A rapid and simple method for the determination of a series of macroelements (sodium, magnesium, phosphorus, chlorine, potassium, and calcium) and trace elements (manganese, iron, and zinc) by wavelength dispersive X-ray fluorescence has been developed and validated for infant cereal matrices. Reference values were obtained by inductively coupled plasma optical emission spectroscopy and by potentiometry. The 88 investigated samples were commercially available products. Pellets of 4 g were prepared under 10 tonnes of pressure. For each sample, 3 pellets were prepared and analyzed. Limits of quantification and repeatabilities were evaluated. Calibrations were established with 43 samples, and method validation was made using a second set of 45 samples. An evaluation of this alternative method was done by comparison with data obtained from the reference methods. The results show the good performances of the alternative method to routine infant cereals analysis.

A simple and rapid method for the determination of iron, copper and zinc in food premixes (used during human food processing) by energy dispersive X-ray fluorescence (XRF) has been established and validated using 25 samples. Reference values were obtained by inductively coupled plasma-optical emission spectroscopy after microwave acidic digestions. Studied samples presenting wide ranges of concentrations: Fe=500–35000 mg/kg, Cu=50–4000 mg/kg and Zn=700–32000 mg/kg were quantified in 200 s by XRF measurements using a rhodium tube.

A method for the multielement analysis of mineral premixes using inductively coupled plasma optical emission spectrometry (ICP-OES) was developed and validated. Due to the lack of certified premix samples, the validation was performed on five different purchased premixes. A microwave-assisted acid hydrolysis was used to bring the elemental composition into solution. A standardized dilution scheme permitted the determination of different ranges of elemental concentrations found in premixes. Calcium, chromium, copper, iron, magnesium, manganese, molybdenum, selenium, and zinc were determined simultaneously by ICP-OES. Robust repeatability and intermediate reproducibility were estimated and found to be sufficient for three out of five premixes. The same was true for accuracy which had been estimated by the determination of recovery from spiked premixes. Insufficient repeatability and accuracy for two pet food premixes was due to their heterogeneity. Using a larger sample size for these premixes significantly improved the repeatability and intermediate reproducibility for several elements. The developed multielement method performed well on homogeneous mineral premixes, but high repeatability data are to be expected from pet food premixes due to their high heterogeneity.

. Tin is considered to be a priority contaminant by the Codex Alimentarius Commission. Tin can enter foods either from natural sources, environmental pollution, packaging material or pesticides. Higher concentrations are found in processed food and canned foods. Dissolution of the tinplate depends on the of food matrix, acidity, presence of oxidising reagents (anthocyanin, nitrate, iron and copper) presence of air (oxygen) in the headspace, time and storage temperature. To reduce corrosion and dissolution of tin, nowadays cans are usually lacquered, which gives a marked reduction of tin migration into the food product. Due to the lack of modern validated published methods for food products, an ICP-AES (Inductively coupled plasma–atomic emission spectroscopy) method has been developed and evaluated. This technique is available in many laboratories in the food industry and is more sensitive than atomic absorption. Conditions of sample preparation and spectroscopic parameters for tin measurement by axial ICP-AES were investigated for their ruggedness. Two methods of preparation involving high-pressure ashing or microwave digestion in volumetric flasks were evaluated. They gave complete recovery of tin with similar accuracy and precision. Recoveries of tin from spiked products with two levels of tin were in the range 99±5%. Robust relative repeatabilities and intermediate reproducibilities were <5% for different food matrices containing >30 mg/kg of tin. Internal standard correction (indium or strontium) did not improve the method performance. Three emission lines for tin were tested (189.927, 283.998 and 235.485 nm) but only 189.927 nm was found to be robust enough with respect to interferences, especially at low tin concentrations. The LOQ (limit of quantification) was around 0.8 mg/kg at 189.927 nm. A survey of tin content in a range of canned foods is given.

The dissolution of oils in organic solvents as recommended in official methods (AOCS) causes inaccuracies in analysis due to solvent volatilization. This study describes a stable microemulsion procedure which enables direct injection of the sample into the GFAAS using an autosampler. The calibration for Cu, Fe, Ni, and Pb was found to be linear in the 0 to 100 or 150 mug/L range (R-2>0.99). Typical edible oils were used to validate the method. The recovery of the four metals for spiked samples was found to be >90%. The limits of quantification were suitable for the determination of the maximum tolerated amounts. Robust relative repeatability limits of the measurements were maximum 30%. The dissolution of oils in organic solvents as recommended in official methods (AOCS) causes inaccuracies in analysis due to solvent volatilization. This study describes a stable microemulsion procedure which enables direct injection of the sample into the GFAAS using an autosampler. The calibration for Cu, Fe, Ni, and Pb was found to be linear in the 0 to 100 or 150 mug/L range (R-2>0.99). Typical edible oils were used to validate the method. The recovery of the four metals for spiked samples was found to be >90%. The limits of quantification were suitable for the determination of the maximum tolerated amounts. Robust relative repeatability limits of the measurements were maximum 30%.

The presented colorimetric procedure only requires simple laboratory equipment and is suitable as a routine procedure for checking concentrations of iodine in fortified culinary products. The Moxon and Dixon colorimetric procedure for iodine determination has been optimised for the determination of iodide and iodate in fortified culinary products, always containing high salt levels. The high sensitivity of the method permits a high dilution of the product solutions, thus reducing interferences from the inherent colour of the products. The calibration is linear in the range from 0 to 12 microg L(-1) of iodine with R2 > 0.99. A series of commercial culinary products were used to validate the method. Recoveries of iodine, added as iodide and/or iodate, were generally in the range 100+/-10%. High concentrations of chloride are essential to obtain a complete recovery of iodate. Limit of quantification was estimated to be 2 mg kg(-1) of product, based on 2-3 g of product. Concentrations of iodine determined with this method were similar to those obtained by an ICP-MS procedure.