I'm using the vanillin-sulphuric acid method to cuantify saponins but the colour that I observe is yellow instead of red-purple.
The method I follow from the literature is:
- 1 ml of sample extract + 0.25 ml 8% (v/v) vanillin in methanol + 2.5 ml 72% H2SO4
- Incubate mixture in 70ºC water bath for 15 min and then in ice for 5 min.
- Read absorbance at 560 nm.
Any sugestion or solution for this problem?
Thanks!
Reaction of sulphuric acid-oxidised triterpene saponins with vanillin, which gives a red-purple colour for measurement at a wavelengths ranging from 473 to 560 nm.
Madam please check the article in RG
https://www.researchgate.net/publication/292178247_Quantitative_determination_of_the_saponin_content_and_GC-MS_study_of_the_medicinal_plant_Cassytha_fiiformis_linn_leaves
the answer is
1 ml of sample extract + 0.25 ml 8% (v/v) vanillin in methanol + 2.5 ml 72% H2SO4
- Incubate mixture in 70ºC water bath for 15 min and then in ice for 5 min.
- Read absorbance at 560 nm.
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