Determination of Vitamin-A in Fortified Oil using UV Spectrophotometer (ECSA-HC:2007)

Summary

In this video, viewers are guided through the process of determining the vitamin A concentration in soybean oil. The procedure involves three main steps: sample and blank preparation, taking absorbance readings, and performing calculations. Key tools used include a micro-pipette, UV spectrophotometer, and hexane. The process covers preparing oil samples, setting up the spectrophotometer, measuring absorbance, and calculating vitamin A concentrations in the form of retinol and retinal. Results reveal vitamin A concentrations of 20.21 ppm as retinol and 37.88 ppm as retinal permeated.

Takeaways

• 😀 The experiment aims to determine the vitamin A concentration in soybean oil using UV spectrophotometry.
• 😀 The procedure involves three main steps: sample and blank preparation, taking absorbance readings, and performing calculations.
• 😀 Key equipment for the analysis includes a balanced mission micro pipette, UV spectrophotometer, volumetric flask, quartz cuvette, and hexane.
• 😀 The first step is to prepare a sample and a blank solution using 2 grams of oil, both diluted with hexane to a final volume of 25 ml.
• 😀 A UV spectrophotometer is used to measure absorbance, and the wavelength is set to 325 nm for the analysis.
• 😀 The sample and blank absorbances are measured and recorded to calculate the concentration of vitamin A.
• 😀 The absorbance of the sample is recorded as 0.648, and the absorbance of the blank is 0.358.
• 😀 After collecting the absorbance data, the next step is to calculate the vitamin A concentration using known coefficients and equations.
• 😀 Two forms of vitamin A are measured: retinol and retinyl palmitate, with respective calculations resulting in 20.21 ppm and 37.88 ppm.
• 😀 The correct procedure for cleaning and preparing the cuvette is critical for accurate results, including washing with hexane and drying the outer surface with tissue paper.

Q & A

What is the purpose of the experiment described in the video?

The purpose of the experiment is to determine the vitamin A concentration in soybean oil.

What are the three main steps involved in the experiment?

The three main steps are sample and blank preparation, taking absorbance, and calculation of the vitamin A concentration.

What equipment and materials are needed to conduct the test?

The equipment and materials needed are a balance, micro pipette, UV spectrophotometer, volumetric flasks, quartz cuvettes, hexane, and unfortified soybean oil.

How are the sample and sample blank prepared?

To prepare the sample, 2 grams of the oil sample is added to a volumetric flask, and hexane is used to dilute it to 25 ml. The same procedure is followed for the sample blank, but using unfortified oil.

What is the significance of washing the quartz cuvette with hexane?

Washing the quartz cuvette with hexane ensures that it is free from any contaminants that could affect the absorbance readings during the test.

What wavelength is used for measuring absorbance in this experiment?

The wavelength used for measuring absorbance is 325 nanometers.

What does the instrument do when it asks for 'blank or diluent'?

The instrument asks for the blank or diluent to set a baseline for absorbance measurements, ensuring that any absorbance is solely due to the sample and not the solvent.

What are the absorbance values obtained for the sample and sample blank?

The absorbance of the sample is 0.648, and the absorbance of the sample blank is 0.358.

What is the formula used to calculate the vitamin A concentration in the sample?

The vitamin A concentration is calculated using the retinal permeated absorption coefficient in hexane, sample absorbance, sample weight, and final volume of the sample.

What are the estimated concentrations of vitamin A in the sample as retinol and retinal permeated?

The estimated vitamin A concentration as retinol is 20.21 ppm, and as retinal permeated, it is 37.88 ppm.