Screening Analysis of Trace Heavy Elements in Powdered Milk by EDXRF

Introduction

One of the methods used for testing for heavy metals in foods is the color reaction method, but since this method does not provide for attribution of metals (elements) or is influenced by sample components, elemental analysis such as AA (atomic absorption spectrophotometry) is used. But due to the laborious sample preparations, such as component extraction and acid decomposition, etc., that are required, in addition to subjective variation in colorimetric determination, these methods have become a problem in the manufacturing process and in quality control. Therefore, we investigated the use of the EDX method, which enables convenient analysis from sample pretreatment to measurement and finally to determination in the examination of powdered milk. Generally, quantitation by EDX is difficult at concentrations below 1 ppm, as the lower limits of quantitation indicate in Table 1. However, in the case of powdered milk, since this standard value is multiplied by about 7.7 times by using the powdered state prior to dissolution in hot water, use of the EDX, which permits quantitation of powder as is makes it possible to conduct screening assays to determine whether the quantitative value is less or greater than the reference value.

July 9, 2015 GMT