Preview

Determination of Reducing Sugars Using Dns

Good Essays
Open Document
Open Document
602 Words
Grammar
Grammar
Plagiarism
Plagiarism
Writing
Writing
Score
Score
Determination of Reducing Sugars Using Dns
INTRODUCTION
Determining the sugar concentration of food samples is very important especially in industries where quality control is monitored.
One method to determine the sugar concentration of reducing sugars is by heating with 3,5 dinitrosalicylic acid(DNS) which produce a red-brown product Miller(1959)The reaction is direct,thus the method is preferred over the Benedict’s test method. The concentration of the coloured complex can be determined with the spectrophotometer at Absorbance 540.The sugar concentration of unknown sample can then be read off a calibration curve(standard curve) created using known sugar concentrations.The dilutions of a solution of known concentration are used to determine the concentration of unknown.
Being familiar with the background information about reducing sugars and various methods used to identify them,Biotechnology students were provided with a Fructose sample solution and were required to find its concentration

Materials
• A freshly prepared solution of DNS was provided
• Sugar solution of unknown concentration
• Stock sugar standard(fructose solution in saturated benzoic acid)
• Working sugar standards(fructose solutions diluted 1 in 4 before use
Boiling water bath
Method
A serial dilution was made by using 1ml of DNS reagent with 3ml of working sugar standards and made up to 4 tubes.One tube of unknown was made by mixing 1ml of DNS with 3ml sugar solution.A blank was prepared by adding 1ml DNS to 3ml distilled water.The tubes were covered with marble and were placed in a water bath for 5 minutes.They were cooled to room temperature and then read at 540nm against the blank.

Results
Below is the tabulated form of the absorbance reading obtained from the spectrophotometer at 540nm:
Table 1: Absorption values of the 5 tubes
Tube Absorbance(nm) Concentration( g/ml) Dilution
1 0.152 250 0.5
2 0.150 125 0.25
3 0.078 62.5 0.125
4 0.071 31.25 0.0625
U(unknown) 0.145 Unknown

Below is the



References: 1. Skoog,D.A.et al (1996) Fundamentals of Analytical Chemistry,7th ed, Saunders College Publishing, New York,pg 563-573 2. Miller,G.L.(1972)Analytical Chemistry,Kalyani Publishers,New Delhi,pg 426 3. Dr Mokwena’s source.

You May Also Find These Documents Helpful

  • Good Essays

    For solution A, the 1% sugar solution, 5 grams of sugar were added to a 250ml graduated cylinder and then tap water was added up to the 250ml mark. A small piece of plastic wrap was placed over the top of the graduated cylinder and the solution was mixed. Next, the contents were poured into a small saucepan over the stove. The graduated cylinder was then filled with 250 more milliliters of water, and then poured into the saucepan as well. The mixture was then heated on the stove and stirred until the sugar was dissolved. Once this happened, the solution was removed from the saucepan, poured into a container, and labeled as 1% sugar solution.…

    • 977 Words
    • 4 Pages
    Good Essays
  • Good Essays

    Lab for Chemistry 221

    • 612 Words
    • 3 Pages

    Introduction: This experiment was conducted to determine the amount of sugar in a can of Coke and to and use a calibration curve. 5 different solutions were made, each containing 100mL of water and between 1 and 7 grams of sugar. The calibration curve was used to determine the sugar in the can of Coke. The measurements used are grams and milliliters. The calibration curve is used to determine the grams of sugar just by using the density of the can of Coke. In this experiment the main equation was density = mass / volume.…

    • 612 Words
    • 3 Pages
    Good Essays
  • Good Essays

    Lab Report

    • 1398 Words
    • 6 Pages

    The amount of glucose and glycerol were determined from the homogenate sample as well. Samples A(+) and B(-) were used to determine glucose. Sample A had 8mg/ml amylogloucosidase in .2M citrate buffer, pH 5.0 and was incubated at 37° Celsius for two hours to allow for the enzyme to digest the glycogen. Sample B was the control, where only .2M citrate buffer, pH 5.0 was added which was used to measure the amount of free glucose. While incubating, glycerol was determined by using 3 ml triglyceride reagent incubated at 37°celsius for 5 minutes. After warmed, 30 microliters of homogenate was added to…

    • 1398 Words
    • 6 Pages
    Good Essays
  • Satisfactory Essays

    By using a spectrophotometer with the unknown solution, a percent transmittance of 56 appeared. The concentration of the unknown solution was then easily plotted on a graph to show the corresponding data.…

    • 258 Words
    • 2 Pages
    Satisfactory Essays
  • Good Essays

    Food Dyes Lab

    • 671 Words
    • 3 Pages

    The spectrometer tests required a computer with Logger Pro software, samples of Gatorade Frost Riptide Rush as well as red 40 and blue 1 dyes, DI water, a spectrometer, cuvettes. In order to prepare the dilutions and replicated solution 10mL & 100mL graduated cylinders, various beakers, a 200mL erlenmeyer flask, and a glass stirring rod.…

