Polyethylene glycol column chromatography

Total ethanol may be determined by gas chromatography using a Stabilwax (polyethylene glycol) column with helium carrier gas under isothermal (35°C) conditions [8], Analyte detection is performed using with a flame ionization detector [8]. The level of ethanol is typically 6 % w/w. 

The IR-spectra of 41 tobacco alkaloids and related compounds have been tabulated (S5). Nornicotine, nicotine, myosmine, nicotyrine, anabasine, anatabine, and dihydronicotyrine were separated from an extract of tobacco alkaloids by countercurrent partition (86). Thin-layer chromatography has been used to separate nicotine, nornicotine, anabasine, and nicotyrine (57). The use of gas chromatography to separate tobacco alkaloids has been studied. The retention times of 11 tobacco alkaloids on polyethylene glycol columns has been reported (88) and the effect of the column packing on the retention times of pyridine bases has been described (89). Mixtures containing pyrrolidine, piperidine, pyridine, and various alkylated pyridines have been separated using programed temperature control (90). 

FIGURE 7.3 Gas chromatography- ame ionization detector chromatogram with some components identi-ed by means of mass spectrometry (top) and a time-intensity aromatogram of grapefruit oil (bottom). The separation was performed on a polyethylene glycol column (30 m x 0.32 mm ID, 0.25 pm Im thickness). (From Lin, J. and Rouseff, R.L., Flavour Fragr. /., 16, 457, 2001. With permission.)... 

The purity of the product was checked by vapor phase chromatography on a polyethylene glycol on Teflon column at 72°, 15 p.s.i., and a flow rate of 102 ml. of helium per minute. The sample appeared to be homogeneous, but, since the amine tails badly on the column, it is not possible to detect the presence of a small amount of water (less than 3%). 

Figure 4.20 Calibration curves for size-exclusion liquid chromatography. Column, TSK GEL G3000SW, 120 cm x 7.5 mm i.d. eluent, 0.2 m sodium phosphate buffer pH 6.8 flow rate, 1.0 ml min-1. Standards 1, protein-, 2, dextran, and 3, polyethylene glycol.

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]. 

Gas Chromatography. A Hewlett-Packard 5890 gas Chromatograph (Hewlett-Packard, Avondale, PA) with a flame ionization detector (FID), equipped with a 60 m X 0.32 mm I.d. DB-WAX column (df > 0.25 pm, bonded polyethylene glycol, J W Scientific, Folsom, CA) was employed. Helium carrier gas was used at a flow rate of 1.64 mL/min (30 C). The oven temperature was programmed from 30 C (4 min isothermaQ to 180 C at 2 C/min. A spirt ratio of 128 was used. The injector and detector were maintained at 200 C and 220 C, respectively. A 60 m X 0.32 mm i.d. DB-1 column (df - 0.25 pm, bonded dimethyl polysiloxane, J W Scientific, Folsom, CA) was used to anal e the sample prepared by vacuum steam distillation-extraction. Helium carrier gas was used a t a flow rate of 1.60 mL/min (30 C). The oven temperature was programmed from 30 C (4 min isothermal) to... 

Fig. 2. Chromatography of iodinated human pregnancy-specific /3i-glycoprotein (PSj8,G) on a 40 X 1cm Sephadex G-IOO column eluted with 50 raM phosphate buffer, pH 7.5. Binding of the tracer in the presence and in the absence of an antiserum to PS/SiG is shown by the dashed lines, the separation procedure being addition of polyethylene glycol as described in Table II. Earlier fractions, containing aggregated I-labeled PS iG, give an unacceptably high assay blank value. Selection of the later fractions yields material with an acceptable blank and also shows the best distinction between blank and zero standard. From data kindly supplied by A. T. Al-Ani.

To a solution of 6.2 g (0.05 mol) of methyl phenyl sulfide in 50 mL of 95% ethanol is added 54.8 (0.1 mol) of the supported oxidant in one portion at room temperature. The mixture is stirred vigorously until the sulfide has been completely consumed, as detected by gas-liquid chromatography with a 5% Carbowax 20 M (a polyethylene glycol compound) column (5 h). After filtration of the solid and removal of most of the ethanol by evaporation of the filtrate, 25 mL of dichloro-methane is added. The solution is dried with anhydrous sodium sulfate and evaporated to dryness to give 5.54 g (88%) of methyl phenyl sulfoxide, bp 98-102 °C at 1 mm of Hg. 

---