Tutorial Penggunaan Alat Spektrofotometer UV-Vis

Summary

This tutorial provides a detailed guide on using the UV-Vis Spectrophotometer (Thermo Scientific Genesys 10S) at the Pharmacy Academy in Jember. The process includes preparing samples of citric acid at varying concentrations, calibrating the machine with a blank solution, and scanning for the maximum wavelength of absorbance. It then shows how to create a calibration curve from the obtained absorbance values, which are used to calculate the concentration of unknown samples. The tutorial emphasizes accuracy in sample preparation and measurements to ensure reliable results in pharmaceutical analysis.

Takeaways

• 😀 The tutorial demonstrates how to use the UV-Vis Spectrophotometer (Thermo Scientific Genesys 10S) at the Pharmacy Academy of Jember for a quantitative chemical analysis experiment.
• 😀 The spectrophotometer has six sample holders, including spaces for blank and sample solutions, where proper sample positioning is critical for accurate readings.
• 😀 A proper preparation of samples is essential, with concentrations of citric acid ranging from 10 to 50 PPM being used for the experiment.
• 😀 Cleanliness is key: Before measurements, cuvettes need to be rinsed with distilled water or appropriate solvents and dried with tissue to avoid contamination and ensure precise results.
• 😀 The first step involves scanning to determine the maximum wavelength of the sample solution, typically setting the wavelength range from 200 to 400 nm for analysis.
• 😀 Proper calibration of the instrument is necessary, including scanning settings like wavelength, speed, and the interval for measurements (e.g., 5 nm or 50 nm).
• 😀 Blank solutions are measured first to calibrate the spectrophotometer, ensuring that the baseline absorbance of the solvent is accounted for before measuring the samples.
• 😀 The spectrophotometer is used to measure the absorbance of sample solutions at specific wavelengths, and the goal is to identify the peak absorbance for each solution.
• 😀 After obtaining absorbance values, a calibration curve is created by plotting the concentration of the samples against their absorbance readings.
• 😀 If discrepancies or errors are found in the readings (e.g., incorrect sample preparation), the experiment must be repeated, adjusting the samples and measurements as necessary.
• 😀 The final concentrations of samples are calculated using the calibration curve equation, and all procedures should be meticulously documented to avoid errors during analysis.

Q & A

What is the purpose of the tutorial in the provided script?

The tutorial aims to guide students in using the UV-Vis spectrophotometer (Genesis 10S) for quantitative analysis in pharmaceutical chemistry experiments at Jember Pharmacy Academy.

How long should the spectrophotometer be left to stabilize before use?

The spectrophotometer should be left to stabilize for approximately 30 minutes before use to ensure accurate readings.

What is the role of the blank sample in the spectrophotometry process?

The blank sample, typically distilled water or another solvent, is used to calibrate the spectrophotometer and set a baseline for absorbance. It ensures that only the absorbance of the actual samples is measured.

How should the cuvette be positioned in the spectrophotometer?

The cuvette should be inserted with the clear side facing the optical path of the spectrophotometer to ensure accurate measurements.

What are the sample concentrations used in this tutorial?

The sample concentrations used are 10 ppm, 20 ppm, 30 ppm, 40 ppm, and 50 ppm of citric acid.

What is the scanning wavelength range set on the spectrophotometer for this analysis?

The scanning wavelength range is set from 200 nm to 400 nm to measure the absorbance of the samples.

Why is it important to measure the blank sample before the actual samples?

Measuring the blank sample first ensures the spectrophotometer is correctly calibrated, eliminating any background absorbance from the solvent and allowing accurate measurement of the sample absorbance.

How do you determine the maximum absorbance wavelength of a sample?

The maximum absorbance wavelength is determined by looking for the peak on the absorption curve, where the absorbance value is highest. In the case of citric acid, it is at 210 nm.

What is the purpose of creating a calibration curve in this experiment?

The calibration curve is used to establish a relationship between absorbance and concentration, allowing for the determination of unknown concentrations in future samples based on their absorbance values.

What should be done if there are discrepancies in the sample readings?

If discrepancies occur, check the sample preparation for accuracy, ensure the cuvettes are clean, and verify that the spectrophotometer is calibrated correctly. Repeating the measurements might be necessary if issues persist.