Determination of potassium and calcium in vegetables by x-ray fluorescence spectrometry

A method based on XRF was used for the determination of the total concentration of potassium and calcium, in the presence of each other and irrespective of the nature of their chemical compounds, in the roots and leaves of spinach and radish plants. The enhancement of potassium K x‐rays due to K x‐rays of calcium present in the samples was avoided by selective excitation of the sample with external conversion calcium K x‐rays in a compact triaxial double reflection geometry set‐up. The absorption of calcium and potassium K x‐rays in the samples was taken care of in terms of counts under K x‐ray peaks only. The overlapping of the calcium K x‐ray photopeak with the potassium K x‐ray photopeak due to the limited resolution of the Si(Li) spectrometer was estimated and counts under the calcium K x‐ray photopeak were corrected accordingly. The results for whole plants of spinach and radish agreed with those normally quoted in nutrition books.