RESEARCH TO DETERMINE OF THE CONTENT OF SOME HEAVY METALS IN OCIMUM TENUIFLORUM IN THE NORTH CENTRAL REGION BY ATOMIC ABSORPTION SPECTROSCOPY (AAS)

Abstract

The content of some heavy metals such as cadmium, copper, iron, manganese, nickel, lead, and zinc (Cd,
Cu, Fe, Mn, Ni, Pb, Zn) in Ocimum Tenuiflorum grown in the two provinces of Nghe An and Ha Tinh in the
North Central region of Vietnam has been determined using atomic absorption spectroscopy with flame
atomization (F-AAS) after sample digestion in microwave oven. The analysis results were compared with the
agricultural crop guidelines of FAO/WHO, showing that the heavy metal content was within the limits. The
analysis results were also compared with some other studies on Ocimum Tenuiflorum finding that the
content of Cu, Fe, Mn, Zn was higher, while the content of Cd, Ni, Pb was lower. According to WHO
standards on medicinal herbal ingredients, the content of Cd, Cu, Mn, Pb below the permissible limits in all
samples; the content of Fe in HN1, HN3, HN5 samples exceeded the recommended value; the content of Zn
in the HN4 sample exceeded the permissible limits. The concentration range of heavy metals varies, with the
levels of toxic metals such as Cd, Pb, and Ni all below the detection limit for all samples. For other heavy
metals, the content of Fe and Mn in sample HN1 (191.606; 96.429 mg/kg); the content of Cu and Zn in
sample HN4 (16.597; 133.561 mg/kg) is the highest. The analysis method used has a low detection limit,
achieving thresholds lower than 59 ppb for Cd, Fe, Mn, Ni, Pb, Zn and 0.1 ppm for Cu. The relative
standard deviation (% RSD) of 10 repeat measurements of low-concentration heavy metal content is all less
than 3.530%; and the recovery of elements are in the range from 87.652 to 109.812%, which meets AOAC
requirements for trace.