Capillary transfer line

This trap is not used in typical flash pyrolysis experiments. However, if the pyrolysate is generated for a longer period of time, and it is not delivered to the chromatographic column similarly to a typical injection, a cryofocusing attachment is necessary. In principle, this consists of a short tube through which passes a capillary transfer line (or part of the column). The cryofocusing tube can be cooled at subambient temperatures for a determined period of time and condenses the sample injected in the GC. At the start of the GC run, the cryofocusing tube can be rapidly heated to evaporate the condensate. 

One way around this problem is to dispense with the trapping and separation stage by continuous sampling of the atmosphere around the Aermal probe. This can be achieved by using a small-bore silica-glass capillary transfer line which also serves to reduce the pressure fix)m atmospheric to that which could be accommodated by the ion source of the mass spectrometer. The capillary tube... 

Glass microfluidic chips with inserted nano-ESI emitters, electroosmotic pumping capillaries, or capillary transfer lines inserted in the liquid sheath interface of a Q-TOF instrument, were also used for the CE analysis of standard peptide/protein digests and of gel-isolated proteins from complex cellular extracts (H. influenza, P. Some of these chips enabled sam-... 

Instrumentation. NO, adsorption/desorption profiles were obtained using a Seiko TG/DTA 320 coupled to a VG Micromass quadrapole MS. The two instruments were coupled a heated (ntf C ) fused silica capillary transfer line... 

Thermogravimetry-mass spectrometry was done with a Perkin Elmer TAS 2 TGA connected by a capillary transfer line to a Hewlett Packard mass selective detector. A heating rate of 40 C7min was used so that the volatiles would rapidly desorb from the sample. Helium was used as a carrier gas at a pressure of 40 psi. The time traces of water and NMP were done at mass to charge ratios of 18 and 99 respectively. 

The molecular evolution profiles of the thermal degradation products were then studied by a TPPy-MS system in which the capillary separation column was replaced by a deactivated stainless steel capillary transfer line maintained at 300°C. Figure 3.23 shows the thermal degradation profiles using... 

V, Pyrex capillary transfer line from g.c. to atomizer. 

The Supersonic or skimmer system is more costly and more difficult to use but it gives many advantages on the capillary transfer line no condensation in the transfer line, no collision between the molecules and with the transfer line wall, possibility to detect high mass species (above 500 amu)... 

Figure 2.2 Schematic representation of an on-column interface. The eluent leaving the HPLC detector enters the valve and in the stand-hy position, leaves it to go to waste. When the valve is switched on, the eluent is pumped through the transfer line into the inlet of the on-column injector. The liquid floods the capillary wall, thus creating a layer that will retain the solutes. Evaporation occurs from the rear pait of the solvent so refocusing the chromatographic hand. At the end of the transfer, the valve is switched off, and the eluent again flows to waste.

Chlornitrofen and nitrofen conditions for GC/MS column, cross-linked methyl silicone capillary (12 m x 0.22-mm i.d., 0.33- am film thickness) column temperature, 60 °C (1 min), 18 °C min to 265 °C inlet, transfer line and ion source temperature, 260, 200 and 200 °C, respectively He gas column head pressure, 7.5 psi injection method, splitless mode solvent delay, 3 min electron ionization voltage, 70 eV scan rate, 0.62 s per scan cycle scanned mass range, m/z 100-400. The retention times for chlornitrofen and nitrofen were 11.8 and 11.3 min, respectively. The main ions of the mass spectrum of chlornitrofen were at m/z 317, 319 and 236. Nitrofen presented a fragmentation pattern with the main ions at m/z 283, 202 and 285. ... 

Principles and Characteristics Thermospray ionisation (TSP) involves introduction of a relatively high flow (0.2-2mLmin ) of solvent into the ion source of a mass spectrometer, and is therefore suitable as an interface for HPLC-MS, using standard bore columns. A vaporiser probe (essentially a resistively heated capillary tube of about 100 xm i.d.) acts as a transfer line for taking solvent and solute into the source. The source is heated to prevent condensation of the solvent, and the temperature of the capillary is chosen so as to ensure vaporisation of the solvent. In this way, a vapour jet is generated, which contains small, electrically charged droplets if the solvent is at least partially aqueous and... 

