Abstract
A spectrophotometric determination of pyridine using nonpoisonous potassium thiocyanate instead of toxic potassium cyanide has been deviced. The recommended procedure was as follows.
To 1.0 ml of potassium thiocyanate solution (SCN 70 ppm), 2.0 ml of chloramine T solution (0.08 w/v% in 0.043 M phosphate buffer, pH 6.4) was added. The mixture was kept for 15 minutes in a water bath at 50°C. To this solution each one ml of the neutral sample solution containing pyridine and the 1-phenyl-3-methyl-5-pyrazolone solution (0.1 w/v% in 4 v/v% ethylen glycol monomethyl ether) was added, and the resultant solution was allowed to stand for 45 minutes at 50°C. After cooling in water, the absorbance was measured at 610 nm against a reagent blank. The calibration curve followed the Beer's law in the range of 07 ppm of pyridine in sample solutions. The coefficient of variation is about 0.7% at 6 ppm pyridine. The influence with diverse compounds on the determination were examined.
