Method validation and measurement uncertainty calculations for analysis of mineral element and heavy metals in foods by microwave plasma–atomic emission spectrometry (MP–AES)

Method validation is the objective testing of the suitability of a method or measurement procedure for specified purposes and proving with written evidence. The measurement uncertainty is a parameter that shows the distribution of probabilities that can be attributed to the measurement result reported together with the analysis result. For this purpose, method validation and measurement uncertainty calculations of the Microwave Plasma-Atomic Emission Spectrometer (MP–AES) device in the Laboratory of the Department of Food Engineering, Faculty of Engineering and Natural Sciences of Gümüşhane University, were performed on four different food matrices (cabbage, flour, fish, and juice) selected to represent all foods. The analyzes of 14 metals (Na, K, Ca, Mg, Fe, Al, Cu, Zn, Ni, Co, Cr, Mn, Cd and Pb) were carried out. As validation parameters; LOD, LOQ, repeatability, reproducibility, accuracy and spiked/recovery tests were performed. In the studies, the LOD values for the studied metals ranged from 0.8 to 12.6 µg/L, and the LOQ values ranging from 2.6 to 41.9 µg/L. As a result of the recovery studies applied for 14 metals with additions of 0.050, 0.50 and 2.0 mg/L to the cabbage, flour, fish and fruit juice matrices, it was determined that the recovery rates ranged from 98.49% to 104.19%. The pooled standard deviations of %RSDr(pool) and %HRSDr obtained as a result of reproducibility studies were in the range of 0.54–1.80% and 2.20–3.62% for cabbage matrix, respectively; in the range of 0.35–1.89% and 2.32–3.36% for flour matrix, respectively; for fish matrix 0.22–1.79% and 2.12–3.58%, respectively; Values ranging from 0.49–1.76% and 2.28–2.94%, respectively, were obtained for the juice matrix. The pooled standard deviations of %RSDR(pool) and %HRSDR obtained as a result of reproducibility studies were in the range of 1.05-8.31% and 3.33-4.95% for cabbage matrix, respectively; between 1.15%-4.65% and 3.47-4.91% for flour matrix, respectively; values ranging from 0.52-7.32% and 3.23-5.19% for fish matrix, respectively; For the juice matrix, values ranging from 0.57-9.50% and 3.43-5.23% were obtained, respectively. As the %RSDr(pool) and %RSDR(pool) values are smaller than %HRSDr and %HRSDR values within the framework of these results, the suitability of the results obtained from the study has been determined. In validation studies for metals studied in cabbage, flour, fish and juice matrices, the measurement uncertainty (k=2, expanded uncertainty at 95% confidence interval) was within the range of 0.9–1261 mg/kg for the cabbage matrix; in the range of ±19–988 mg/kg for flour matrix; Values ranging from ±26–1756 mg/kg for fish matrix and ±0.002–0.105 mg/L for fruit juice matrix were obtained. As a result, in this study, method validation studies and measurement uncertainty calculations were made for the metals studied using selected food matrices in the MP–AES device, and the method used was validated and the data obtained from the device were interpreted correctly and reliably.