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Composition of tomatoes and tomato products in antioxidants (WG1) page 92
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Reagents: Solution of metaphosphoric acid (33.5-36.5) 6%.L+Ascorbic acid
Apparatus HPLC with spectrophotometric detector UV-Vis wavelength: 254nm
HPLC Column Merck Lichrosorb RP18 (10 µm) 250x4 mm
Paper filter and 0,45 µm Millex (Millipore)
Standard preparation:
0,1 g of L+ascorbic acid are weighed and directly diluted with 100 ml of redistilled
water (sol.1000 ppm). Then prepare 2 solutions with note concentrations 20 and 50 ppm for
the calibration curve.
Sample (tomato derivatives) preparation
Fresh tomatoes are diluted with metaphosphoric acid (6%) to obtain the final
concentration of ascorbic acid not over the standard max concentration. Filter with paper filter
and with Millipore 0.45 µm.
Dilutions: Tomato juice : x5
Tomato puree : x10
Tomato paste : x20
HPLC Conditions :
Detector UV 254 nm
Column Merck Lichrosorb RP18 10 µm 250x4 mm
Temperature Ambient
Flow 1 ml/min
Injection volume 20 µl
Retention time 10 min
Mobile phase metaphosphoric acid 0,3% (Isocratic)