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Nutritional information about human milk is essential as early human growth and development have been closely linked to the status and requirements of several macro- and micro-elements. However, methods addressing whole mineral profiling in human milk have been scarce due in part to their technical complexities to accurately and simultaneously measure the concentration of micro- and macro-trace elements in low volume of human milk. In the present study, a single laboratory validation has been performed using a “dilute and shoot” approach for the quantification of sodium (Na), magnesium (Mg), phosphorus (P), potassium (K), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), selenium (Se), molybdenum (Mo) and iodine (I), in both human milk and milk preparations. Performances in terms of limits of detection and quantification, of repeatability, reproducibility and trueness have been assessed and verified using various reference or certified materials. For certified human milk sample (NIST 1953), recoveries obtained for reference or spiked values are ranged from 93% to 108% (except for Mn at 151%). This robust method using new technology ICP-MS/MS without high pressure digestion is adapted to both routinely and rapidly analyze human milk micro-sample (i.e. less than 250 μL) in the frame of clinical trials but also to be extended to the mineral profiling of milk preparations like infant formula and adult nutritionals.

Official MethodSM 2011.14/ISO 15151:2018/IDF 229:2018 uses microwave digestion of samples and inductively coupled plasma–atomic emission spectrometry for determination of nine elements, including Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn. The method was evaluated in a collaborative study of 25 products, including 13 fortified nutritional products (powders, ready-to-feed liquids, and liquid concentrates), five product placebos, six dairy products (liquids, powders, butter, and processed cheese), and the National Institute for Standards and Technology (NIST) Standard Reference Material (SRM) 1849a, in compliance with AOAC INTERNATIONAL Standard Method Performance Requirement (SMPR®) 2014.004. This study significantly expanded the applicability of Official Method 2011.14 beyond the original scope of chocolate milk powder, dietetic milk powder, infant cereal, peanut butter, and wheat gluten. The study included 14 collaborators from 11 countries, and results were compared to SMPR 2014.004. Accuracy of the method was demonstrated using NIST SRM 1849a, yielding recoveries across all laboratories of 98–101% for the nine elements. Precision for the 13 fortified nutritional product samples was 2.2–3.9% for repeatability (relative SD of repeatability) and 6.0–12.2% for reproducibility (RSDR). Excluding Mn, which was present at a wide range of concentrations, the reproducibility was 6.0–9.5%, meeting the performance requirements of SMPR 2014.004. Placebo samples (not fortified with Cu, Fe, Mn, or Zn) yielded acceptable repeatability of 1.8–2.9% for Ca, K, Mg, Na, and P (minerals) but 5.4–29.4% for the low levels of Cu, Fe, Mn, and Zn (trace elements). Reproducibility for the placebos showed the same pattern, with acceptable reproducibility (5.4–10.3%) for minerals but not for the low levels of the trace elements (13.2–82.8%). In the six dairy product samples, repeatability ranged from 1.6 to 3.6% for the minerals, Zn, and the low range of Mn but from 9.4 to 24.6% for Cu, Fe, and the high range of Mn, where concentrations were low as for the nutritional placebos. Reproducibility in the dairy samples was 5.3–8.8% for the minerals but 11.4–55.0% for the trace elements. The mean concentrations of Cu, Fe, and Zn in the dairy products were similar with those in the placebo products, while Zn was present at levels more similar with the fortified nutritional products. Thus, the method met the SMPR criteria except where the trace minerals were present at very low levels. Based on these results, the AOAC Stakeholder Panel for Infant Formula and Adult Nutritionals recommended Final Action status of the expanded applicability of the method. The method was adopted as Final Action by the AOAC Official Methods Board.

