Characteristic detection and determination of alphatic aldehydes.

Aliphatic aldehydes can be detected and determined by reaction with propionaldehyde (3-phenyl-2-quinoxalinyl) hydrazone in ethanolic solution. The red color is produced within 20 min at 40°, then faded gradually. Detectable responses are obtained with aliphatic aldehydes but not with aromatic aldehydes, glucose, and ketones. With acetaldehyde, propionaldehyde, butyraldehyde, and iso-butyraldehyde, absorbance of the reaction mixture measured at 465 nm is directly proportional to the concentration. Acetaldehyde can be determined in the concentration range of 5×10-5 to 1×10-3M and other aldehydes in the range of 1×10-4 to 1×10-3M.