DETERMINATION OF PLASMA THEOPHYLLINE IN THE NEWBORN BY HIGH-RESOLUTION GAS-CHROMATOGRAPHY AND SPECIFIC DETECTION

  • 1 January 1978
    • journal article
    • research article
    • Vol. 36  (6) , 497-507
Abstract
A micromethod was described for the determination of blood theophylline concentration in premature newborn infants. The method includes the specificity of separation in gas phase chromatography on a glass capillary column, and the sensitivity of thermo-ionic detection. After addition of isobutyl-3-methyl-1-xanthine, an internal standard, extraction was performed in acid pH, with the mixture dichloromethane-isopropanol. The derivation consists of an N-pentyl reaction. Analysis was carried out on a glass capillary column SE 30 measuring 75 m/0.3 mm. The technique was simple and rapid. Its pediatric application was particularly studied; the limit of quantitative detection was 0.1 mg/l. The plasma sample may be 0.5 ml. The reproductibility was about 2% in usual therapeutic doses. The specificity of the method has been widely debated, in particular the stages of extraction, derivation, separation and detection. The analysis requiring systems of specific detection require a chromatographic apparatus with a high power of resolution; this was illustrated by an example.