Micro and macro GLC determination of ethambutol in biological fluids

Previously available GLC methods for ethambutol may only be used to measure quantities of drugs much greater than those found in biological fluids such as plasma and dialysate. A previously published GLC method for plasma samples is extended to measure ethambutol in dialysate. A second GLC method, involving derivatization with bis(trimethylsilyl)trifluoroacetamide and subsequent quantitation using a flame-ionization detector, is described for urine samples. With a dual-column and dual-detector gas--liquid chromatograph, simultaneous micro (plasma and dialysate) and macro (urine) determinations of ethambutol are possible.