State any four conditions necessary for analysis of a sample by colorimetry? ?

1. The sample must be in a liquid form or easily soluble in a suitable solvent.
2. The sample must not contain any interfering substances that could affect the colorimetric analysis.
3. The sample must be of a known concentration or the concentration must be accurately determined before analysis.
4. The colorimetric method used must be appropriate for the specific analyte being measured in the sample.

1. The analyte must absorb light in the visible region of the spectrum.
2. The absorption must be proportional to the concentration of the analyte.
3. The sample must be free of interfering substances that also absorb light in the same region of the spectrum.
4. The instrument used must be properly calibrated.