Fortified Milk Powder Research Articles

Metabolism and transcriptional response mechanisms insight into the Lacticaseibacillus paracasei under the intervention of milk powder storage by-products

To explore the influence of milk powder storage by-products on the probiotic activity, Lacticaseibacillus paracasei JY025 fortified milk powder was used to evaluate the change of bacterial activity and the accumulation of Maillard and lipid oxidation by-products during long-term storage. Based on the above results, this study further clarifies the effect mechanism of milk powder by-products on the metabolism and transcriptional response of Lacticaseibacillus paracasei JY025. The results of the strain JY025 growth ability and its metabolic ability of various carbon sources under different by-product interventions indicated that the Maillard by-products (higher concentrations) and the lipid oxidation by-products inhibit the growth metabolic of Lactobacillus. The transcriptomic analysis of strains under different interventions further suggested the intervention of Maillard by-products with a specific concentration improve the ability of Lactobacillus to utilize carbohydrates, which helps to provide additional energy and improve the tolerance of Lactobacillus to lipid oxidation by-product stress.

Fortification of milk powder with cashew apple juice using maltodextrin as a carrier material: A novel dairy recipe.

Food preservation and fortification pose significant challenges in the fruit and dairy sectors, particularly in developing regions with limited infrastructure and rising production volumes. Cashew apples, rich in antioxidants such as vitamin C and polyphenolic compounds, often go to waste due to their high perishability. In Goa, India, these discarded fruits are used to produce "Feni," an alcoholic beverage, but broader utilization strategies are still needed. This study introduces a novel approach to extend the shelf life of dairy products like milk powder and enhance their nutritional content by fortifying it with cashew apple juice (CAJ) through spray drying. In order to reduce moisture content during spray drying and to obtain a free-flowing powder of the final product, maltodextrin was added. Maltodextrin alters the adhesive properties of the fruit juice droplets on surfaces and facilitates the formulation of free-flowing powder. The key parameters including solubility, bulk density, and glass transition temperature, along with structural analyses such as X-ray diffraction, field emission scanning electron microscope, and Fourier transform infrared spectroscopy, were evaluated to compare the fortified CAJ milk powder with its commercial counterparts. Experiments determined optimal spray-drying conditions, achieving a free-flowing powder at inlet and outlet temperatures of 140 and 60°C, respectively, with a 7% maltodextrin concentration (18 DE). The resulting milk powder displayed a Tg value of 76.7 ± 2.3°C, falling within the acceptable range of 65 to 98°C, demonstrating the feasibility of this fortification method based on the spray-drying process parameters.

Voltammetric Sensor Based on Molybdenum-Vanadium-Lithium-Borate Glassy Matrix and Its Application for the Determination of Iron in Fortified Milk Powder

Voltammetric Sensor Based on Molybdenum-Vanadium-Lithium-Borate Glassy Matrix and Its Application for the Determination of Iron in Fortified Milk Powder

Mechanistic insights into the changes of biological activity and physicochemical characteristics in Lacticaseibacillus paracasei fortified milk powder during storage

To clarify the change mechanism of biological activity and physicochemical characteristics in Lacticaseibacillus paracasei JY025 fortified milk powder (LFMP) during storage, morphological observation, JY025 survival, storage stability, and metabolomics of LFMP were determined during the storage period in this study. The results showed that the LFMP had a higher survival rate of JY025 compared with the bacterial powder of JY025 (LBP) during storage, which suggested that milk powder matrix could reduce strain JY025 mortality under prolonged storage in the LFMP samples. The fortification of strain JY025 also affected the stability of milk powder during the storage period. There was lower water activity and higher glass transition temperature in LFMP samples compared with blank control milk powder (BCMP) during storage. Moreover, the metabolomics results of LFMP indicated that vitamin degradation, Maillard reaction, lipid oxidation, tricarboxylic acid cycle, and lactobacilli metabolism are interrelated and influence each other to create complicated metabolism networks.

