ions, and 1:102 for sulfate and perchlorate ions.