Abstract:

At present, the standard for determining potassium content in water-soluble fertilizers containing humic acid is the NY/T 1977-2010 potassium tetraphenylborate gravimetric method. This method is operated manually, the steps are relatively cumbersome, and the detection efficiency is low. Solid samples were ultrasonically treated for 6-8 min in motified method, while samples were boiled and heated for 30 min in the original method. Precipitation filtration method was compared with the flame spectrophotometer method and the inductively coupled plasma spectrometer method. It was concluded that the results of the flame photometer method were consistent with those of the precipitation method when the potassium oxide content was ≤9.5%, and the results were higher when the potassium oxide content was >9.5%. The advantage of the new method was that it could be performed in batches, with high accuracy, which greatly improved the detection efficiency. The results of inductively coupled plasma (ICP) method were significantly different from those of precipitation method and flame spectrophotometer, which were positive deviations, so it was not appropriate to measure the potassium content of humic acid water-soluble fertilizers by ICP method.

Key words: humic acid, water-soluble fertilizer, potassium content, ICP spectrometer, flame photometer