Direct Injection Method for Gas Chromatographic Measurement of Inhalation Anesthetics in Whole Blood and Tissues

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Abstract
A direct injection method for gas chromatography has been developed for rapid measurement of the concentration of inhalation anesthetics in whole blood and tissue. By the use of a specially designed sample vaporizing apparatus attached to the gas chromatograph, a 5 to 10 [mu]l sample of blood or liquefied tissue is injected directly into the sample space and heated at 100[degree]C. for a period of 60 to 90 sec. Only the gas components vaporized from the sample are introduced into the column and detector. The residue of the sample can easily be removed from the sample space. An ultrasonic wave homogenizer is used for preparation of tissue samples. Gas chromatography is done by the use of a single column, Molecular Sieve Type 5-A coated with 0.3% diethylene glycol succinate, combined with a hydrogen flame ionization detector for measurement of cyclopropane, halothane, methoxyflurane and diethyl ether. For analysis of nitrous oxide, however, Molecular Sieve Type 13-X was used with a thermal conductivity detector. Coefficient of variation of the reproducibility of peak height is less than 5% for each anesthetic. The entire procedure is simple and practically applied to clinical determination of the depth of anesthesia.