The measurement uncertainty was estimated for the determination of calcium and magnesium in milk using microwave plasma torch atomic emission spectrometry (MPT-AES) and the uncertainty parameters were discussed and compared in detail. The results show that the "whole method" performance parameters, such as precision and recovery, and sampling are the three main contributors to uncertainty. In addition, the content of calibration solution is the main contributor to measurement uncertainty in the determination of magnesium. When coverage factor k=2 and confidence level approximately 95%, the expanded uncertainties were determined as 18.6 and 3.2 mg/L for Ca and Mg, respectively.

The method for the determination of copper, zinc, manganese, iron, magnesium, calcium in wild pine tea by microwave plasma torch-atomic emission spectrometry (MPT-AES) was developed. The effect of nitric acid concentration in the sample solution and co-ionized elements on the emission intensity of copper, zinc, manganese, iron, magnesium and calcium was investigated in detail. The experimental conditions were optimized and showed that the detection limits of metal Cu, Zn, Mn, Fe, Mg and Ca are 3.6, 7.7, 6.1, 14.1, 0.5 and 0.9 ng/mL, respectively, and the RSD of the method is between 1.05%～6.46%, the recoveries are 97.25%～103.37%. This demonstrated that the proposed method is simple, accuracy and efficient, providing a well-established analytical method．