Mass spectrometry-based protein and peptide profiling for food frauds, traceability and authenticity assessment.

The ever-growing use of mass spectrometry (MS) methodologies in food authentication and traceability originates from their unrivalled specificity, accuracy and sensitivity. Such features are crucial for setting up analytical strategies for detecting food frauds and adulterations by monitoring selected components within food matrices. Among MS approaches, protein and peptide profiling has become increasingly consolidated. This review explores the current knowledge on recent MS techniques using protein and peptide biomarkers for assessing food traceability and authenticity, with a specific focus on their use for unmasking potential frauds and adulterations. We provide a survey of the current state-of-the-art instrumentation including the most reliable and sensitive acquisition modes highlighting advantages and limitations. Finally, we summarize the recent applications of MS to protein/peptide analyses in food matrices and examine their potential in ensuring the quality of agro-food products.

Mass spectrometric determination of disulfide bonds and free cysteine in grass carp IgM isoforms.

Disulfide bonds are fundamental in establishing Ig structure and maintaining Ig biological function. Here, we analysed disulfide bonds and free cysteine in three grass carp IgM isoforms (monomeric, dimeric/trimeric, and tetrameric IgM) by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). The results revealed that Cys574 residue status at the C-terminal tail differed substantially in monomeric IgM in comparison with polymeric IgM, Cys574 was found as free thiol in monomeric IgM, while it formed disulfide linkages in dimeric/trimeric and tetrameric IgM. Five intra-chain disulfide bonds in the CH1~CH4 and CL1 domains, as well as one H-H and one H-L inter-chain disulfide linkages, were also observed and shown identical connectivity in monomeric, dimeric/trimeric, and tetrameric IgM. These findings represent the first experimental assignments of disulfide linkages of grass carp IgM and reveal that grass carp IgM isoform formation is due to alternative disulfide bonds connecting the Cys574 residue at the C-terminal tail.

Site-Specific N-Glycan Characterization of Grass Carp Serum IgM.

Immunoglobulin M (IgM) is the major antibody in teleost fish and plays an important role in humoral adaptive immunity. The N-linked carbohydrates presenting on IgM have been well documented in higher vertebrates, but little is known regarding site-specific N-glycan characteristics in teleost IgM. In order to characterize these site-specific N-glycans, we conducted the first study of the N-glycans of each glycosylation site of the grass carp serum IgM. Among the four glycosylation sites, the Asn-262, Asn-303, and Asn-426 residues were efficiently glycosylated, while Asn-565 at the C-terminal tailpiece was incompletely occupied. A striking decrease in the level of occupancy at the Asn-565 glycosite was observed in dimeric IgM compared to that in monomeric IgM, and no glycan occupancy of Asn-565 was observed in tetrameric IgM. Glycopeptide analysis with liquid chromatography-electrospray ionization tandem mass spectrometry revealed mainly complex-type glycans with substantial heterogeneity, with neutral; monosialyl-, disialyl- and trisialylated; and fucosyl-and non-fucosyl-oligosaccharides conjugated to grass carp serum IgM. Glycan variation at a single site was greatest at the Asn-262 glycosite. Unlike IgMs in other species, only traces of complex-type and no high-mannose glycans were found at the Asn-565 glycosite. Matrix-assisted laser desorption ionization analysis of released glycans confirmed the overwhelming majority of carbohydrates were of the complex-type. These results indicate that grass carp serum IgM exhibits unique N-glycan features and highly processed oligosaccharides attached to individual glycosites.

Determination of crizotinib in human and mouse plasma by liquid chromatography electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS).

An LC-ESI-MS/MS method using high-throughput solid-phase extraction (SPE) was developed and validated to measure crizotinib in human and mouse plasma to support ongoing clinical and preclinical pharmacokinetic studies. Chromatographic separation of mouse or human plasma extracts was performed on a Supelco Discovery c18 column (50 mm × 2.1mm, 5.0 µ) with gradient elution using a combination of acidified aqueous and methanol (MeOH) mobile phases. The mass-to-charge transition monitored for detection and quantitation of crizotinib was m/z 450.2>260.2 while the stable label internal standard (ISTD) was monitored at m/z 457.2>267.3. The validation studies demonstrated that the assay is both precise and accurate with %CV<9% and accuracies within 8% of nominal target concentration across all concentrations tested for both the human and mouse plasma matrices. Sample volumes required for analysis were 50 and 25 µL for human plasma and mouse plasma, respectively. Calibration curves were linear over a range of 5-5,000 ng/mL for human plasma and 2-2,000 ng/mL for mouse plasma. The use of a 96-well plate format enabled rapid extraction as well as compatibility with automated workflows. The method was successfully applied to analyze crizotinib concentrations in plasma samples collected from children enrolled on a phase I pediatric study investigating the use of crizotinib for treatment of pediatric brain tumors.

LC-ESI-MS/MS, a modified method for simultaneous quantification of isoflavonoids, flavonoids, alkaloids and saponins in a Chinese herbal preparation Gegen-Qinlian decoction / 药物分析学报

A sensitive and reliable liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS) method was established to simultaneously quantitate four categories of compounds (isoflavonoids, flavonoids, alkaloids and saponins) in Gegen-Qinlian decoction (GQD). These compounds were separated by a Shiseido CAPCELL PAK C18 column with a linear gradient consisting of 0.1% (v/v) formic acid in water (A) and 0.1% (v/v) formic acid in acetonitrile (B), and delivered at a flow rate of 0.3 mL/min. All the analytes were determined by electrospray positive ionization tandem mass spectrometry in a multiple reaction monitoring (MRM) mode. Linearity, accuracy, precision, recovery and stability of the method were evaluated with the validation over the range of 4.0-538 5 ng/mL. The proposed method was applied to the analysis of a Chinese herbal preparation GQD successfully.

LC-ESI-MS/MS, a modified method for simultaneous quantification of isoflavonoids, flavonoids, alkaloids and saponins in a Chinese herbal preparation Gegen-Qinlian decoction / 西安交通大学学报·英文版

A sensitive and reliable liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/ MS) method was established to simultaneously quantitate four categories of compounds (isoflavonoids, flavonoids, alkaloids and saponins) in Gegen-Qinlian decoction (GQD). These compounds were separated by a Shiseido CAPCELL PAK C18 column with a linear gradient consisting of 0.1% (v/v) formic acid in water (A) and 0.1% (v/v) formic acid in acetonitrile (B), and delivered at a flow rate of 0.3 mL/min. All the analytes were determined by electrospray positive ionization tandem mass spectrometry in a multiple reaction monitoring (MRM) mode. Linearity, accuracy, precision, recovery and stability of the method were evaluated with the validation over the range of 4.0-5385 ng/mL. The proposed method was applied to the analysis of a Chinese herbal preparation CQD successfully.