Gas-chromatographic conditions

Wax esters have similar relative molecular masses to diacylglycerols and are eluted under comparable gas chromatographic conditions. Alternatively, the alcohol and fatty acid moieties can be released by saponification and their methyl esters subjected to gas chromatography. 

Some samples were analyzed using a Carlo Erba Fractovap 2350 with flame ionization detector. Hydrogen was used as carrier gas at 0.8 kg/cm, and the samples were injected in a split mode (1 60). The other gas chromatographic conditions and the column were as described above. 

A calibration standard was prepared by concentrating the solution containing 60 mg oil, 0.2 mg ethyl heptanoate and 160 ml pentane to the equivalent volume (ca. 0.2 ml). A Perkin - Elmer Sigma 2B gas chromatograph equipped with a flame ionization detector was used for analysis. The gas chromatographic conditions were as follows ... 

Constant-temperature water bath at 37°C Steam bath Gas chromatograph Conditions ... 

The total extracts or diluted oleoreslns could also be analysed under these gas chromatographic conditions. While the aldehydes emerging early are mixed up with the volatile oil components, the zlngerone and the shogaol peaks elute separately and later. 

M. Kokko, Effect of variations in gas chromatographic conditions on the linear retention indices of selected chemical warfare agents, J. Chromatogr., 630, 231-249 (1993). 

Gas Chromatograph Conditions. The GC was a VARIAN 6000 with a flame ionization detector. The injection port was heated at 200°, the detector at 250°. The detector range was 10-12 AFS, attenuation 64 except as noted. The column was 25m X 0.32mm fused silica DB5 with a 1.0 micron film thickness (bonded SE54, J W Scientific, Rancho Cordova, CA). The carrier gas was hydrogen at 47 cm/s. The column was temperature programmed from an initial temperature of 35 C, held for 4 min., to a final temperature of 200 C at 4°C/min. 

Gas Chromatographic Conditions. All analyses were performed on a Hewlett Packard 5890 GC equipped with a 5970 Mass Selective Detector or a Hewlett Packard 6890 GC equipped with a Nitrogen Phosphorous Detector (Hewlett Packard, Inc., Avondale, PA). A DB 35 (35% phenyldimethylpolysiloxane), 30 m x 0.25 mm ID X 0.25 [im column (J W Scientific, Inc., Folsom, CA) was used for all analyses. Carrier gas was helium at a linear velocity of 30 cm/sec. Samples were analyzed using split injections (split ratio = 30 1) with injector and detector (NPD) temperatures of 260°C and 250°C, respectively. Oven temperature programming was as follows initial temperature of 80°C for 1 min increase temperature at 3.5°C/min to 115°C increase at 15°C/min to 180°C increase at 60 C/min to 190°C hold at 190°C for 6 min. 

Although polar materials constitute the major portion of the pentane solubles, saturates and aromatics are also found in appreciable concentrations (Table V). The relatively low H/C ratio of the saturate fraction suggests a high concentration of saturated cyclics or olefins. Thermogravimetric analysis indicated that only about 40% of the pentane solubles is volatile under typical gas chromatographic conditions. 

Gudzinowicz and Martin emphasize the possibility of thermally induced molecular rearrangements, particularly for vinyl compounds, under otherwise normal gas chromatographic conditions. Such molecular changes impose a definite limitation upon the usefulness of this method, and their absence under actual separation conditions should first be established. 

Oxy-7 and 8 gas condensate was later compared in a separate correlation with Oxy-6 gas condensate. This produced 37 eorrelated peaks for these 2 waters (Table 3 and Fig. 3). A greater number of correlations is likely in a 2-water correlation versus a 7-water because there is less ehanee of obtaining incomplete data and hence no correlation (e.g., small peaks dose to the detection limits for the gas chromatographic conditions). The 37 peaks included all the 22 peaks common to the 7 waters. These 22 compounds constitute a migority of the total detected nitrogenous compounds in every water sample (Table 2). Furthermore, the totals for correlated peaks are minimum values because some peaks may have been inadvertently or unavoidably exduded from the comparison for any of a number of reasons (e.g., peaks too small to be consistently selected by the peak detection program). 

