High-performance liquid chromatography

Chromatography

Derivatization

Solid phase extraction

Isotope dilution

Physical chemistry

Extraction (chemistry)

Reagent

Selected reaction monitoring

Protein precipitation

Mass spectrometry

Chemistry

Detection limit

Tandem mass spectrometry

Food Chemistry

This study developed a sensitive and easy method to directly analyze Nε-(carboxymethyl)lysine (CML) by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Acetonitrile and water were used as the binary mobile phase without ion pair reagents, while BEH Amide column was applied to detect CML. The target substance without derivatization could be well retained and separated after the pretreatment conditions were optimized. Oasis MCX solid phase extraction (SPE) cartridge showed the best recovery rate of CML 96.7 % and purification ability among the tested SPE cartridges. There was no obvious difference in pretreatment abilities with or without protein precipitation on the CML quantitative analysis. The recovery rates 97-98 % for CML were achieved by UPLC-MS/MS, as well as the detection limit and quantification limit were 0.05 mg/kg and 0.15 mg/kg sample, respectively. This method was suitable for quantifying CML content with high recovery rate and low detection and quantification limit in sterilized milk.

Quantitative determination of Nε-(carboxymethyl)lysine in sterilized milk by isotope dilution UPLC-MS/MS method without derivatization and ion pair reagents