Determination of Phosphorus and Potassium in Commercial Inorganic Fertilizers by Inductively Coupled Plasma-Optical Emission Spectrometry: Single-Laboratory Validation, First Action 2015.18

J AOAC Int. 2016 Jul;99(4):914-922. doi: 10.5740/jaoacint.16-0050.

Abstract

A previously validated method for the determination of both citrate-EDTA-soluble P and K and acid-soluble P and K in commercial inorganic fertilizers by inductively coupled plasma-optical emission spectrometry was submitted to the expert review panel (ERP) for fertilizers for consideration of First Action Official Method(SM) status. The ERP evaluated the single-laboratory validation results and recommended the method for First Action Official Method status and provided recommendations for achieving Final Action. Validation materials ranging from 4.4 to 52.4% P2O5 (1.7-22.7% P) and 3-62% K2O (2.5-51.1% K) were used for the validation. Recoveries from validation materials for citrate-soluble P and K ranged from 99.3 to 124.9% P and from 98.4 to 100.7% K. Recoveries from validation materials for acid-soluble "total" P and K ranged from 95.53 to 99.40% P and from 98.36 to 107.28% K. Values of r for citrate-soluble P and K, expressed as RSD, ranged from 0.28 to 1.30% for P and from 0.41 to 1.52% for K. Values of r for total P and K, expressed as RSD, ranged from 0.71 to 1.13% for P and from 0.39 to 1.18% for K. Based on the validation data, the ERP recommended the method (with alternatives for the citrate-soluble and the acid-soluble extractions) for First Action Official Method status and provided recommendations for achieving Final Action status.

MeSH terms

  • Calibration
  • Citric Acid / chemistry
  • Edetic Acid / chemistry
  • Fertilizers / analysis*
  • Oxides / analysis
  • Phosphorus / analysis*
  • Phosphorus Compounds / analysis
  • Potassium / analysis*
  • Potassium Compounds / analysis
  • Quaternary Ammonium Compounds / chemistry
  • Spectrophotometry, Atomic / standards
  • Validation Studies as Topic

Substances

  • Fertilizers
  • Oxides
  • Phosphorus Compounds
  • Potassium Compounds
  • Quaternary Ammonium Compounds
  • Phosphorus
  • Citric Acid
  • phosphorus pentoxide
  • potassium oxide
  • ammonium citrate
  • Edetic Acid
  • Potassium