Analyses of the brominated vegetable oil in soft drinks using gas chromatography-flame ionization detector and atmospheric pressure gas chromatography-quadrupole/time-of-flight mass spectrometry

Analysis of serum total bilirubin content based on dual-position joint spectrum of "M plus N" theory and the logarithmic method

At present, in the chemical quantitative analysis of complex solutions based on spectroscopy, the accuracy of the content analysis of complex solution is difficult to meet the requirements due to the overlapping spectral lines, low signal-to-noise ratio, and scattering characteristics of various components of complex solution. In this paper, the logarithmic method is used to preprocess the spectral data in the spectral preprocessing stage, and the two-position and multi-mode joint spectral strategy of "M plus N" theory is applied to the quantitative analysis of serum components. The serum samples are illuminated by dual-position ultraviolet LED light source, and the two spectra of the vertical position and the coaxial facing position of the light source and the optical fiber are collected respectively. Then the partial least square (PLS) method was used to establish models to analyze the concentration of total bilirubin in serum by the spectrum of vertical position, the spectrum of coaxial facing position, and the spectrum of the combination of the former two. Among the experimental results, the model established by the combination of the two spectra collected by two positions has a good result. The correlation coefficient of all samples predicted by this model is 0.971223, and the root mean square error is 1.96645 μmol/L. This study shows that the method of the logarithmic, collecting spectra and analyzing the composition content of complex solutions by using the multi-location and multi-mode strategy of "M + N" theory can effectively improve the prediction accuracy of the model and has practical significance for the chemical quantitative analysis of complex solutions based on spectroscopy.

[Attempt to Calculate the Efficiency of Methylation Using 1H-NMR for Analyzing Brominated Vegetable Oil]

We studied the efficiency of methylation for analyzing brominated vegetable oil (BVO). In this report, we investigated whether ¹H-NMR is an applicable method for assessing the efficiency of methylation to analyze BVO. ¹H-NMR sufficiently calculated the efficiency of methylation using each integral and the numbers of protons derived from the methyl group, which is characteristic in products, and the methine group, which is characteristic in unreacted substances. Additionally, the efficiency of methylation calculated via ¹H-NMR was in good agreement with changes in the peak area of BVO fatty acid methyl esters (BVOFAMEs) after various heating times obtained from GC-FID analysis. Therefore, ¹H-NMR is applicable for calculating the efficiency of methylation to analyze BVO.