[Polarographic determination of titanium in natural water].
Titanium has a very sensitive catalytic polarographic wave in the system of cupferon-hexamine-sodium sulfate at pH 6.0-6.4. The catalytic current was proportional to the content of titanium. High blank of the reagents could be improved by extraction with the system of cupferron-chloroform. For determination, samples were filtered with quantitative filter paper, but it was not necessary for drinking water samples. The filtration was acidified with HCl to 0.5% (V/V) and heated in a boiling water bath for 30 min, 5 ml sample was sufficed to most analyses. The detection limit was 0.12 microgram/L. The coefficient of variation was 8% for 6 determinations at 0.2 microgram/L. Three levels of titanium were spiked to one sample, and it was found that the recoveries were 96-101%. The proposed method was applied to rain water, well-head water, well water, tap water and river water. The content of titanium of most samples was less than 2 micrograms/L.