Phenol standard curve by UV-1200 ultraviolet spectrophotometry - Database & Sql Blog Articles

Phenol Standard Curve Using Ultraviolet Spectrophotometry

Key words: ultraviolet spectrophotometry; standard curve; UV-1300; UV-1500; quantitative analysis. I. Experimental Objective 1. To understand the basic principles of ultraviolet (UV) spectroscopy for qualitative and quantitative analysis. 2. To learn how to operate a UV-visible spectrophotometer effectively. II. Experimental Principle Organic compounds containing benzene rings or conjugated double bonds exhibit characteristic absorption in the ultraviolet region. The maximum absorption wavelength (λmax), molar absorptivity (ε), and the shape of the absorption curve are essential for identifying substances. Since absorbance (A) is highest at λmax, it is the most sensitive point for concentration determination. In this experiment, the absorption spectrum of phenol aqueous solution is analyzed to find λmax and quantify the sample accordingly. When measuring low or high concentrations, adjusting the transmittance by a factor of 10 can improve accuracy. The principle follows Lambert-Beer's Law: A = εbc. III. Instruments and Reagents - Instruments: UV-1300 and UV-1500 UV-visible spectrophotometers, 1 cm quartz cuvettes (2 pieces), 50 mL colorimetric tubes (5 pieces), 5 mL pipettes (1 piece). - Reagents: Phenol standard solution (100 mg/L). IV. Experimental Procedure 1. Preparation of Analytical Solutions: Take five 50 mL colorimetric tubes and add 0.5 mL, 1.0 mL, 1.5 mL, 2.0 mL, and 2.5 mL of the 100 mg/L phenol standard solution using a pipette. Dilute each to the 25 mL mark with deionized water and mix thoroughly. Record the data in a table. 2. Determination of Maximum Absorption Wavelength: Prepare a phenol solution with a concentration of 8 mg/L. Use a 1 cm quartz cuvette and deionized water as a reference. Scan the wavelength range from 200 nm to 330 nm on the UV-Vis spectrophotometer and plot the absorption curve. Identify λmax1 and λmax2 from the curve. 3. Preparation of the Standard Curve: Measure the absorbance of each phenol solution at the selected λmax, starting from the lowest to the highest concentration. Plot the absorbance versus concentration to create a standard working curve. V. Data Recording and Analysis Record all experimental results and analyze the standard curve. This method is widely used in environmental monitoring, quality control, and chemical analysis. Keywords: ultraviolet spectrophotometry; standard curve; UV-1300; UV-1500; analytical instrument.