6 May / June 2016
Figure 4. Annotated SIR profile of a lager beer annotated with saccharides found to be present.
A sherry wine profile is shown in Figure 5 (A–E). The main analytes found to be present in sherry are fructose and glucose (Figure 5B). A small amount of arabinose was present (Figure 5A), along with trace levels of sorbitol and mannitol (Figure 5C). Maltose was also apparent (Figure 5D). The DP3 compounds were absent (Figure 5E), as would be expected, since wine is derived from grapes rather than from grains.
The quantification of various fruit juices is shown in Table 2. Fructose, glucose, and sucrose were present in the orange, apple, and pineapple juices. The amounts and ratios of sugars in these juices are similar to those reported elsewhere [2,3]. Of particular interest was the detection of sorbitol in pomegranate juice. Sorbitol is not usually present in pomegranate juice [4] and its detection could be evidence of adulteration. The grape juice sample showed fructose, glucose, but no sucrose as expected [2,3].
Figure 7. SIR profile of an apple juice sample annotated with saccharides found to be present.
Table 2. Calculated concentrations from the quantification studies of the various fruit juices profiled in this study (g/L).
Figure 5. SIR profile of a sherry wine annotated with saccharides found to be present.
CONCLUSIONS
• The ACQUITY QDa Detector coupled to the ACQUITY Arc System provides improved sensitivity and selectivity to analyse and quantify mono and disaccharide samples in a single injection.
• Mass detection is a viable alternative to Refractive Index (RI) or Evaporative Light Scattering (ELS) methods.
• This enhanced sensitivity allows the analysis of samples at higher dilution levels, which minimises matrix effects.
Figure 6. SIR profile of a whiskey annotated with saccharides found, and an unknown saccharide found to be present at m/z 215.
Figure 6 (A–E) shows the SIR profile of a whiskey sample. The presence of arabinose (Figure 6A), fructose and glucose (Figure 6B) was evident. Of particular interest was an unknown saccharide apparent in Figures 6B (m/z 215) and 8C (m/z 217) at retention time 4.85 min. Using retention time alone with an RI or ELS detector, this peak would most likely have been misidentified as mannitol. The presence of this peak at both m/z 215 and m/z 217 indicated that this component has the same mass as a monosaccharide, rather than an alditol. Mannitol does not have an ion at m/z 215, as can be seen in Figures 1 and 2. Finally, the SIR chromatograms from an apple juice sample are shown in Figure 7 (A–E). The presence of arabinose, fructose, glucose, sorbitol, and sucrose are highlighted.
• The combination of mass detection and chromatographic separation provides increased selectivity in identifying analytes of interest, while reducing false positives.
REFERENCES
1. M Castellari et al. Determination of Carboxylic Acids, Carbohydrates, Glycerol, Ethanol, and 5-HMF in Beer by High-Performance Liquid Chromatography and UV–Refractive Index Double Detection. Journal of Chromatographic Science. 39: 236–238, January 2001.
2. M L Sanz et al. Inositols and carbohydrates in different fresh fruit juices. Food Chemistry. 87: 325–328, 2004.
3. M Benvenuti. Analysis of Food Sugars in Various Matrices. Waters application note no. 720004677EN, May, 2013.
4. R Jahromi. 6.21 Reference Guide for Pomegranate. Revision June 2012.
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