Rj. Geise et al., DETERMINATION OF CHLORIDE, SULFATE, NITRATE, AND PHOSPHATE IN N-METHYL-2-PYRROLIDONE AND GAMMA-BUTYROLACTONE BY CAPILLARY ELECTROPHORESIS, Journal of liquid chromatography, 16(17), 1993, pp. 3699-3712
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.