DETERMINATION OF NETILMICIN IN SERUM BY THIN-LAYER DENSITOMETRY AND FLUORESCENCE POLARIZATION IMMUNOASSAY

A newly developed thin-layer chromatographic method (TLC) for the quantitative determination of netilmicin in serum is described and compared with fluorescence polarization immunoassay (FPIA). The TLC procedure involves solid-phase extraction of the aminoglycoside from serum and chromatography on reversed-phase thin layer. Post-chromatographic derivatization is carried out using 2,2-diphenyl-1-oxa-3-oxonia-2-boratanaphthalene (DOOB) as fluorescence reagent. The calibration curve for netilmicin in serum is linear in the range 1.0-5.0 mug/ml and the detection limit is about 0.2 mug/ml (correlation coefficient r = 0.9963, mean coefficient of variation V(xo) = +/- 5.3 %). A total of 25 serum samples from patients treated with netilmicin was measured by TLC and the results were compared with those of FPIA (Abbott TDx). There is no statistically significant difference between the two procedures (y = -0.35 + 1.094 . x, Passing/Bablok). Thus the TLC-procedure is an altemative for the determination of netilmicin in serum, that possesses the necessary sensitivity of other comparable methods.