3-cyanopropyl phenyl

Chlorthalidone RP Cyanopropyl Phenyl (w/P-cyclodextrin in mp) Walhagen and Edholm, 1991... 

The ethyl acetate solution of organic species from the pre-treatment scheme shown in Figure 1 is suitable for analysis by this method. In order to cover the range of common explosives several chromatography columns with different types of stationary phase are required to allow for difierent polarities and volatihties. Dimethylsiloxane, phenyl-modified dimethylsiloxane, cyanopropyl- phenyl- vinyl-modified dimethylsiloxane, and polyethylene glycol have been found to represent a useful set of stationary phases. Carefully optimised temperature programming is also needed to obtain the requisite resolution and avoid interferences [19, 20]. 

Figure 24-16 Split and splitless injections of a solution containing 1 vol% methyl isobutyl ketone (b.p. 118°C) and 1 vol% p-xylene (b.p. 138°C) in dichloromethane (b.p. 40°C) on a BP-10 moderately polar cyanopropyl phenyl methyl silicone open tubular column (0.22 mm diameter x 10 m long, film thickness = 0.25 m, column temperature = 75°C). Vertical scale is the same for A-C. In D, signal heights should be multiplied by 2.33 to be on the same scale as A-C. [From R J. Marriott and P. D. Carpenter, Copillory Gas Chromatography Injection," J. Chem. Ed. 1996, 73, 96.]...

Fused silica capillary columns give better separation than packed columns. Columns having inside diameters of 0.25, 0.32, and 0.53 mm and film thickness between 0.25 and 1 pm have found use in herbicides analysis. The stationary phase is generally made out of phenyl silicone, methyl silicone, and cyanopropyl phenyl silicone in varying compositions. Some common columns are DB-5, DB-1701, DB-608, SPB-5, SPB-608, SPB-1701, Rtx-5, AT-1701, HP-608, BP-608, or equivalent. Use helium as carrier gas flow rate 30 cm/s on narrowbore columns with 0.25 or 0.32 mm ID and 7 mL/min for megabore 0.53 ID columns. 

Figure 7. Solvent analysis using a cyanopropyl phenyl methyl silicone stationary phase.

The polarity of the column packing is in the following order cyanopropyl>phenyl>ODS Cig. It is understandable that the ODS column is not suitable for the separation because of its low polarity. Both the cyanoprophyl and phenyl columns could separate these solutes efficiently, but the latter exhibited shorter separation times. 

Some special configurations of gas chromatographic columns are reported. The Siemens RGC 402 online gas chromatograph instrument for BTEX measurements reported in Ref. 61 uses a W-COT-CP-WAX CB in series with a WCOT-CP-SIL to achieve in a first step of 4 min the separation of higher volatiles in the second column where these are retained. In the second step, both columns are disconnected from each other in order to continue the separation process of both fractions simultaneously in different columns. For the separation of fractions of compounds of different polarities (BTEX, trichloroetehene, tetrachloroethene, ethylacetate, and nonane), two columns of different polarities, DB-5 (5% phenyl-95% methyl silicone), and DB-1701 (14% cyanopropyl phenyl silicone) were switched in parallel. ... 

Cyanopropyl—methil 50% phenyhnethyl polysiloxane 95% Dimethyl—5% phenyl polysiloxane 14%-Cyanopropyl-phenyl)-methylpolysiloxane (5%-Phenyl)-methylpolysiloxane 95% Dimethyl-5% phenyl polysiloxane Bwcyanopropyl phenyl polysiloxane >75% bwcyanopropy 1 polysiloxane 35% Heptakis(6-0-tert-butyldimethylsilyl-2,3-di0-methyl)-b-cyclodestrine in OV-1701 95% Dimethyl-5% phenyl polysiloxane 14% Cyanopropyl 1% vinyl 85% methyl polysiloxane... 

