Page 351 - Analytical method for food addtives

238 Analytical methods for food additives

suitable mobile phase for washing would have the following composition: 50 parts
per volume of mobile phase + 50 parts per volume of acetonitrile.
Suitable chromatographic conditions for identification are:
Chromatographic columns
Type reversed phase (RP)
Stationary phase and column spherical particles of 3 µm, for column lengths
of 100 mm, up to 10 µm for lengths of 300 mm
Internal diameter 4.0 mm
Guard column recommended (optional)
Examples Lichrospher® 100 RP 18, Superspher® RP
Select B
Nucleosil 100-5 C18 AB, µBondapak C18
Partisil ODS 3
Flow rate 0.8 mL/min up to 1 mL/min
Injection volume 10 µL up to 20 µL
Detection
Photometrical (UV) at a
wavelength of 217 nm for aspartame
227 nm for acesulphame-K
265 nm for saccharin
220 nm for all intense sweeteners, if detector
does not allow a wavelength switch in one run

Mobile phase
In general the following proportions have given satisfactory results:
• phosphate buffer solution I + acetonitrile [90:10, volume parts, (V/V)]
• phosphate buffer solution II + acetonitrile (80:20, V/V)
• phosphate buffer solution II + acetonitrile (85:15, V/V)
• phosphate buffer solution II + acetonitrile (90:10, V/V)
• phosphate buffer solution II + acetonitrile (95:5, V/V)
• phosphate buffer solution II + acetonitrile (98:2, V/V)
• phosphate buffer solution II + phosphoric acid pH = 2.8
Determination
For the determination by the external standard method, integrate the peak areas or
determine the peak heights and compare the results with the corresponding values
for the standard substance with the nearest peak area/height, or use a calibration
graph. To prepare a calibration graph, inject a suitable amount of standard
solutions of appropriate mass concentrations. Plot the peak heights or peak areas
of the standard solutions against the corresponding mass concentrations in
milligrams per litre. Check the linearity of the calibration graph. Alternatively, the
calibration may also be evaluated mathematically by the regression. Check the
linearity of the regression graph.
(For further details see BS EN 12856:1999.) 13