Q: What is XRF and how is it used by the pet food industry?
A: XRF spectrometers use an X-ray tube to excite inner-shell electrons of the atoms in a sample. Consequently, XRF photons with characteristic energies for the electron transitions are emitted. By collecting these photons, we can determine the elemental composition of the sample.
XRF is used in pet food research and development (R&D) and production to determine macro and micro mineral nutrients as well as heavy metal contaminants such as lead, arsenic, cadmium and mercury. You can measure elemental concentrations from ppm (µg/g) levels up to 100 percent in one measurement in powders, grains, solids, slurries and liquids. XRF is less sensitive for lighter elements and reaches ppm detection limits around the Z = 14 (Silicon, Si). The lightest element currently being measured with XRF in pet food-related materials is typically Sodium (Na) – in rare cases Fluorine (F).
Q: Which materials can be analysed by XRF along the pet food production chain?
A: Basically, any raw material, intermediate product and final feed can be analysed by XRF. In most cases, XRF is used along the production chain of dry (processed) pet food, pet food supplements and blends. This includes minerals, mineral premixes, dry ingredient blends, forages, hay, edible oils and, of course, final feed pellets. This means you can verify the quality of your calcium sulphate or sodium chloride before it enters production, check if the mineral premix has the correct cation-anion ratio, and determine trace levels of heavy elements before product release.
Q: What are the benefits of using XRF versus other techniques?
A: The main benefits of using XRF over other techniques such as inductively coupled plasma optical emission spectroscopy (ICP-OES) are ease-of-use, short time-to-result, and low costs of operation. XRF requires minimal sample preparation and can provide results in a matter of minutes after sampling. In contrast, ICP-OES requires sample digestion or dissolution, which can be time-consuming and introduce potential inaccuracies due to incomplete dissolution or large dilutions. Moreover, XRF spectrometers do not need expensive or hazardous consumables or labware and can be operated after minimal training.
XRF is a non-destructive technique, meaning the same sample can be analysed using other techniques such as FT-NIR, which is used for the determination of eg, moisture, fat, protein and fibre contents.
Q: How does XRF cope with more challenging pet food samples, like wet canned food?
A: If you follow appropriate sample preparation procedures, wet canned food, from meat-based to plant-based ingredients, from natural to processed products, can be analysed accurately by XRF. The main challenges are sample homogeneity and loss of water during the analysis. Emulsified meat samples extracted from the production process can be measured without further preparation in liquid cups. More heterogeneous samples can be homogenised using a cryogenic grinder. Some sample might lose water during the analysis, in which case the analysis time may be reduced, or the samples may be dried at around 110°C prior to analysis. No matter what sample type you want to analyse, we can provide the necessary guidance.
Q: What are some of the current trends and developments in pet food production that require XRF analysis?
A: One trend is increasing demand for specialised diets and feed for different dog breeds and life stages. For example, large-breed dogs may need more calcium and phosphorus than small-breed dogs, while senior dogs may need less sodium and more antioxidants than young dogs. XRF can help pet food manufacturers to tailor their products to meet these specific nutritional needs and preferences.
