Abstract:

A method was developed for the determination of N-carbamyl-L-glutamic acid (NCG) in feedstuff by high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The feedstuff samples were extracted with methanol, cleaned-up by a ProElut mixed-mode of strong anion exchange inverse column (PXA). Then the samples were separated with HPLC and detected with MS/MS in multiple reaction monitoring (MRM) mode via positive electrospray ionization (ESI⁺). The fragment ions of m/z 148.0 and m/z 84.0 were used for qualitative analysis, and m/z 130.0 was selected for quantitative analysis. The limit of detection for NCG was 24 μg/kg (S/N >3), and the limit of quantification was 80 μg/kg (S/N >10). The standard calibration curve was linear over the range of 20-1000 μg/L, and the correlation coefficient was 0.9999. The recoveries of NCG in feedstuff were 104.0%, 103.5%, 95.3%, at the three spiked levels of 80, 200, 500 mg/kg with the relative standard deviations (RSDs) of 7.5%, 6.3% and 5.8%. The results showed that the method is simple, fast, highly sensitive, specific and with good purification effect. It can be applied to the analysis and determination of NCG in feedstuff.

Key words: N-carbamyl-L-glutamic acid, feedstuff, high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS), solid phase extraction (SPE)