Spectrophotometer

Definition

A spectrophotometer is an analytical instrument used to measure the amount of light that a sample absorbs. It quantifies concentrations of compounds in solutions by measuring absorbance at specific wavelengths.

5 Must Know Facts For Your Next Test

1. Spectrophotometers are crucial for determining microbial growth by measuring the optical density (OD) of a culture at 600 nm (OD600).
2. They are used to assess the effectiveness of antimicrobial drugs by monitoring changes in bacterial cultures' OD after drug exposure.
3. In immunoassays like ELISAs, spectrophotometers measure color changes resulting from enzyme-substrate reactions to quantify antigen or antibody concentrations.
4. The Beer-Lambert Law, which relates absorbance to concentration and path length, is fundamental to spectrophotometric analysis.
5. Proper calibration and maintenance of spectrophotometers are essential for accurate and reproducible results.

Review Questions

• How does a spectrophotometer help in determining microbial growth?
• What role does a spectrophotometer play in testing the effectiveness of antimicrobial drugs?
• Why is the Beer-Lambert Law important in spectrophotometric analysis?

Related terms

Optical Density (OD): A measure of how much light is absorbed by a sample; often used to estimate microbial cell concentration.

Beer-Lambert Law: A principle that relates the absorption of light to the properties of the material through which the light is traveling.

ELISA (Enzyme-Linked Immunosorbent Assay): A plate-based assay technique designed for detecting and quantifying substances such as peptides, proteins, antibodies, and hormones.