Rapid analysis of water samples by graphite furnace atomic absorption spectrometry using hot injection

Abstract

Injection of water samples on to a graphite tube pre-heated to 120 °C allowed instantaneous drying. This, coupled with omission of the ashing stage, enabled heating programmes of 10-s duration to be developed for the determination of aluminium, copper and lead by graphite furnace atomic absorption spectrometry. Copper was determined directly on a pyrolytic graphite coated tube with a precision equal to that obtained with a conventional programme. Recoveries of 105 ± 7%(n= 11) were achieved. The recovery for lead obtained with an uncoated tube and a lanthanum-nitric acid modifier was 97 ± 8%(n= 6) and results obtained for water samples agreed well with those achieved in another laboratory. A hot-injection programme for aluminium gave low recoveries and poor precision with both uncoated and pyrolytic graphite coated tubes, however, the addition of palladium modifier improved the precision and recovery to 98 ± 4%(n= 5). An inter-laboratory comparison of results for aluminium in 20 samples gave a correlation coefficient of 0.966. It is concluded that these short programmes giving cycle times in the 40–47-s range (including automatic injection time) allow satisfactory routine analysis and justify the use of hot injection for fast analysis.