![]() ![]() Migration time is fairly constant, but can slightly vary according to the state of the capillary. The absorption peaks for the internal standard and the sorbic acid are obtained on average 1 to 1.5 minutes after the start of the migration phase live. This is preferable when several analyses are carried out in series, because the electrolytic properties are maintained longer. Certain capillary electrophoresis apparatus propose large-capacity vials for migration buffer solutions. The migration lasts approximately 1.5 to 2 minutes under a potential difference of + 25 kV, in normal polarity (cathod at the exit).ĥ.2.9. The injection is done under a pressure of 0.3 psi (2.1 kPA) for 10 seconds.ĥ.2.8. Second Pre-rinse under pressure 30 psi (210 kPA) with the migration buffer (3.2) for 30 seconds.ĥ.2.7. First Pre-rinse under pressure 30 psi (210 kPA) with sodium hydroxide solution 0.1 N (3.4.1) for 30 secondsĥ.2.6. Reading of the signal in direct mode (sorbic acid absorbs in the UV spectrum).ĥ.2.5. The molten silica capillary is 31 cm long, with a diameter of 50 microns.ĥ.2.4. These conditions may be slightly changed depending on the equipment used.ĥ.2.1. Rinse with the migration buffer (3.2) at 20 psi (140 kPA) for 30 min. Rinse with sodium hydroxide solution (3.4.1) 0.1 N at 20 psi (140 kPA) for 12 min.ĥ.1.3. Rinse with sodium hydroxide solution 1N (3.4.2) at 20 psi (140 kPA) for 8 min.ĥ.1.2. Qsp 10 ml with demineralized water (3.1.5)īefore its first use, and as soon as the migration times increase, the capillary must be conditioned according to the following process:ĥ.1.1. The wine samples are prepared as follows, which involves a 1/20 dilution: Hippuric spdium (3.1.4) in an aqueous solution 0.5 g.L-1 Sodium dihydrogenophosphate (3.1.1): 5 mM The migration buffer is made up in the following way: Demineralised water (< 15 MOHMS) or double-distilled Sodium hydrogenophosphate purity > 99%ģ.1.4. Sodium dihydrogenophosphate purity > 96%ģ.1.2. At the capillary outlet, detection is carried out in the ultraviolet spectrum at 254 Nm.ģ.1.1. The negatively charged sorbate ion naturally enables easy separation by capillary electrophoresis. The present method is used to determine the sorbic acid in wines in a range from 0 to 300 mg/l. OIV-MA-AS313-18 Determination of sorbic acid in wines by capillary electrophoresis ![]()
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