Lacticaseibacillus paracasei JY025 fortified milk powder: In vitro digestion characteristics and accelerated storage stability

To clarify the reciprocal influence between the fortified bacterial powder of Lacticaseibacillus paracasei JY025 (LBP) with milk powder matrix during the gastrointestinal digestion and storage period, the digestion characteristics and storage stability of Lacticaseibacillus paracasei JY025 fortified milk powder (LFMP) were explored in this study by the in vitro simulated digestion and the accelerated storage. The results showed that the milk powder matrix significantly improved the survival of JY025 during the simulated digestion (the highest improvement of 27%) and storage period (the highest improvement of 37%), which suggests the milk powder matrix can be an effective strategy to enhance the viability of probiotics during the digestion and storage period. Moreover, the digestion characteristics and the physicochemical properties of the milk powder matrix were changed due to the fortified LBP during the simulated digestion and storage period. The fortified LBP decreased the particle size of milk powder digest and promoted the hydrolysis of milk protein during digestion due to the effect of both maltodextrin (wall material) and bacteria. The fortified LBP also increased the particle size of milk powder matrix and decreased the Maillard reaction of milk powder matrix during the storage period, which is closely related to the storage condition.

Development of a Screening Tool to Estimate Vitamin A Intake and Comparison with Detailed Dietary Assessment Methods

Abstract Objectives We aimed to develop and validate a tool to estimate vitamin A (VA) intake and identify children at risk of intake above the tolerable upper intake level (UL). Methods We developed, pilot-tested, and refined a screening tool to estimate VA intake among Filipino children 12–18 mo of age. Data were entered into tablets with pre-loaded food composition data to calculate VA intake immediately. The screening tool was used to identify children likely to have “adequate” (one group: 200–500 µg retinol activity equivalents, RAE/d) or “high” (two groups: >600 µg retinol/d) intake. Interviewers administered four 24-h recalls, one 12-h observed weighed record with 12-h recall, and a 30-d supplement questionnaire. Breastmilk intake and VA concentration were measured among breastfeeding children. We compared the screening tool and detailed dietary assessment (DDA) results for primary VA sources, group mean usual intake, and prevalence of intakes above the UL. Results Major VA sources were similar between methods: fortified milk powders, multivitamin supplements, and breastmilk; contributions from intervention programs (e.g., micronutrient powders, fortified staple foods) were low. Mean usual retinol intakes for the high groups (n = 47 and 39, respectively) were 1218 and 1313 µg/d by screening tool vs. 1096 and 931 by DDA; 70 and 77% had usual intake above 600 µg/d. In the adequate group (n = 37), mean total VA intake was 375 and 559 µg RAE/d by screening and DDA, respectively. Conclusions This screening tool provides a reasonably good rapid estimate of VA intake among Filipino children and can be useful for identifying groups with adequate to excessive intakes. Funding Sources Bill & Melinda Gates Foundation.

Milk Powder Fortified with Potassium and Phytosterols to Decrease the Risk of Cardiovascular Events among the Adult Population in Malaysia: A Cost-Effectiveness Analysis.

This study evaluated the cost-effectiveness of the consumption of a milk powder product fortified with potassium (+1050.28 mg/day) and phytosterols (+1200 mg/day) to lower systolic blood pressure and low-density lipoprotein cholesterol, respectively, and, therefore, the risk of myocardial infarction (MI) and stroke among the 35–75-year-old population in Malaysia. A Markov model was created against a do-nothing option, from a governmental perspective, and with a time horizon of 40 years. Different data sources, encompassing clinical studies, practice guidelines, grey literature, and statistical yearbooks, were used. Sensitivity analyses were performed to evaluate the impact of uncertainty on the base case estimates. With an incremental cost-effectiveness ratio equal to international dollars (int$) 22,518.03 per quality-adjusted life-years gained, the intervention can be classified as very cost-effective. If adopted nationwide, it would help prevent at least 13,400 MIs, 30,500 strokes, and more than 10,600 and 17,100 MI- and stroke-related deaths. The discounted cost savings generated for the health care system by those who consume the fortified milk powder would amount to int$8.1 per person, corresponding to 0.7% of the total yearly health expenditure per capita. Sensitivity analyses confirmed the robustness of the results. Together with other preventive interventions, the consumption of milk powder fortified with potassium and phytosterols represents a cost-effective strategy to attenuate the rapid increase in cardiovascular burden in Malaysia.

