Page 39 - Analytical method for food addtives

16 Analytical methods for food additives

n-butanol. The azorubine was analysed using reversed phase, ion pair gradient
elution HPLC with diode array detection. A summary of the procedure for
this method is given in the Appendix for this chapter and the performance
characteristics are given in Table 2.3. The method was also used for skimmed milk
using the sample preparation and extraction procedure as for soft drinks. If the
extraction procedure had been followed for flour-based products the performance
characteristics would probably have been improved.
A reverse phase HPLC method for the analysis of six dyes including azorubine
(carmoisine) was applied to a number of food samples (three beverages, gelatin
3
dessert and a strawberry-flavoured syrup and found to be suitable. Separation was
performed on a Nova-Pak C18 column using methanol–NaH PO /Na HPO , pH 7,
2 4 2 4
buffer solution (0.1 M) as mobile phase with an elution gradient system and UV–
vis detection at 520 nm. Under optimum conditions (details given in the Appendix)
dyes were eluted in 4 min. The procedure for this method is given in the Appendix
with a summary of the statistical parameters being given in Table 2.4. This method
has also been used to compare the results for the simultaneous determination of
dyes in foodstuffs when new methods have been developed i.e. by capillary zone
electrophoresis. 5

2.3 Recommendations
1
For azorubine, analytical methods using extraction followed by spectoroscopy are
in place for a full range of beverages, sauces and starchy and fatty foods. There are
no recent publications for azorubine in chocolate products, therefore this is an area
that requires method development.

2.4 References

1 Pearson’s Composition and Analysis of Foods, 9 ed. Kirk R and Sawyer R, Longman
Scientific, Harlow (1989).
2 ‘Determination of synthetic coal-tar dyes in soft drinks, skimmed milks and cakes:
collaborative trial’, Dennis J, Chapman S, Brereton P, Turnbull J, Wood R. J. Assoc.
Publ. Analysts (1997) 33, 161–202.
3 ‘A reverse phase HPLC method to determine six food dyes using buffered mobile phase’,
BerzasNevado J J, GuiberteauCabanillas C, ContentoSalcedo A M. Analytical Letters
(1998) 31(14), 2513–2535.
4 ‘Separation and determination of dyes by ion-pair chromatography’, BerzasNevado J J,
GuiberteauCabanillas C, ContentoSalcedo A M. Journal of Liquid Chromatography &
Related Technologies (1997) 20(18), 3073–3088.
5 ‘Method development and validation for the simultaneous determination of dyes in food
stuffs by capillary zone electrophoresis’, BerzasNevado J J, GuiberteauCabanillas C,
ContentoSalcedo A M. Analytica Chimica Acta (1999) 378(1–3), 63–71.
6 ‘Extraction of organic acids by ion-pair formation with tri-n-octylamine. VII. Compari-
son of methods for extraction of synthetic dyes from yogurt’, Puttermans M L, DeVoogt
M, Dryon L, Massart D. J. Assoc. Off. Anal. Chem. (1995) 68(1), 143–145.