Analytical Sciences

Optically Specific Detection of D- and L-Lactic Acids by a Flow-Injection Dual Biosensor System with On-line Microdialysis Sampling

Yoko NANJO,*^,** Takayuki YANO,** Ryuzo HAYASHI,* and Toshio YAO**

*Oji Scientific Instruments, 4-3-1 Jokoji, Amagasaki, Hyogo 660-0811, Japan
**Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuencho, Naka, Sakai, Osaka 599-8531, Japan

A flow-injection dual biosensor system with microdialysis sampling is proposed for the simultaneous determination of D-lactic and L-lactic acids. The dialysate from the microdialysis tube is delivered to a sample loop of the six-way autoinjector and then automatically injected into the flow-injection line with a dual enzyme electrode arranged in perpendicular to the flow direction. The dual enzyme electrode is constructed by hybridizing a poly(1,2-diaminobenzene) film into two sensing parts which respond selectively to D-lactic and L-lactic acids, respectively, without any cross-reactivity. The proposed flow-injection analysis method can be successfully applied to the simultaneous determination of D,L-lactic acids in alcoholic beverages.

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