Determination of cadmium in paper for food contact by inductively coupled plasma mass spectrometry

Abstract

This work proposed the method validation for cadmium (Cd) determination in paper for food contact material (FCM). The paper based FCMs was digested using microwave digestion in acidic condition. After that, Cd was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). It is necessary that the laboratory has to validate testing method to evaluate whether the validated method is fit for intended use. The performance characteristics were studied including instrument working range, limit of detection (LOD), limit of quantitation (LOQ), bias, intermediate precision, matrix effect and measurement uncertainty. Under the studied condition, the linearity in the range of 0.040 – 0.40 mg/kg with the correlation coefficient (r) of 0.9999 was obtained. The LOD and LOQ were 0.0024 mg/kg and 0.040 mg/kg, respectively. The bias and precision studies showed that percentage of recovery and relative standard deviation (RSD) of Cd were between 86.5 – 92.1% and less than 10%, respectively. Moreover, the expanded uncertainty of the proposed method was less than ±20% at the confidence level of 95%. Thus, it can be concluded that this test method for Cd determination in paper based FCM was valid and fit for the intended use.