Zur Methodik der quantitativen Guajacolbestimmung im Harn.

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Abstract
To most of the 24-hr. sample add strong NaOH and evaporate carefully to about 100 cc. on the water bath. Wash with water, to about 300 cc, into a distillation flask fitted with a separatory funnel; run in 10-20% by vol. of syrupy H3PO4. Distill until the Millon reaction becomes negative, running in more water if needed. Reflux the distillate 1-1.5 hrs. with 10% of fuming HI to convert guaiacol to catechol. To an aliquot (e.g., 50 cc.) add a good excess (up to 150 cc.) of bromine water and cool in ice water 15-20 min. Filter off the brown pptd. tribromophenols etc. To a 50 cc. aliquot of the filtrate add 10% NaOH to decolorization, then 25 cc. satd. Na2CO3, 10 cc. Denis-Tisdall phosphomolybdotungstic acid reagent, and water to 100 cc. Of a 0.1% standard catechol solution, treat 5-10 cc. with Na2CO3, etc. as above. Compare the blue color after 10-20 min. at room temp. The catechol values can be converted directly to guaiacol, since secondary phenols normally are present in urine only in traces (nor was much absorbed guaiacol eliminated as catechol). Expts. with known phenol-guaiacol mixtures averaged 97% recovery. Total phenols +guaiacol can be detd. in 20-30 cc. of urine: free of uric acid and protein by silver lactate and a drop of colloidal ferric hydroxide, hydrolyze by brief warming with conc. HC1, extract twice with 50 cc. ether. Wash the ether extract with 20% Na2CO3, then extract with 10% NaOH and prepare the latter as above for color comparison.

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