title: Comparison of four methods for forage nitrate analysis.
abstract: Twenty forage samples were collected and selected for variation in nitrate content. Each forage samples was analyzed 4 times by 4 different methods: diphenylamine spot plate, spectrophotometric, nitrate-selective electrode, and high-performance liquid chromatographic. Five feed extracts were spiked with 2 different amounts of nitrate and analyzed by each method. The spectrophotometric and nitrate-selective electrode had similar percent recoveries, which were close to 100%. The nitrate-selective electrode method had the least variation of the 4 methods. The diphenylamine spot plate method had the poorest average recovery, greatest variation, and was the least accurate. The average coefficients of variation for all samples within a method were 15%, 12%, 6.4%, and 16 for the diphenylamine spot plate, spectrophotometric, nitrate-selective electrode, and high-performance liquid chromatographic methods, respectively. The variation in the nitrate-selective electrode method was lower (P < 0.05) than the other methods. The results from this study suggest that the nitrate-selective electrode method is more accurate and precise than the other methods of analysis tested.
authors.affiliation: Diagnostic Laboratory, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins 80523, USA.
authors.forename: C L
authors.initials: CL
authors.lastname: Bedwell
authors.forename: D W
authors.initials: DW
authors.lastname: Hamar
authors.forename: M L
authors.initials: ML
authors.lastname: Hoesterey
authors.forename: J P
authors.initials: JP
authors.lastname: Sonderman
authors.forename: K G
authors.initials: KG
authors.lastname: Odde
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003124:Colorimetry / Q000379:methods; D004159:Diphenylamine; D004563:Electrochemistry / Q000379:methods; D009566:Nitrates / Q000032:analysis*; D006109:Poaceae; D013053:Spectrophotometry / Q000379:methods
chemical_list: D009566:Nitrates; D004159:Diphenylamine