Spectrophotometric and digital photometric determination of xylose in acid hydrololysates of corn cobs and Sargassum sp.) using phloroglucinol.

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

Aldemita, Ma. Desiree B. Kaligayahan, Joy Elaine P.

Abstract

Digital photometry was evaluated as an alternative method to visible spectrophotometry in the analysis of xylose in acid hydrolysates of corn cobs and Sargassum sp. using phloroglucinol as reagent. Photographs of standards and unknown solutions were taken using a digital camera (16.1 MP Sony Cyber-Shot DSC-W570). The average RGB values of the images were obtained using a computer software (RGB Analysis of Color Images) and used to calculate a*, b* and % luminance for the calculation of xylose content. Optimization of camera settings was first done in order to obtain high quality photographs of potassium permanganate (KMnO4) solutions and correlation coefficients (r) for the calibration curves close to 1. Two known concentration of KMnO4 solutions (0.05 and 0.10 mM) were prepared to validate the accuracy of the method. The average concentrations of the KMnO4 solutions using spectrophotometry were 0.048 ± 2.04 x 10-3 and 0.099 ± 6.37 x 10-4 mM for 0.05 and 0.10 mM, respectively; corresponding values using digital photometry (average values from a*, b* and % luminance) were 0.048 ± 5.16 x 10-3 and 0.105 ± 5.35 x 10-3 mM. Spectroscopic and digital photometric results showed no significant difference using t-test performed at 95% confidence level. For acid hydrolysates of corn cobs and Sargassum sp., the average xylose concentration obtained from spectrophotometry were 22.2 ± 1.04 and 0.55 ± 0.06 mg/mL respectively; corresponding results from digital photometry (average values from a* and % luminance) were 23.3 ± 1.63 and 0.57 ± 0.13 mg/mL respectively. Spectroscopic and digital photometric results for sample analysis were repeatable and showed no significant differences using t-test performed at 95% confidence level. This study showed that digital photometry is a practical and accurate alternative method to spectrophotometry for the analysis of xylose.

Language

English

Location

UPLB Main Library Special Collections Section

Call Number

LG 993.5 2012 C42 /B66

Document Type

Thesis

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