Comparison of spectrophotometry and digital photometry in the analysis of vitamin C using 1,10- phenanthroline and rhodamine B.

Date

3-2012

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Del Rosario, Ernesto J.

Committee Member

Ma. Desiree B. Aldemita Charisse T. Reyes

Abstract

Digital photometry was used for the determination of vitamin C in two fruit juices and commercial tablets using 1,10-phenanthroline and rhodamine B as reagents. Fresh pomelo and tomato juices, together with commercial vitamin C tablets (“Cevit” and “Poten-Cee”) were used as samples. The experiments utilized a light box containing a light source and a digital camera. Computer software that determines RBG values was used in color analysis of photographs of the solutions. Three digital photometric plots (a*, b* and % luminance) were used to determine the vitamin C content of samples. The suitability of the light box was evaluated by comparing the linearity of standard solutions of potassium permanganate obtained from digital photometry with the ideal value (r2 = 0.999) using t-test at 95% confidence interval. The accuracy of the method was also tested by analyzing known amounts of vitamin C (0.15µg/mL and 0.30 µ/mL) and comparing the experimental and actual values. Statistical analysis was done at 95 % confidence interval. Samples were then subjected to analysis using digital photometry and the values were compared with those obtained using spectrophotometry. To further validate the method, the experimental values were compared with their literature or claimed values by computing their per cent differences. The vitamin C concentration of each sample determined using 1,10-phenathroline was also compared with that obtained using rhodamine B. Results show that at 95% confidence interval, there was no significant difference between the concentration of vitamin C for each sample by spectrophotometry and digital photometry using two reagents. Test of repeatability was also done; statistical analysis shows that there was no significant difference between replicate experiments at 95% confidence interval. Therefore, it can be said that digital photometry using 1,10-phenanthroline and rhodamine B is a practical alternative method for the determination of vitamin C in different samples.

Language

English

Location

UPLB Main Library Special Collections Section

Call Number

Thesis

Document Type

Thesis

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