The lncos-50 is a relatively low-cost benchtop instrument as opposed to the research grade instruments discussed earlier. The gas chromatography-mass spectrometer transfer lines allow it to be used with either the Hewlett Packard 5890 or the Varian 3400 gas chromatographs. The Incos 50 provides data system control of the gas chromatography and accessories such as autosampler or liquid sample concentration. It can be used with capillary, wide-bore or packed columns. It performs electron ionization or chemical ionization with positive or negative detection. It also accepts desorption or other solids controls. 

With the advent of capillary GC, [50-54] the need for separators and the concomitant risk of suppression of certain components vanished. Capillary columns are operated at flow rates in the order of 1 ml min and therefore can be directly interfaced to EI/CI ion sources. [48,49] Thus, a modem GC-MS interface basically consists of a heated (glass) line bridging the distance between GC oven and ion source. On the ion source block, an entrance port often opposite to the direct probe is reserved for that purpose (Chap. 5.2.1). The interface should be operated at the highest temperature employed in the actual GC separation or at the highest temperature the column can tolerate (200-300 °C). Keeping the transfer line at lower temperature causes condensation of eluting components to the end of the column. 

On-line coupling between a gas chromatograph and an atomic spectrometry detector is fairly simple. Typically, the output of the CG capillary column is connected to the entrance of the atomisation-ionisation system simply via a heated transfer line. When separation is performed by liquid chromatography (EC), the basic interface is straightforward a piece of narrow-bore tubing connects the outlet of the EC column with the liquid flow inlet of the nebuliser. Typical EC flow rates of 0.5-2 ml min are within the range usually required for conventional pneumatic nebulisation. 

Fig. 10. Scheme of coupling of the GC with the ICP-MS instrument 1, torch 2, injector supply 3, PTFE piece+PTFE Swagelok adapter 4, Swagelok T-joint 5, commercial transfer line 6, stainless-steel transfer tube 7, transfer capillary. Reprinted from De Smaele et al. [123] by permission of Elsevier Science. 

Carey and Caruso [126] also summarised the two main approaches to interfacing the SFC restrictor with the ICP torch. The first method, used with packed SFC columns, introduces the restrictor into a heated cross-flow nebuliser and the nebulised sample is subsequently swept into the torch by the nebuliser gas flow. Where capillary SFC systems are used, a second interface design is commonly employed where the restrictor is directly introduced into the central channel of the torch. This interface is more widely used with SFC-ICP-MS coupling [20]. The restrictor is passed through a heated transfer line which connects the SFC oven with the ICP torch. The restrictor is positioned so that it is flush with the inner tube of the ICP torch. This position may, however, be optimised to yield improved resolution. The connection between the transfer line and the torch connection must be heated to prevent freezing of the mobile phase eluent after decompression when exiting the restrictor. A make-up gas flow is introduced to transport the analyte to the plasma. This... 

Derivatization was conducted by the addition of a 10% H-ethyl-diiso-propylethylamine solution and a-bromo-2,3,4,5,6-pentafluorotoluene. Sample obtained from the derivatization procedure were dissolved in ethyl acetate prior to injection in splitless mode using a DB-1 capillary column. Helium was used as the mobile phase, and the injector temperature was set at 290 °C with a transfer line temperature of 270 °C. Sample detection used ion trap MS for detection, with the detector being set at negative chemical ionization with m/z = 262 (for CCA) and m/z = 286 (for the internal standard). The limit of quantitation was 5 ng/ml, and the average recovery ranged from 92.0% to 114%. In addition, the extraction efficiency ranged from 48.2% to 55.6% for concentrations of 5, 50, and 250 ng/ml. Samples were reported to be stable for up to 6 months when stored at 18 °C. 

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