Strontium Isotopic Fingerprinting of Atmospheric Particulate Matter by Quadrupole Inductively Coupled Plasma Mass Spectrometry

The strontium (Sr) isotopic composition of the atmospheric particulate samples was measured using singlequadrupole inductively coupled plasma mass spectrometry. After the multivariate optimization of the main operating conditions (sample uptake rate, spray chamber temperature, and quadrupole voltages), the 87Sr/86Sr isotopic ratio was measured with an internal precision of similar to 0.1% (%RSD, n=12) at the Sr concentration of 2-10 mu g L-1 and similar to 0.2% at 0.5-2 mu g L-1. The isobaric interferences were mathematically fixed, whereas the instrumental mass bias was efficiently corrected by a combination of internal corrections based on the measurement of the 88Sr/86Sr ratio and bracketing external calibration. Finally, an optimized Sr isolation procedure produced a low procedural blank (0.05 +/- 0.01 mu g L-1) and good recovery (78 +/- 7%) at a low Sr concentration (0.5-2 mu g L-1). The applicability of the developed method was demonstrated by the analysis of a time series of PM10 samples collected from the Antarctic Plateau, which are characterized by a low Sr concentration and limited sample mass. The results were in excellent agreement with those published in the literature.