Soft drink sample, HPLC analysis

Figure 7.5. HPLC analysis of sweetener, flavors, and preservative in a soft drink sample using gradient reversed-phase chromatography and UV detection. Chromatogram courtesy of PerkinElmer, Inc.

Numerous CE separations have been published for synthetic colours, sweeteners and preservatives (Frazier et al., 2000a Sadecka and Polonsky, 2000 Frazier et al., 2000b). A rapid CZE separation with diode array detection for six common synthetic food dyes in beverages, jellies and symps was described by Perez-Urquiza and Beltran (2000). Kuo et al. (1998) separated eight colours within 10 minutes using a pH 9.5 borax-NaOH buffer containing 5 mM /3-cyclodextrin. This latter method was suitable for separation of synthetic food colours in ice-cream bars and fmit soda drinks with very limited sample preparation. However the procedure was not validated for quantitative analysis. A review of natural colours and pigments analysis was made by Watanabe and Terabe (2000). Da Costa et al. (2000) reviewed the analysis of anthocyanin colours by CE and HPLC but concluded that the latter technique is more robust and applicable to complex sample types. Caramel type IV in soft drinks was identified and quantified by CE (Royle et al., 1998). 

A method is described for the determination of the preservatives SA and BA in foods (including yogurt, soft drinks, and fruit juices) based on HPLC on a hydrogen-sulfonated divinyl-benzene-styrene copolymer column, isocratic elution with 0.01 N sulfuric acid/acetonitrile (75 25) mobile phase and UV detection at 220 nm (for BA) and 258 nm (for SA). Soft drinks and fruit juices merely require dilution and filtration before injection yogurt samples require treatment with potassium ferricyanide (III) and ZnS04 before analysis. Recovery of SA from yogurt was 95-110% the detection limit was 0.01 mg/kg. The recovery of BA from soft drinks and fruit... 

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