How can I measure cucurbitacin by spectrophotometer?

Pramod Sargar

To measure cucurbitacin by spectrophotometer, you can use one of the following methods:

Direct UV method

Prepare a standard solution of cucurbitacin E in a suitable solvent, such as methanol or ethanol.

Prepare a series of dilutions of the standard solution.

Measure the absorbance of each dilution at the wavelength of maximum absorption for cucurbitacin E (around 263.5 nm).

Plot a calibration curve of absorbance versus concentration.

Prepare a sample solution of the cucurbitacin-containing extract.

Measure the absorbance of the sample solution at the wavelength of maximum absorption.

Determine the concentration of cucurbitacin in the sample solution using the calibration curve.

PMA reaction method

Prepare a solution of phosphomolybdic acid (PMA) in a suitable solvent, such as sulfuric acid or phosphoric acid.

Prepare a solution of the cucurbitacin-containing extract.

Mix the sample solution with the PMA solution and incubate for a period of time (usually 5-10 minutes).

Measure the absorbance of the reaction mixture at the wavelength of maximum absorption (around 400 nm).

Determine the concentration of cucurbitacin in the sample solution using a calibration curve prepared with standard solutions of cucurbitacin E treated with PMA in the same way.

Here are some additional tips for measuring cucurbitacin by spectrophotometer:

Use a quartz cuvette with a path length of 1 cm.
Make sure that all of your glassware is clean and dry.
Use distilled or deionized water to prepare all solutions.
Zero the spectrophotometer with the blank solution before measuring the absorbance of the samples.
Run the calibration curve in duplicate or triplicate to improve accuracy.
If you are using the PMA reaction method, be sure to incubate the sample and PMA solution for the same amount of time before measuring the absorbance.

Is there any method or way to identify vanadium dimer V2O74- and H2VO4- through V51NMR and Raman spectroscopy?

What extraction procedures are used for lab based extraction of cucurbitacins?