Abstract: Objective To establish an inductively coupled plasma mass spectrometry（ICP-MS） method for the determination of 10 elemental impurities,including lead（Pb）,arsenic（As）,mercury（Hg）,cadmium（Cd）,cobalt（Co）,vanadium（V）,nickel（Ni）,lithium（Li）,antimony（Sb）,and copper（Cu）,in magnesium chloride pharmaceutical excipient（for injection）. Methods With rhodium（Rh）,bismuth（Bi）,and scandium（Sc） as internal standards,the matrix effect and signal drift were corrected by adding internal standards elements on-line,the contents of 10 elemental impurities were determined by standard curve method using the kinetic energy discrimination（KED） collision model combined with the standard model. Results The response values of each tested element showed a good linear relationship with their mass concentration（r≥0.999 2）. The average recovery rates of high,medium,and low levels were 72.7%-108.9%,with relative standard deviation（RSD）（n=9）<20.0%,and the RSD of the repeatability and intermediate precision test were <20.0%（n=6） and <25.0%（n=12）. The detected concentration and quantitative concentration were both much lower than 30% of the limit specified in Guideline for elemental impurities Q3D announced by international conference on harmonization（ICH）. The test results of 10 batches of samples from 3 manufacturers did not exceed the limit value,except that Li element has certain risk and should be controlled,other elements have low safety risk. Conclusion The established method has been validated to have high specificity,high sensitivity,system applicability that meets requirements,good accuracy and precision,and can be used to determine 10 kinds of elemental impurities in magnesium chloride.

Key words: Pharmaceutical excipient, Magnesium chloride, Inductively coupled plasma mass spectrometry, Elemental impurities