Development of analytical methods for the determination of copper and manganese in infant formula using high resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample analysis
Two fast, simple and reliable methods for the determination of Cu and Mn in infant formula composed of different types of raw materials (rice, oats, bovine milk and soybean) were developed using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) and direct solid sample analysis. All measurements were carried out without any chemical modifier and with aqueous standard solutions for calibration. The optimum pyrolysis temperature was 1300 °C for both analytes, and atomization temperatures were 2300 °C and 2100 °C for Cu and Mn, respectively. The characteristic mass was 8.0 pg for both analytes; the limits of detection and quantification were 0.003 μg g−1 and 0.01 μg g−1, respectively, for Cu, based on a sample mass of 3.0 mg, and 0.01 μg g−1 and 0.04 μg g−1, respectively, for Mn, based on a sample mass of 1.0 mg. The concentrations obtained ranged from 1.3 to 6.8 μg g−1 for Cu and 0.7 to 17.2 μg g−1 for Mn. The accuracy of the methods was evaluated using the certified reference material NIST SRM 1568a (rice flour) and the results presented no significant difference between the certified and found concentrations. The methods are sensitive, simple and do not require any sample pretreatment besides milling and homogenization of samples.