Spectrophotometers and Colorimeters – Mobile Science

March 1st, 2010

Color and Spectral Analysis

DR890-Clrmtr-RZ-48470-S Colorimeters measure light absorbed by a sample after a chemical reagent produces a color change. The intensity of absorbed light is directly proportional to the concentration of the compound, therefore colorimeters can accurately measure the concentration of various compounds in the sample. Colorimeters measure light wavelengths in the visible light range. The Hach DR 890 colorimeter has four fixed wavelengths: 420, 520, 560, and 610 nm. Hach colorimeters function with specific compound test kits for relatively quick and accurate analysis. The instruments are pre-programmedwith a variety of test methods which can reduce operator error and simplify analysis.

DR2800-LFZCS Spectrophotometers, sometimes referred to as UV-Vis spectrophotometers, also measure the intensity of light passing through a sample. They are used to determine the absorbance of light in a sample, ultimately allowing for the determination of color, concentration, or other pertinent information. Spectrophotometers operate using a broader wavelength range than colorimeters, including UV and visible wavelengths; 190–1100 nm. The broader spectral range increases the number of analytes detected by the instrument to almost twice as many substances as colorimeters with greater accuracy.

In short, a colorimeter provides an overall measure ment of the light absorbed, while a spectrophotometer measures the light absorbed at varying wavelengths.

Tips:

• When choosing between a colorimeter and a spectrophotometer, look at the available tests and ranges to find the appropriate instrument for your job. Although spectrophotometers are more versatile, a colorimeter will often suit your job requirements.

• Review the test procedures you will be using prior to going out to the jobsite. Look at the required reagents and required apparatus sections to ensure you have everything you will need. They are at the end of each test.

• Ensure that the unit’s battery is charged, or has fresh batteries. Some spectrophotometers require AC power, so plan accordingly.

Pine rents the following Hach instruments;