Artefact formation of formaldehyde in milk powders: Impact of analytical conditions

Formaldehyde (FA) was analyzed in milk powders by isotope dilution LC-MS/MS using 2,4-dinitrophenylhydrazine (DNPH) as the derivatization agent. Analytical conditions (temperature and time) applied for derivatization were shown to strongly impact the levels of FA detected in micronutrient-fortified milk powders. In particular, vitamin C and ferrous iron catalyzed FA formation when derivatization was conducted at 60 °C, as described by several authors. Artefact formation of FA was demonstrated in a model study using 2H2-glycine and a freeze-dried raw cow's milk with added micronutrients. A limited survey of commercial fortified milk powders showed that FA levels were about 4-fold lower when analyses were conducted at room temperature as compared to 60 °C (0.65 ± 0.25 mg/kg and 2.57 ± 0.51 mg/kg, respectively). Based on data obtained at room temperature, FA exposure from fortified milk powders does not represent a safety concern even under worst-case assumptions. This study highlights the need and importance of adopting an international standard for FA analysis in foods.

Impact of diet on vitamin D status in a selected population of pregnant mothers in Sri Lanka

Context: Results of various studies have shown severe vitamin D deficiency in the Indian subcontinent in all age groups and insufficiency in populations of South-East and East Asia. There are no data available in Sri Lanka on vitamin D status in pregnant mothers. Vitamin D supplements are not provided routinely in state sector clinics. Institute of Medicine of the National Academy of Sciences in the USA recommends safe upper limit of dietary vitamin D as 4000 IU.Aims: Thus, our aim of this study was to assess vitamin D status and adequacy of vitamin D intake through diet among pregnant mothers.Settings and Design: This is a secondary analysis of data of a prospective cohort study.Methods and Material: 89 pregnant mothers in their 3rd trimester were recruited. Food frequency questionnaire based on 7-day estimated food record method was used. Analysis of blood sample was done for vitamin D, parathyroid hormone (PTH), calcium, inorganic phosphorous and alkaline phophatase levels.Statistical analysis used: Spearman’s correlation and independent sample t-test were performed.Results: We found that 12.4%, 50.6% and 37.1% were vitamin D deficient, insufficient and sufficient respectively. 25(OH)D and PTH showed a significant negative correlation (r=0.296; P<0.01). Yet, serum PTH level was above the cut-off only among 4.5%. Further, only 13.5% subjects had high ALP (>240 IU/L). Average daily intake of vitamin D through diet was 1289.4 ± 1225.6 IU/day (range 56 IU- 5400 IU). Significant Main source of vitamin D was fortified milk powder and small fish.Conclusions: High rate of vitamin D insufficiency/deficiency was observed and this novel finding in our cohort suggests investigating vitamin D status in pregnant mothers at a national level. Vitamin D intake through diet was not adequate in our study sample. Further, rigorous trails are needed to evaluate the requirement for supplementation to optimise the bone metabolism during pregnancy in Sri Lanka.

Impact of diet on vitamin D status in a selected population of pregnant mothers in Sri Lanka

Context: Results of various studies have shown severe vitamin D deficiency in the Indian subcontinent in all age groups and insufficiency in populations of South-East and East Asia. There are no data available in Sri Lanka on vitamin D status in pregnant mothers. Vitamin D supplements are not provided routinely in state sector clinics. Institute of Medicine of the National Academy of Sciences in the USA recommends safe upper limit of dietary vitamin D as 4000 IU. Aims: Thus, our aim of this study was to assess vitamin D status and adequacy of vitamin D intake through diet among pregnant mothers. Settings and Design: This is a secondary analysis of data of a prospective cohort study. Methods and Material: 89 pregnant mothers in their 3rd trimester were recruited. Food frequency questionnaire based on 7-day estimated food record method was used. Analysis of blood sample was done for vitamin D, parathyroid hormone (PTH), calcium, inorganic phosphorous and alkaline phophatase levels. Statistical analysis used: Spearman’s correlation and independent sample t-test were performed. Results: We found that 12.4%, 50.6% and 37.1% were vitamin D deficient, insufficient and sufficient respectively. 25(OH)D and PTH showed a significant negative correlation (r=0.296; P<0.01). Yet, serum PTH level was above the cut-off only among 4.5%. Further, only 13.5% subjects had high ALP (>240 IU/L). Average daily intake of vitamin D through diet was 1289.4 ± 1225.6 IU/day (range 56 IU- 5400 IU). Significant Main source of vitamin D was fortified milk powder and small fish. Conclusions: High rate of vitamin D insufficiency/deficiency was observed and this novel finding in our cohort suggests investigating vitamin D status in pregnant mothers at a national level. Vitamin D intake through diet was not adequate in our study sample. Further, rigorous trails are needed to evaluate the requirement for supplementation to optimise the bone metabolism during pregnancy in Sri Lanka.