A simple and fast method for the quantification of a series of macro elements (Na, Mg, P, Cl, K and Ca) and trace elements (Mn, Fe, Cu and Zn) by Energy Dispersive X-Ray Fluorescence (ED-XRF) was developed and validated using samples of commercial dry pet foods. All samples were systematically analyzed by reference methods (i.e. Potentiometry for chloride and Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) for other elements) and by ED-XRF. A calibration set of 33 samples was selected to uniformly cover the concentration ranges of each element and their reference method values were used to calibrate the ED-XRF device. A second set (the validation set) was composed of 46 other samples, which were analyzed as unknowns. During this validation step, the elemental concentrations obtained by ED-XRF were systematically evaluated against those obtained from the reference methods. Using robust statistics, for the 10 investigated analytes, the bias between both methods was found to be not significantly different from 0 and the relative uncertainties RSD(u) were found to be lower than 15 %. This study demonstrated that ED-XRF is a fast and reliable method for minerals quantification in dry pet foods.

A single-laboratory validation (SLV) is presented for the simultaneous determination of 10 ultratrace elements (UTEs) including aluminum (Al), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), mercury (Hg), molybdenum (Mo), lead (Pb), selenium (Se), and tin (Sn) in infant formulas, adult nutritionals, and milk based products by inductively coupled plasma (ICP)/MS after acidic pressure digestion. This robust and routine multielemental method is based on several official methods with modifications of sample preparation using either microwave digestion or high pressure ashing and of analytical conditions using ICP/MS with collision cell technology. This SLV fulfills AOAC method performance criteria in terms of linearity, specificity, sensitivity, precision, and accuracy and fully answers most international regulation limits for trace contaminants and/or recommended nutrient levels established for 10 UTEs in targeted matrixes.

The minerals and trace elements that account for about 4% of total human body mass serve as materials and regulators in numerous biological activities in body structure building. Infant formula and milk products are important sources of endogenic and added minerals and trace elements and hence, must comply with regulatory as well as nutritional and safety requirements. In addition, reliable analytical data are necessary to support product content and innovation, health claims, or declaration and specific safety issues. Adequate analytical platforms and methods must be implemented to demonstrate both the compliance and safety assessment of all declared and regulated minerals and trace elements, especially trace-element contaminant surveillance. The first part of this paper presents general information on the mineral composition of infant formula and milk products and their regulatory status. In the second part, a survey describes the main techniques and related current official methods determining minerals and trace elements in infant formula and milk products applied for by various international organizations (AOAC INTERNATIONAL, the International Organization for Standardization, the International Dairy Federation, and the European Committe for Standardization). The third part summarizes method officialization activities by Stakeholder Panels on Infant Formula and Adult Nutritionals and Stakeholder Panel on Strategic Food Analytical Methods. The final part covers a general discussion focusing on analytical gaps and future trends in inorganic analysis that have been applied for in infant formula and milk-based products.

A fully validated and rapid quantitative method is presented for determination of inorganic arsenic [arsenite, As(III) and arsenate, As(V)] and organic arsenic species (methylarsonic acid, dimethylarsinic acid, and arsenobetaine) by ion chromatography paired with inductively coupled plasma/MS after ultrasonic-assisted enzymatic extraction (UAEE) in rice- and seafood-based raw materials and finished products. This method gives toxicological meaning to arsenic analysis, since the sum of the toxic chemical forms As(III) and As(V) can be determined. In contrast to classical water–methanol extraction, UAEE enables drastic acceleration of sample extraction (5 min instead of several hours), while total arsenic extraction efficiency is improved without species conversion. Validation was performed to evaluate the method for selectivity, linearity, LOD/LOQ (0.007–0.020 mg/kg), trueness, precision (HorRat values, 0.2–0.6), recovery (93–122%), and uncertainty. The method was also satisfactorily tested using two proficiency tests. Performance characteristics are reported for four certified reference materials, standard reference material (SRM) 1568a (rice flour), Institute for Reference Materials and Measurements 804 (rice flour), SRM 2976 (mussel tissue), certified reference material-627 (tuna fish), and several commercial food samples populating five AOAC triangle food sectors. The results indicated that this speciation method is cost-efficient, time-saving, and accurate, as well as fit-for-purpose, according to International Organization for Standardization/International Electrotechnical Commission 17025:2005 standard, and could be used for routine analysis.

