Determination of lead residue levels in raw milk from different regions of Mashhad (north‐east of Iran) by AAS method

The aim of this study was to test the presence of lead in raw milk from different regions of Mashhad (north‐east of Iran) through atomic absorption spectrometry (AAS).

A total of 60 samples of raw cow's milk were collected from the bulk holding tanks of 20 dairy farms of Mashhad and analysed immediately.

The mean level of lead content was 4.07 ng/ml, with a range from 0.02 to 44 ng/ml and a standard deviation of 7.54 ng/ml. The Pb concentration of one sample exceeded 20 ng/ml (maximum concentration accepted by Codex). Lead residue in 70 per cent of the samples was below 5 ng/ml and the Pb concentration in 10, 9.18 and 9.18 per cent of the samples was, respectively, in the range of 5‐10, 10‐15 and 15‐20 ng/ml. The results obtained for limit of detection (LOD) and limit of quantification (LOQ) in μgkg⁻¹ were, respectively, 0.65 and 2.1 while for the recovery 94.47 per cent.

The results reduce the public concern about lead contamination in milk in this region.

No research had been done to detect lead residue in raw milk in this region. Milk is not a major source for lead poisoning in Mashhad.