Location: Wheat, Sorghum and Forage ResearchTitle: Comparison of the Use of Gas Chromotography, Spectrophotometry, and Near Infrared Spectropscopy to Quantify Prussic Acid Potential in Forages) Author
Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2010
Publication Date: 3/29/2011
Citation: Goff, B., Moore, K., Fales, S., Nikolau, B., Pedersen, J.F. 2011. Comparison of the Use of Gas Chromotography, Spectrophotometry, and Near Infrared Spectropscopy to Quantify Prussic Acid Potential in Forages. Journal of Agriculture and Food Chemistry. 1523-1526. Interpretive Summary: Forage sorghum is a highly productive forage crop, but has the potential to be poisonous to livestock consuming it due to it containing a compound called dhurrin. When chewed by livestock, enzymes found in other plant tissues are released which break down dhurrin causing release of hydrogen cyanide. In some circumstances, for example feeding immature forage sorghum, this causes a disorder known as prussic acid poisoning in livestock which can result in their death. It is therefore important that rapid and accurate testing procedures for hydrocyanic acid be available to producers. The current standard method for estimating hydrogen cyanide (HCN) uses spectrophotometery. In this study an alternative method using gas chromatography was shown to provide more accurate estimates of HCN potential than the spectrophotometer method. Near-Infrared Spectroscopy (NIRS) equations which provide rapid and inexpensive estimates of HCN were developed for the GC and spectrometer methods. Both yielded acceptable Near-Infrared Spectroscopy equations, however, using GC as the calibration method resulted in more accurate and repeatable estimates.
Technical Abstract: Sorghum [Sorghum bicolor (L.) Moench] has been shown to contain the cyanogenic glycoside dhurrin, which is responsible for the disorder known as prussic acid poisoning in livestock. The current standard method for estimating HCN uses spectrophotometery to measure the aglycone of the dhurrin, p-hydroxybenzaldehyde (p-HB). Errors may occur due to the inability of this method to solely estimate the absorbance of p-HB at a given wavelength. The objective of this study was to compare the use of a gas chromatography (GC) and Near-Infrared Spectroscopy (NIRS) methods to estimate the potential for prussic acid (HCNp) of sorghum and sudangrasses over three stages maturities. It was shown that the GC method yielded more accurate estimates of HCNp than the spectrophotometer method. Both methods yielded robust equations with the NIRS method, however, using GC as the calibration method resulted in more accurate and repeatable estimates.