hplc (4)


High performance liquid chromatography and high-resolution mass spectrometry (HPLC-MS/MS) was used to identify gelatin from seven commercial cyprinid fishes;, black carp, grass carp, silver carp, bighead carp, common carp, crucian carp, and Wuchang bream.

By comparison with theoretical mammalian collagen (bovine and porcine collagen), the common and unique theoretical peptides were found in the collagen of grass carp, silver carp, and crucian carp, respectively.  Seven common characteristic peptides were obtained from the fish gelatins. Moreover, 44, 36, and 42 unique characteristic peptides were detected in the gelatins of grass carp, silver carp, and crucian carp, respectively.

The researchers concluded that the combined use of common and unique characteristic peptides could verify fish gelatin in comparison with mammalian gelatin.

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The aim of this study by Brazilian researchers was to identify authenticity markers to distinguish between true and false cinnamon, and use mid-infrared spectroscopy (MIR) with chemometric analysis as a fast screening method. A  total of 129 samples of cinnamon were obtained from Brazil, Sri Lanka and Paraguay. The samples were analysed by hplc (high performance liquid chromatography) and MIR. The levels of eugenol, cinnamaldehyde and coumarin were measured.  Samples of true cinnamon had higher levels of eugenol and cinnamaldehyde and lower levels of coumarin, and they also had higher antioxidant activity. Principal component analysis (PCA) of both the hplc and MIR results was able to separate the two types of cinnamon, and partial least square discriminant analysis (PLS-DA) was able to differentiate between the true and false cinnamon with 94.4% and 100% accuracy for the compositional analysis and MIR respectively.

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6054485892?profile=RESIZE_400x Squalene is a triterpene, and tyrosol is a simple phenol. Both are found in relatively high amounts compared to other terpenes and phenols respectively in extra virgin olive oil, and are reduced significantly during refining to produce refined olive oil. Both squalene and tyrosol can be determined by hplc (high performance liquid chromatography) after extraction with 2-propanol or liquid-liquid extraction respectively. The feasability of this screening method was first tested on measuring the two markers in 10 commercial samples of EVOO, one commercial sample of virgin olive oil, 2 commercial samples of olive oil (a blend of extra virgin and refined olive oil), and 10 types of vegetable oils. In addition, the method was tested on 6 brands of blended oils (5 of which were 20% EVOO/80% sunflower oil, and one 30% EVOO/70% grapeseed oil). Further samples of olive oil using 50% EVOO, and blended oils with 20% EVOO were prepared. After determining squalene and tyrosol in all of the samples and plotting squaline on the y-axis, and tyrosol on th x-axis, there was discrimination between EVOO and all the other samples, and olive oil samples were differentiated from blended oils. Although this showed feasibility of the screening method, more samples at different concentrations of EVOO, and of virgin olive oil are required to find the sensitivity of the method.

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Researchers applying a multi-step approach using HPLC, UV–Vis, FT-IR and NMR analyses, uncovered a new type of adulteration of a commercial product labelled as “saffron”, and sold packed in powder form in a major consuming country.  Applying the four methods and NMR data from in-house databases, they uncovered a  “tailor-made” case of 100% substitution of saffron by a mixture of exogenous chemical compounds in such a way that the commercial product would approximately mimic not only the appearance of saffron but also its UV–Vis spectrum and specific absorbance values. The findings indicated a sophisticated practice, including total substitution of saffron constituents by tartrazine and sunset yellow along with propane-1,2-diol, propan-2-ol and acylglycerols, probably as emulsifier agents. 

Read the abstract at: Multi-step approach uncovers saffron fraud

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