Laser ablation inductively coupled plasma mass spectrometry for multi-elemental determination in dried blood spots†
An approach by laser ablation (LA) coupled with inductively coupled mass spectrometry (ICP-MS) for multi-element determination in whole blood is described. The method allows quantitative determination of several major (K, Na and S), minor (Ca, Cu, Fe, Mg, P, Rb and Zn), and trace elements (Al, As, Ba, I, Li, Pb, Sb, V and Tl) in dried blood spot (DBS) samples. Optimum conditions and validation were assessed using Seronorm™ level II and Seronorm™ level III certified reference materials. Laser ablation of DBS samples was performed using a focused Nd:YAG laser beam in linear scan mode (wavelength 213 nm, laser fluency 3.0 J cm−2, repetition rate 20 Hz, laser spot diameter 90 μm, depth 0 μm, and scan speed 8 μm s−1). Different quantification strategies for the LA-ICP-MS data using matrix-matched calibration or a prearranged external calibration/addition set were applied. 13C and 32S were used for signal intensity normalization. Using a matrix-matched calibration curve and 13C or 32S as internal standards for normalization, the limits of quantification were found to be from 1.9 μg L−1 to 1094 mg L−1. Accuracy (analysis of Seronorm™ level II) was satisfactory after statistical evaluation by applying a t-test at the 95% confidence level. The repeatability and reproducibility of the methods were generally below 14%. The method was applied to several DBS samples from newborns.