Monitoring Of Ion Chromatography On Preparation Of Silica Microspheres

Silica is one of the most common HPLC column packings matrix at present, it has astable chemical properties and thermal stability, good mechanical strength. But trace metalion impurities cause irreversible adsorption to alkaline compound, and destroy the biologicalmacromolecules, especially chromatographic peak of polypeptide and protein samples, themetal impurities seriously influence the efficiency of chromatographic separation. Ionchromatography is the more popular detection method in recent years, it can analyze manyinorganic cations or anions at the same time. It is fast and simple, high sensitivity andselectivity, wide and good separation. An analytical method for the determination of metalions in silica by ion chromatography with reverse aqua regia digestion is proposed, and themethod is applied the monitoring of metal ions in silica in the synthetic process.Chromatography separation is performed on Shodex YS-50with2.5mmol/L methanesulfonic acid and3.0mmol/L oxalic acid as mobile phase, column temperature of40℃, iteffectively separates and detectes six metal ions (sodium, zinc, potassium, iron, magnesium,calcium) in ion chromatographic system. The established method has a good linear correlationand linear correlation coefficient is above0.999. The limit of detection is from0.16μg/mL to0.42μg/mL. A stable and accurate method is established for determination of metal ions.The pretreatment method of sample is further systematically studied for details. Theoptimum conditions for the pretreatment are as follow: digestion reagent is hydrofluoric acidand against aqua regia, reducing agent is ascorbic acid. Under the optimized conditions, sixmetal ions (sodium, zinc, potassium, iron, magnesium, calcium) can be obtained goodbaseline resoluions. The chromatography peak area RSD of five experiments is below5%andthe average recovery is from87%to108%. The results demonstrates that the proposedmethod is simple, rapid, sensitive and reproducible for determination of metal ions in actualsilica samples.Under the optimization of pretreatment conditions, the metal ions of lab-synthesis silicaand its material are determined, and the main source of metal ions in silica is studied. Themetal ions are tested in prepation process of silica by sol-gel and polymerization inducedcollid aggregation, it is great significant that metal ions are controlled and mornitored for thepreparation process of silica.