Suppressed ion chromatography methods for the routine determination of ultra low level anions and cations in ice cores

The concentration of trace ionic species in snow and ice samples was determ ined using suppressed ion chromatography (IC) with conductivity detection a nd ultra-clean sample preparation techniques. Trace anion species were dete rmined in a single 24-min run by combining sample preconcentration with gra dient elution using Na2B4O7 eluent. The detection limits (ranging from 0.00 1 to 0.006 muM) are the lowest reported in the literature. Cation species w ere analysed by direct injection of 0.25 ml and isocratic elution with a H, SO, eluent. The clean preparation techniques showed no evidence of a differ ence (Student's t-test) between Milli-Q water samples analysed directly and processed Milli-Q ice samples. These robust, ultra-clean IC methods were r outinely applied to the analysis of large number of samples to produce a hi gh-resolution trace ion ice core record from Law Dome, East Antarctica. (C) 2001 Elsevier Science BN. All rights reserved.