A rapid and precise method for determining theophylline in serum.

We report a spectrophotometric method for determining theophylline that is useful as a routine method for monitoring serum theophylline concentrations. The recovery of theophylline from serum is essentially 100% whem compared with aqueous standards taken through the entire procedure. Barbiturates, which interfere with most ultraviolet spectrometric methods for theophylline, do not interfere with this method. The procedure requires less than 45 min for completion and is more sensitive than most spectrophotometric methods for determining theophylline.