    • 671 Words
    • 3 Pages
    Good Essays
  • Powerful Essays

    Amount of product (glucose and fructose) produced is what is being measured for this lab. This is an indicator of sucrase activity because the…

    • 1209 Words
    • 5 Pages
    Powerful Essays
  • Powerful Essays

    The point of this lab is to determine if a substance contains carbohydrates such as a reducing sugar and/or polysaccharides. This will be done by using Benedict’s reagent and Iodine stain tests. Benedict’s reagent will react to reducing substances in the solution by oxidizing it and changing the structure of the reducing sugar to form a colored precipitate. The color of this precipitate can be used to determine the concentration of reducing sugars in the substance. If the precipitate is blue no reducing sugars are in the substance. If the precipitate is bluish green, green, yellow, or orange it does contain reducing sugars. Iodine stain will be used to determine if the solution contains polysaccharides.…

    • 1115 Words
    • 5 Pages
    Powerful Essays
  • Better Essays

    Bio Spectroscopy Lab

    • 1273 Words
    • 6 Pages

    The purpose of this lab is to identify the concentration of unknown 276 using absorption values obtained from the spectrophotometer. When using these absorbance values in relation to similar fast green dilution solutions, the concentration of unknown 276 was achieved by drawing a line of best fit on a scatter plot (refer to figure 2 within this lab). By using absorption values of other solutions such as fast green stock solution and chloroplast pigments, information about high absorbency wavelengths was gained. By plotting this information in an “absorption spectrum” graph, the maximum absorption was easily identified for fast green, chlorophyll A and chlorophyll B (refer to figures 1 and 4 within this lab). The graphs in general can be closely related and compared to Beer’s Law stated above. For example, when referring to figure 2 (within this lab) concentration curve for fast green, absorption is in relation to concentration, where as when the concentration of a substance is increased, higher values of light was absorbed (Jones et al., 2007).…

    • 1273 Words
    • 6 Pages
    Better Essays
  • Good Essays

    b. Benedict's Test: monosaccharide + Benedict's solution (light blue)  green to red depending on concentration of sugars…

    • 3277 Words
    • 15 Pages
    Good Essays
  • Good Essays

    Hydrogen and Points

    • 968 Words
    • 4 Pages

    1. List whether each of the following substances was positive or negative for reducing sugar, as indicated by the Benedict's test. (6 points)…

    • 968 Words
    • 4 Pages
    Good Essays
  • Good Essays

    Eight8 g of sugar were placed on the scale, and then transferred into the volumetric flask (Table 8 shows the calculations of the molecular weight, moles, mass, volume and molarity recorded before doing so). Distilled water was added to the sugar until a total of 25mL were in the flask. Then the flask was capped, and the solution was mixed together until the sugar was dissolved. Once dissolved, the solution was transferred into the glass beaker, and certain aspects were measured and recorded in table 9. Once this step was complete, 2.5 mL were removed from the solution, and diluted in the volumetric flask. The steps were then repeated using different amounts of the diluted solution each time .…

    • 684 Words
    • 3 Pages
    Good Essays
  • Better Essays

    Copper In Brass Lab

    • 1053 Words
    • 5 Pages

    One test tube was then filled half full with the same solution of nitric acid and wiped clean of finger prints and smudges. This sample was used as a blank to set the zero absorbance for the spectrophotometer. The direction of the test tube was marked and noted for future use. The student then selected a New Absorbance vs. Concentration experiment in SpectroPro. This was done in order to calibrate the spectrophotometer. The wavelength setting was set on the spectrophotometer at 620nm and the machine was set absorbance, listed as unit (A). The student set the blank to zero absorbance and finished the calibration of the spectrophotometer. The solution in the test tube was then discarded and the test tube was set…

    • 1053 Words
    • 5 Pages
    Better Essays
  • Good Essays

    Macromolecules of Life

    • 671 Words
    • 4 Pages

    To add Benedict’s reagent to four substances, glucose, starch, onion juice, and distilled water, to test the detection of sugar in each.…

    • 671 Words
    • 4 Pages
    Good Essays
  • Better Essays

    Yeast Fermentation lab

    • 2222 Words
    • 9 Pages

    The first factor being measured is the type of sugar used in the fermentation of yeast. The types of sugar being used in the experiment is glucose, sucrose, and lactose. Glucose is a monosaccharide and is used in the first step of glycolysis in order to help create pyruvates, which are then used to create ethanol as long as there is no mitochondria or oxygen present. Sucrose is a disaccharide, commonly referred to as sugar, it’s used worldwide, and mainly harvested from sugarcanes. Sucrose is composed of two…

    • 2222 Words
    • 9 Pages
    Better Essays
  • Better Essays

    Preservatives

    • 12475 Words
    • 50 Pages

    Maximum saccharose concentration that can be achieved in the liquid phase of the product is 67.89%; however higher total sugar quantities (up to 70-72%) found in products are explained by an increased reducing sugar solubility resulting from saccharose inversion.…

    • 12475 Words
    • 50 Pages
    Better Essays