Analysis of Vitamin D₂ and Vitamin D₃ in Infant and Adult Nutritional Formulas by Liquid Chromatography-Tandem Mass Spectrometry: A Multilaboratory Testing Study.

A multilaboratory testing study was conducted on AOAC First Action Method 2016.05 "Analysis of Vitamin D2 and Vitamin D3 in Fortified Milk Powders, Infant Formulas, and Adult/Pediatric Nutritional Formulas by Liquid Chromatography-Tandem Mass Spectrometry." Nine laboratories participated in the analysis of duplicate samples of 20 nutritional products. The samples were saponified at high temperature with lipid-soluble components extracted into isooctane; an aliquot was washed and vitamin D derivatized with 4-phenyl-1,2,4-triazoline-3,5-dione to form a high-molecular mass, easily ionizable adduct, extracted into acetonitrile and analyzed by reversed-phase LC-tandem MS. Stable isotope-labeled internal standards were used for quantitation to correct for losses in extraction and variation in derivatization and ionization efficiencies. Acceptable precision as RSD was demonstrated; repeatability ranged from 1.9 to 5.8% RSDr and reproducibility values ranged from 6.4 to 12.7% RSDR, with samples meeting the precision limits specified in the vitamin D Standard Method Performance Requirements and the guidelines recommended for the Horwitz ratio. Method accuracy was assessed using NIST 1849a Standard Reference Material, with a P-value of 0.32, indicating an absence of bias against the certified value. As expected, placebo samples not fortified with vitamin D returned negligible results.

Analysis of Vitamin D₂ and Vitamin D₃ in Fortified Milk Powders and Infant and Nutritional Formulas by Liquid Chromatography-Tandem Mass Spectrometry: Single-Laboratory Validation, First Action 2016.05.

A method for the determination of vitamin D2 and vitamin D3 in fortified milk powders and infant and adult nutritional formulas is described. Samples are saponified at high temperature and lipid-soluble components are extracted into isooctane. A portion of the isooctane layer is transferred and washed, and an aliquot of 4-phenyl-1,2,4-triazoline-3,5-dione is added to derivatize the vitamin D to form a high-molecular-mass, easily ionizable adduct. The vitamin D adduct is then re-extracted into a small volume of acetonitrile and analyzed by RPLC. Detection is by tandem MS, using multiple reaction monitoring. Stable isotope-labeled vitamin D2 and vitamin D3 internal standards are used for quantitation to correct for losses in extraction and any variation in derivatization and ionization efficiencies. A single-laboratory validation of the method using AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) kit samples was performed and compared with parameters defined according to the vitamin D Standard Method Performance Requirements (SMPR(®)). Linearity was demonstrated over the range specified in the SMPR, with the LOD being estimated at below that required. Method spike recovery (vitamin D2, 97.0-99.2%; and vitamin D3, 96.0-101.0%) and RSDr (vitamin D3, 1.5-5.2%) were evaluated and compared favorably with limits in the vitamin D SMPR. Acceptable bias for vitamin D3 was demonstrated against both the certified value for National Institute of Standards and Technology 1849a Standard Reference material (P(α = 0.05) = 0.25) and AOAC INTERNATIONAL reference method 2002.05 (P(α = 0.05) = 0.09). The method was demonstrated to meet the requirements of the vitamin D SMPR as defined by SPIFAN, and was recently approved for Official First Action status by the AOAC Expert Review Panel on SPIFAN Nutrient Methods.

Analysis of Vitamin D2 and Vitamin D3 in Fortified Milk Powders and Infant and Nutritional Formulas by Liquid Chromatography-Tandem Mass Spectrometry: Single-Laboratory Validation, First Action 2016.05.

