Rapid serum gentamicin assay by enzymatic adenylation

An improved, rapid and accurate enzymatic adenylation assay for gentamicin has been developed. It can be completed in one hour with an accuracy of +/- 2.7% (+/- 1 SD) for the range of gentamicin concentrations of 6-12 microgram/ml. Concentrated enzyme was used to prepare a complete adenylation mixture, which was stored frozen in aliquots suitable for daily assays. A special apparatus designed for efficient washing of phosphocellulose disks was used in the assay.