Plating, silver-spray

Fig. 1. Lacquer-coated optical readout laser disk master. Plating by (a) electroless silver spray coating and by (b) vacuum evaporation. Scale bar, cm.

Organochloride. For the estimation of chlorine containing insecticides, the developed plate is sprayed with a 1.0% ethanolic silver nitrate solution containing five milliliters of concentrated ammonia solution. After drying the sprayed plate in air, it is irradiated with U.V. light (366 nm) for ten minutes. After exactly ten minutes, the area of the developed spots is measured and compared with that of the control insecticide run on the same TLC plate. 

Use Photographic film, catalyst for ethylene oxide, indelible inks, silver plating, silver salts, silvering mirrors, germicide (as a wall spray), hair dyeing, antiseptic, fused form to cauterize wounds, lab reagent. 

Alkyl halides can be visualized if a dilute solution of silver nitrate is sprayed on the plates. Silver halides are formed. These halides decompose if exposed to light, giving rise to dark spots (free silver) on the TLC plate. 

Applications of volumes of solution down to 100 nl has been undertaken with a 1 pi Hamilton syringe in conjunction with a micrometer. After drying, HPTLC plates are sprayed to wetness with silver colloidal solution by a spray atomizer. Colored spots arising on the HPTLC plate are used to locate the separated molecules. The spot color varies from pale yellow through orange to violet depending on the nature and concentration of the compounds. 

Note Rhodamine B is a universal reagent that can be used on silica gel, talc, starch [5] and cellulose layers, just as on urea [1] or silver nitrate-impregnated [7] phases. Liquid paraffin-impregnated silica gel and RP layers are less suitable, since the background to the chromatographic zones is also intensely colored. It is often possible to increase the detection sensitivity by placing the plate in an atmosphere of ammonia after it has been sprayed or dipped, alternatively it can be oversprayed with sodium or potassium hydroxide solution. 

Armstrong, B., 1977, Chemical spray silvering, Appl. Optics 16, 2785 Burge, J. H., Anderson, D. S., 1994, Full-aperture interferometric test of convex secondary mirrors using holographic test plates, SPIE 2199, 181 U.S. Patent 5,737,079. 

Injection volumes of 5pl were used for both sample solutions and comparison standards. Qualitative residue confirmation was accomplished with thin layer chromatography using silica gel. Plates were developed with 1% chloroform in n-heptane, and visualized with alkaline silver nitrate spray as the chromogenic agent. Alternatively, p,p5-DDT and p,p5-TDE were confirmed by treatment with 5% methanoic potassium hydroxide [40]. Partial confirmation of Dieldrin was achieved by fractionating the analysis solution on a Mills column, thus isolating Dieldrin in the second fraction [35],... 

Plasma-sprayed, flame-plated, or electrolytically deposited coatings of powders of Al O Ci O TiN, WC, and Ti02 can be applied as wear-resistant ceramics on metal substrates with or without Co, Ni, or Cr incorporated to improve mechanical properties. Silver, barium fluoride—calcium fluoride, and other modifying materials have also been found useful in ceramic coatings for improved friction and wear properties (35). Diamond coatings are also being developed (36). 

Post-Treatments. Although many post-treatments have been used over plated metals, chromate conversion coatings remain as the most popular. Chromates are used to improve corrosion resistance, provide good paint and adhesive base properties, or to produce brighter or colored finishes. Formulations are usually proprietary, and variations are marketed for use on zinc, zinc alloys, cadmium, copper and copper alloys, and silver (157). Chromates are also used on aluminum and magnesium alloys (158,159). More recently, chromate passivation has been used to extend salt spray resistance of autocatalytic nickel plated parts. 

Silver nitrate-ammonium hydroxide-sodium chloride A mixture of silver nitrate (0.05 M)/ ammonium hydroxide (5%) is sprayed on the plate, followed by drying and further spraying with 10% aqueous sodium chloride to yield yellow/brown spots. 

Silver nitrate-fluorescein A mixture of silver nitrate (2%)/sodium-fluorescein (0.2%) in 80% ethanol is sprayed on the plate to yield yellow spots on a pink background. 

Silver nitrate-formaldehyde The plate is consecutively sprayed with 0.05 M ethanolic silver nitrate, 35% aqueous formaldehyde, 2 M potassium hydroxide, and, finally, a solution made of equal volumes of hydrogen peroxide (30%) and nitric acid (65%). Each spraying is preceded by a 30-min drying, and at the end, the plate is kept in the dark for 12 h before exposure to sunlight to yield dark gray spots. 

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