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US 3,937,799 AGranted
Radioassay of vitamin B-12 employing bentonite
AssigneeBio-Rad Laboratories, Inc.
InventorsNathan Lewin, James E. Fries, C. Steven Richards
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AssigneeBio-Rad Laboratories, Inc.
InventorsNathan Lewin, James E. Fries, C. Steven Richards
Estimating the term…
Radioassay for vitamin B-12 using the unknown quantity of non-radioactive vitamin B-12 released from serum mixed with the radioactivity of a known quantity of radioactive vitamin B-12 tracer. A solution of intrinsic factor having a binding capacity less than the quantity of serum vitamin B-12 and radioactive vitamin B-12 is used to bind a portion of the vitamin B-12 mixture. The vitamin B-12 not bound to intrinsic factor is removed by addition of a bentonite-containing tablet. The quantity of radioactive vitamin B-12 bound to intrinsic factor is compared with standard values and the unknown serum vitamin B-12 obtained. In the steps of the procedure the acid assay medium is pre-combined with the radioactive tracer so that the radioactive vitamin B-12 tracer receives the same treatment as serum vitamin B-12. Certain of the other reagent solutions are pre-combined and the concentration of the components adjusted so that the volume used of each of these other reagent solutions is the same in different assay steps. Thus, fewer pipetting steps are necessary.
In the method for the radioassay of vitamin B-12 in a serum sample solution in which a radioactive vitamin B-12 tracer and serum vitamin B-12 compete for intrinsic factor (IF) of limited binding capacity, and thereafter free radioactive vitamin B-12 and free serum vitamin B-12 are separated from IF and the radioactive vitamin B-12 and serum vitamin B-12 bound thereto prior to measuring radioactivity for reference to standard values, the improvement comprising separating free radioactive vitamin B-12 and free serum vitamin B-12 from IF and the radioactive vitamin B-12 and serum vitamin B-12 bound thereto by adding an effective amount of bentonite to adsorb free radioactive vitamin B-12 and free serum vitamin B-12 whereby the supernatent solution of IF with bound radioactive vitamin B-12 and serum vitamin B-12 can be physically segregated from solid bentonite with adsorbed free radioactive vitamin B-12 and free serum vitamin B-12.
A method for separating free vitamin B-12 and a blood serum solution comprising combining an effective amount of bentonite with said solution to adsorb vitamin B-12 not bound by serum protein, and separating bentonite with said adsorbed vitamin B-12 relative to said solution.
An improved radioassay for vitamin B-12 including the steps of providing a first solution containing acid and a preselected amount of radioactive vitamin B-12;
Dependencies are inferred from the claim text.