Method development and determination of potassium and phosphorus in oil palm organic fertilizers by microwave plasma atomic emission spectrometry (MP-AES)

In this study, the suitability of the external and standard addition methods was evaluated by the determination of phosphorus (P) and potassium (K) in oil palm organic fertilizers produced in Kelang Valley, Malaysia. A Comparison of the calibration methods for the P and K analyses was conducted by microwave plasma atomic emission spectrometry. In the external method, deviation from linearity was significantly observed for the element effect, acid effect and fertilizer matrix effect on the P and K analyses. A stronger deviation was encountered for P compared to K for the parameters studied. On the other hand, the determination of both the concentrations of P and K was successfully carried out using the standard addition method. The matrix effect caused by the presence of polyatomic ions and other elements was found to be almost negligible.