Titrimetric, spectrophotometric and polarographic determination of resorcinol, catechol and phloroglucinol

Simple titrimetric, spectrophotometric and polarographic methods are described for the determination of micro-amounts of resorcinol, catechol and phloroglucinol. These methods are based on the iodination of the above compounds in a buffered solution in which the resulting iodide, after removal of the excess of iodine, is oxidised with bromine to give the iodate, which is determined titrimetrically, spectrophotometrically or polarographically. An iodination time of 1 min at pH 5.7 is used for resorcinol and catechol and at pH 4 for phloroglucinol. The determination ranges are 10–1 000 µg of resorcinol and 20–1 000 µg of catechol and phloroglucinol by the titrimetric method, 5–30 µg of resorcinol, catechol or phloroglucinol by the spectrophotometric method and 1–1 000 µg of resorcinol, catechol or phloroglucinol by the polarographic method.