Recommendations References analytical methods for food additives
E122: Azorubine
19
Table 2.1 Summary of methods for azorubine in foods
a Method
Matrix Sample
Column Mobile phase
Detection Reference
preparationextraction IP-RP-HPLC
Lemonade, Ion pairs with cetylpyridinium
Spherisorb C8 Gradient elution 1.5 mLmin
Diode-array 2
cake crumb, chloride from aqueous solutions
with phosphate buffer containing at 520 nm
skimmed milk into n-butanol cetylpyridinium chloride,
acetonitrile and methanol RP-HPLC
Bitters Diluted with water and filtered Nova-Pak C18
Gradient elution 2 mLmin 520 nm
3 using methanol and 0.1 M sodium
phosphate buffer at pH 7 HPLC
Beverages, Diluted with water and filtered Nova-Pak C18
Gradient elution 1.5 mLmin 520 nm
4 gelatine,
with methanol–phosphate buffer at syrups
pH 7 1:4 containing 5 mM tetrabutyl ammonium bromide
HPLC Yogurt
Shaken with 5 NH
3
. Acetone MicroPak Gradient elution using TBA in
254 nm 6
added and shaken. Centrifuged MCH-10 methanol diluted with methanol–
supernatant concentrated to phosphate buffer at pH 7±0.05
remove acetone. Adjust to pH 4. Shake with polyamide. Centrifuge.
The polyamide washed 3× with water and then shaken with
MeOH–aqNH
3
19:1 HPLC
Confect- Sweets stirred in methanol.
Spherisorb Water–acetonitrile 7:3
520 nm 7
ionery Methanol extract diluted 1:10 ODS-2 with
containing 5 mM octylamine in water and filtered 0.45
µm LiChrospher
orthophosphoric acid at pH 6.4 before injection
RP-18 guard 1 mLmin
column
20 Analytical methods for food additives
Table 2.1 cont’d b
Method Matrix
Sample preparation Method conditions
Detection Reference
Capillary zone Non-alcoholic
Samples used as is or diluted A background solution
216 nm 5
electrophoresis beverages and
with water consisting of 15 mM borate
CZE fruit flavoured
buffer at pH 10.5, hydrodynamic syrups
injection and a 20 kV separation voltage
Spectro- Beverages,
Samples diluted in 5 mL acetate Analysed by spectrophotometry
427 nm 8
photometric gelatine, syrups
buffer and diluted to 25 mL with using a Beckman DU-70 instrument
water Solid-phase
Colourings Sample solution mixed with 1 M
The mixture was shaken for 15 min Absorbance
9 spectro-
caramel, HCl, ethanol sufficient for a 10
then the gel beads were filtered off, measured at
photometry confectionery
conc., water and Sephadex DEAE packed into a 1 mm cell and
525 nm and A-25 gel
absorbance measured 800 nm
Rapid clean-up Various foods
Liquid samples as is. Solid Colour separated on reverse phase
TLC or 10
method for samples dissolved in water and
C18 Sep-Pak cartridge and eluted spectrophotometric
spectro- filtered through sintered glass
with aqueous isopropanol solutions photometric and
filter TLC methods
Spectro- Soft drinks
Ion-pair formation with octadecyl- Extraction of the ion-pair into
550 nm 11
photometric trimethylammonium bromide at
n -butanol
pH 5.6