Penicillinase optodes: substrate determinations using batch, continuous flow and flow injection analysis operation conditions

Determination of penicillin G is shown with two different sensor types and with three different working conditions for each sensor. A universal sensor head has been constructed for this purpose, which allows use in either batch, continuous-flow or flow injection analysis (FIA) mode. In addition, two different immobilization techniques are compared. While the simple entrapment of penicillinase and fluorescein (coupled as isothiocyanate to dextran) in polyacrylamide gel shows good stability with time, the cross-linked gelatin-penicillinase-FLUOS optode loses its activity after one week. On the other hand, the sensitivity and concentration range for determination of penicillin G are similar for both polyacrylamide and gelatin optodes. Both optodes have comparable response times of about 60 s (or 10 s using law "integration time" for signal processing). Comparing all three different working conditions, there is a decrease in sensitivity in the order continuous flow > batch > FIA.