Final answer:
In a chromatography experiment, data collection can typically be stopped after detecting the compound with the highest boiling point. In this case, the ethanol peak should be the last one observed due to its stronger hydrogen bonding and higher boiling point compared to methanol and water.
Step-by-step explanation:
When analyzing mixtures in a laboratory setting using chromatography, data collection can often be stopped after the detection of the compound with the highest boiling point or the one that elutes last from the column. The compounds mentioned have similar molar masses, so their boiling points and elution order are more likely determined by their polarity. Ethanol and methanol both form strong hydrogen bonds due to their hydroxyl groups, but methanol, being the smaller molecule, tends to have a lower boiling point. Therefore, the last peak you're likely looking for in your chromatogram is the ethanol peak, as it should elute after methanol and water. However, this generalized guidance can vary depending on the specific chromatography method and conditions used, so it's crucial to refer to the specific experimental procedures of your lab.