Micro-dialysis can be used for continuously harvesting body fluids, while a multi-component analysis of the dialysates
by infrared spectrometry offers splendid opportunities for monitoring substrates and metabolites such as glucose, lactate
and others small enough to penetrate the semi-permeable dialysis membranes. However, a drawback of this process are
variable recovery rates, which can be observed especially for subcutaneously implanted catheters in human subjects.
Isotonic perfusates were investigated with acetate and mannitol as recovery markers for the dialysis of human serum at
37°C to mimic in vivo patient monitoring. The latter non-ionic substance has been suggested for application when other
ionic substances such as bicarbonate or pH are also to be determined. Simultaneously for acetate and mannitol, the
depletion of the marker substances from the perfusates using different micro-dialysis devices was investigated under
various flow-rates. Relationships between relative dialysate marker concentrations and glucose recovery rates were
determined based on multivariate calibrations. For quantification, classical least squares with reference spectra for
modelling the serum dialysates was used, rendering a basis for reliable blood glucose and lactate measurements.
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