title: Determination of Phosphorus and Potassium in Commercial Inorganic Fertilizers by Inductively Coupled Plasma-Optical Emission Spectrometry: Single-Laboratory Validation, First Action 2015.18.
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.
authors.affiliation: Thiex Laboratory Solutions, 46747 214th St, Brookings, SD 57006.
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Thiex
mesh_terms: D002138:Calibration; D019343:Citric Acid / Q000737:chemistry; D004492:Edetic Acid / Q000737:chemistry; D005308:Fertilizers / Q000032:analysis*; D010087:Oxides / Q000032:analysis; D010758:Phosphorus / Q000032:analysis*; D017553:Phosphorus Compounds / Q000032:analysis; D011188:Potassium / Q000032:analysis*; D017680:Potassium Compounds / Q000032:analysis; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D013054:Spectrophotometry, Atomic / Q000592:standards; D054928:Validation Studies as Topic
chemical_list: D005308:Fertilizers; D010087:Oxides; D017553:Phosphorus Compounds; D017680:Potassium Compounds; D000644:Quaternary Ammonium Compounds; D010758:Phosphorus; D019343:Citric Acid; C012500:phosphorus pentoxide; C068440:potassium oxide; C481046:ammonium citrate; D004492:Edetic Acid; D011188:Potassium