Method Review by Stakeholder Panel for Infant Formulas and Adult Nutritionals (SPIFAN). Method Review by Expert Review Panel for Nutrient Methods. *
This method was awarded the 2017 Method of the Year Award by AOAC International at the AOAC Annual Meeting & Conference, Atlanta, GA, USA, 25th September 2017.
An optical biosensor immunoassay exploiting surface plasmon resonance is described for the quantification of β‑lactoglobulin in milk. Samples were diluted with buffer, and the protein estimated from binding with a polyclonal antibody immobilised on the sensor surface. Analytical method performance characteristics including range, detection limit, precision and accuracy were determined and reported. The temporal variability in the β‑lactoglobulin content of milk from pasture-fed cows during early lactation and across a production season was investigated. The content of β‑lactoglobulin decreased from >10 mg/mL in early colostrum to <5 mg/mL in mature milk, and the β‑lactoglobulin content of skim milk powder trended from 25 to 60 mg/g across a season. In view of its allergenicity, these data will improve understanding of the expression of innate β‑lactoglobulin in the milk of pasture-grazed dairy herds, thereby providing information that is applicable to the formulation of bovine milk-based products.
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 highmolecular mass, easily ionizable adduct, extracted into acetonitrile and analyzed by reversed-phase LC-tandem MS. Stable isotopelabeled 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% RSD(r) and reproducibility values ranged from 6.4 to 12.7% RSD(R), 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.
Background: Biotin and folate are B‑group vitamins that play a critical role in numerous metabolic reactions and are supplemented to infant and adult nutritional formulas as free biotin and folic acid. Objective: A rapid method for the analysis of biotin and folic acid that is applicable to liquid milk, milk powders, infant formula, and milk-based nutritional products is described. Methods: Samples are autoclaved, centrifuged, filtered, and analyzed by high performance liquid chromatography-tandem mass spectrometry, with quantitation accomplished by the internal standard technique. Results: The method was shown to be accurate, with acceptable spike recovery (biotin: 96.5–108.2%; folic acid: 92.6–104.4%), and no bias (α = 0.05) against either a certified reference material (biotin: p = 0.70; folic acid: p = 0.23) or established analytical methods (biotin: p = 0.10; folic acid: p = 0.48) was found. Acceptable precision was confirmed with repeatability relative standard deviation and Horwitz ratio values (biotin: RSDr = 0.5–5.6%, HorRatr = 0.1–0.6; folic acid: RSDr = 2.0–3.1%, HorRatr = 0.3–0.5). Method detection limit and ruggedness experiments further demonstrated the suitability of this method for routine compliance testing. Conclusions: This rapid method is intended for use in high-throughput laboratories as part of routine product compliance release testing of biotin and folic acid as part of the manufacture of infant formulas and adult nutritional products.
Sample preparation techniques for the analysis of vitamin D3 in food matrices typically utilise a saponification step, either at room temperature or at elevated temperatures. A calciferol (vitamin D2 or isotope labelled vitamin D3) is generally chosen as the internal standard to compensate for changes of previtamin D3-vitamin D3 isomerisation during analysis, as well as to correct for analyte loss through complex sample preparation steps. Manufacturing practices and processing parameters contribute to previtamin D formation in food products. A significant proportion (5.6–8.3%) of the total vitamin D3 in premixes was found as previtamin D3, indicating that it is likely, depending upon storage temperature and the time since manufacture, that a vitamin D3-fortified food product will contain a similar proportion of previtamin D3 prior to analysis. Conversely, freshly-prepared internal standard solutions have low previtamin D levels (<1%). In lieu of direct measurement, this discrepancy in previtamin D content between the internal standard and analyte forms of vitamin D will lead to analytical bias. To mitigate this as a source of potential error, it is recommended that sample pre-treatment steps are appropriately set and controlled. Based on this work, saponification times greater than 300, 120, or 60 min for temperatures of 60, 70, or 80 ℃ respectively should be employed and that saponification at room temperature be avoided.
Conventional methods using HPLC with UV detection have used vitamin D2 as an internal standard with the expectation that this fully compensates for the heat-dependent equilibrium of vitamin D3 with its previtamin. Previtamin D has a different spectral absorptivity from vitamin D and may be present in different proportions in samples and standards. Therefore, vitamin D2 and vitamin D3 and their previtamin forms must be chromatographically resolved to achieve accurate quantitation of total vitamin D. This study identified four chromatographic columns (ACE C18, ACE C18 AR, Vydac 201 TP C18 and Polaris C18-Ether) with adequate selectivity that should be applied for food testing and further confirmed that both parent vitamins isomerise at the same rate under thermal conditions.
Received: 15 May 2016; Accepted: 15 June 2016; Published: 01 January 2017
Citation Journal Paper Manuscript Abstract.ris MLA APA Chicago Harvard Vancouver
Method Review by Stakeholder Panel for Infant Formulas and Adult Nutritionals (SPIFAN). Method Review by Expert Review Panel for Nutrient Methods.
* This method was awarded the 2017 Method of the Year Award by AOAC International at the AOAC Annual Meeting & Conference, Atlanta, GA, USA, 25th September 2017.
