An improved analytical method for the quantification of iron, copper and manganese in non-centrifugal sugars (NCS)

Abstract

Many of the food commodities have dedicated sample preparation, analysis and standard reference methods to determine the multi-element composition using different spectrometry techniques. The composition of elements in non-centrifugal sugars (NCS), like Ca, Fe, Mg, K, and Zn have been reported in the literature by several investigators, however, the analytical protocol is not standardised. NCS serves as a good source of Fe, Cu and Mn sharing considerable percentages of the recommended daily allowance (RDA). The mineral content in NCS varies significantly depending on the feedstock and production process employed. In the present work, we have developed an integrated sample preparation and analytical method for Cu, Fe and Mn in NCS. Response surface methodology (RSM) was employed for the optimization of microwave-assisted digestion. Central composite design (CCD) helped to elucidate the optimum conditions and interactive effects of independent variables like acid volume (12 ml, HNO3), hold time (17.5 min), microwave power (750 W) and sample weight (0.55 g) in the digestion process. Furthermore, the inductively coupled plasma optical emission spectrometry (ICP-OES) method was developed for the quantification of the said trace elements. Analytical curves were drawn for the respective elements and the limits of detection (LOD (mg/kg); 0.006 (Cu), 0.005 (Fe) and 0.005 (Mn)) and limits of quantification (LOQ (mg/kg); 0.020 (Cu), 0.023 (Fe) and Mn (0.016)) were determined. Moreover, the repeatability and reproducibility of the method were examined. The precision and accuracy of the method were found to be well within the recommended limits as per the literature. The proposed method would help to determine the nutritional value of a given NCS sample in a reliable manner.