On-line microdialysis sampling coupled with flame atomic absorption spectrometry for continuous in vivo monitoring of diffusible magnesium in the blood of living animals.

A novel on-line microdialysis sampling coupled with flame atomic absorption spectrometry (FAAS) with an attractive application is reported. Microdialysates perfused through implanted microdialysis probes were directly introduced into the flame atomizer of a FAAS system using 0.2% HNO(3) as carrier solution at a nebulizer uptake flow rate of 6mlmin(-1). The interval for each determination was 90s (60s sampling time, 10s read time and 20s washing time). The analytical characteristics of the on-line microdialysis-FAAS system were validated as follows: linearity range, 0-300mgl(-1); detection limit (3sigma, n=7), 0.53mgl(-1); precision (R.S.D., n=50), 4.1%. By comparing Mg levels in the blood of living rabbits with the results obtained from in vivo no net flux (NNF) method, the accuracy of the proposed on-line method was found to be good. The present method can be successfully applied to the in vivo monitoring of diffusible Mg in the blood of living rabbits after magnesium sulfate (MgSO(4)) administration with a temporal resolution of 1.5min.