Rapid minichromatography for purification of samples prior to radioimmunoassay

A method is presented for the treatment of serum or other biological fluids to remove interfering substances prior to radioimmunoassay. Studies with radioimmunoassay systems for measuring serum levels of insulin revealed the presence of such interfering substances, which could be removed by utilizing small columns of Sephadex G-25 prepared in disposable pipet tips. The columns were centrifuged at low, and finally, higher speeds, to recover the sample volume with essentially no alteration in insulin activity. Validity of the technique was evaluated by both parallelism and recovery studies. This system offers considerable advantages over previous extraction and chromatography procedures in terms of simplicity, reproducibility, and recovery