PAG Extension Practice Test

Centrifuging a sample before measuring it with a colorimeter is crucial because it effectively removes suspended particles that could interfere with the measurement of light absorbance. In a colorimetric analysis, it is essential to have a clear solution to ensure that the light passing through the sample is not scattered or absorbed by these particles. If the sample contains suspended solids, they can scatter light and lead to inaccurate results, as the colorimeter will measure not only the target analyte but also the scattering effects from these particles. By centrifuging, the solids are separated from the liquid portion of the sample, allowing for a more accurate determination of the concentration of the substance of interest based on the intensity of color developed in the solution.

The other options, while related to sample preparation and analysis, do not address the primary reason for centrifugation in this context. For instance, centrifugation does not inherently increase the concentration of glucose or enhance color intensity, nor is its main intention to prevent contamination.