X-ray powder diffraction is one of the fundamental methods used for the characterization of solid substances. Using this method, I analyzed 12 samples of dietary supplements intended for muscle mass gain and regeneration. I performed a qualitative analysis using the Crystallographica Search-Match (CSM) software and the Powder Diffraction File (PDF-5+) database. By comparing the matches of diffraction peaks in the standard and sample diffractograms, I determined which phases were present in the individual samples. I then conducted a quantitative analysis using the TOPAS software, where I determined the mass fractions of the previously identified phases using the Rietveld method.
I found that the ingredients in the dietary supplements varied, primarily consisting of various amino acids, whey, and sugars. In some samples, amino acids predominated, while in others, they were present in negligible amounts. Most of the sweeteners listed by the manufacturers on the packaging were synthetic, as these are much sweeter. The diffractograms of samples that primarily contained whey showed high background noise with few or no visible diffraction peaks. The whey samples proved unsuitable for analysis using X-ray powder diffraction. In the qualitative analysis of the other samples, these issues were not present, although I was not always able to explain all the diffraction peaks. Due to the nature of my samples, I mainly dealt with organic compounds, which are less represented in the commonly used PDF-2 powder diffraction database. This was why I mostly performed the qualitative analysis using the PDF-5+ database, though even in this collection, I could not find some of the compounds listed on the labels. Some of the sample diffractograms were very complex, making the analysis of these samples much more difficult without the label information. In the case of complex samples, the quantitative analysis did not always match the mass fractions stated on the label. If we rely on the accuracy of the label and are confident in the homogeneity of the substance in the product container, the most likely reason for the discrepancy is the intense overlapping of diffraction peaks.
The results of the methods used in this work are also negatively affected by the presence of a larger amount of amorphous phase and the granularity of the sample. In such cases, it is important to recognize that the results of the quantitative analysis are approximate and that it may be useful to verify them with another quantitative analysis method.
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