Densitometers transmittance

For semiquantitative or quantitative analyses, the separated dyes can be measured with a reflectance densitometer or they can be extracted from the plate or paper and measured by transmittance spectrophotometry. 

Figure 7. Flow and instrumentation diagram for high temperature, balanced pressure bench-scale unit. LR, level recorder LT, level transmitter TR, temperature recorder FR, pressure recorder FR, flow recording RD, densitometer PC, pressure controller TC, temperature controller GM, gas meter F, filter VSD, variable speed drive PCV, pressure regulator CV, control valve SV, solenoid valve S, gamma ray source.

The zones as recorded (if on an absorbance, rather than a transmittance basis) can be quantitated by measuring the area under the peaks by planimetry, triangulation, cutting out and weighing or simply counting squares or the densitometer may have an integrating facility. 

Measurement of optical density of colored image. Macbeth densitometer was used for measurement of transmittance density. 

After excitation and plate development the data in columns 2 and 3 of Table 8-6 were obtained from densitometer readings. The percentage transmittance readings of Table 8-6 must be converted to relative intensity readings by reference to the plate calibration curve previously prepared and... 

A Schoeffel SD 300 double-beam densitometer was equipped with an optical density computer. Model SDC 300 (Schoeffel Instrument Corp.). The output was recorded on a Honeywell 10-in. strip recorder (Honeywell) provided with a disc integrator Model 252 A (Disc Instruments, Inc.). Scanning and recording took place in the direction of the chromatography at a speed of 4 in./min. The excitation wavelength in the fluorescence quenching transmittance mode was 265 nm, and the monochromator and exit slits were 1.5 and 1 mm, respectively Ref... 

Optical quantitation in TLC, 273-306 assessment in QTLC, 300-305 testing and validation, 301-305 basic principles of quantitation, 274-287 discontinuum theory, 276-280 measurement of fluorescence, 281-287 densitometers, 287-291 reflectance mode, 287-288 special scanning procedures, 289-291 transmittance, 288-289 integration in QTLC, 293-300 quantitative evaluation with digital cameras, 291-293... 

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