Gelatin is a well-known ingredient in the food, pharmaceutical, and cosmetic industries. It is colorless and flavorless and is used for example as a thickener in many sweets or in capsules. Gelatin is a natural product and can be derived from collagen obtained from e.g. cattle, fish, chicken, and horses. Depending on source and preparation methods (acidic or alkali) many different types of gelatin with varying quality are obtained.
The need for analysis
You might remember a few years ago there was news from China about toxic gelatin capsules containing high concentrations of chromium. It was estimated that these toxic capsules contained 20 – 90 times the permitted chromium content because a company was using cheaper industrial grade gelatin to produce capsules for human consumption. This story highlights the importance of good quality control of all gelatin for human consumption. Consequently, the food and pharmaceutical quality testing regulations include testing for heavy metals such as chromium (Cr), zinc (Zn), copper (Cu) and iron (Fe).
Heavy metal testing of gelatin
The United States, European, and Japanese pharmacopeias all have monographs requiring testing for heavy metals such as Cr, Zn, and Fe. In the food industry, the Food Chemical Codex and the European Regulation No. 853/2004 stipulate the residue limits for a number of elements including Cu, Cr, Zn, and Fe. In the case of Cr, the United States Pharmacopeia (USP) states acceptance criteria of not more than 10 ppm.
Our application specialists were wondering whether X-ray fluorescence spectrometry (XRF), a technique approved by the pharmacopeia, would be able to quantify these heavy metals within the rigorous limits required by the food and pharmaceutical regulatory agencies. We used a few grams of gelatin powder for each measurement and just put it into a loose powder sample cup. The results were a pleasant surprise. XRF is actually an excellent tool to quantify heavy metals in gelatin, even below the required limits. Additionally, XRF has a number of advantages over other techniques: it only needs minimal sample preparation and it is fast and non-destructive with potential for automation.
We have summarized our results in a datasheet titled “Trace element determination of Cr, Fe, Cu and Zn in gelatin”.