Measurement, colour

ISO 7724-1-1984, CIE Standards Colorimetric Observers Paints and Varnishes—Colorimetry, Part 1, Principles-, ISO 7724-2-1984, Part 2, Colour Measurement, ISO, Geneva, Swit2erland. 

When present in macro quantities, aldehydes and ketones can be determined by conversion to the 2,4-dinitrophenylhydrazone which can be collected and weighed. When present in smaller quantities (10 3M or less), although hydrazone formation takes place, it does not separate from methanol solution, but if alkali is added an intense red coloration develops the reagent itself only produces a slight yellow colour. Measurement of the absorbance of the red solution thus provides a method for quantitative determination. 

See also Spectrophotometry Colour change interval 264 Colour measurement classification of methods, 651... 

Certain commercial developments in the last twenty years or so have had important effects on the pattern of pigments production. One is the rapid growth of textile production in the Asia Pacific region and another is the development of automated dyeing methods, coupled with instrumental methods of colour measurement and of computerised colour recipe prediction. 

DIN 5033-3-1979 Teil 1 Grundbegriffe derFarbmetrik. ISO 7724-1-1984 CIE Standards colorimetric observers Paints and varnishes - Colorimetry, Part 1 Principles ISO 7724-2-1984, Part 2 Colour measurement. 

Kimerle [27] reviewed the ecotoxicology of LAS focusing on the results rather than on the method of analysis, for which the author referred to the review undertaken by Painter and Zabel [30], alluding only to two papers on biota sample preparation. Litz et al. [31] determined the concentration of LAS in rye grass by Azure A active substances (AzAAS). AzAAS is a non-specific colorimetric method, which has not been used as frequently as MBAS (see Chapter 3.1). Briefly, it consists of the formation of an ion association complex with a dyed solution of Azure A (cationic). The complex formed is solvent-extractable and is separated from unreacted dye prior to colour measurement. 

In terms of the Munsell hue (see Chap 6) the colour of red beds varies usually between 5YR-2.5YR (reddish-brown to red), but may also extend into 10RP-7.5RP (red-purple). A more detailed colour measurement using the CIE D a b system places the red beds within a space encircled by a range of synthetic hematites of different crystal sizes, as seen in Figure 15.2. This makes it likely that the colour of red beds is determined by hematite. 

AG (now Datacolor International) software. Finally, the Colour Measurement Committee (CMC) of the Society of Dyers and Colourists in the United Kingdom made some compromises and published a formula based on the J P Coates work but incorporating the CIELAB coordinates [53], This was made a British standard (BS 6923) and soon was adopted by textile associations around the world. The usefulness of such an equation has been demonstrated many times in the textile industry and in some papers from manufacturers of textured, molded polypropylene as well. 

J. F. Verrill, P. J. Clarke, J. O Halloran, and P. C. Knee, NPL Spectrophotometry and Colorimetry Club, Intercomparison of Colour Measurements, NPL Report QU 113, National Physical Laboratory, Teddington, United Kingdom, 1995. 

J. F. Verrill, Intercomparison of Colour Measurements Synthesis Report, Report EUR 14982 EN, European Commission, Brussels, 1993. 

There are other minor nonequivalencies of ISO test procedures compared to ASTM standards, but for color difference the ISO Test Procedure No. 105 is unique. Those who use Colour Measurement Committee (CMC) procedures—particularly CMC 2 1 Lightness to Color ratio—claim that it facilitates a uniform description for acceptability decisions that is better than any other system in existence. These equations permit the use of a single number tolerance, DEcmc, in a nearly uniform color space. The CMC formula is a modification to the perceptibility CIELAB formula. It is fully described elsewhere in this book, but it deserves some brief notice here because, after all, it is an ISO procedure. The CMC developed the basic British Standard No. 6923, Calculation of Small Color Differences. Soon afterward, in 1989, the American Association of Textile Chemists and Colorists (AATCC) adopted AATCC Test Method 173, CMC Calculation of Small Color Differences for Acceptability. Ford Motor Company indicated a preference for using CMC 2 1 ratio color difference for plastics weathering data for plastics interior trim materials. 

Fabric hand is defined as the estimated quality of a fabric, evaluated as reaction of the sense of touch, which is integrated in our brain to a total value. Important components of the sensory perception are the smoothness, compressibility and elasticity of the textile sample. As the hand of fabrics is primarily a subjective feeling - similar to the impression of colour - there have been many efforts to find methods for objective evaluation of the fabric hand. While instrumental colour measurement is very common in textile quality control, the automated measurement of fabric hand is still a topic of discussion and subjective manual hand evaluation is still the most important method. Simple methods to measure some aspects of fabric hand were described by Dawes and Owen. Many factors such as the colour of the textile, the hght and the surroundings, influence the manual evaluation of fabric hand. The American Association of Textile Chemists and Colorists has published guidelines for subjective hand evaluation. ... 

Flow injection methods in which amoxicillin was hydrolysed by immobilised (1-lactamase, the penicilloic acid reacted with iodine and the blue starch - iodine colour measured [141], and in which the red colour produced by oxidative condensation with l-nitroso-2-naphthol in the presence of ceric ions was measured [142], have been reported. They are capable of 30 and 40 samples per hour respectively. 

The use of online colour measurement for process control purposes has been reviewed by GilchrisF and Ferus Comclo. "... 

Gilchrist, A, Control of dyeing processes by colour measurement . Rev. Prog. Color., 1995, 25, 35. 

Stock, N. 1993. Direct non-destructive colour measurement of pharmaceuticals. Anal. Proc. 30 41 43. 

Colour measurement to obtain a reference standard (usually light and dark limits) for pigmented (opaque) and dyed (translucent/transparent) materials. 

Determination of TBC in Styrene To determine the amount of inhibitor p-tert butyl catechol (TBC) present, the styrene monomer is extracted with aqueous NaOH and the aqueous layer containing the TBC as the coloured quinone is separated and the colour measured spectrophotmetrically at a wavelength of 485 run using NaOH of 1.0 N solution as a reference standeud. ASTM Method (D2120-82) is used for determining concentration of inhibitor, in styrene monomer. This method covers the measurement of the amount of residual TBC iii styrene monomer in the range from 0-100 ppm. 

This book will add considerably to cmrently available information on food colorants and conventional colour measurement. A wider look at the philosophy... 

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