Capillary tip temperature

The heated capillaries tip temperatures Condensation effects in the beginning of the teflon FTIR capillary and in the glass MS interchangeable capillary tip during the first experiments indicated that the temperature in both capillary tips was lower than that in the heated part of the capillaries. Thin thermocouples were mounted subsequently, on these tips to measure the actual temperatures during an experiment. The measured FTIR/MS capillary tip temperatures at different TGA furnace temperatures have been collected in Table 6.1. 

Table 6.1 The FTIR/MS capillary tip temperatures as a function of the TGA furnace temperature (FTIR/MS heated transfer lines at 200°C).

TGA furnace temperature, °C FTIR capillary tip temperature, °C MS capillary tip 8 temperature, 1 °C 8... 

An additional external heating source was used to solve this problem. Two Osram Xenophot HLX 64 635 (15 Volt, 150 Watt) IR heaters mounted on moveable support arms were used to heat the MS capillary tip, a third one was used to heat the FTIR capillary tip. These three heaters are controlled by one Eurotherm 808 controller with the measuring and the alarm thermocouples mounted near the small ball-joint of the MS heated transfer line/TGA furnace coupling, see Figure 6.6. The measurement of the FTIR/MS capillary tip temperatures was repeated using only these extra heating sources (no TGA furnace switched on), the results are listed in Table 6.2. 

These data show that the capillary tip temperatures after this modification can be brought in line with the TGA furnace temperature (and hence the sample temperature) up to about 210°C/215°C. 

A goniometer telescope was used to observe the sessile water drops and to measure their contact angles. The water drops were applied to the surface from a microburet which was firmly mounted on a micromanipulator. Contact was maintained between the water drop and the capillary tip of the microburet, thus allowing water to be added to or withdrawn from the drop in determining hysteresis. The capillary was a needle of sufficiently small dimension not to distort materially the sphericity of the drop s surface. All measurements were made at room temperature, which ranged from 23°-25°C. 

Direct liquid introduction (DLI) methodology has been described elsewhere (9). A thermospray probe and source (TSP, Model TS 360Q) were acquired from Vestec Corp. (Houston, TX) and later modified to include a probe tip heater incorporated in a copper block. Because of thermal contact, however, there was considerable interaction between the source temperature, the probe tip temperature and the temperature of the capillary. For this reason, attempts to optimize the ion currents by adjusting temperatures had limited success. Typical temperatures of the tip of the interface were 199- 205°C with source temperatures of230-240°C. The two mobile phases used were 0.1M ammonium acetate and 4 1 (v/v) 0.1 M ammonium acetate acetonitrile. The flow rate was 1.0 ml/min 1. Samples were admitted to the TSP probe via a Rheodyne (Model 7125) valve. 

Centrifuge the dissolved hydrolysates for 30-60 sec in a microcentrifuge at room temperature to remove residual particulate matter. Spot the dissolved sample on a marked TLC plate (see Fig. 5 Section G 1.3). Apply 0.2 to 0.5 1 of the sample at a time with a micropipette fitted with a capillary tip and dry between each application, using an air line fitted with a filter and a 1-ml syringe to focus the flow. It is possible in some circumstances to spot the whole hydrolysate obtained from a membrane-bound protein. Up to four samples can be spotted on each plate. Apply marker dye on the indicated position on the plate (see Fig. 5). 

Many parameters can influence the transformation of polymer solutions into nanofibers through electrospinning. These parameters include (a) solution properties, such as viscosity, elasticity, conductivity and surface tension (b) governing/operating variables, such as hydrostatic pressure in the capillary tube, electric potential at the capillary tip and the gap (distance between the tip and the collecting screen) and (c) ambient parameters such as solution temperature, humidity and air velocity in the electrospinning chamber. ... 

Immersion electrodes are the most common glass electrodes. These are roughly cylindrical and consist of a barrel or stem of inert glass that is sealed at the lower end to a tip, which is often hemispherical, of special pH-responsive glass. The tip is completely immersed in the solution during measurements. Miniature and microelectrodes are also used widely, particularly in physiological studies. Capillary electrodes permit the use of small samples and provide protection from exposure to air during the measurements, eg, for the determination of blood pH. This type of electrode may be provided with a water jacket for temperature control. 

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