title: Ion chromatographic determination of phosphorus soluble in different extracting media in fertilizers.
abstract: A new method based on ion chromatography (IC) was developed for the determination of phosphorus in fertilizers. Fertilizers were extracted with water, mineral acids, and 2% formic acid, 2% citric acid, and neutral ammonium citrate solutions according to European Regulation No. 2003/2003 of the European Parliament and the Council of October 13, 2003, or the Decree of the Italian Agriculture Minister of June 17, 2002; the extracts were analyzed by direct injection, after simple filtration, by IC on an IonPac AS19 (250 x 4 mm id) column, using a KOH (21-50-21 mM) gradient and suppressed conductivity detection. The calibration plot was linear over the range of 5-50 mg/L (r(2) of >0.999). The method was evaluated by comparison with a gravimetric method according to established norms. Associated uncertainty at the 95% confidence level was established as 0.47% for the determination of 3-46% P2O5 by IC. A good chromatographic separation of phosphorus forms such as phosphates and phosphites, and some other important anions like nitrates, chlorides, and sulfates present in many commercial fertilizers was also possible, with a linear response over the range of 5-50 mg/L. After a more complete validation, this IC determination of phosphorus could replace more tedious methods such as those using gravimetric determinations.
authors.affiliation: Ministry of Agricultural Alimentary and Forestry Policies, Central Inspectorate for Fraud Repression (ICRF) Laboratory, Viale Venezia, Conegliano (TV), Italy. ra.mazzei@politicheagricole.it
authors.forename: Raffaele Antonio
authors.initials: RA
authors.lastname: Mazzei
authors.forename: Stefano
authors.initials: S
authors.lastname: Scuppa
mesh_terms: D002852:Chromatography, Ion Exchange / Q000379:methods* / Q000706:statistics & numerical data; D005308:Fertilizers / Q000032:analysis*; D010710:Phosphates / Q000032:analysis; D017905:Phosphites / Q000032:analysis; D010758:Phosphorus / Q000032:analysis* / Q000302:isolation & purification; D015203:Reproducibility of Results; D012995:Solubility
chemical_list: D005308:Fertilizers; D010710:Phosphates; D017905:Phosphites; D010758:Phosphorus