A method for the determination of vitamin D2 and vitamin D3 in fortified milk powders and infant and adult nutritional formulas is described. Samples are saponified at high temperature and lipid-soluble components are extracted into isooctane. A portion of the isooctane layer is transferred and washed, and an aliquot of 4-phenyl-1,2,4-triazoline-3,5-dione is added to derivatize the vitamin D to form a high-molecular-mass, easily ionizable adduct. The vitamin D adduct is then re-extracted into a small volume of acetonitrile and analyzed by RPLC. Detection is by tandem MS, using multiple reaction monitoring. Stable isotope-labeled vitamin D2 and vitamin D3 internal standards are used for quantitation to correct for losses in extraction and any variation in derivatization and ionization efficiencies. A single-laboratory validation of the method using AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) kit samples was performed and compared with parameters defined according to the vitamin D Standard Method Performance Requirements (SMPR(®)). Linearity was demonstrated over the range specified in the SMPR, with the LOD being estimated at below that required. Method spike recovery (vitamin D2, 97.0-99.2%; and vitamin D3, 96.0-101.0%) and RSDr (vitamin D3, 1.5-5.2%) were evaluated and compared favorably with limits in the vitamin D SMPR. Acceptable bias for vitamin D3 was demonstrated against both the certified value for National Institute of Standards and Technology 1849a Standard Reference material (P(α = 0.05) = 0.25) and AOAC INTERNATIONAL reference method 2002.05 (P(α = 0.05) = 0.09). The method was demonstrated to meet the requirements of the vitamin D SMPR as defined by SPIFAN, and was recently approved for Official First Action status by the AOAC Expert Review Panel on SPIFAN Nutrient Methods.

Determination of vitamin A and vitamin E esters in infant formulae and fortified milk powders by HPLC: Use of internal standardisation

An HPLC method is described using normal phase conditions with an unbonded silica column to determine concentrations of supplementary vitamin A and vitamin E esters and β-carotene in infant formulae. The method utilises selective dual-channel fluoresence for vitamins A and E and visible absorbance for β-carotene. An attribute of the method is the use of retinol propionate, α-tocopheryl propionate and all-E-β-apo-8′-carotenoic acid ethyl ester internal standards to compensate for analytical variations associated with these labile vitamins. Extraction is performed without saponification, with the aid of protease to remove vitamin encaspsulation and facilitate vitamin partition into hydrocarbon solvent. Figures of merit indicate the method is suitable for its intended purpose in the highly regulated infant formula environment, including liquid formulations. The method is extendable to whole milk powders where total vitamin A content data can be calculated by summing the innate long-chain vitamin A esters with the added esters.

Absorption and Bioavailability of Nano-Size Reduced Calcium Citrate Fortified Milk Powder in Ovariectomized and Ovariectomized-Osteoporosis Rats

The aim of this study was to evaluate the effects of fortification and nano-size reduction on calcium absorption and bioavailability of milk powder formula in sham, ovariectomized, and ovariectomized-osteoporosis rats as a menopause and menopause-osteoporosis model. Skim milk powder and skim milk powder fortified with calcium citrate and the suitable doses of inulin, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and vitamins D3, K1, and B6 were formulated based on the North American and Western European recommended dietary allowances. Optimization on cycle and pressure of high-pressure homogenizer was done to produce nano-fortified milk powder. In vivo study demonstrated that fortification and calcium citrate nano-fortified milk powder increased absorption and bioavailability of calcium, as well as bone stiffness and bone strength in sham, ovariectomized, and ovariectomized-osteoporosis rats. This study successfully developed an effective fortified milk powder for food application.

Zinc Absorption from Fortified Milk Powder in Adolescent Girls.

Zinc (Zn) is essential for development, growth, and reproduction. The Mexican government subsidizes micronutrient-fortified milk for risk groups, with positive effect on the targeted groups' plasma Zn level, inferring a good absorption is achieved although it has not being measured. The aim of this study was to determine the impact of micronutrient-fortified milk intake during 27days on Zn absorption in adolescent girls from northwest Mexico. Therefore, Zn absorption was evaluated in 14 healthy adolescent girls (14.1years old) with adequate plasma Zn levels, before and after 27days of fortified Zn milk intake. Fractional Zn absorption (FZA) was calculated from urinary ratios of stable isotopic Zn tracers administered orally and intravenously on days 0 and 27, and total absorbed Zn (TZA) was calculated. At the beginning, Zn intake was 6.8 ± 0.85mg/d (mean ± SE), and 50% of the adolescent girls did not achieve their requirement (7.3mg/d). Additionally, FZA was negatively correlated with Zn intake (r =-0.61, p = 0.02), while TZA (1.06mg/d) was insufficient to cover the physiologic requirements of adolescent girls (3.02mg/d). At the end of the intervention, all the girls reached the Zn intake recommendation and TZA, 3.09mg/d, which was enough to meet the physiological requirement for 57% of the adolescent girls. Therefore, the low Zn intake and the Zn status of adolescent girls were positively impacted by Zn-fortified milk intake and its good absorption rate.

