Ultraviolet lamp

Most of the thiazoles studied absorb in the ultraviolet above 254 nm, and the best detection for these compounds is an ultraviolet lamp (with plates containing a fluorescent indicator). Other indicator systems also exist, among which 5% phosphomolybdic acid in ethanol, diazotized sulfanilic acid or Pauly s reagent (Dragendorff s reagent for arylthiazoles), sulfuric anisaldehyde, and vanillin sulfuric acid followed by Dragendorff s reagent develop alkylthiazoles. Iodine vapor is also a useful wide-spectrum indicator. 

Atomic Absorption Spectroscopy. Mercury, separated from a measured sample, may be passed as vapor iato a closed system between an ultraviolet lamp and a photocell detector or iato the light path of an atomic absorption spectrometer. Ground-state atoms ia the vapor attenuate the light decreasiag the current output of the photocell ia an amount proportional to the concentration of the mercury. The light absorption can be measured at 253.7 nm and compared to estabUshed caUbrated standards (21). A mercury concentration of 0.1 ppb can be measured by atomic absorption. 

Fluorescent ultraviolet lamps within an apparatus that allows condensation cycles rather than the water spray typical of xenon arc tests have been developed for plastics testing (279). The spectral cutoff wavelength of the lamps used in the apparatus determines the severity of the test. Ultraviolet B (UVB) 313 lamps allow a significant irradiance component below 290 nm, which is normally filtered out by the earth s atmosphere. Ultraviolet A (UVA)... 

The ultraviolet lamps used in the photochlorination process serve to dissociate the chlorine into free radicals and start the radical-chain reaction. Other radical sources, such as 2,2 -a2obisisobutyronitrile, have been used (63,64). Primary by-products of the photochlorination process include 1,1,2-trichloroethane (15—20%), tetrachloroethanes, and pentachloroethane. Selectivity to 1,1,1-trichloroethane is higher in vapor-phase chlorination. Various additives, most containing iodine or an aromatic ring in the molecule, have been used to increase the selectivity of the reaction to... 

Color-order systems, such as the many MunseU collections available from Macbeth, have been described previously. Essential for visual color matching is a color-matching booth. A typical one, such as the Macbeth Spectrahte, may have available a filtered 7500 K incandescent source equivalent to north-sky daylight, 2300 K incandescent illumination as horizon sunlight, a cool-white fluorescent lamp at 4150 K, and an ultraviolet lamp. By using the various illuminants, singly or in combination, the effects of metamerism and fluorescence can readily be demonstrated and measured. Every user should be checked for color vision deficiencies. 

In contrast to the above use PMMA sheet has been used as the bed in indoor ultraviolet lamp operated solaria. Here the ultraviolet radiation is so intense as to require the use of special formulations with adequate ultraviolet resistance. 

Ultra-lampe, /. ultraviolet lamp, -marinfarbe, /. ultramarine color. 

A solution of ethyl azidoformate (10 g, 87 mmol) in anhyd benzene (250 mL) was photolyzed at 60-70 C for 60 h, using a high-pressure Hg ultraviolet lamp, whereupon N2 was evolved and the solution became yellow. The benzene and remaining azido ester were removed under reduced pressure, and the yellow-brown oily residue distilled under high vacuum to give a yellow oil yield 8.35 g (67%) bp 46-47 C/5 x 10"3 Torr bp 130 C/0.2 Torr. 

Thin-layer plates were made with silica gel-calcium sulfate and each contained a mixture of zinc silicate and zinc cadmium sulfide as phosphors. Separated components are generally visible under ultraviolet light by fluorescence quenching. This was true, in part, for the pyrethrins, except that some of the separated components possessed a natural fluorescence under the ultraviolet lamps. 

If a serious leak is suspected, use a fluorescent tracer dye to identify the source of the leak. These dyes can be seen in drains and other dark places with the aid of an ultraviolet lamp at concentrations of below 1 ppm. 

FT Feed Trank, MF Microfiltration module, UV ultraviolet Lamp, NF Nanofiltration module. 

Fig. 17 Cadmium selenide QDs, dissolved in toluene, fluorescing brightly in the presence of a ultraviolet lamp, in three noticeably different colors (blue 481 nm, green 520 nm, and orange 612 nm). The blue QDs have the smallest particle size, the green dots are slightly larger, and the orange dots are the largest. (Adapted from http //www. amazingrust.com/ experiments/current proj ects / Misc.html)...

Equipment. Lamps used include an RC-500 xenon lamp obtained from Xenon Corp., Woburn MA 01801 a Portacure 1000F/1500F mercury lamp, American Ultraviolet, Murray Hill, N.J. 07974 and a Fusion Systems F300 ultraviolet lamp system operated with a V-bulb. 

Most of the reactions described in the following chapters were monitored by Thin Layer Chromatography (TLC) using plastic TLC plates coated with a thin layer of Merck 60 F254 silica gel. The products were detected by using an ultraviolet lamp or the TLC plates were treated with p-anisaldehyde reagent, prepared as explained below, and then heated to 120 °C to stain the spots. After visualization and measurement, the Rf values were recorded. 

Prepare Van Urk reagent by adding 0.5 g p-dimethylamino-benzaldehyde, 100 ml water, 100 ml concentrated sulfuric acid. Dissolve 1 mg substance in 1 ml ethanol and mix with 2 ml Van Urk reagent and illuminate for 10 minutes with an ultraviolet lamp (black light). Psilocin gives a blue-grey, psilocybin a red-brown color. 

