Comparison of Potassium Content of Fertilizers by Atomic Absorption and Sodium Tetraphenylboron

Abstract

Atomic absorption spectrophotometry is a rapid and simple screening method for determining potassium in fertilizers, especially when a large number of samples are processed. The potassium content of 1190 fertilizer samples was determined by both atomic absorption (4038Å) at a dilution of 1:400 and by the sodium tetraphenylboron method; correlation between the two methods was significant (r = 0.96). Triplicate analyses of 101 samples by each method showed precision of 0.229% by STPB and 0.424% by atomic absorption; standard deviation of the difference between the two procedures was 0.50%. Other elements normally found in fertilizers did not interfere at 4038Å.