Determination of blood lead using a 4-0 mm paper punched disc carbon sampling cup technique.

239-244. The method described is designed to overcome difficulties associated with presentation of the sample and its analysis for lead in blood. Chromium-51 studies on the effect of spread showed that imprecision resulted when discs of less than 4·0 mm diameter were punched from a given blood spot. The best standard deviation and relative standard deviation for increasing lead concentrations was obtained when 4·0 mm discs were used. Small daily voltage variations to the carbon cup workhead required that the non-specific absorption should be controlled to 0·02 absorbance at the ashing step. The occurrence of a second non-atomic signal was not considered significant since it had a different volatilization temperature to lead. Several advantages of the method are stated. A comparison of 4·0 mm against 6·5 mm punched discs was investigated using 33 samples of blood ranging from 9·0 to 126 μg of lead per 100 ml blood. Correlation (r = 0·970) and regression lines are shown. Absolute sensitivity of the method was 25 × 10 g.