Dietary supplements for pets play a key role in maintaining animal health, as they are intended to support joints, improve digestion, and promote skin and coat health. This thesis focuses on the analysis of these supplements, which are often complex mixtures of organic and inorganic substances. Twelve selected samples were analyzed using X-ray powder diffraction to determine their qualitative and quantitative phase composition, and the results were compared with the product labels.
X-ray powder diffraction is one of the fundamental methods for characterizing solids. It enables the identification of crystalline phases in samples by comparing sample diffractograms with standards from databases such as PDF-2. Qualitative analysis was performed using Crystallographica Search-Match (CSM) and X'Pert HighScore Plus software, while the Rietveld method in Topas software was used to determine the mass fractions of substances within the crystalline fraction of the samples.
The analysis revealed that most identified substances matched the information on the product labels (e.g., methylsulfonylmethane, calcium carbonate, sodium chloride, potassium chloride). Some identified substances differed to some extent from those listed on the label: for example, instead of the declared glucosamine sulfate, a mixture of glucosamine hydrochloride and potassium sulfate was present in all samples; in one preparation, anhydrous and hydrated calcium hydrogen phosphate were present instead of dicalcium phosphate. Furthermore, although several labels listed lactose or even dry lactose, lactose monohydrate was consistently identified. In one case, lactose or sugars were not mentioned on the label at all, despite being the predominant substance in the
sample. Certain ingredients from the labels, such as vitamins and biotin, were not detected, which is attributed to their low concentrations below the detection limit of the method (between 0.1 and 1%). Components such as milk derivatives, oils, yeast, starch, and pectin were also not identified, as they are non-crystalline and lack the characteristic diffraction maxima required for identification. It is important to note that the determined mass fractions refer to the proportion of substances within the crystalline part of the sample; in samples with a significant amount of amorphous phase, the actual mass fractions of the crystalline phases relative to the total sample mass are lower. Despite these limitations, X-ray diffraction provided substantial useful information regarding the phase composition of pet dietary supplements.
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