[Determination of guanidinoacetic acid in feed by ion chromatography coupled with ultraviolet detection]

A novel ion chromatography method for the determination of guanidinoacetic acid (GAA) in animal feed samples was developed. The optimal detection mode, chromatography column, gradient condition of mobile phases and sample pretreatment conditions were investigated. Using a linear gradient of methane sulfonic acid and ultraviolet detector at 200 nm, the interfering substances in feed samples and GAA could be separated successfully on a Dionex IonPac^TM CS16 cation exchange analysis column. The calibration curves showed a range of linearity between 0.5 and 200 mg/L, and a high linear regression coefficient of 0.9999 was obtained for GAA. The limits of detection and limits of quantification of GAA in formula feed and concentrate feed were 4.5 and 15 mg/kg, respectively. The limit of detection and limit of quantification of GAA in compound-premix were 9.0 and 30 mg/kg, respectively. The recoveries of this method for GAA were investigated, and the recoveries were all more than 94% in formula feed, concentrate feed and compound-premix feed for pig and poultry. This method can meet the requirements of the determination of GAA in feed samples for the feed production enterprise and evaluation center.