White reference plate

For most other purposes, both before and after processing, color is measured using a colorimeter such as a Minolta Chroma Meter (Minolta Corp., Ramsey, NJ). The instrument is calibrated against a standard-white (Minolta) reference plate. Hunter L (whiteness), a (greenness) and b (yellowness) values were determined for each sample and made directly from the potato surface (Nourian et al., 2003). 

Reflectance values on Cobas Ready as on any diffuse reflector are measured as the quantities of light reflected from a reagent layer saturated with a serum sample (/,) or from a white or black reference plate (/ and 4), each normalized to the incident light intensity monitored by the reference photodetector... 

The flow chart of the color acquisition procedure is given in Figure 3. The color machine vision system should be white balanced before taking measurement of samples. This can be accomplished by first measuring a white reference target to establish a base line. The R,G,B values of a sample are then acquired. To compare the machine vision measured tri-stimulus values against that of published standard color plates, R,G,B values from CMVS were transformed to L a b values. This transformation required two steps first, R,G,B is converted to X,Y,Z by Eq. 3. Next, Eq. 4 is used to convert X,Y,Z to L, a, b color coordinates. 

Fig, 14.12 Visible staining, indicated by CIELAB A values, plotted on logarithmic scales versus the FD C Red 40 content of the initially blue cut pile carpet (BCP), blue level loop carpet (BLL), and white level loop carpet (WLL). White standard plate as the reference (target). (Reproduced with permission from Ref. 90. Copyright 1995 by AATCC). 

Add 2 drops of color reagent. Compare color produced with reference compounds on spot plate or other white porcelain surface. 

A solution of ursodeoxycholic acid (reference substance) in methanol (20 mg/ml) in a white graduated flask was allowed to stand in a window from ca. 2.0 p.m. untU ca. 10.0 a.m. the following day. From this reference substance and from a new batch to be tested, test solutions of equal concentration and also a diluted reference solution were prepared. The reference substance (100 pg and 0.5 pg) was apphed to two TLC silica gel 60 plates without fluorescence indicator, and both plates were dried for 3 min with a warm-air fan heater (grade I). One plate was then exposed to direct sunhght for 5 min. The development was then performed in the solvent system described in the DAC 1992. Figure 106 shows the two plates after derivatization with the phospho-molybdic acid reagent. 

Figure 3.3.7 Photographs of crystals of l,3-bis(m-nitrophenyl)urea, MNPU. From top to bottom yellow prisms (a form), white needles ((3/6 form) and yellow plates (y form). Since it is difficult to visually distinguish between the [3 and 6 forms, we will refer to them as the (3/6 form.

At the end of the sublimation there germinates through the mediation of the spirit, a shining white soul which flies to heaven with the spirit. This is clearly and manifestly the stone.140 Edinger continues, referring specifically to the image in Plate 1-11 ... 

Figure 11.6 Mean (a) and ims (6) axial velocity distributions lor three cases in Table 11.1 at a cross-stream plane near the TARS outlet (UC LDV data [6]) levels mean velocity between —10 m/s (blue) and 36 m/s (white) rms velocity between 1 m/s (blue) and 20 m/s (white) more details are in [6]. (Refer color plate, p. X.)...

When the solvent has reached the top of the plate, the plate is removed from the developing chamber, dried, and the separated components of the mixture are examined. Because the components are usually colourless or white, a UV lamp or blacklight (UV264) is used to make the spots fluoresce. Iodine vapour, copper sulphate and other coloured reagents can also be applied to induce characteristic colours to spots of antioxidants. Once visible, the Rf values of the spots can be determined by dividing the distance travelled by the coloured product by the total distance travelled by the solvent (the solvent front). Each antioxidant has a distinctive Rf value. These values should be the same regardless of the distance travelled by the solvent, but are dependant on the solvent used, and the type of TLC plate. For this reason, TLC should be performed on reference samples of antioxidants at the same time as the tmknown materials are analysed. 

Figure 3. White light micrographs of analyte deposited on stainless steel plate (a) DNT crystals on stainless steel plate (b) image of DFTT after adding Ti02-(Reproduced with permission from reference 15.)...

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