Received: 10 April 2017; Accepted 30 May 2017; Published: 12 June 2017
Citation Citation Paper Manuscript Abstract.ris MLA APA Chicago Harvard Vancouver
An optical biosensor immunoassay exploiting surface plasmon resonance is described for the quantification of β‑lactoglobulin in milk. Samples were diluted with buffer, and the protein estimated from binding with a polyclonal antibody immobilised on the sensor surface. Analytical method performance characteristics including range, detection limit, precision and accuracy were determined and reported. The temporal variability in the β‑lactoglobulin content of milk from pasture-fed cows during early lactation and across a production season was investigated. The content of β‑lactoglobulin decreased from >10 mg/mL in early colostrum to <5 mg/mL in mature milk, and the β‑lactoglobulin content of skim milk powder trended from 25 to 60 mg/g across a season. In view of its allergenicity, these data will improve understanding of the expression of innate β‑lactoglobulin in the milk of pasture-grazed dairy herds, thereby providing information that is applicable to the formulation of bovine milk-based products.
Received: 19 April 2017; Accepted: 30 May 2017; Published: 23 November 2017
Citation Journal Paper Manuscript Abstract.ris MLA APA Chicago Harvard Vancouver
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 highmolecular mass, easily ionizable adduct, extracted into acetonitrile and analyzed by reversed-phase LC-tandem MS. Stable isotopelabeled 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% RSD(r) and reproducibility values ranged from 6.4 to 12.7% RSD(R), 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.
Received: 19 February 2018; Accepted: 27 March 2018; Published: 23 November 2019
Citation Journal Paper Manuscript Abstract.ris MLA APA Chicago Harvard Vancouver
Background: Biotin and folate are B‑group vitamins that play a critical role in numerous metabolic reactions and are supplemented to infant and adult nutritional formulas as free biotin and folic acid. Objective: A rapid method for the analysis of biotin and folic acid that is applicable to liquid milk, milk powders, infant formula, and milk-based nutritional products is described. Methods: Samples are autoclaved, centrifuged, filtered, and analyzed by high performance liquid chromatography-tandem mass spectrometry, with quantitation accomplished by the internal standard technique. Results: The method was shown to be accurate, with acceptable spike recovery (biotin: 96.5–108.2%; folic acid: 92.6–104.4%), and no bias (α = 0.05) against either a certified reference material (biotin: p = 0.70; folic acid: p = 0.23) or established analytical methods (biotin: p = 0.10; folic acid: p = 0.48) was found. Acceptable precision was confirmed with repeatability relative standard deviation and Horwitz ratio values (biotin: RSDr = 0.5–5.6%, HorRatr = 0.1–0.6; folic acid: RSDr = 2.0–3.1%, HorRatr = 0.3–0.5). Method detection limit and ruggedness experiments further demonstrated the suitability of this method for routine compliance testing. Conclusions: This rapid method is intended for use in high-throughput laboratories as part of routine product compliance release testing of biotin and folic acid as part of the manufacture of infant formulas and adult nutritional products.
Received: 11 October 2018; Accepted: 07 January 2019; Published: 15 January 2019
Citation Journal Paper Manuscript Abstract.ris MLA APA Chicago Harvard Vancouver
Sample preparation techniques for the analysis of vitamin D3 in food matrices typically utilise a saponification step, either at room temperature or at elevated temperatures. A calciferol (vitamin D2 or isotope labelled vitamin D3) is generally chosen as the internal standard to compensate for changes of previtamin D3-vitamin D3 isomerisation during analysis, as well as to correct for analyte loss through complex sample preparation steps. Manufacturing practices and processing parameters contribute to previtamin D formation in food products. A significant proportion (5.6–8.3%) of the total vitamin D3 in premixes was found as previtamin D3, indicating that it is likely, depending upon storage temperature and the time since manufacture, that a vitamin D3-fortified food product will contain a similar proportion of previtamin D3 prior to analysis. Conversely, freshly-prepared internal standard solutions have low previtamin D levels (<1%). In lieu of direct measurement, this discrepancy in previtamin D content between the internal standard and analyte forms of vitamin D will lead to analytical bias. To mitigate this as a source of potential error, it is recommended that sample pre-treatment steps are appropriately set and controlled. Based on this work, saponification times greater than 300, 120, or 60 min for temperatures of 60, 70, or 80 ℃ respectively should be employed and that saponification at room temperature be avoided.
Received: 16 July 2018; Accepted: 26 February 2019; Published: 27 February 2019
Citation Journal Paper Manuscript Abstract.ris MLA APA Chicago Harvard Vancouver
Conventional methods using HPLC with UV detection have used vitamin D2 as an internal standard with the expectation that this fully compensates for the heat-dependent equilibrium of vitamin D3 with its previtamin. Previtamin D has a different spectral absorptivity from vitamin D and may be present in different proportions in samples and standards. Therefore, vitamin D2 and vitamin D3 and their previtamin forms must be chromatographically resolved to achieve accurate quantitation of total vitamin D. This study identified four chromatographic columns (ACE C18, ACE C18 AR, Vydac 201 TP C18 and Polaris C18-Ether) with adequate selectivity that should be applied for food testing and further confirmed that both parent vitamins isomerise at the same rate under thermal conditions.