Direct radioimmunoassay for the detection of barbiturates in blood and urine

A radioimmunoassay has been developed for the detection of barbiturates in blood and urine without any pre-treatment of the sample. It is based on a radioiodinated derivative of 4-hydroxyphenobarbitone which allows use of relatively simple gamma-counting procedures. The assay can detect therapeutic levels of barbiturates in very small amounts (50 μl) of blood and urine samples. It is cheap, rapid, simple to perform and is broadly specific for the barbiturate class of drugs to the exclusion of related drugs. The assay is, therefore, very well suited to the task of screening large numbers of samples for the presence of barbiturates. (author)