Determination of 20 Impurity Elements in MOS Grade Pyridine Reagent by Inductively Coupled Plasma Mass Spectrometry with Direct Sampling

In view of the complicated digestion pretreatment would contaminate the ultra-pure reagent, and direct injection method could not only control the source of contamination, but also avoid the loss of volatile elements, the method mentioned by this article was proposed. The multi-element mixed standard solutions with 6 concentration levels were added into the MOS grade pyridine reagent to be tested, and the inductively coupled plasma mass spectrometry was used for determination. The addition amounts of 20 impurity elements (lithium, beryllium, boron, potassium, calcium, vanadium, chromium, iron, cobalt, nickel, gallium, germanium, arsenic, molybdenum, cadmium, indium, antimony, barium, lead and bismuth) were used as the horizontal coordinates, and the response value ratios of the corresponding element to the internal standard were used as the ordinates to draw the working curves. The interference of organic matter was eliminated by optimizing the flow rate of oxygen, flow rate of atomized gas and sampling depth, and the interference of mass spectrum was eliminated by collision mode (for lithium, beryllium, boron, calcium, vanadium, cobalt, nickel, gallium, germanium, arsenic, molybdenum, cadmium, indium, antimony, barium, lead and bismuth) or reaction mode (for potassium, chromium and iron), and the matrix effect was corrected with standard addition method and internal standard method for quantitative analysis. It was shown that the optimized flow rate of oxygen was 30 mL·min^-1, flow rate of atomized gas was 0.55 L·min^-1, and sampling depth was 4.5 mm. In the reaction mode, when the flow rate of hydrogen was 1.40 mL·min^-1, the values of background equivalent concentration of potassium, chromium and iron were low. The detection limits of 20 impurity elements were in the range of 0.001-0.383 μg·L^-1. The spiked sample was determined 7 times, and RSDs of the determined values were less than 6.0%, with recoveries ranged from 91.0% to 127%.