Colorants, detection

Note The natural fluorescence colors of some flavonoids [7, 9] and anthracene derivatives [16] are altered by the ammonia treatment. This makes possible differentiation on the basis of color. Detection limits per chromatogram zone have been reported of 2 ng for morphine and heroin [2], 6 ng for ochratoxin A [5] and 1 pg for penicillic acid [13]. 

Yang, T. T., Sinai, P., Green, G., Kitts, P. A., Chen, Y. T., Lybarger, L., Chervenak, R., Patterson, G. H., Piston, D. W. and Kain, S. R. (1998). Improved fluorescence and dual color detection with enhanced blue and green variants of the green fluorescent protein. J. Biol. Chem. 273, 8212-6. 

This fluorophore has excitation maxima at 375 and 400 nm and an emission maximum at 410 nm. The small Stoke s shift may create some difficulty in discrete excitation without contaminating the emission measurement with scattered or overlapping light. The extinction coefficient of the molecule in water is about 27,000M 1cm 1. Cascade Blue and Lucifer Yellow derivatives can be simultaneously excited by light of less than 400 nm, resulting in two-color detection at 410 and 530 nm. 

Although UV/VIS diffuse reflectance spectroscopy has not been used extensively in the study of pharmaceutical solids, its applications have been sufficiently numerous that the power of the technique is evident. The full reflectance spectra, or the derived colorimetry parameters, can be very useful in the study of solids that are characterized by color detectable by the human eye. It is evident that questions pertaining to the colorants used for identification purposes in tablet formulations can be fully answered through the use of appropriately designed diffuse reflectance spectral experiments. With the advent of newer, computer-controlled instrumentation, the utility of UV/VIS diffuse reflectance as a characterization tool for solids of pharmaceutical interest should continue to be amply demonstrated. 

Remote non-contacting temperature, humidity and color detection for hair care equipment... 

Chemiluminescent labeling systems have been developed, based on the incorporation of fluorescein-11-dUTP into a DNA probe. An anti-fluorescein antibody covalently bound to the enzyme HRP is then bound to the incorporated fluorescein label. HRP catalyses the breakdown of luminol and the chemiluminescent signal is detected by autoradiography with X-ray film or by fluorescence scanning instrumentation. Chemiluminescence is more sensitive than enzyme-based color detection systems. Furthermore the labeled gene probes are stable and give results quickly (160). 

A modification of these coloring systems has recently been developed that leads to more sensitive detection. Chemiluminescent substrates have been designed that are converted by the enzymes to products that generate a light signal that can be captured on photographic film. This increases the level of sensitivity about 1000-fold over standard color detection methods. 

Fleyeh H 2005 Traffic signs color detection and segmentation in poor light conditions Proceedings of the IAPR Conference on Machine Vision Applications, Tsukuba Science City, Japan, Mai 16-18, pp. 306-309. 

Anthony, W.L. and Beher, W.T., Color detection of bile acids using thin layer chromatography,. /. Chromatogr., 13, 570, 1964 Chem. Abs., 60, 13546c, 1964. 

Various experimental conditions have been optimized for DNA sequencing on a glass chip. These conditions include separation matrix (denaturing 3-4% LPA), separation temperature (35—40°C), channel length (7.0 cm), channel depth (50 pm), injector parameters (100-pm or 250-p.m double-T injector, 60-s loading time). These optimal conditions facilitated the one-color detection of separation of 500 bases of M13mpl8 ssDNA in 9.2 min, and four-color detection of 500-base separation in 20 min [548]. 

When a longer CE channel (40 cm) on a glass chip was used, the average DNA read length (four-color-detection) was successfully increased to 800 bases in 80 min (98% accuracy) for M13mpl8 DNA (or the DNA with a 2-kbp human chromosome 17 insert). For comparison, a commercial capillary-based DNA sequencer took 10 h to complete the same 800-base analysis [968]. Moreover, DNA sequencing up to 700 bp (with 98% accuracy) has been achieved in 40 min using an 18-cm plastic microchannel [969]. 

Lam KS, Wade S, Abdul-Latif F, Lebl M, Application of a dual color detection scheme in the screening of a random combinatorial peptide library, J. Immunol. Methods, 180 219-223, 1995. 

To develop a four-color detectable laser-induced fluorescence (LIF) detection system for capillary elec-... 

Flow cytometer We use a Becton Dickinson FACS Vantage instrument. Whatever flow cytometer to which you have access, the machine must be set up appropriately because dual-color detection will be used, the machine may require color compensation adjustment (see Subheading 3.3.). It is important, therefore, that control reactions are included in each experiment (see Note 5). It is wise to use... 

Figure 11.4. A spotted DNA array with two-color detection of hybridization. An example of a spotted DNA array (16 X 20 elements) is shown after hybridization with two differentially labeled cDNA preparations, Cy3 (pseudo-colored green) and Cy5 (pseudo-colored red). The overlaying of the green and red images produces the image shown. The hue of each spot, ranging from green to red, indicates the relative expression level for the gene specific for each spot (image courtesy Packard Biochip Technologies). See color insert.

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