of Total Carbohydrates Using the Phenol-Sulfuric Acid Method
Lab 7—Determination of Total Carbohydrates Using the Phenol-Sulfuric Acid Method
This lab introduced the students to analyzing carbohydrate content using a spectrophotometer and phenol-sulfuric acid methods.
Virginia Smith
983976633
Lab Partner: Jeff Martz
Due Date: 3-22-11
Introduction
The objective of this lab was to have students use a spectrophotometer to analyze the carbohydrate content in the sample. Phenol-sulfuric acid methods were also applied to determine the total quantity of carbohydrates in the food. It is important to study carbohydrate content because the absorbtivity of different carbohydrates varies. The compounds in the sample will react with phenol to produce a yellow-gold color, which can then be measured using a spectrophotometer. The results are expressed in terms of a single carbohydrate, usually glucose. Single carbohydrates are digestible and are absorbed in the body to provide metabolic energy.
Materials and Methods
This experiment was conducted as described in the laboratory manual (Roberts 2011) with the following minor modifications. Firstly, the determinations for the standard curve are done in duplicate in large test tubes. Secondly, the dilution schemes for the glucose unknown, one corn syrup sample and one Gatorade sample are as follow:
Glucose Unknown for Standard Curve 100 μg
Stock Solution (10,000 μg/mL) ----------------> 99 mL H2O
Table 1. Dilution Scheme of Unknown Glucose Sample
%
mL of Solution mL of H2O
0
0
5
20
1
4
40
2
3
60
3
2
80
4
1
100
5
0
Corn Syrup Solution 1 g Corn Syrup 0.5mL CS solution
1 g/L Corn Syrup ----------------> 1000 mL H2O ---------------------> 10 mL H2O
Gatorade 1 mL Gatorade
21 g/ 355 mL----> 85μg/1000ml ----------------> 1000 mL H2O
Results
Figure 1. Standard Curve of the Unknown Glucose
This lab introduced the students to analyzing carbohydrate content using a spectrophotometer and phenol-sulfuric acid methods.
Virginia Smith
983976633
Lab Partner: Jeff Martz
Due Date: 3-22-11
Introduction
The objective of this lab was to have students use a spectrophotometer to analyze the carbohydrate content in the sample. Phenol-sulfuric acid methods were also applied to determine the total quantity of carbohydrates in the food. It is important to study carbohydrate content because the absorbtivity of different carbohydrates varies. The compounds in the sample will react with phenol to produce a yellow-gold color, which can then be measured using a spectrophotometer. The results are expressed in terms of a single carbohydrate, usually glucose. Single carbohydrates are digestible and are absorbed in the body to provide metabolic energy.
Materials and Methods
This experiment was conducted as described in the laboratory manual (Roberts 2011) with the following minor modifications. Firstly, the determinations for the standard curve are done in duplicate in large test tubes. Secondly, the dilution schemes for the glucose unknown, one corn syrup sample and one Gatorade sample are as follow:
Glucose Unknown for Standard Curve 100 μg
Stock Solution (10,000 μg/mL) ----------------> 99 mL H2O
Table 1. Dilution Scheme of Unknown Glucose Sample
%
mL of Solution mL of H2O
0
0
5
20
1
4
40
2
3
60
3
2
80
4
1
100
5
0
Corn Syrup Solution 1 g Corn Syrup 0.5mL CS solution
1 g/L Corn Syrup ----------------> 1000 mL H2O ---------------------> 10 mL H2O
Gatorade 1 mL Gatorade
21 g/ 355 mL----> 85μg/1000ml ----------------> 1000 mL H2O
Results
Figure 1. Standard Curve of the Unknown Glucose