The same trans fat analysis can be performed by 13C NMR. The arrows on the stacked plot indicate the regions of the spectrum tat correlate to trans fat carbon chemistry.
In a previous post we described the regression analysis of 1H NMR data at 300 MHz with trans fat content of various edible oils. Below is the regression analysis obtained on 60 MHz data. We are currently blending the samples to increase the spread and number of datapoints in the analysis.
This topic has become pertinent again with the interest of FDA in trans-fat content in processed foods - more information here.Back in 2006 we performed a cursory analysis of trans fat reference materials that we purchased from AOCS. We performed a series of 1H NMR analysis and performed a chemometric PLS analysis correlating the 1H NMR spectral variability to trans fat content, PUFA (polyunsaturated fatty acid content), SAFA (saturated fatty acid content), and MONO (monounsaturated fatty acid content). Excellent correlations were obtained between wt% values obtained by GC analysis and the rapid 1H NMR analysis (2 minutes on a 300 MHz NMR). 1H NMR spectra on the standard samples are shown in the figures below as well as the GC data that was used in the regressions. A PCA analysis of the NMR data nicely categorized the various types of samples as well as the trans fat contents of the samples with nice separation being shown in the PC1 vs PC2 score plot. The various correlations for trans fat, SAFA, PUFA, and MONO are shown below.
We recently performed an analysis of a competitive product for a company working on developing "herbal supplements" for erectile dysfunction. They ended up not paying for the analysis so we thought we would just publish it generically as a "point of interest". It was described to us that the product worked incredibly well which immediately made it suspicious ... NB: we didn't actually try it out ourselves. The bottom line is that the product was not "herbal" at all .. it was thiosildenafil an analog of Viagra. "Herbal Supplement" Viagra Stacked comparison plot. COSY Beware out there. If you are on alpha-blockers for heart condition and buy an innocent looking "herbal" for ED issues .. it may actually be pharmaceutical grade viagra with all the use warnings that go with it.
"Utilization of MNova in a Commercial NMR Testing Laboratory for: 1) Development of Automated Quantitative Analysis Methods by Direct Internal Standard NMR Measurements, and 2) Pre-Processing of Large NMR Datasets for Chemometric Regression Analyses to Derive Chemical and Physical Properties" - presented by John Edwards at the MNova Users Meeting - SMASH 2013 - Santiago de Compostela, Spain, September 22, 2013 PDF of Presentation Automated 1H qNMR analysis of complex mixtures - example of aloe vera powder 200x Final automated analysis output for aloe vera analysis - assignments and quantitative output. Chemometric analysis - spectrum processing and X-matrix preparation performed in MNova - ascii output imported into Eigenvector Research Solo for PLS regression or PCA analysis. Correlation of 1H NMR at 300 or 60 MHz with GC analysis of EPA and DHA content (wt%).
At the recent ACS NERM 2013 meeting Adam Dicaprio of Process NMR Associates presented two topics on sour beer analysis by NMR. "Small Molecule Chemistry of Spontaneously Fermented Coolship Ales" ... PDF Technical Poster "When Beer Goes Sour: An NMR Investigation" ... PDF - Oral Presentation NMR Assignments of interest. 1H qNMR obtained from relative molar ratios established from compaison of maleic acid internal standard with small molecule signals.
At the recent ACS NERM 2013 meeting in New Haven CT, John Edwards gave a talk on the comparison of 60 and 300 MHz 1H NMR based predictive models for EPA and DHA omega-3 fatty acid content in a fish oil manufacturing process. The presentation can be found here..... PDF Presentation Note - spectra are read into the chemometrics software backwards ...