Traps combination

Suppose that we wish to calibrate the volume of trap E connected to manometer D on the vacuum line in Fig. 5.2. A known quantity of a gas, such as CO, is condensed into trap E using the calibrated bulb and the techniques just outlined in Example 5.3.G. The stopcocks are then turned so that trap E communicates with the central manometer D but is isolated from the rest of the vacuum system. At this point, the cold trap is removed from E, the trap is allowed to come to room temperature, and the pressure and room temperature are measured. The volume of the manometer-trap combination is determined from the known moles of gas, the pressure, and the temperature, using the ideal gas law. The process is repeated with successively larger samples of CO2, and a plot of volume versus pressure is constructed from the data. Since the bore of the manometer is of constant diameter, this plot should be a straight line. It also is possible to... 

Solids caught in condenser traps combined with solids left on reactor wall. 

Data-dependent acqnisition (DDA) is a mode of operation, where the MS experiment performed in a particular scan is based on the data acqnired in a previons scan. In a simple form, a DDA experiment switches the instrument from full-scan MS acquisition to full-scan product-ion MS-MS when the total-ion intensity or a selected-ion intensity exceeds a preset threshold. This avoids the need to perform two consecutive injections for the identification of unknowns in a mixture first to obtain the m/z values for the intact protonated molecules of the unknowns, and second to acquire the product-ion MS-MS spectra of these unknowns in a time-scheduled procedure, switching between various preselected precursor ions as a function of the chromatographic retention time. The DDA was promoted by Thermo Finnigan upon the introduction of the API-ion trap combinations [44-46]. Similar procedures are available for other commercial ion-trap systems, as well as for triple-quadrupoles, e.g.. Information Dependent Acquisition (IDA) from Applied Biosystems MDS Sciex, Data-directed Analysis (DDA) from Waters, and Smart Select from Bruker. 

Pitfall cone traps The pitfall cone (PC) trap combines the characteristics of both pitfall and probe traps to enable trapping of insects active at the surface level and in deeper layers of the bulk grain mass (Cogan et al., 1991). The PC trap is reported to be cheaper than the probe trap but is equally as effective in the detection of O. surinamensis, C. ferrugineus, and R. dominica in grains in bins. 

Figure 2 Gas chromatographic separation of hydrocarbons found in an urban air sample. Open capillary, 0.32 mm i.d. x 60 m length stationary phase, DB-1 (dimethyl polysiloxane) film thickness, 0.25 pm carrier gas, helium temperature programme, 5°C isothermal for 3 min, 5-50°C at a rate of 3°C min 50-220°C at a rate of 5°C min detector, flame ionization. With this method, a total of 142 hydrocarbons could be separated and identified 128 of them were found in the urban air sample. (After Ciccioli P, Cecinato A, Brancaleoni E, Frattoni M, and Liberti A (1992) Use of carbon adsorption traps combined with high resolution GC-MS for the analysis of polar and nonpolar C4-C14 hydrocarbons involved in photochemical smog formation. Journal of High Resolution Chromatography 15 75.)...

Simoes, C., Domingues, P, Domingues, M.R.M. (2012) Identification of Free Radicals in Oxidized and Glycoxidized Phosphatidylethanolamines by Spin Trapping Combined with Tandem Mass Spectrometry. Rapid Commun. Mass Spectrom. 26 931-939. 

There are several technologies for LC-MS analyzers, ion trap, single quadrupole, double quadrupole, triple quadrupole, etc. Although there is no validated conclusion coming from collaborative trials, the best option seems to be triple quadrupole or, even better, ion trap combined with triple quadrupole. 

Optical Trapping Combined with Raman Spectroscopy... 

In the SFE DI experiment the restrictor was inserted into an SFE sample collection tube, which was kept cold by immersion into dry ice. These experiments were also repeated five times, each time with a fresh sample, and the volatiles were trapped/combined in the same tube. After the SFE isolations, about 1 mL of methylene chloride was added to dissolve the residue sticking on the side walls of the sample collection tube. The extract was then transferred into a small tapered vial. The vial was kept under dry ice and concentrated with a gentle stream of nitrogen to 0.5 mL, and 1 pL of this extract was manually injected with the GC in splitless injection mode. For experiments 2 and 3 an SFE chamber pressure of 4000 psi was used. These two experiments were also performed on a different gas chromatography mass spectrometry (GCMS) system, the Hewlett Packard (Palo Alto, CA, U.S.A.) 5890 Series II GC coupled with a 5970 mass selective detector. 

Tenax and would be able to collect aroma chemicals with a wide range of polarities. Figure 9 shows the effect of collection time on the aroma chemicals collected. The Zenith trap is capable of collecting sufficient quantities of headspace material in around 5 minutes for quantitative GC/MS analysis. The Zenith trap combines the advantages of SPME and dynamic headspace. It overcomes the problems of fiber fragility, long extraction times, and the need to analyze and combine the results of several SPME fibers. 

Recently, ion traps with hybrid ionization have appeared on the market. They offer the possibility of working under internal ionization, external ionization, or a combination of both. The changes in configuration are simple. This kind of ion trap combines the advantages of both systems it is very efficient in terms of detection limits and very robust because its performances resist the presence of interfering compounds from the matrix. 

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