How can the purity of a sample be determined?

Determining the purity of a sample is most effectively achieved by comparing its response against a pure standard. This method typically involves analyzing the sample using techniques such as spectroscopy, chromatography, or mass spectrometry, where the measured response (such as peak area or intensity) is compared to that of a known pure substance. The purity can be quantified based on the amount or ratio of the desired component in the sample relative to impurities or other compounds.

In analytical chemistry, having a pure standard allows for accurate calibration and comparison, which is essential for confirming or quantifying the presence of certain substances in the sample. The greater the similarity in the responses between the sample and the pure standard, the higher the inferred purity of the sample.

Other methods mentioned, such as measuring thermal stability, identifying color, or assessing odor, are not definitive for determining purity. These approaches may provide some qualitative information but lack the precision and specificity required to assess purity quantitatively.