Cerebrospinal fluid elemental analysis by using a total sample consumption system operated at high temperature adapted to inductively coupled plasma mass spectrometry
A total consumption low sample introduction system has been applied for the first time to the multielement analysis of non-diluted cerebrospinal fluids (CSFs) by means of inductively coupled plasma mass spectrometry (ICP-MS). A 2.5 μL sample volume has been injected into an air carrier stream in agreement with the air-segmented injection principle. The sample plug has been turned into an aerosol by means of a high efficiency nebulizer (HEN) and further introduced into the so-called high temperature torch integrated sample introduction system (hTISIS). A transient signal has been thus obtained. For spiked CSF real samples it has been verified that the higher the temperature, the greater the sensitivity. Under optimized conditions, the hTISIS provides peak areas around four times higher than those provided by the spectrometer default device (i.e., a double pass spray chamber). Additional advantages provided by the former system include limits of detection up to 6 times lower and narrower peaks as compared to those reported for the double pass spray chamber. Furthermore, the use of the hTISIS is not detrimental from the point of view oxide production and doubly charged ion generation. Regarding the extent of non-spectral interference caused by the CSF matrix, it has been verified that, with the hTISIS, recoveries for spiked real samples were close to 100% for a set of 14 different elements (V, Cr, Mn, Co, Ni, Cu, As, Se, Mo, Cd, Sb, Ba, Tl and Pb). Meanwhile, in segmented flow injection mode, the reference system provided recoveries from 200 to 500%, depending on the element and the sample, thus demonstrating the occurrence of matrix effects.