Identification and determination of N-ε-carboxymethyllysine by gas-liquid chromatography

Comparative LC–MS/MS profiling of free and protein-bound early and advanced glycation-induced lysine modifications in dairy products

“…The value measured for UHT milk in the present study of 8.77 ± 7.02 ng CML mg −1 protein −1 (CML free + CML p-b ) is in good accordance with the findings of Fenaille et al [20], who determined 34.1 ng CML mg −1 protein −1 by LC-MS/MS after reduction with NaBH 4 and subsequent acid hydrolysis. A higher content of 259 ± 197 ng CML mg −1 protein −1 determined by GC/MS after acid hydrolysis of proteins was reported by Büser et al [15], however this may be due to the artifactual formation of CML from FL because a reduction prior to proteolysis was omitted. For pasteurized milk, in this study a total content of 1.30 ± 0.73 ng CML mg −1 protein −1 (CML free + CML p-b ) was obtained, equivalent to 51 ± 24 ng CML mL −1 sample −1 .…”

“…CML, for instance, was quantified by ELISA in infant formulas [12], heated milk and milk powder [13] and human breast milk [14], by using a chromatographic technique, e.g. GC/MS [15,16], HPLC/FD [17,18] or by LC-MS/MS [19,20] for CML analyses in raw, pasteurized and UHT milk, as well as in infant formulas. Pyrraline (Pyr), a pyrrole derivative containing the N ε -amino group of Lys, which is presumed to be one of the most abundant AGEs in foodstuffs [21], was determined by ion exchange chromatography in combination with photodiode array detection [22].…”

Dietary Advanced Glycation End Products and Their Role in Health and Disease

“…Because of the above problems with the ELISA test, since the late 1980s, chromatographic methods (GC and LC) have been employed to determine carboxymethyllysine content in foods (85,(87)(88)(89)(90). Lately, the development of HPLC and ultra-pressure liquid chromatography equipment, combined with mass spectra detectors (tandem MS), allowed several laboratories to investigate the carboxymethyllysine content in different food matrices and compare their results with those obtained by the immunochemical method (84,86).…”

Simultaneous analysis of lysine, Nɛ-carboxymethyllysine and lysinoalanine from proteins

“…Quantifiable amounts of CML have been detected in sterilized milk (34.3 mg/100 g protein, n = 1), powdered milk (7.1 mg/100 g protein, n = 1), evaporated milk (49.9 mg/100 g) and cocoa milk (15.7 mg/100 g) [17]. On the other hand, Büser et al [12], Hewedy et al [16] and Fenaille et al [19] detected CML in UHT milk (1.1-25.9 mg/100 g), Hartkopf et al [15] in condensed milk (39.0 mg/100 g) and Charissou et al [14] in cereal products, like cookies (0.5-3.5 mg/100 g), toasted bread (0-1.3 mg/100 g) and corn flakes (0.6-0.8 mg/100 g). However, to date ranges of CML in foods have not been established.…”

“…Moreover, other oxidative pathways such as lipid peroxidation and serine oxidation may also be involved [8][9][10]. CML formation can be estimated in food or protein model system mainly through gas chromatography (GC) [9,[11][12][13][14], high performance liquid chromatography (HPLC) [15][16][17][18][19], matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) [20,21,22] and enzyme-linked immunosorbent assay (ELISA) [5,[23][24][25][26][27].…”