ИСТИНА

Detection of heavy metal traces in polar ice and snow samples is the challenging analytical problem. The ultra low concentrations of such metals as Pb, Cd, Bi, REE etc. down to ppt – sub-ppt levels dictate extremely hard requirements at every stage of the analysis starting with sample collection in the field, sample pre-treatment and final measurements by an analytical technique. About 20 years ago practically the only technique for direct analysis at such low levels was Laser Atomic Fluorescence Spectroscopy (LAFS). It allowed the detection of Pb, Cd, Bi at 0.2 ppt level using 20-30 μL sample volume. At that time the limits of detection (LOD) of the alternative ICP-MS technique were of the same order, but the minimal sample volume was about 1 mL. Since than the tremendous technical progress of the ICP-MS has provided the break-through. Nowadays, the sector-field instruments SF-ICP-MS have won the leading position among the instrumental techniques for elemental analysis. This technique has the best metrological parameters and enables the direct detection of sub-ppt concentrations of many metals in multielement mode. The comparison of LAFS and ICP-MS will be discussed in the talk. In the end brief overview of the specific analytical problems for which the laser based techniques are still the only alternatives will be given.