Detection method of free and combined carboxy methyl lysine in milk and dairy products

Abstract

The invention discloses a detection method of free and combined carboxy methyl lysine in milk and dairy products. According to the detection method, isotope dilution high performance liquid chromatography- tandem ion trap mass spectrometry is adopted to detect free carboxy methyl lysine and carboxy methyl lysine combined with protein in milk and dairy products. According to the detection method, using of ion-pairing agent is avoided; no derivatization pretreatment is needed; efficiency, accuracy, sensitivity, and reproducibility are high; linearity range is wide; the detection method possesses unique features in analysis of the content of free carboxy methyl lysine and carboxy methyl lysine combined with protein in milk and dairy products, can be used for rapid and accurate qualitative and quantitative analysis on free carboxy methyl lysine and carboxy methyl lysine combined with protein in milk and dairy products, and can be used for detection of free and combined carboxy methyl lysine in milk and dairy products preferably.

Description

technical field [0001] The invention relates to the technical field of food detection and analysis, in particular to an isotope dilution high performance liquid chromatography tandem ion trap mass spectrometry for detecting free and protein-bound carboxymethyllysine in milk and dairy products. Background technique [0002] During food processing, the Maillard reaction is prone to produce harmful substances represented by glycation end products (AGEs). Carboxymethyllysine, as a well-defined marker of AGEs, widely exists in food. [0003] Lysine has an ε-amino group, which can easily become a highly reactive carbonyl target, so foods and biological tissues rich in lysine are more prone to Maillard reactions. As a protein-rich food, dairy products are not only rich in lysine, but also high in reducing lactose (lactose is more likely to react with lysine than glucose and maltose to form carboxymethyl lysine. acid). Numerous studies have shown that carboxymethyl lysine produce...

AI Technical Summary

Problems solved by technology

Ion-pair reagents increase the retention time while inhibiting the ionization efficiency, reducing the corresponding value of the mass spectrum signal, and the retention time of the target chromatographic peak is also unstable, which ultimately reduces the sensitivity of the detection method and is not conducive to qualitative and quantitative analysis.

On the other hand, because the ion-pair reagent is difficult to wash off from the chromatographic column, it will cause irreversible damage to the chromatographic column, thereby greatly shortening the service life of the chromatographic column. In addition, NFPA also greatly damages the mass spectrometer.

In order to avoid the use of ion-pair reagents, the Chinese patent CN103293243A published on November 3, 2013 utilizes 9-fluorenylmethyl chloroformate to carry out pre-column derivatization of carboxymethyl lysine to derivatize carboxymethyl lysine in C18 chromatography. The retention time on the column was extended to about 4.95min, which increased the complexity of the pre-treatment

The Chinese patent CN103616466A published on March 5, 2014 uses a hydrophilic chromatographic column (HILLIC) to replace the C18 column to detect carboxymethyllysine, but the retention time is only 3.47min, and the retention effect is not very ideal

HILLIC columns have a narrow range of use and poor applicability. They only have a good retention effect for a small number of highly hydrophilic compounds, and are not as commonly used as C18 columns.

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