Determining concentrations with spectrophotometer

The labels on these beverages do not specify how much dye we are consuming. We did this experiment to find out which soda uses the most dye. Using a spectrophotometer, we measured how much light is absorbed by various known concentrations of red dye. After collecting this data, a standard curve was made that correlated the concentration of red dye 40 to its absorbance rate.

Determining concentrations with spectrophotometer

Scott, and Gregg J. If the solution is pure, one can use a spectrophotometer to measure the amount of ultraviolet radiation absorbed by the bases. DNA can also be quantified by measuring the UV-induced emission of fluorescence from intercalated ethidium bromide.

This method is useful if there is not enough DNA to quantify with a spectrophotometer, or if the DNA solution is contaminated.

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Strategies for accurately quantifying nucleic acids using these approaches are discussed here. Zero the spectrophotometer with a sample of solvent. For more accurate readings of the nucleic acid sample of interest, dilute the sample to give readings between 0.

Spectrophotometry - Wikipedia

For a 1-cm pathlength, the optical density at nm OD equals 1. Low ratios could be caused by protein or phenol contamination. The diluted sample gave a reading of 0. To determine the concentration of DNA in the original sample, perform the following calculation: To maintain constant background staining of the gel, include 0.

Use a UV light to photograph the gel. Compare fluorescence intensities and estimate DNA concentrations.

Determining concentrations with spectrophotometer

Also spot several DNA standards of known concentration. Let the gel stand for a few hours at room temperature to allow small contaminating molecules to diffuse away.

Determining concentrations with spectrophotometer

Compare fluorescence intensities and estimate nucleic acid concentrations.Choose five concentrations for your standards. You want the standard concentrations to be separated from each other by about the same interval -- e.g., molar, molar, molar, etc.

Using UV-Vis Spectroscopy to determine concentration | Physics Forums

-- and in about the same range as what you expect your unknown will be. After determining the λ the relationship between absorbance and concentration was directly proportional with a molar absorptivity of M-1cm.

The data obtained reinforced the connection between the color of a standard solutions were directly proportional to their concentrations (Table 1, Figure 1). Lab 2 Spectrophotometric Measurement of Glucose Objectives 1.

Learn how to use a spectrophotometer. 2. Produce a glucose standard curve.

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3. Perform a glucose assay. Safety Precautions Three additional tubes will be used to test the different concentrations of glucose standard. These tubes can be labeled Standard A, Standard B, and Standard. Using the Spectrophotometer Introduction In this exercise, you will learn the basic principals of spectrophotometry and serial dilution and • the application of Beer’s law to determine concentrations and extinction coefficients.

• the use of spectrophotometry to identify compounds • the use of standard curves in analyzing data.

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In chemistry, spectrophotometry is the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength. determining concentrations of unknown samples, and determining the pKa of various samples. Using the Spectrophotometer Introduction In this exercise, you will learn the basic principals of spectrophotometry and serial dilution and • the application of Beer’s law to determine concentrations and extinction coefficients.

• the use of spectrophotometry to identify compounds • the use of standard curves in analyzing data.

Spectrophotometry - Wikipedia