RAPID NORMAL RAMAN-SPECTROSCOPY OF SUB-PPM OXY-ANION SOLUTIONS - THE ROLE OF ELECTROPHORETIC PRECONCENTRATION

Normal Raman spectroscopy is used as an on-line detector for capillary electrophoresis (CE) to detect sub-ppm mixtures of nitrate and perchl orate in water. Field-amplified injection, a form of sample stacking, into a running electrolyte of 0.1 M KCL increases the analyte concentr ation at the detection window by up to 1800 times its starting value. Raman bands of nitrate (1047 cm(-1)) and perchlorate (934 cm(-1)) are measured in a total separation time of less than 3 min, with only 1-s integration times. The Raman spectroscopy of solutions originally 1 x 10(-5) M nitrate (620 ppb) and perchlorate (1 ppm) is demonstrated.