Separation of Inorganic Anions Using Methacrylate-Based Monolithic Column Modified with Trimethylamine in Ion Chromatography Capillary System

Abstract

Methacrylate-based monolithic column was prepared in fused-silica capillary (80  0.32 mm i.d.) by in situ polymerizetion reaction using glycidyl methacrylate as monomer; ethylene dimethacrylate as crosslinker; 1-propanol, 1,4-butanediol, and water as porogenic solvents. The monolith matrix was modified with trimethylamine to create strong anion exchanger via ring opening reaction of epoxy groups. The morphology of the monolithic column was studied by using Scanning Electron Microscope (SEM). This column had good mechanical stability and permeability. The effects of various mobile phases for separation of inorganic anions were investigated. Iodate, bromate, nitrite, bromide, and nitrate were separated within 11 min using 100 mM potassium chloride as mobile phase and detected at 210 nm. This method showed good precision of retention time, acceptable linearity and good sensitivity. Under the optimum condition, the RSD of the retention time was in the range of 1.09% -1.75% (n = 6). The calibration curve showed linear relationships between the peak area and the concentration. The limits of detection (LOD) and the limits of quantitation (LOQ) were between 0.08 -0.18 mM and 0.26 -0.61 mM, respectively. This method was applied to the determination of inorganic anions in tap water and ground water samples.

Development of Micro-Flow-Controlled Techniques and Novel Stationary Phases in Capillary Liquid Chromatography

“…In addition, when glycidyl methacrylate (GMA) is used as the monomer, the epoxy group in GMA could be easily further modified with other functional groups such as primary, secondary or tertiary amines, etc., for the separation of various compounds. We have successfully fabricated methacrylate-based monolithic columns modified with trimethylamine [73], diethylamine [74], triethylamine [75] as well as PEG [76] for the separation of inorganic anions. Compared to silica-based monoliths, these polymeric monoliths generally exhibit poorer column efficiency especially for the separation of small molecules and ions; however, the chromatographic results showed that trimethylamine-or PEG-modified monoliths could be a good alternative for the rapid determination of anions without significant swelling or shrinkage occurred in the capillary.…”