90 



acid in complex samples due to the lack of a molecular ion (M"^') formed by EI of 



lactic acid and due to the presence of additional ions, characteristic of instrument 

 parameters, which contribute to the difficulty in identifying this compound by library 

 searching of EI spectra. 



Altering Attraction 



Previous work with altering attraction via acidification consisted of the 

 addition of sulfuric acid to solutions of carboxylic acid salts in acetone. TTie purpose 

 of the sulfuric acid addition was to increase the concentration of the free acid versus 

 the sodium salt rather than to examine possible enhancement of attraction [19]. 

 Mosquitoes responded to these acidified solutions by exhibiting a greater activation 

 to flight; however, there was little increase in directional attraction. 



The increase in attraction effected by the acidification of lactic acid solutions 

 had not been examined. Logically, addition of acid should increase the proportion 

 of free acid (volatile) relative to the dissociated form (involatile). This should 

 increase attraction; addition of base should produce the opposite effect. The utility 

 of mass spectrometry in this case was in its application to the examination of possible 

 solution-phase reactions involving lactic acid and the methanol solvent. Specifically, 

 this is an examination for products of acid-catalyzed or base-catalyzed esterification. 



