DETERMINATION OF CHLORIDE, SULFATE, NITRATE, AND PHOSPHATE IN N-METHYL-2-PYRROLIDONE AND GAMMA-BUTYROLACTONE BY CAPILLARY ELECTROPHORESIS

N-methyl-2-pyrrolidone (NMP) and gamma-butyrolactone (BLO) are importa nt solvents in the semiconductor and electronics industry. These appli cations demand solvents with low levels (< 0.5 ppm) of anions. Traditi onally, analytical methods have not kept pace with the requirements de sired by the electronics industry. Recently, ion chromatography (IC) h as provided lower detection levels for anions. However, capillary elec trophoresis (CE) for anion analysis possesses unparalled resolution an d efficiencies, with analysis times reduced by up to a factor of ten o ver IC. Using die method of standard additions, the concentrations of chloride, sulfate, nitrate and phosphate were determined in 1:20 aqueo us dilutions of NMP and BLO. A lower limit of detection for the undilu ted solvent sample of 40 ppb (2 ppb limit for 1:20 dilution of sample) was found for each of the four anions of interest.