Influence of nano-size reduction on absorption and bioavailability of calcium from fortified milk powder in rats

The present study aimed to investigate the effects of fortification and nano-size reduction on absorption and bioavailability of calcium from the fortified milk in ovariectomized (OVX) and OVX-osteoporosis rats. The main goal was to determine the effect of daily consumption of experimental diets on serum calcium, feces calcium, bone calcium, bone breaking strength and bone morphology among rats. This study was conducted to optimize the preparation of nano-fortified milk powder. Then, the calcium bioavailability in 64 female OVX rats and OVX-osteoporosis rats was investigated. The results revealed that bone breaking strength (maximum load) and bone calcium increased with consumption of nano-fortified diet compared with fortified diet. The same observations were seen for bone morphology. OVX rats exhibited higher calcium bioavailability and absorption than OVX-osteoporosis rats with regard to fortified and nano-fortified diets. The amount of calcium absorption from fortified and nano-fortified milk powders in OVX rats was 63.54% and 89.06%, respectively. The bioavailability of calcium from fortified and nano-fortified milk powders in OVX rats was 24.64% and 41.65%, respectively. Moreover, the calcium bioavailability (%) from fortified and nano-fortified milk powders in OVX-osteoporosis rats was 9.74% and 30.17%, respectively. In OVX-osteoporosis group, the absorption levels of calcium from the same experimental diets were 60.54% and 89.09%, respectively.

Pyridoxine analysis by high performance liquid chromatography and validation in fortified milk powder

Vitamin B6 analysis by reverse-phase high performance liquid chromatography and its validation in milk powder prompted this study. The calibration curves for pyridoxal, pyridoxamine and pyridoxine were evaluated and method precision and accuracy assessed. It was found that the working range was adequate for all the analytes. The analytical procedure was verified by testing the enzymatic efficiency, precision and accuracy. In milk powder samples pyridoxine was the only vitamer found in quantities above the considered limit of quantification and the accuracy showed Z-scores lower than 2. Uncertainty estimation based on method validation results was 0.066 mg/100g, for a vitamin B6 content of 0.61 mg/100 g. It was concluded that the method is adequate for vitamin B6 quantification in powder milk.

Review of milk and dairy programmes affecting nutrition

This review examined milk programmes affecting nutrition in developing countries through multiple pathways. Four programme typologies were identified: dairy production and agriculture, school-based, fortified milk and milk powder and blended foods. Evidence was rated by inference level with plus signs indicating positive design features: probability (1), plausibility (2) and adequacy (3). Six of the 24 studies were rated 1, demonstrating a causal link between milk intervention and nutrition outcome. High-quality evaluations and cost-effectiveness analyses are needed. Milk programming that capitalises on its nutritional advantages, positive public perception and complementary poverty reduction strategies shows potential for improving nutrition globally.

Determination of cyanuric acid using exact matching isotope dilution mass spectrometry

A high-accuracy double isotope dilution mass spectrometric method using an exact matching approach with GC coupled to a mass spectrometer for the analysis of cyanuric acid in fortified milk powder was developed. Various parameters for sample clean-up such as the type of SPE cartridge, GC column and type of derivatizing agent used were investigated. The method was found to be linear in the concentration range of 0.03 to 2 mg/kg of cyanuric acid in milk powder. LOD and LOQ were found to be 0.9 and 3 μg/kg, respectively. Recoveries in the range of 95.7 to 102.2% were obtained for the in-house fortified milk powder samples, with RSD of measurements in the range of 0.2 to 3.0%. A metrological approach was undertaken to examine all possible biases that contributed to the combined measurement uncertainty of the method. This high-accuracy method can serve as a reference method for techniques commonly applied in routine testing laboratories.