From Big Medical Encyclopedia

GUAIAC TEST — qualitative test on blood in urine, a gastric juice, emetic and fecal masses and so forth. Principle: interaction of hydrogen peroxide or the ozonized turpentine with guaiac pitch to - that, oxidized in ozonide due to peroksidazny properties of blood pigments therefore blue coloring appears. Of the item is usually made at suspicion on the concealed hemorrhage of internals.

Technology of definition

In a test tube pour 5 ml of the fresh not filtered urine, define its reaction by a litmus paper and if alkali reaction, lead up to neutral or subacidic. Contents of a test tube are boiled and after cooling add 1 — 2 ml of 2% of freshly cooked spirit solution of guaiac and 8 — 10 drops of 3% of solution of hydrogen peroxide. Reaction will be more sensitive if to replace hydrogen peroxide with the ozonized turpentine which is prepared by keeping of the turpentine poured by a thin coat at the room temperature (to a siropoobrazny state).

The research on the occult blood of gastric contents, emetic masses and other liquids by means of G. is made by the item as well as urine. Kal previously pound with ice acetic to - that to semi-fluid gruel, extract ether and carry out test with radio extract.

Of the item it is very sensitive and allows to find insignificant traces of blood. It must be kept in mind that at a research a calla positive G. can be received by the item for the account of maintenance of blood pigments in food. Therefore before G.'s carrying out of the item it is necessary to exclude within three days meat from the diet investigated.

See also the Benzidine test , Weber-van-Deena test .

Bibliography: The guide to clinical laboratory trials, under the editorship of E. A. Kost and L. G. Smirnova, page 377, M., 1964; The Reference book on clinical laboratory methods of a research, under the editorship of E. A. Kost, page 276, M., 1975.

B. V. Kulibakin.