Method Development/ Validation and Uncertainty Measurement for Determination of Zinc (Zn) Using Atomic Absorption Spectrophotometry Technique

Samples of fertilizer are analyzed to determine their nutrient content; however, the findings vary depending on the method used. The major goal of the study was to design as well as to test a method for determination of Zinc through Atomic Absorption Spectrophotometer. The Soil & Water Testing Laboratories, Dera Ghazi Khan, validated the use of the Atomic Absorption Spectrophotometer Technique to measure the Zinc concentration in fertilizer samples. Repeatability, reproducibility, detection limit, quantification limit, linearity, recovery, selectivity and bias were all tested as part of the technique of validation process. The results revealed that the repeatability, (Relative standard deviation of 1.01), reproducibility (T-value 0.05 is less that tabulated-T value 2.0262, LOD 0.98 % Zinc in the sample, LOQ 0.9 % Zinc in the sample), recovery 98.9%, Linear curve for the Zinc Conc. was attained from 0.5 mg Kg-1 to 2.0 mg Kg-1 (Zn) showing Linearity R2 = 0.999 %. The laboratory participated in Proficiency testing program of USA (Magruder Fertilizer Sample Check Program) Test results of the Zn samples analyzed by this method of Zinc have Z-score values of -0.93 and 1.65 during 2021 and 2022 which fall in acceptable range (i.e., -2 to +2). The uncertainty of the method was 0.0011%. Hence the Soil and water testing Laboratory, Dera Ghazi Khan is capable of performing Zinc analysis by the suggested method as per standard. Based on this relationship, we may conclude that the strategy worked quite well. As a result, the approach can be used to determine Zinc levels in fertilizer samples.