GF-AAS Determination of Trace Amounts of Lead and Cadmium in Morinda Officinalis with Direct Suspension Sample Introduction

0.050 0 g of the dried and powdered morinda officinalis sample (passed through 0.074 mm sample sieve) was taken and dispended in 10.0 mL of agar solution (containing 0.1 g of NH₄H₂PO₄ as matrix modifier) with an ultrasonotor for 5 min, to make a suspension of the sample which was introduced into the instrument for GF-AAS determination of lead and cadmium. Ashing temperatures for lead and cadmium were set at 850℃ and 800℃, respectively. As shown by the results, linear relationships between values of absorbance and mass concentration of lead and cadmium were found in definite ranges, with detection limits (3s×V/b) of 2.17×10^-9mg and 3.4×10^-10mg respectively. Test for recovery was made by standard addition method, giving results in the range of 98.8%-103% and 98.3%-104%, respectively. Values of RSDs (n=7) were found 2.7% (for Pb) and 1.2% (for Cd).