Gelatin is a flavorless foodstuff, derived from collagen obtained from various animal by-products. It is commonly used in food, pharmaceuticals, photography, and cosmetics manufacturing. In these highly regulated industries gelatin is required to meet stringent quality standards. 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. This work demonstrates the capabilities of the Epsilon 1 to meet these residue limits.
Measurements were performed using an Epsilon 1 energy dispersive X-ray fluorescence spectrometer, equipped with a 50 kV silver-anode X-ray tube, 6 filters and a high-resolution silicon drift detector. The data was automatically processed by the Epsilon 1 software.
Gelatin is a flavorless foodstuff, derived from collagen obtained from various animal by-products. It is commonly used in food, pharmaceuticals, photography, and cosmetics manufacturing. In these highly regulated industries gelatin is required to meet stringent quality standards. 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. This work demonstrates the capabilities of the Epsilon 1 to meet these residue limits.
Measurements were performed using an Epsilon 1 energy dispersive X-ray fluorescence spectrometer, equipped with a 50 kV silver-anode X-ray tube, 6 filters and a high-resolution silicon drift detector. The data was automatically processed by the Epsilon 1 software.
Eight in-house standards were used to set up the calibrations for Cr, Fe, Cu and Zn in bovine and porcine gelatin. Five grams of loose powder were weighed into a disposable liquid cup for measurement.
A single measurement condition was used to analyze Cr, Fe, Cu and Zn in the standards (Table 1). The total measurement time was only 5 minutes per standard. Figure 1 shows the XRF spectrum of one of the porcine standards.
Table 1. Measurement conditions
Figures 2- 5 show the respective calibration graphs for Cr, Fe, Cu and Zn in gelatin. The graphs show very good correlations between the concentrations and the measured intensities. Detailed calibration results are shown in Table 2. The RMS (root mean square) value equals 1 sigma standard deviation. The lower limits of detection (LLD; 3 sigma) are also shown in Table 2.
Table 2.Calibration details
(* RMS: The more accurate calibrations have the smaller RMS values.)
Figure 1. XRF spectrum of porcine gelatin standard
Figure 2. Calibration graph for Cr in gelatin
Figure 3. Calibration graph for Fe in gelatin
Figure 4. Calibration graph for Cu in gelatin
Figure 5. Calibration graph for Zn in gelatin
To test the instrument precision, a fish gelatin sample was measured more than 1500 times consecutively over 17 days. The average concentration and RMS value are shown in Table 3. All four elements show excellent repeatability. The stability test for Cr in a fish gelatin sample is graphically illustrated in Figure 6.
Table 3. Repeatability results of a fish gelatin sample measured over 17 days
Figure 6. Graphical representation of the repeatability test of Cr in fish gelatin sample measured over 17 days
The results clearly demonstrate the excellent capability of Epsilon 1 for the analysis of Cr, Fe, Cu and Zn in bovine, porcine and fish gelatin. The high resolution and sensitivity of the silicon drift detector combined with powerful software algorithms make it possible to quantify traces of metals within the limits required by pharmaceutical and food regulations. Furthermore, the repeatability of the measurements demonstrate that the Epsilon 1 is a very stable instrument for trace analysis of gelatin.
