Phenylethyl Resorcinol is a chemical compound commonly used in skincare products for its skin-lightening and anti-aging properties. To determine its assay using UV-Vis (Ultraviolet-Visible) spectroscopy, To prepare a suitable solution and follow a standard protocol. Here's a general procedure for conducting a UV-Vis assay:

Materials and Reagents:

Phenylethyl Resorcinol standard sample
Suitable solvent (eg, methanol or ethanol)
UV-Vis spectrophotometer
Quartz cuvettes
Pipettes and volumetric flasks
Deionized or distilled water
Stirring rod
Weighing balance
UV-Vis software for data collection and analysis
Procedure:

Sample Preparation:
a. Weigh an appropriate amount of Phenylethyl Resorcinol standard sample accurately. The exact amount will depend on the expected concentration and the solvent used. Create a standard curve to determine the concentration.

b. Dissolve the standard sample in the selected solvent (eg, methanol or ethanol) to make a stock solution. Ensure the sample is fully dissolved by stirring.

c. Dilute the stock solution to create a series of standard solutions with different known concentrations. For example, make solutions with concentrations of 10, 20, 30, 40, and 50 µg/mL.

UV-Vis Spectrophotometer Setup:
a. Turn on the UV-Vis spectrophotometer and allow it to warm up for the recommended time.

b. Set the wavelength range to an appropriate value, typically in the UV-Vis range, such as 200-400 nm.

c. Ensure the cuvettes and instrument are clean and free of any particles that may interfere with the measurement.

Blank Correction:
a. Prepare a blank solution using the same solvent used for the standard samples. The blank solution will serve as a reference to account for any absorbance due to the solvent.

b. Place the blank solution in a cuvette and insert it into the spectrophotometer. Set the spectrophotometer to zero absorbance using the blank solution.

Measurement:
a. Take one of the standard solutions and place it in a cuvette.

b. Insert the cuvette into the UV-Vis spectrophotometer.

c. Record the absorbance at the specific wavelength for Phenylethyl Resorcinol.

d. Repeat steps ac for each of the standard solutions.