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The determination of hydroxide by ion chromatography (IC) is demonstrated using a monolithic octadecylsilyl (ODS)-silica gel column coated first with a nonionic surfactant (polyoxyethylene (POE)) and then with a cationic surfactant (cetyltrimethylammonium bromide (CTAB)). This stationary phase, when used in conjunction with a 10 mmol/l sodium sulfate eluent at pH 8.2, was found to be suitable for the rapid and efficient separation of hydroxide from some other anions, based on a conventional ion-exchange mechanism. The peak directions and detection responses for these ions were in agreement with their known limiting equivalent ionic conductance values. Under these conditions, a linear calibration plot was obtained for hydroxide ion over the range 16 μmol/l to 15 mmol/l, and the detection limit determined at a signal-to-noise ratio of 3 was 6.4 μmol/l. The double-coated stationary phase described above was shown to be superior to a single coating of cetyltrimethylammonium bromide alone, in terms of separation efficiency and stability of the stationary phase. A range of samples comprising solutions of some strong and weak bases was analyzed by the proposed method and the results obtained were in good agreement with those obtained by conventional potentiometric pH measurement.

Item Type:	Refereed Article
Keywords:	Monolithic columns; Stationary phases, LC; Coated columns; Hydroxide; Inorganic anions; Surfactants
Research Division:	Chemical Sciences
Research Group:	Analytical Chemistry
Research Field:	Separation Science
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Chemical Sciences
Author:	Haddad, PR (Professor Paul Haddad)
ID Code:	31935
Year Published:	2004
Web of Science® Times Cited:	13
Deposited By:	Chemistry
Deposited On:	2004-08-01
Last Modified:	2010-02-02
Downloads:	0