Trienzyme sensor

Similar to the work described by Spohn et al. [34], a trienzyme sensor was developed recently for the determination of branched-chain amino acids (L-valine, L-leucine, and L-isoleucine). Leucine dehydrogenase, NADH oxidase, and peroxidase were coimmobilized covalently on tresylate-hydrophylic vinyl polymer beads and packed into a transparent PILL tube (20 cm X 1.0 id), which was used as flow cell. The sensor was free of interferences from protein and NH4+ and it was stable for 2 weeks. The sensor system was applied to the determination of branched-chain amino acids in plasma with recoveries ranging from 98 to 100% [36],... 

R. C.H. Kwan, P.Y.T. Hon, K.K.W. Mak and R. Renneberg, Amperomet-ric determination of lactate with novel trienzyme/poly(carbamoyl) sulfonate hydrogel-based sensor, Biosens. Bioelectron., 19(12) (2004) 1745-1752. 

For creatine determination the appropriate bienzyme electrode was used. Creatinine and creatine could be assayed in parallel by combining a trienzyme electrode and a bienzyme electrode. Both electrodes reached a steady signal 2 min after sample addition. With a 25 pi sample volume the linear range was 1-100 mg/1. The sensors were stable for more than 500 measurements. The CV of creatine determination in serum was 1.3% with 21.7 mg/1 and 11.7% with 8.2 mg/1, and a day-to-day CV of 8.4% was achieved. Comparison with the Jaffe method for 55 serum... 

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