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Quantitative Estimation of Pentose. When pentoses are heated with conc. HCl , furfural is formed which condenses with orcinol in the presence of ferric ions to give a blue-green color. * Principle. ∆. +. HCl. Furfural. Pentose. * Principle. Fe+3. +. Blue Green Complex. Furfural.
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Quantitative Estimation of Pentose • When pentoses are heated with conc. HCl , furfural is formed which condenses with orcinol in the presence of ferric ions to give a blue-green color.
* Principle ∆ + HCl Furfural Pentose
* Principle Fe+3 + Blue Green Complex Furfural Orcinol
Materials 1. Orcinol reagent (0.2% in conc. H2SO4 ). 2. Ribose 2mg/ml (0.2%) in water. 3. Colorimeter or spectrophotometer.
60 5 55 10 50 45 15 40 20 35 25 30 Tube # Blank St. unk. 25 min. Boiling Water Bath Orcinol (ml) 7.5 7.5 7.5 Pentose (ml) 0 2.5 2.5 D.W (ml) 2.5 0 0 Mix Well COOL to Room Temperature in cold water Read the Optical Density at 665 nm
* Calculations Absorbance of Unknown Absorbance of Standard = Concentration of Unknown Concentration of Standard CUn. = A Un. × C St. A St. Samar A. Damiati