Capillary lamps

High-pressure mercury lamps operate at pressures about 10 atmospheres and essentially two types are used in industrial applications. The point source lamp focuses on a small-diameter spot, thus delivering an intense radiation to that spot. The capillary lamp is used for narrow webs up to approximately 20 cm (8 in.) wide.4 They are capable of producing a wider spectrum than the medium-pressure lamps and operate with higher power (150-2880 W/cm). Their disadvantage is a relatively short operating life, typically hundreds of hours. 

Experimental Results. The general procedure was similar to that already described. With the monochromator utilizing a large hollow, glass prism filled with ethyl cinnamate the quartz capillary lamp gave about 25,000 ergs per second of quite pure radiation... 

P 32] Pyrene (20 mM), 1,4-dicyanobenzene (40 mM) and sodium cyanide (1 M) were reacted in propylene carbonate and water. A 100 pi solution of pyrene (20 mM), 1.4-dicyanobenzene (40 mM) in propylene carbonate and a 100 pi solution of sodium cyanide (1 M) in water were fed by programmable dual-syringe pumps via fused-silica capillary tubes into a micro-channel chip [29]. Both solutions were fed with equal flow velocity. A 300 W high-pressure mercury lamp was used as light source. After passing an optical filter made of a CUSO4 solution, the whole chip was irradiated after formation of a stable oil/water interface inside. The oil phase was collected at the exit. 

Atomic oxygen was generated by photolysis of ozone which passed through a quartz capillary tube (0 2 mm and lehgth 60 mm), using the 253.7 nm line from a low-pressure mercury lamp (LI). 

A round-bottomed, standard-taper flask with a Claisen head carrying an ebullition capillary and a thermometer and attached to a two-necked flask with one neck for vacuum takeoff is satisfactory. It is important that the setup allow for heating by either flame or infrared lamp to melt the solid distillate and prevent its clogging the vapor passage. 

Convergent Bioscience has an interesting approach to detection in CE by using a CCD (charge-coupled device) camera to image the entire capillary (Figure 7). A UV-transparent capillary is needed and the entire capillary is excited with a xenon lamp. This is useful in cIEF... 

Capillary overheating Detector lamp either is not on or is weak. Also, poor selected optical wavelength Light Intensity through cell is low... 

CE instruments are thermostated to dissipate excessive Joule heat. Generally that covers only the main part of the capillary, and not, e.g., the autosampler with the buffer and sample vials. In some instruments, it is difficult to control the autosampler temperature due to the near presence of extraneous heating sources such as the detector lamp. Also, some labs... 

This chapter sheds light on the different validation requirements and methods to investigate them. Evaluation of the typical validation characteristics, namely accuracy, precision, specificity, DL, QL, linearity, and range in CE, has been discussed in details. Validation in CE is similar to validation in other separation techniques such as HPEC, but in CE, the capillary surface properties and namely the EOF have to be especially addressed. Eurther, the instrument performance has to be carefully considered during validation and method transfer. Here, the condition of the lamp and the thermostating system is of particular importance. 

FIGURE 7.6 Schematic of a laser-induced fluorescence detector. A lamp with focusing optics and an appropriate band-pass filter could be used in place of the laser excitation when tightly collimated light is not required. The emitted fluorescence is detected by a PMT that can be operated in current mode or photon counting mode. Inset shows the mutually perpendicular arrangement of excitation, capillary, and detection optics. 

We see capillary action at work in many phenomena. If a paintbrush is dipped into water, the water rises into the narrow spaces between the bristles by capillary action. Hang your hair in the bathtub, and water seeps up to your scalp in the same way. This is how oil moves up a lamp wick and how water moves up a bath towel when one end hangs in water. Dip one end of a lump of sugar in coffee, and the entire lump is quickly wet. The capillary action occurring between soil particles is important in bringing water to the roots of plants. 

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