SP-2401" and 3% SP-2250. ° Detectors used by EPA standards procedures, include photoionization (PID)," electron capture (ECD)," Eourier transform infrared spectrometry (PTIR), " and mass spectrometry detectors (MSD)." ° Method 8061 employs an ECD, so identification of the phthalate esters should be supported by al least one additional qualitative technique. This method also describes the use of an additional column (14% cyanopropyl phenyl polysiloxane) and dual ECD analysis, which fulfills the above mentioned requirement. Among MSDs, most of the procedures employ electron impact (El) ionization, but chemical ionization (CI) ° is also employed. In all MSD methods, except 1625, quantitative analysis is performed using internal standard techniques with a single characteristic m/z- Method 1625 is an isotope dilution procedure. The use of a FTIR detector (method 8410) allows the identification of specific isomers that are not differentiated using GC-MSD. 

Problems presented by this approach included the presence of impurities contributed by the diene, etc. The approach currently used in our laboratory involves direct GC/flame ionization detector (FID) analysis on medium- or wide-bore cyanopropyl/ phenyl/methyl silicone bonded-phase columns. The key prerequisite is to stabilize the sample against anionic polymerization by prior addition of a low level of an appropriate protonic acid stabilizer. 

High-resolution gas chromatography (HRGC) has been widely applied for the determination of PCB contents in water samples [112]. PCBs can be separated on a 30-50 m fused silica capillary column with various chemically bonded stationary phases. Table 20.6 shows combinations of column lengths, stationary phases, oven temperature programs, and detectors. Polysiloxane (95% dimethyl-5% phenyl) is the most widely used stationary phase, although 5% diphenyl polydimethylsiloxane, 7% methyl-7% cyanopropyl-phenyl polysiloxane, 95% dimethyl 5% phenyl polysiloxane, 50% phenyl-methyl-polysiloxane are also used. 

Figure 3.4 Two-dimensional separation of dimethylnaphthalenes in crude oil using a 50 m methyl (95%)/phenyl (5%) polysiloxane primary column and a 50 m methyl (50%)/phenyl (25%)/cyanopropyl (25%) polysiloxane secondary column. The top trace indicates the primary separation monitor, while the following chromatograms indicate individual heart-cut secondary analysis. Reproduced from R.G. Schafer and J. Holtkemerr, Anal. Chim. Acta. 1992, 260, 107 (20).

The most commonly used siloxane modifiers are those having phenyl, trifluoro-propyl and cyanopropyl substituents. Introduction of phenyl units into the polydimethylsiloxane backbone either in the form of methylphenylsiloxane or diphenyl-siloxane increases the thermal and oxidative stability, glass transition temperature and the organic solubility characteristics of the resulting copolymers. At low levels (5-10 percent by weight) of incorporation, bulky phenyl groups also break up the regularity of polydimethylsiloxane chains and inhibit the crystallization (Tc... 

Figure 2.6 Reagents used for the deactivation of silanol groups on glass surfaces. A - disilazanes, B > cyclic siloxanes, and C -silicon hydride polysiloxanes in which R is usually methyl, phenyl, 3,3,3-trifluoropropyl, 3-cyanopropyl, or some combination of these groups. The lover portion of the figure provides a view of the surface of fused silica with adsorbed water (D), fused silica surface after deactivation with a trimethylsilylating reagent (E), and fused silica surface after treatment with a silicon hydride polysiloxane (F).

With the advent of improved column deactivation, elution of more polar analytes has become possible. For this type of analytes, columns coated with selectively separating stationary phases may provide the most rapid analysis. This is the background to the increasing demand for moderately polar and polar stationary phases. Users want universal columns, that is, columns that can solve a number of analytical tasks. For that purpose, tire new generation of stationary phases should include phases in which different types of functional groups such as phenyl and cyanopropyl are present simultaneously (48). 

Chromatographic separation is generally carried out on octadecyl, octyl, phenyl, and polymeric reversed-phase columns, although polar stationary phases such as silica (153) or cyanopropyl (141, 142) have been also used in Ure analysis of sedecamycin and pirlimycin residues, respectively. 

In addition, column-switching between three columns coupled together for sample cleanup, concentration of analyte, and analytical separation proved to be a rugged, automated means of isolating dexamethasone from bovine tissues (528). The analyte, along with co-eluting matrix components, was heart-cut from the first, phenyl-silica, column and collected on a second, silica, column. The second column was then backflushed with a stronger eluent onto the third, cyanopropyl-silica, column where the analyte was finally resolved from matrix components. 

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