ISO 23293 pdf free download

ISO 23293-2020 pdf free download.Milk-based infant formula powders一 Quantification of whey protein content by sodium dodecyl sulfate-capillary gel electrophoresis (SDS-CGE).
7.2.6 Perform the electrophoresis at constant voltage with applied field strength of —497 V/cm and a capillary thermostatted to 25 °C using recirculating liquid coolant.
7.2.7 The generated current should be approximately 27 pA.
7.2.8 To avoid reagent depletion, programme the system to increment the vial position of all reagents every eight cycles.
7.3 Electropherogram processing
7.3.1 Electropherogram integration
Automatically integrate the electropherograms from the valley located at 0.5 mm to I mm before the 10 kl)a internal protein standard peak (include any peak immediately adjacent to the 10 kDa internal protein standard) to the valley between the end of K-caSein peak and the peak of Ig H and BSA (no negative peaks should be generated by the integration). Then, perform a manual integration from the valley before the peak of Ig H and BSA until the end of the last peak in the electropherogram (integrate all peaks including those after the peak of Ig H and BSA if present). Examples of electropherograms including the automated and manual integration regions are given in EigureA.2 and A3 for SMP and infant formulas, respectively. Examples of integration parameters are listed in Table A.1.
7.3.2 Identification of the casein region
In SMP. the casein integration area starts just before the 13-casein peak (the highest peak of the electropherogram) and stops at the valley between the end of the x-casein peak and the peak of Ig H and BSA. For infant formulas, identify the 13-casein peak and the valley by comparison with the SMP electropherogram.
8 System suitability
8.1 General
Test the system suitability using the 10 kDa internal protein standard (5.6) and the SDS-MW size standard (Si). Define the migration time of the 10 kDa internal protein standard for each combination of instrument. capillary and reagents beforehand. The acceptance criteria for the system suitability are as follows.
8.2 The migration time of the 10 kDa internal protein standard should correspond to the value initially
established ±5 %. The seven MW markers (10 kDa, 20 kDa, 35 kDa, 50 kDa, 100 kDa, 150 kDa and
225 kDa) should be completely separated (see Figure A4).
EXAMPLE Using a Beckman Coulter/Sciex instrument, capillaries and reagents2), the migration time of the 10 kDa internal protein standard is 12.3 mm ± 0,5 mm and the seven MW markers are completely separated within 30 mm (see figureAA).
8.3 The acceptance criteria for the separation cycles are:
— the migration time of the 10 kDa internal protein standard should correspond to the value initially established ±5 %;
— the degree of baseline drop from the internal standard until the valley between the end of x-casein and the peaks of Ig H and BSA should not exceed 25 % of the height of the internal protein standard in the sample.
2) This is an example of a suitable product available commercially. This information is given for the convenience of users of this document and does not constitute an endorsement by ISO or IDF of this product.
9 Calculations and expression of results
9.1 Calculation of whey protein content
Separately sum peak areas in three regions, two at each end of the electropherogram (lower molecular weight and higher molecular weight whey proteins) and one in the middle. The middle region corresponds to casein proteins (A), and the two others are summed together to obtain whey proteins (A). The area of the internal standard should not be included in the calculation of A. Refer to the blank run to identify potential degradation products of the 10 kDa internal protein standard. If present, they should not be included in the calculation of A.
Calculate the whey protein, W, content as a percentage using Formulae (1) and (2.).ISO 23293 pdf download.