1)The production of authentic tequila is restricted to the blue agave and a defined geographical area in west-central Mexico. Two basic categories of tequila can be distinguished: “100% agave” and “mixed” tequila. High-quality “100% agave” tequila uses pure agave juice for fermentation and Mexican law states that these authentic tequilas must be bottled in Mexico. A mixed tequila is manufactured by adding up to 49% (w/v) of sugar from sugar cane for fermentation. The low-quality tequila is usually shipped in bulk containers for diluting and bottling in the importing countries. Due to frequent fraud in the labeled quality of tequila, there is a need to verify the authenticity of a tequila using chemical analysis. Figure 1 shows an ion chromatogram for an authentic 100% agave tequila and a commercial mixed tequila. The difference in anion content is due to the different sources of water used in final dilution and bottling steps. a) In reversed-phase liquid chromatography, a nonpolar groups such as (C18) is attached the surface of the stationary phase particle.What type of a group is attached the surface of the stationary phase in the separation of anions? b) Can you give a chemical formula for a group that meets your criteria in part a? c) What properties affect the retention time of the anions? d)How can the mobile phase be changed to make the anions elute more rapidly or more slowly from the column?
1)The production of authentic tequila is restricted to the blue agave and a defined geographical area in west-central Mexico. Two basic categories of tequila can be distinguished: “100% agave” and “mixed” tequila. High-quality “100% agave” tequila uses pure agave juice for fermentation and Mexican law states that these authentic tequilas must be bottled in Mexico. A mixed tequila is manufactured by adding up to 49% (w/v) of sugar from sugar cane for fermentation. The low-quality tequila is usually shipped in bulk containers for diluting and bottling in the importing countries. Due to frequent fraud in the labeled quality of tequila, there is a need to verify the authenticity of a tequila using chemical analysis. Figure 1 shows an ion chromatogram for an authentic 100% agave tequila and a commercial mixed tequila. The difference in anion content is due to the different sources of water used in final dilution and bottling steps.
a) In reversed-phase liquid chromatography, a nonpolar groups such as (C18) is attached the surface of the stationary phase particle.What type of a group is attached the surface of the stationary phase in the separation of anions?
b) Can you give a chemical formula for a group that meets your criteria in part a?
c) What properties affect the retention time of the anions?
d)How can the mobile phase be changed to make the anions elute more rapidly or more slowly from the column?
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