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.

ABSTRAK

Penelitian tentang penentuan asam benzoat, natrium sakarin dan kafein telah dilakukan secara Kromatografi Cair Kinerja Tinggi (KCKT) Fasa Balik. Kondisi optimum analisis dari ketiga senyawa di atas adalah fasa gerak metanol-bufer fosfat (1:7) dengan pH 4,5, laju alir 1 mL/min, kolom C18 (150 x 4,6 mm i.d.) dengan temperatur 40 o C dan pendeteksian dengan Spektrofotometer UV/Vis pada panjang gelombang 220 nm. Metoda ini diaplikasikan pada beberapa sampel minuman ringan. Kadar ketiga senyawa ini di dalam sampel tidak melebihi batas maksimum yang diizinkan yaitu berdasarkan SNI 01-0222-1995 untuk natrium sakarin dan asam benzoat serta SNI 01-6684-2002 untuk kafein. Standar Deviasi Relatif ketiga senyawa ini berdasarkan waktu retensi dan luas puncak secara berturut-turut adalah; asam benzoat 0,37% dan 0,59%, natrium sakarin 0,16% dan 0,21%, kafein 0,38% dan 0,60%. Hasil perolehan kembali dari ketiga senyawa ini adalah asam benzoat 100,82%, natrium sakarin 94,92%, kafein 90,32%. Standar Deviasi Relatif dan perolehan kembali ketiga senyawa ini memenuhi persyaratan metoda AOAC.