Purple screenings

Another field technique for screening soils for the presence of TNT, 2,4-dinitrotoluene (2,4-DNT) and RDX was reported [99]. The color reagents were KOH for TNT (red color) and sodium sulfite for 2,4-DNT (blue-purple color). In screening soil for the presence of RDX, the first step would be to remove any potential contaminants - nitrite and nitrate ions - from the soil, using an ion exchange resin. The RDX is then reduced by zinc powder and the resulting N02 ions are detected by the Griess reaction. Detection limits were estimated to be 1 mg of TNT or RDX and 2 mg of 2,4-DNT per 1 kg of soil. 

A study of 74 Andean potato landraces found about an 11-fold variation in total phenolics and a high correlation between phenolics and total antioxidant capacity (Andre et al., 2007a). We screened tubers from hundreds of cultivars and wild potato species for phenolics and found over a 15-fold difference in the amount of phenolics in different potato genotypes. Many phenolics are colorless, and thus are relevant phytonutrients for white-fleshed cultivars, which are the consumer-preferred t5q)e of potato in many countries. Russet Norkotah has high amounts among the white-fleshed cultivars, about 4 mg/g DW. S. Pinnatisectum, a purple-fleshed wild species. 

Relationships in glycolysis and gluconeogenesis. Points at which ATP is produced or consumed are indicated. Compounds in the same metabolic pools are indicated by purple boxes. Three small pseudocycles (la, II, III) in the paired sequences occur between glycogen and pyruvate, or between glycogen and glucose (lb, II, III). Only enzymes that are unique to either glycolysis or gluconeogenesis are indicated (screened in blue). 

Most studies to screen for biogenic amine-producing lactic acid bacteria use differential media that contain the precursor amino acid and a pH indicator. This indicator, usually purple bromocresol, will change colour when the medium is alkalinized and this colour change will be observed in the medium if the lactic acid bacteria produce amines (Bover-Cid and Holzapfel 1999 Choudhury et al. 1990 Maijala 1993). 

DPPH (l,l-diphenyl-2-picryhydrazyl) is a purple-colored stable free radical that is reduced to the yellow-colored diphenylpicrylhydrazine by free radicals. The DPPH assay measures one electron, such as hydrogen atom donating activity and hence provides a measure of free radical scavenging activity. This assay is suitable for the initial screening of multiple samples, such as plant extracts. Reaction mixtures containing test samples dissolved in DMSO and DPPH in absolute ethanol are incubated at 37°C for 30 min in a 96-well plate and absorbance measured at 515 nm. ... 

The number of purple colonies obtained in each sample is recorded on the worksheet for the jug-harvesting data along with the number of the technician who screened that sample (Fig. 3). 

Figure 2. 1500-ml aliquots of the contents of each jug are placed in white photographic developing trays to screen for purple colonies. The average colony size is 1-2 mm. 

The visualization of hybridization between the RNA probe and the DNA fragments on the blot is based on an enzyme-linked immunoassay. An antidigoxigenin/alkaline phosphatase conjugate is bound to the digoxigenin component of the probe and then incubated with the substrates X-phosphate and nitroblue tetrazolium (see Section 2.) under alkaline conditions, which will result in purple-blue precipitates on the membrane within a couple of hours. Color detection thus saves time and money as it does not require X-ray films, cassettes, and intensifier screens. For a permanent record the result can be photocopied or photographed. 

Screening for LSD Ehrlich s reagent produces a characteristic purple to deep-blue color with lysergic acid diethylamide (LSD). 

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