For studies on the interrelationsship among nicotine, nornicotine, anabasine and anatabine during the biosynthesis in Nicotiana glutinosa, Alworth and Rapoport used almost the same gas chromatographic conditions as reported above. On a polybutylene glycol column the alkaloids mentioned were satisfactorily resolved. 

RELATIVE RETENTION TIMES OF TERTIARY strychnos ALKALOIDS11 gas chromatographic conditions, see Figure 17.8... 

GAS CHROMATOGRAM OF 0.2 ug TRIMETHYLSILYL DERIVATIVE OF LSD Gas chromatographic conditions, see Figure 18.1... 

An interesting use was made of solubility analysis in a stability study of propoxyphene hydrochloride13. In this study, propoxyphene hydrochloride was stored at 80°C, 105°C, and 130°C. Both the solubility analysis and the alternate IR assay showed the thermal stability of propoxyphene hydrochloride. Gas chromatography can be used to measure the slow hydrolysis of propoxyphene hydrochloride in aqueous solutions. The hydrolytic products are propionic acid and (+)-a-4-(Dimethylamino)-3-methy1-1,2-diphenyl-2-butanol. With suitable gas chromatographic conditions either product can be quantitated. A chloroform extraction of an alkaline solution of propoxyphene hydrochloride (where degradation has occurred) can be assayed using the previously described IR method. 

Suitable gas chromatographic conditions for the analysis of carbonyl difluotide in mixtures with phosgene, carbonyl chloride fluoride, COj and air are as follows [84a] ... 

The cyclopropanes thus formed are conveniently analyzed by NMR spectroscopy since they are unstable to various gas chromatographic conditions. The stereospecific addition of bromo(phenyl)carbene to an alkene (at least 95%) has been reported. It should be stressed that the reaction of alkenes with aryldibromomethanes and alkyllithiums gave arylcyclop-ropanes, rather than l-aryl-l-bromocyclopropanes. - ... 

Gas chromatography-mass spectrometry (GC-MS) was carried out on selected samples either to confirm compounds Identified by retention times or to Investigate the Identities of other peaks of Interest. Samples were run on a Finnigan Model 9610 GC coupled to a Finnigan Model 4021 quadrupole MS. Mass spectrometrlc data were acquired and processed with a Flnnlgan-INCOS 2300 Data System. The MS was operated In electron Impact mode with 70 eV electron energy. Gas chromatographic conditions were comparable to those used for GC-FID. 

Each laboratory used its own optimised procedure for the sample preparation, clean-up, method of injection, calibration and gas chromatographic conditions [33]. Calibrants were obtained as pure crystalline certified materials from BCR [32] in addition, CBs 105, 128, 149, 156, 163 and 170 were obtained from BCR after characterisation in an independent laboratory of the identity of the compound by elemental analysis, NMR and melting point determination, and of the purity of the crystalline materials by GC-MS, GC-ECD [32] these pure compounds were used to prepare calibration solutions for these congeners. Each laboratory prepared separate calibration solutions in iso-octane of the appropriate concentration to calibrate the detector within the approximately linear range. Calibration procedures used by the participants are described in details in the certification report [32]. 

To aid in the detection of sulfur and nitrogen-containing compounds, the extract was analyzed on a HP6890 gas chromatograph equipped with an atomic emission detector (AED) (Hewlett Packard, Wilmington, PA). The gas chromatograph conditions were the same as those described above. 

Identincation. The components in the fractionated oils mentioned above were analyzed by GC and GC/MS resulting in the identification of 12 hydrocarbon terpenes and 72 oxygenated compounds. Gas chromatographic conditions were OV-101 column, 50 m X 0.25 mm i.d., 80 C to 200 C at 2 C/min. GC/MS was conducted with a JEOL JMS-SX102AQQ (El mode, 70 eV) equipped with a JEOL MP-7010 data processor unit. The analytical conditions were almost the same as the GC conditions OV-101, 50 m X 0.25 mm i.d. temperature program, 80-200 C at 2 °C/min He, 0.64 mL/min split injection (1 50). NIST public data library of MS spectra (data number 49,496) which was supplied from JEOL LTD was used for matching of mass spectral pattern. 

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