Latifatun Ni’mahv, Catur Rini Widyastuti, Rahimsyah ljas Nur Rasyid

Development and Verification of Potassium Determination Method in Solid NPK Fertilizer by Atomic Absorption Spectrophotometry

Introduction

Development and verification of potassium determination method in solid npk fertilizer by atomic absorption spectrophotometry. Develops & validates an accurate, precise, and efficient P₂O₅ digestion method for potassium determination in NPK fertilizer using AAS. Ideal for large samples.

Abstract

The measurement of potassium levels in solid NPK fertilizer using the K₂O digestion method still requires repeatability to ensure the validity of the measurement results. This study aims to develop and validate a method for determining potassium levels using the P₂O₅ digestion method in accordance with SNI 2803:2012, employing a pragmatic approach based on SNI 7763:2018. Potassium analysis was performed using an Atomic Absorption Spectrophotometer (AAS) with several validation parameters. The potassium levels measured using both the K₂O and P₂O₅ digestion methods were 14%. The method demonstrated linearity, with a correlation coefficient (r²) of 0.9986. The precision values for the K₂O and P₂O₅ digestion methods, based on Relative Standard Deviation (%RSD) < 2/3 CV Horwitz, were 1.6% < 1.8% and 1.1% < 1.8%, respectively, while t-calculated (0.646) < t-tabulated (2.179). Accuracy, as indicated by the percentage recovery for the K₂O and P₂O₅ digestion methods, was 108% and 101%, respectively. The P₂O₅ digestion method is categorized as an accurate, precise, and efficient technique for determining potassium levels in solid NPK fertilizer samples, particularly in large quantities

Review

This manuscript addresses a significant analytical challenge within agricultural chemistry: the accurate and reliable determination of potassium levels in solid NPK fertilizers. The authors correctly identify the existing K₂O digestion method as having issues with repeatability, necessitating the development of a more robust alternative. By proposing and validating a P₂O₅ digestion method in conjunction with Atomic Absorption Spectrophotometry (AAS), and adhering to national standards (SNI 2803:2012 and SNI 7763:2018), the study aims to provide a much-needed improvement for quality control and assurance in the fertilizer industry. The methodology employed a comprehensive validation strategy, directly comparing the proposed P₂O₅ digestion method against the traditional K₂O digestion. The analytical performance of the new method was rigorously evaluated across several key parameters. Both methods yielded consistent potassium levels (14%), and the P₂O₅ method demonstrated excellent linearity (r² = 0.9986). Precision was robust for both, with %RSD values well below the Horwitz criterion (1.1% for P₂O₅ vs. 1.6% for K₂O), and statistical analysis (t-calculated < t-tabulated) further confirmed method reliability. Crucially, the P₂O₅ method showed superior accuracy with a recovery of 101%, significantly closer to the ideal 100% compared to the 108% recovery for the K₂O method. In conclusion, this study successfully develops and validates an improved method for potassium determination in solid NPK fertilizers. The P₂O₅ digestion method, coupled with AAS, is clearly demonstrated to be accurate, precise, and efficient, especially beneficial for laboratories processing large sample quantities. The adherence to recognized national standards enhances its practical applicability and credibility within the industry. This work provides a valuable, validated protocol that directly addresses existing analytical limitations, offering a reliable tool for ensuring the quality and accurate labeling of NPK products. The findings are well-supported by the presented data and represent a significant contribution to the field.

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