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BS ISO 23293:2020 pdf free

BS ISO 23293:2020 pdf free.Milk-based infant formula powders一Quantification of whey protein content by sodium dodecyl sulfate-capillary gel electrophoresis (SDS-CGE).
5 Reagents and materials
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and distilled or demineralized water or water of equivalent purity.
Data from the multi-laboratory study was obtained with chemicals from the SDS-MW kit 390953 from Beckman Coulter/Sciex’). The SDS-MW gel separation buffer recipe described below (Sd) was tested in a separate study and found to be equivalent to the commercial SDS-MW gel separation buffer included in the kit. One laboratory used home-made reagents (5.2 to 55). All laboratories used the 10 kDa internal protein standard (5k) and the SDS-MW size standard (51) from the kit. Use of equivalent standards requires prior verification.
5.1 SDS-MW gel separation buffer, tris(hydroxymethyl)aminomethane (Tris), boric acid, SDS, EDTA, glycerol and dextran 2000’).
Dissolve 0,726 6 g Tris base and 0,371 0 g boric acid in 9 ml water. Add 20 mg SDS. 1 g dextran 2000, 14,6 mg EDTA, and 1 ml glycerol. Mix thoroughly. Leave overnight to allow complete dextran solubilization.
NOTE Dextran 2000 has an average molecular weight of 2 000 000 Da.
5.2 SDS-MW sample buffer, 100 mmol/l Tris, pH 9,0, 1 % SDS.
Dissolve 109,4 mg of Tris base, 15,2 mg of Tris hydrocholoride and 0,1 g of SDS in 10 ml water.
5.3 Acidic wash solution, hydrochloric acid, substance concentration c = 0,1 mol/l.
5.4 Basic wash solution, sodium hydroxide, c = 0,1 mol/l.
5.5 .mercaptoethanoI.
5.6 10 kDa internal protein standard, mass concentration p = S mg/mi.
5.7 SDS-MW size standard, 10 to 225 kDa,p = 16mg/mi.
5.8 Sample running pre-solution.
Mix the SDS-MW sample buffer (5.2) with the 10 kDa internal protein standard (5k) using an 84:1 ratio. Prepare a sufficient volume based on the total number of samples to be analysed in the sample set (90 p1 of sample running pre-solution is needed per sample).
6 Apparatus
Usual laboratory glassware and equipment and, in particular, the following.
6.1 Capillary electrophoresis instrument, equipped with UV detector set at 220 nm and capable of maintaining the capillary and sample tray at 25 °C ± 2 °C.
Suitable software should be available for peak integration.
6.2 Bare, fused-silica capillaries, of 50 pm internal diameter x 30cm, with effective length of 20 cm.
6.3 Temperature controlled water bath or heating block, capable of maintaining a temperature of
6.4 MIcro centrifuge, with adaptors for 1,5 ml centrifuge vials.
6.5 Vortex.
6.6 Adjustable pipettes and tips, volume 0120 Id, 100 gil and 1 000 gil.
6.7 Safe-lock micro-centrifuge vials, volume of 1,5 ml or 2,0 ml.
6.8 Round-bottom centrifuge tubes, volume of 10 ml.
6.9 Analytical balance, weighing to four decimal places.
7 Procedure
7.1 Sample preparation
7.1.1 Weigh 500 mg ± 20 mg of infant formula powder into a 10 ml centrifuge tube. A skim milk powder
(SMP) sample is used as a reference to align the whey and casein regions in the infant formula samples.
Prepare the SMP using a sample mass of 135 mg ± S mg.
7.1.2 Disperse the sample in 5 ml of water. Vortex each tube until the solution appears homogeneous. Each final solution contains between 10 mg/mI and 15 mg/mI of protein.
7.1.3 Pipette 10 gil of each sample solution into separate microcentrifuge vials.
7.1.4 Sequentially add 85 gil of the sample running pre-solution (&8) and 5 gd of -mercaptoethanol
(55) to each micro-centrifuge vial. Mix well before heating the vials in a water bath or heating block at
95 °C ± 5 °C for 10 mm. Cool down to room temperature. Centrifuge at room temperature for 1 mm at
about 5 000g (approximately 7 000 r/min in a table-top centrifuge).
7.1.5 Vortex before transferring each sample into corresponding injection vials.
7.2 CGE analysis
7.2.1 The separation and the quantification have proven to be satisfactory if the following experimental conditions are followed.BS ISO 23293 pdf download.

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