A single-laboratory validation (SLV) and a ring trial (RT) were undertaken to determine nine nutritional elements in food products by inductively coupled plasma-atomic emission spectroscopy in order to improve and update AOAC Official Method 984.27. The improvements involved optimized microwave digestion, selected analytical lines, internal standardization, and ion buffering. Simultaneous determination of nine elements (calcium, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, and zinc) was made in food products. Sample digestion was performed through wet digestion of food samples by microwave technology with either closed or open vessel systems. Validation was performed to characterize the method for selectivity, sensitivity, linearity, accuracy, precision, recovery, ruggedness, and uncertainty. The robustness and efficiency of this method was proved through a successful internal RT using experienced food industry laboratories. Performance characteristics are reported for 13 certified and in-house reference materials, populating the AOAC triangle food sectors, which fulfilled AOAC criteria and recommendations for accuracy (trueness, recovery, and z-scores) and precision (repeatability and reproducibility RSD and HorRat values) regarding SLV and RT. This multielemental method is cost-efficient, time-saving, accurate, and fit-for-purpose according to ISO 17025 Norm and AOAC acceptability criteria, and is proposed as an improved version of AOAC Official Method 984.27 for fortified food products, including infant formula.

A single-laboratory validation (SLV) and a ring trial (RT) were undertaken to determine nine nutritional elements in food products by inductively coupled plasma-optical emission spectrometry in order to modernize AOAC Official MethodSM 984.27. The improvements involved extension of the scope to all food matrixes (including infant formula), optimized microwave digestion, selected analytical lines, internal standardization, and ion buffering. Simultaneous determination of nine elements (calcium, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, and zinc) was made in food products. Sample digestion was performed through wet digestion of food samples by microwave technology with either closed- or open-vessel systems. Validation was performed to characterize the method for selectivity, sensitivity, linearity, accuracy, precision, recovery, ruggedness, and uncertainty. The robustness and efficiency of this method was proven through a successful RT using experienced independent food industry laboratories. Performance characteristics are reported for 13 certified and in-house reference materials, populating the AOAC triangle food sectors, which fulfilled AOAC criteria and recommendations for accuracy (trueness, recovery, and z-scores) and precision (repeatability and reproducibility RSD, and HorRat values) regarding SLVs and RTs. This multielemental method is cost-efficient, time-saving, accurate, and fit-for-purpose according to ISO 17025 Norm and AOAC acceptability criteria, and is proposed as an extended updated version of AOAC Official MethodSM 984.27 for fortified food products, including infant formula.

We measured the translational diffusion of fractions of dextrans labelled with fluorescein isothiocyanate, in Sephadex gel beads permeated by aqueous solutions of these molecules. The molecular weights of these fractions were between 5400 and 200 000 and measurements of their diffusion coefficients inside a gel bead (D) and in the free solution (D0), were performed using the fluorescence recovery after photobleaching method (FRAP). We also determined the coefficient of partitioning (Kav) of these fractions between the gel and the free solvent, with a new microfluorimetric method. We found that, for Sephadex G-50, G-75, G-100, G-150 and G-200 gels, Kav varied with the Stokes radius (rs) of the dextran molecules, in agreement with the formula of Laurent and Killander (J. Chromatogr. 14 (1964) 317). For Sephadex G-100, G-150 and G-200 gels, D/D0 varied with rs according to the theory of Ogston et al. (Proc. R. Soc. Lond. 333 (1973) 297). In addition, these theories predict a relation linking D/D0 to Kav which was wen verified. Our work is the first systematic study of the translational diffusion of macromolecules in a chromatography gel. These measurements should allow a better evaluation of the factors which influence the resolution in exclusion chromatography. In addition, the diffusion of macromolecules in gels may provide models for the diffusion of these molecules in the cytoplasm of living cells and in connective biological tissues.