Comparison of four methods for forage nitrate analysis.
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.
Bedwell
C L
CL
Diagnostic Laboratory, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Ft. Collins 80523, USA.
Hamar
D W
DW
Hoesterey
M L
ML
Sonderman
J P
JP
Odde
K G
KG
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
D009566:Nitrates; D004159:Diphenylamine