Solvent venting

Morristown, NJ) for the ion source. No carrier gas separator was used. For determination of nitrosamines and TBDMS derivatives of hydroxy-nitrosamines, columns and operating conditions were identical to those for GC-TEA analyses For most work, the He flow rate was 15 cc/min and the column effluent was split 1 1 between a flame ionization detector and the mass spectrometer. The stainless steel splitter, solvent vent valve (Carle Instruments, Fullerton, CA), and associated plumbing were... 

Solvent venting, without splitting Liquid sample from syringe into cold inlet. Solvent is vented at low temperature, condensing nonvolatiles. Heat programming subsequently vaporises the residues, which enter column as in splitless injection Dilute samples thermally labile Broad, some focusing required 1-1000 80-95... 

Solvent venting WCOT 1 ppm (FID) Limitations in solvent detector compatibility... 

The advent of high-resolution capillary gas chromatography (HR-CGC) with on-column injection has resulted in improved GC analysis of polymer additives [92-94]. The solution of the additive mixture is injected directly into the cold end of the capillary column by means of a cold injector. Thus, sample discrimination, the instantaneous evaporation of the sample solvent, is avoided. The nonvaporising, on-column injection combined with very high resolution of the capillary columns allows accurate separation, identification and quantification of additives of complex mixtures. With the solvent venting technique, the sample is introduced into the column without splitting and sample concentrations... 

Programmed temperature vaporisation Capillary Split Pulsed split Splitless Pulsed splitless Solvent vent High concentration High concentration Low concentration Low concentration Low concentration ... 

Drinking water, river water Preconcentration of 2.5 mL water onto C18 extraction disks, rinsing with additional 1 mL and purging disk with gas to remove residual water. Elution with ethyl acetate directly onto GC precolumn with solvent venting. GC/NPD Tap water 20 pg/mL (ppt) river water 20-50 pg/mL >95 (<4% RSD at 200 PPt) Kwakman et al. 1992... 

Pond water Micro liquid-liquid extraction of 1.5 mL water with 1.5 mL methyl t-butyl ether. 500 pL of extract slowly introduced into GC pre-column with solvent venting. cap. GC/FPD 0.02 pg/L (ppb) 102 (5% RSD) at 0.50 pg/l level van der Hoff et al. 1993... 

Extraction of analytes from water using SPE elution with ethyl acetate (108 pL) directly onto retention gap with solvent venting. 

When a PTV instead of a classic injector was utilized in the analysis of penicillin residues, the sensitivity and the precision of the analysis were markedly improved (45). With the cooled PTV injector, some microliters could be injected, and the split-splitless mode allowed solvent venting at low injector temperatures with open slit in a first step, and quantitative transfer of volatile or derivatized drugs by a freely selected linear heat-up rate between 2-12 C/s in the splitless mode in the second step. Sensitivity could be enhanced by multiple injections before heat-up. Nonvolatile components of a sample did not contaminate the chromatographic system, since they accumulated in the glass vaporization tube, which could be changed easily. 

FIGURE 13.10 Generic setup for (a) on-line SPE-HPLC implemented with a simple valve-switching system (G. Maio, R. Morello, F. Arnold, and K.-S. Boos, Analysis of Antimycotic Drugs in Biofluids by On-Line SPE-LC Application note LPN 1859-01 06/06 Diones Corporation, Sunnyvale, CA 94088-3603 Figure 2, p. 1, 2006. With permission.) and for (b) on-line SPE-GC implemented with a large volume injector with a solvent venting option. 

Over the last decade, ICP-MS has proven to be a highly sensitive and selective technique for the determination of trace and ultratrace amounts of metals in various samples. It allows multielement detection in a single run and offers isotopic information of the elements of interest [12-14]. Solvent venting to prevent plasma instability is unnecessary, unlike in GC/MIP-AES, and no carbon accumulates, as it does on the MIP discharge tube. These features make the hyphenation GC/ICP-MS unique. 

Polypropylene Aqueous food-simulating solvents Capillary SEC. Column 10 m x 50 mm i.d. SB-Biphenyl-30, 0.25-pm film. Mobile phase = CO2, linear flow rate 3 cm/sec. Pressure program, 100-400 bar temperature program, 55-100°C. 1-pL injection using solvent venting with gas purging. Retention gap was 1.8 m x 100 pm deactivated fused silica. Detection by FID and MS. Pentaerythrityl-tetrakis((3-(3,5-di-rert-butyl-4-hydroxy-phenyl) propionate) (V,A -bis(2-hydroxyethyl)-C 12.C14-amine) Tris-2,4-di-tert-butylphenyl)phosphite 32... 

Berg, B.E. Hegna, D.R. Orlien, N. Greibrokk, T. Determination of low levels of polymer additives migrating from polypropylene to food simulated liquids by capillary SFC and solvent venting injection. Chromatographia 1993, 37, 271-276. 

Conventional packed column injection ports are used for the sample introduction on packed and megabore columns. In case of capillary columns, unless a special injection technique is used, the low maximum allowable sample volume which may be introduced on the column negatively affects the experimental detection limits as only a tiny fraction of the derivatized extract is finally processed in the hyphenated system. Online preconcentration and injection of derivatized organolead species can solve that problem. It consists of three consecutive processes taking place in the injection hner sample injection, solvent venting and release of the analytes on to the column. Up to 25 fil can be processed at a time and larger amounts can be handled by successive injections of 20 to 25 /a1 volumes at 1 min intervals to remove the solvent. 

As the QuEChERS-extracts are solved in acetonitrile, they are directly amenable to GC- and LC-applications. However, since acetonitrile is rather difficult to handle by GC using split/splitless inlets, the use of a PTV with solvent vent possibility is highly recommended. Should a PTV not be available and the desired pesticide detection limits cannot be achieved using the split/splitless technique, extract concentration followed by a solvent exchange, if necessary, may be considered. If GC-MSD is employed, a simple evaporative concentration of the extracts by a factor of four should be sufficient. To achieve this, e.g., a 4-mL extract (acidified to pH 5) is transferred into a test tube and reduced to ca. 1 mL at 40 °C using... 

Over the past few years, efforts have been made to develop alternative extraction techniques that allow more efficient extraction, along with reduced solvent volumes, in shorter times, and incorporating high levels of automation. Methods such as accelerated solvent extraction (ASE) uses conventional liquid solvents at elevated pressures (1500-2000 psi) and temperatures (50-200°C) to extract solid samples rapidly, with much less solvent than is required by Soxhlet methods. The sample is placed in extraction cells, which are filled with an extraction solvent and heated for 5-10 min, with the expanding solvent vented to a collection vial. The entire procedure is completed within 10-20 min per sample, and uses only 15-20 ml of solvent. Similarly, microwave-assisted solvent extraction (MAE) requires a relatively short extraction time (< 1 h) and small amount of solvent ( 30ml), and thus offers an attractive... 

Bosboom, J.C. Janssen, H.G. Mol, H.G.J. Cramers, C.A. Large-volume injection in capillary gas chromatography 9. using a programmed-temperature vaporizing injector in the on-column or solvent-vent injection mode. J. Chromatogr. A,... 

Stan, H.J. Linkerhagner, M. Large-volume injection 10. in residue analysis with capillary gas chromatography using a conventional autosampler and injection by programmed-temperature vaporization with solvent venting. J. Chromatogr. A. 1996, 727, 275. 

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