Influence of Pretreatment Process on Accuracy of Determination of Multiple Elements in Milk Powder by Inductively Coupled Plasma-Mass Spectrometry

Sample pretreatment is a key step in element testing, which directly affects the precision and accuracy of analytical results. In order to meet the requirements for the detection of various elements, in this study, we used microwave digestion combined with inductively coupled plasma-mass spectrometry (ICP-MS) operated in the collision reaction mode to determine the content of multiple elements in milk powder, and investigated the influence of sample pretreatment conditions (acid removal time, sample size, and the amount of residual acid) on the detection results. Compared to removing acid mist only, better results were obtained under the following conditions: acid removal temperature was 160 ℃, acid removal time was 97.5 min, and sample size was 0.2500 g, and the amount of residual acid was 1.0 mL. This pretreatment process is characterized by good stability, high precision and high accuracy.