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A rapid determination of Ammonia in urine has been achieved. Gaseous ammonia is evolved by alkylifying urine with a saturated solution of K2CO3 at 80°C followed by separation of the gas phase and measurement of characteristic absorption at 197.2 nm. The linear range of the method is between 0 and 200 μg NH3/ml. The recovery of ammonia from spiked urine samples is 106.5%. Typical results obtained on five samples from healthy subjects are presented and good agreement with a reference method is shown. Automation has been achieved by the use of a mechanical sampler, a heating bath and a peristaltic pump.

The technique of gas-phase atomisation of the volatile hydrides in a heated silica tube and measurement of the resulting atomic-absorption signal has been extended to the determination of lead in air, water and vegetation. The sample solutions, containing 0.7%V/V of nitric acid or 1.0%V/V of perchloric acid, are made to react with 12%V/V hydrogen peroxide solution followed by 4%m/V sodium borohydride solution by means of a peristaltic proportioning pump. The gaseous hydrides generated are swept by a stream of nitrogen into a heated silica tube and the absorbance of lead at 217 nm is recorded. The effects of interferences and their elimination are discussed. Results obtained on a few typical samples by the proposed method and an alternative method are presented.A sensitivity of 0.6 ng ml–1 and a detection limit of 0.1 ng ml–1 have been achieved. The relative standard deviation of the method is 2.5% at a lead concentration of 10 ng ml–1. Up to 50 samples can be analysed in 1 d.