OHST Practice Exam

What is the greatest single error factor in colorimetric sampling devices?

1. Gel coagulation

2. Temperature extremes

3. Pump airflow inaccuracy

4. Interferences by other contaminants

The correct answer is: Interferences by other contaminants

The greatest single error factor in colorimetric sampling devices is interferences by other contaminants. Colorimetric devices work by measuring the absorbance of light at specific wavelengths to quantify the concentration of a target analyte. When other contaminants are present in the sample, they can absorb light at similar wavelengths, leading to inaccurate readings. This can cause significant deviations from the actual concentration of the target substance, ultimately affecting the reliability of the analysis and the conclusions drawn from the data. While other factors like pump airflow accuracy, temperature extremes, and gel coagulation can impact the performance of sampling devices, they do not typically have as profound an effect on the concentration readings as interferences from other substances do. In essence, the presence of interfering contaminants can mask or mimic the signals from the target analyte, making it a critical concern in colorimetric analysis.