Penentuan Kadar Metilen Biru dalam Larutan menggunakan

Spectrofotometer UV-Vis

Praktikum Spectrofotometer UV-Vis

Kelompok 3

Dian Pribadi Perkasa

Dien Puji Rahayu

Beni Ernawan

Ultraviolet-visible Spectroscopy

The study of molecular structure and dynamics through the absorption, emission and scattering of light in ultraviolet-visible spectrum.

Principle and Instrumentation

Electronic Excitation

A = - log (Eout / Ein) x thickness x concentration

Beer-Lambert-Bouguer Law:

Objectives of the Practice

1. To understand the work principle and instrumentation in ultraviolet-visual spectroscopy analysis.

2. Be able and usual to use UV-vis spectrophotometer.

3. To calculate the concentration of methylene blue solution in water using UV-Vis spectroscopy analysis.

Steps in Practice

1. Series of methylene blue solution was prepared to make standard curve Absorption vs Concentration

2. The sample was scanned to obtain a monochromatic wavelength for the maximum absorption wavelength.

3. Absorbance of known and unknown methylene blue solution was measured.

4. The concentration of unknown methylene blue solution was calculated using regression equation of standard curve.

Result and Discussion

1.Peak Absorbance of Methylene Blue

General Properties:

C16H18ClN3SAlso known as Swiss Blue dye

Highly cytotoxicHigh limit concentration for

spectroscopy analysis at order of 10-5 M

Peak absorbance in wavelength 655 nm and 605 nm

Result and Discussion2. Standart Curve

0.0010.0020.0030.0040.0050.0060.0070.0080.0090

0.20.40.60.8

11.21.41.6

f(x) = 161.25 x + 0.0740000000000015R² = 0.995432888585811

Absorbance at 665 nm

Concentration (ppm)

Sample AbsorbanceConcentration

(ppm)A 0,689 0,003815136B 0,846 0,004789082

Conclusion

• Spectroscopy analysis using UV-Vis Spectrophotometer is one of important quantifiable method to analyze concentration of a compound in solution.

• In this practice, concentration of unknown methylene blue solution successfully determined at 0.0038 and 0.0048 ppm based on absorbtion at 655 nm.

Thank you for

your attention