| Summary |
A simple, pure method was described for graphite furnace atomic absorption spectrophotmetry used for Cd and Pb determination in milk serum prepared from spon-taneous souring. Samples of raw milk were collected from the bulk holding tanks of 107 dairy farms in six counties in Taiwan. Raw milk samples were placed at room temperature ( 28 °C ) for 48 h, allowing the pH to lower below 4.6 and the casein and fat to precipitate. Milk serum was filtered and then directly injected into a graphite tube. The standard add-ition method was employed, and 0.1 % phosphoric acid was used as a matrix modifier. During ashing, 15 s of oxygen influx was supplemented to prevent charcoal accumulation on graphite tube. The average recoveries of Cd and Pb from three added concentrations were 93.7 % ± 6.9 % and 94.5 ± 10.1 %, respectively. The Cd and Pb concentrations in milk powder ( Number A-11 ) from International Atomic Energy Agency as analyzed using this method were close to the certified values. The average Cd and Pb contents obtained from 107 samples were .044 ng/ml, ranging from .021 to .173, and 2.03 ng/ml, ranging from .98 to 4.45, respectively, without statistical difference among the six counties.
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