ABSTRACT
According to the working principle of vertical ultrasonic vial washing machine, receiving respective force of small water droplets on the inside wall of vials and the minimum air velocity of blowing off water droplets can be obtained based on the analysis of water-droplet-related parameters. The inside wall model of 7 mL vial created by GAMBIT was divided into fine grids. Then the Realizable k-epsilon Two Equation Turbulence Model was adopted and the flow field of vial by FLUENT software was simulated when air was flushing inside the wall. In that case, the optimal position, inner diameter and the corresponding minimum air velocity of needle can be acquired to meet the needs of vial washing machine applied to 7 mL vial.
Subject(s)
Equipment Design , Models, Theoretical , Needles , SoftwareABSTRACT
A new spectrophotometric method, ion-exchanger colorimetry for measuring iron (Ⅱ) in powdered milk fortified with iron(Ⅱ) has been developed. The method was based on the direct measurement of the resin phase absorbance after the absorption of colored sample complex species. In this method, 1,10-phenanthroline was used as the colour reagent, citric acid-sodium citrate as buffer and citric acid-ammonia as masking agent.The recovery rate of the method was 102%. Coefficient of variation was 5.84%.This method was a sensitive, reliable and simple analytical method for the determination of iron (Ⅱ) in powdered milk fortified with iron (Ⅱ).It was also possible to determine iron(Ⅱ) in powder milk and other food.
ABSTRACT
The riboflavin in dairy products was determined by fluorometric method. According to the property of Na2S2O4 could be able to extinguish the fluorescence of VB2, the concentration of VB2 in milk could be obtained by the difference of two readings of the sample and the sample added Na2S2O4. So the influence of impurities in the samples on measuring could be eliminated. Besides using some modifications such as acidolysis at normal temperature and pressure,proteins were separated from samples by buffer at pH 4.7. The mean recovery rate in this method was over 93% and the coefficients of variation were 5.7-12.8%.