Silanization, column

Novolac molecular weights were measured in THF at 35°C by high pressure size exclusion chromatography using a Waters Model 510 pump (flow rate=1.0 ml/min), 401 differential viscometer detector and a set of Dupont PSM 60 silanized columns. A universal calibration curve was obtained with a kit of 10 narrow molecular weight distribution, linear polystyrene standards from Toya Soda Company. Data acquisition and analysis were performed on an AT T 6312 computer using ASYST Unical 3.02 software supplied with the Viscotek instrument. 

In general the preparation of a polymer monolithic rod is performed as a multi-step procedure (Figure 11). Generally, the stages involved are pre-treatment and preparation of the monolithic matrix by polymerization and derivatization or functionalization. Pre-treatment of the bare capillary is sometimes needed in order to obtain good physical stability. Most columns are therefore polymerized in silanized columns. The capillary column is first washed with a strong alkaline solution such as 1.0 M sodium hydroxide so that the siloxane groups at... 

System (2) has been described for the assay of corticosteroids (cortisone, hydrocortisone, prednisone, and prednisolone) in urine [141]. Prior to introduction into the GC system, the sample was eluted with 2 1 ethyl acetate-methanol, the extracts evaporated to dryness, and then oxidized with sodium bismuthate. Used in the method was a silanized column (132 cm X 5 mm) containing 2,2-dimethylpropane-l,3-diol adipate (0.65%) supported on celite, and operated at 230°C. The carrier gas was argon, and the detector used strontium 90-ionization. The standard deviation was 3.5 % (based on 47 determinations). 

Attach a silanized column to a sturdy support and verify that it is perfectly vertical by holding a small level against the column at three or four different points around it. 

The drug substance is separated from its related substances using a Octadecyl silane column (4 mm ID x 300 mm, 10 pm particle size) and a mobile phase consisting of water, acetonitrile, methanol and acetic acid (650 175 175 1, v/v) at a flow rate of 2.0 mL/minute. Detection of the analytes is achieved at ambient temperafure using UV absorbance at 254 nm. The standard and sample solutions are prepared in a diluent consisting of mobile phase and 5 pL are injected onto the column. All related substances are eluted within 30 minutes and may also be quantitated. The retention time of indapamide is approximately 15 minutes. 

Warsh J J, Chiu A, Godse D D 1982 Simultaneous determination of norepinephrine, dopamine and seratonin in rat brain regions by ion-pair liquid chromatography on octy silane columns and amperometric detection. J Chromatogr 228 131-141... 

Methyl trichlorosilane [75-79-6] M 149.5, b 13,7 /101mm, 64.3 /710.8mm, 65.5 /745mm, 66.1 /atm, d 1.263, n 1.4110. If very pure distil before use. Purity checked by Si nmr, 6 in MeCN is 13.14 with respect to Me4Si. Possible contaminants are other silanes which can be removed by fractional distillation through a Stedman column of >72 theoretical plates with total reflux and 0.35% take-off (see p. 441). The apparatus is under N2 at a rate of 12 bubbles/min fed into the line using an Hg manometer to control the pressure. Sensitive to H2O. [J Am Chem Soc 73 4252 7957 J Org Chem 48 3667 7955.]... 

Methyl vinyl dichlorosilane (dichloro methyl vinyl silane) [124-70-9] M 141.1, b 43-45.5 /ll-11.5mm, 91 /742mm, 92.5 /743.2mm, 92.5-93 /atm, d 1.0917, n 1.444. Likely impurities are dichloromethylsilane, butadienyl-dichloromethylsilane. Fractionate through a column packed... 

Gas chromatographic analysis at 79° using a flame detector in conjunction with a 183 x 0.32 cm. stainless-steel column containing Dow-Corning 550 fluid on silanized support gave peaks for l-bromo-3-chloropropane (6.5 minutes) and 6-chloro-2-hexyne (9.3 minutes) whose areas were shown to be proportional to the mole fractions. The latter were determined by integration of the expanded (50 Hz sweep width)... 

Eigure 3.3 shows the calibration plots for Zorbax PSM columns. (The calibration plots for silanized and unsilanized columns are comparable.) These calibration plots allow the chromatographer to select the appropriate columns for samples. Eor example, the Zorbax PSM 60 column provides resolution of... 

F. Silan, P. Jadaud, F. R. Whitheld and I. W. Wainer, Determination of low levels of the stereoisomers of leucovorin and 5-methylteti ahydrofolate in plasma using a coupled clii-ral-achiral liigh-performance liquid chromatograpliic system with post-cliiral column peak compression , 7. Chromatogr. 532 227-236 (1990). 

The resolution of these columns for protein mixtures, however, was comparably poor. The peak capacity for human serum albumin was near 3 during 20 min gradient elution. Improvement has been reached by covalent binding of PEI (M = 400-600) onto a 330 A silica of 5 pm particle size [38], The peak capacities of ovalbumin and 2a -arid glycoprotein were 30-40 (tgradienl = 20 min). Enhanced peak capacity and resolution probably were due to the more diffuse structure of PEI coupled to silane moieties than that of strictly adsorbed on silica and cross-linked (see Sect, 2.2). Other applications of covalently adsorbed PEI are discussed in Sect. 4.1. 

Analysis of neutral product for active species. The di- and poly sulfonates present in AOS have been isolated from monosulfonates by column chromatography using silanized silica gel by Puschmann [109]. The content of mono-and disulfonates in the fractions obtained were determined gravimetrically. 

The drugs are held on the ion exchanger whereas the sample matrix materials pass through. The packing is then washed with 0.5 ml of 1.0M aqueous ammonium hydroxide and then two, 1 ml aliquots of 5% methanol in water. The sample is then desorbed by two separate aliquots of 1 ml of 0.22M ammonium hydroxide in pure methanol. Finally, the sample is collected in a silanized glass tube and the solvent removed by evaporation under stream of dry nitrogen. The volume of the sample is then made up to 250 pi and 100 pi placed on the column. The separation obtained is shown in figure 3. 

The checkers found considerable variation in the rate of the reaction in different runs, the time required for its completion ranging from 3 to 10 hours. It is therefore advisable to monitor the progress of the reaction. For this purpose small aliquots (ca. 0.05 ml.) were withdrawn from the flask with a syringe and hydrolyzed by injection into a vial containing ether and saturated ammonium chloride. The relative amoimts of enol silane and cyclopropoxy sdane were determined by gas chromatography on an 0.6 cm. X 3.7 m. column of 3% OV-17 coated on 100-120 mesh Chromosorb W. With a column temperature of 120° and a carrier gas flow rate of 20 ml. per minute, the retention times for the enol silane and the cyclopropoxy silane are ca. 1.9 and 2.3 minutes, respectively. 

FIGURE 11.11 (a) Schematic representation of PLC of Heracleum sosnowskyi fruit crude extract, system silanized silica/MeOH + HjO (6 4) (b) rechromatography of fractions I and II from the plate a on Lobar-type column filled with Horisil eluted with 5% MeCN in CHjClj -I- H (7 3) fractions controlled by analytical HPLC in system ClS/MeOH -i- HjO (6 4). For abbreviations, see Figure 11.5. (For details, see Waksmundzka-Hajnos, M. and Wawrzynow-icz, T., /. Planar Chromatogr, 3, 439 141, 1990.)... 

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