Optimization of LC apparatus for determinations in neurochemistry with an emphasis on microdialysis samples.

The popularity of in vivo microdialysis sampling of low-molecular-weight substances has focused attention on improved liquid chromatography procedures for such studies. The complexity of the in vivo experiment, coupled with the complexity of LC, has discouraged some workers from developing this capability in their laboratory. Many small-volume dialysate samples are collected over hours of experiments. Proper handling of the animal (anaesthesia, temperature control, probe size and placement, choice of perfusion media) is critical. Simultaneously giving equal attention to sample collection and storage, derivatization, analysis precision, calibration for accuracy, and preventive maintenance of LC pumps, columns, and detectors is difficult for many laboratories. For reliable LC-based assays for microliter volumes of dialysates minimum human interaction with the samples is desirable. Automation strategies and selection of LC components which we have adopted are described for routine analytes such as biogenic amines, amino acids, choline/acetylcholine, and glucose.