Approximately 1 ml of acetaldehyde, or {HEAD ~ any other aldehyde}, is added to {TAIL ~ the mixture} 
Approximately 1 ml of acetaldehyde , or { HEAD ~ any other aldehyde } , is added to { TAIL ~ the mixture }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL