Wine Analysis

Volatile Acid Measurement - Trouble Shooting and Hints

As with all analysis it pays to think ahead -

What is the volatile acidity concentration levels expected?


• If the expected value is greater by a factor of 10 -
  
  
  • Check that the 0.01M NaOH, not 0.1M NaOH solution was used for the titration.
    
    
  • If the molarity of your NaOH solution was 0.0095 (approximately 0.1), make sure you did not use 0.09 (aprox. 0.1) in your calculations.
    
    
• If the VA value is higher then expected check that the following steps were performed and performed correctly -
  
  
  • Was your sample degassed of CO₂?
    
    
  • Was the distilled water in the conical receiving flask neutralized?
    
    
  • Did you remember to add the freshly prepared 0.3% H₂O₂ solution to your sample?
    
    
  • Did you run a blanc?
    
    
  • Was your NaOH solution standardized or accurately diluted?
    
    
• Detecting the end point during the titration procedure can be difficult without some experience.
  
  Using a pH meter to determine the end point at a pH of 8.3 is more exacting and easier to perform (see acid titration procedure).