1774 CLINICALCHEMISTRY,Vol.37, No.10,1991 Pentobarbital Quantification in the Presence of Phenobarbital by Fluorescence

We developed a method for measuring pentobarbital in samples that also contain phenobarbital. The phenobar-bital is destroyed by adding sodium hydroxide and then heating at 95#{176}Cfor 60 mm. Pentobarbital is not affected by this pretreatment and can then be measured with an Abbott TDx barbiturates kit. Using this method, we ob-tained an average analytical recovery of 98 % of added pentobarbital and a correlation of y = O.953x + 3.4 vs HPLC. The intra-assay CV was 3.7 % at 25.8 mg/L; the interassay CV was 6.2 % at 16.1 mg/L Other long-acting barbiturates, e.g., hexobarbital, are also effectively de-stroyed by this alkali pretreatment. Other short-acting barbiturates, e.g., secobarbital, are not removed and would produce an interference. Addftlonal Keyphrases: analytical error- barbiturate