Detector spectrophotometer

Liquid chromatograph. The instrument should be one that is designed for use with stainless steel columns and is equipped with a pumping system able to maintain a pressure of 15 MPa a UV spectrophotometer detector able to measure UV absorbance at 254nm and a loop-type injector. 

Figure 5.48 A commercial microscope base with a UVMS/NIR spectrophotometer detector and imaging system. Photo courtesy of Dr. Paul Martin, Criac Technologies. 

FIGURE 29,5 FIA system associated with the DPPH method and spectrophotometer detector. 

Two common detectors, which also are independent instruments, are Fourier transform infrared spectrophotometers (FT-IR) and mass spectrometers (MS). In GC-FT-IR, effluent from the column flows through an optical cell constructed... 

Measurement of Whiteness. The Ciba-Geigy Plastic White Scale is effective in the visual assessment of white effects (79), but the availabihty of this scale is limited. Most evaluations are carried out (ca 1993) by instmmental measurements, utilising the GIF chromaticity coordinates or the Hunter Uniform Color System (see Color). Spectrophotometers and colorimeters designed to measure fluorescent samples must have reversed optics, ie, the sample is illuminated by a polychromatic source and the reflected light passes through the analy2er to the detector. 

Detection of the infrared signal is, of course, of prime importance. A range of detectors is available for this purpose, the type used in any particular instrument depending upon the type and quality of the spectrophotometer. 

In the spectrophotometer, the crystal may be placed between source and sample, in which case it acts as a monochromator. Or, it may be inserted between sample and detector, where it acts as an analyzer of the transmitted beam. 

The general operation of the pilot scale reactor has be previously described by Pareek et. al. [3]. However, modifications were required to allow the injection of the gas and liquid tracers, and their subsequent detection at the outlets. The liquid tracer, 5mL Methyl blue solution (lOgL" ), was injected via a syringe inserted into the liquid feed line. Outlet samples were measured with a Shimadzu 1601 UV-Vis Spectrophotometer at a wavelength of 635nm. A pulse (20mL) of helium gas tracer was introduced using an automated control system, with the outlet concentration monitored in real-time with a thermal conductivity detector. Runs were carried out based on a two-level... 

By far, the most frequently used device is the ultraviolet detector. Three types are employed (23) — single wavelength with low pressure mercury source, multiwavelength filter photomer with medium pressure mercury source, and spectrophotometer. 

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