Phases aminopropyl

Figure 2. High performance liquid chromatogram of a preparation of 2-deoxy-2-fluoro-D-glucose. Stationary phase, aminopropyl banded silica mobile phase, 70% aqueous acetonitrile at l.SmL/min. The large peak in the upper panel is 2FDG.

In most cases, the proteia is immobilized onto y-aminopropyl sUica and covalently attached usiag a cross-linking reagent such as -carbonyl diimidazole. The tertiary stmcture or three dimensional organization of proteias are thought to be important for their activity and chiral recognition. Therefore, mobile phase conditions that cause proteia "deaaturatioa" or loss of tertiary stmcture must be avoided. 

Sugar analysis by hplc has advanced greatly as a result of the development of columns specifically designed for carbohydrate separation. These columns fall into several categories. (/) Aminopropyl-bonded siHca used in reverse-phase mode with acetonitrile—water as the eluent. (2) Ion-moderated cation-exchange resins using water as the eluent. Efficiency of these columns is enhanced at elevated temperature, ca 80—90°C. Calcium is the usual counterion for carbohydrate analysis, but lead, silver, hydrogen, sodium, and potassium are used to confer specific selectivities for mono-, di-, and... 

Indeed, the polymeric interface seems to be highly diffuse and hydrophilic because copolymers of N-vinylpyrrolidone and N- (2-hydroxyethyl) acrylamide are readily soluble in water [53]. Besides, aminopropyl-glass adsorbs the acryloyl chloride copolymer so that only 10% of its active functions become amidated. The rest is located on the loops and tails of the attached macromolecules [51]. Thus the steric repulsion of the bonded phase is a probable reason for the high inertness of the packing towards viruses. 

A cleanup procedure is usually carried out to remove co-extracted matrix components that may interfere in the chromatographic analysis or be detrimental to the analytical instrument. The cleanup procedure is dependent on the nature of the analyte, the type of sample to be analyzed, and the selectivity and sensitivity of the analytical instrument used in the analysis. Preliminary purification of the sample extracts prior to chromatographic separation involves liquid-liquid partitioning and/or solid-phase extraction (SPE) using charcoal/Celite, Elorisil, carbon black, silica, or aminopropyl-silica based adsorbents or gel permeation chromatography (GPC). 

Diolsilane solid-phase extraction (SPE) cartridges, 3-mL (J.T. Baker Inc.) Aminopropyl SPE cartridges, 3-mL (J.T. Baker Inc.)... 

Surfactants are separated according to adsorption or partitioning differences with a polar stationary phase in NPLC. This retention of the polar surfactant moiety allows for the separation of the ethylene oxide distribution. Of all the NPLC packings that have been utilized to separate nonionic surfactants, the aminopropyl-bonded stationary phases have been shown to give the best resolution (Jandera et al., 1990). The separation of the octylphenol ethoxylate oligomers on an amino silica column is shown in Fig. 18.4. Similar to the capabilities of CE for ionic surfactants, the ethylene oxide distribution can be quantitatively determined by NPLC if identity and response factors for each oligomer are known. 

Native PEGs represent a rather difficult class of compounds for either RP-HPLC or NP-HPLC due to their high polarity [3]. On polar stationary phases (silica, diol, CN, aminopropyl) they are very strongly retained and strong solvents like methanol or ethanol are needed to elute them. However, such an elution leads to very poor resolution of... 

Datta et al. [40] used pressurised fluid extraction to extract ground fish tissue, and the resulting extract was purified on aminopropyl silica (APS) extraction cartridges. With no further sample preparation, NP and its ethoxylates, up to nonylphenol pentaethoxylate, were quantified using normal phase (APS Hypersil) HPLC with fluorescence detection. 

Few reports exist on the l.c. separation of such cationic carbohydrate oligomers as those resulting from partial hydrolysis of chitosan. The neutral, A -acetylated analogs from chitin hydrolyses are, however, well separated on columns of aminopropyl silica gel and reversed-phase silica gel. ... 

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