Measurement of 33P in faeces by suspension counting of faecal ash

The estimation of 33P in faecal samples by direct suspension counting of finely ground faecal ash particles is shown to be a convenient technique having good accuracy and reproducibility. The sensitivity of the method is such that 75 pCi 33P can be measured with a standard error of 2% in a counting period of 1 h. Using 50 mg of ash for counting, this activity requires a 33P concentration of about 40 pCi/g of faecal homogenate.