The highly conjugated diketo system obtained as a result of irradiation of the stilbosterol solution placed in a closed spectrophotometer cell for a duration of 10 minutes and exposed to a 15-watt short-wave ultraviolet lamp. Ultimately the extinction is duly measured at 418 nm and compared with stilboesterol (RS) treated exactly in the same manner. 

Dansyl chloride (dimethylaminonaphthalene-5-sulphonyl chloride) will react with free amino groups in alkaline solution (pH 9.5-10.5) to form strongly fluorescent derivatives (Figure 10.14). This method can also be used in combination with chromatographic procedures for amino acid identification in a similar manner to the FDNB reagent but shows an approximately 100-fold increase in sensitivity. This makes it applicable to less than 1 nmol of material and more amenable for use with very small amounts of amino acids liberated after hydrolysis of peptides. The dansyl amino acids are also very resistant to hydrolysis and they can be located easily after chromatographic separation by viewing under an ultraviolet lamp see Procedure 10.1. 

Photoionization a gas chromatographic detection system that uti-hzes an ultraviolet lamp as an ionization source for analyte detection. It is usually used as a selective detector by changing the photon energy of the ionization source. 

This system was studied by Schwartz. Toluene at 10 ppm, nitric oxide at 1 ppm, and nitrogen dioxide at 1.2 ppm were irradiated with ultraviolet lamps in a 17-m batch reactor for 270 min. Collected aerosols were successively extracted with methylene chloride and then methanol. The methylene chloride extract was fractionated into water-soluble and water-insoluble material, and the latter fraction was further divided into acidic, neutral, and basic fractions. The acidic and neutral fractions were analyzed by gas chromatography and chemical-ionization mass spectrometry the compounds identified are shown in Figure 3-7. The two analyzed fractions represented only about 5.5% of the total aerosol mass. It is noteworthy that classical nitration of an aromatic ring appears to... 

UVC Lacquer and Test. A white epoxy-acrylate lacquer was applied on all nickel plated sheets with different pretreatments to a thickness of 16 ym and was cured by irradiation with four 10-kW ultraviolet lamps for about 1.2 sec. 

In this system, the ultraviolet absorbance of ozone provides a method for quantifying ozone uptake by aqueous solutions. Pure dry O2 gas passes through a flow meter into an ozone generator consisting of ultraviolet lamps in an aluminum cylinder (10),... 

Thin layer chromatography (TLC) uses the same principles as GC or HPLC but is performed on a glass plate containing an adsorbent, such as silica or alumina, that attracts other molecules to its surface. A small portion of the sample to be analyzed is spotted on the plate. The plate is placed upright in a tank containing a small amount of solvent that then rises up the plate and separates the components of the sample. The separated components can be located with an ultraviolet lamp or by spraying the plate with chemicals to produce color. 

A. a,a,ot, a -Tetrabromo-o-xylene. In a 2-1. three-necked flask equipped with an oil-lubricated Trubore stirrer, a dropping funnel, a thermometer extending nearly to the bottom of the flask, and a reflux condenser (Note 1) attached to a gas absorption trap 2 is placed 117 g. (1.1 moles) of dry o-xylene (Note 2). An ultraviolet lamp such as a General Electric R.S. Reflector Type 275-watt sun lamp is placed about 1 cm. from the flask so as to admit the maximum amount of light. The stirrer is started, and the o-xylene is heated to 120° with an electric heating mantle. A total of 700 g. (4.4 moles) of bromine (n.f. grade) is added in portions from the dropping funnel to the reaction flask at such a rate that the bromine color is removed as fast as it is added. 

By a similar procedure, 1.0 gm of p-bromoazobenzene was isomerized in 10 ml of chloroform by irradiation with a Hanovia type 16200 ultraviolet lamp for 2 hr [108], The same authors, using the same equipment, prepared 1.0 gm of c/s-p,//-azotoluene from 6.0 gm of the trans isomer by irradiation for 4 hr. They eluted the product from an aluminum oxide column with ether [108]. 

Industrial applications involving radiation processing of monomeric, oligomeric and polymeric substances depend essentially on two electrically generated sources of radiation accelerated electrons and photons from high-intensity ultraviolet lamps. The difference between these two is that accelerated electrons can penetrate matter and are stopped only by mass, whereas high-intensity UV light affects only the... 

The power levels of radioactive sources presently available are comparable to the output of the most intense discharge lamps available. Ultraviolet sources produce 10 to 100 w. of useful ultraviolet radiation. Kilocurie sources of 2 Mev. activity produce approximately 20 w. The total available power from such a source having a half-life of 10 years is an order of magnitude lower than the total power output available from an ultraviolet lamp operating for 1000 hours, the normal expectancy for lamps of this type. 

A. Diethyl propionylsuccinate (1). A solution of 412 g. (2.4 mole) of diethyl maleate (Note 1), 278 g. (4.8 mole) of freshly distilled propionaldehyde (Note 2), and 1.2 g. (0.0048 mole) of benzoyl peroxide in a normal 2-1. Pyrex flask is heated under reflux while undergoing irradiation with an ultraviolet lamp (Note 3). The initial reflux temperature is 60°. After 2 hours another 1.2 g. (0.0048 mole) of benzoyl peroxide is added. Strong reflux and irradiation are maintained throughout the entire reaction period. After 18 hours total time, the internal pot temperature reaches 68°. At this point the last 1.2 g. (0.0048 mole) of benzoyl peroxide is added, and the reaction is continued for a total of 30 hours, at which time the pot temperature reaches 74.5°. The reflux condenser is then replaced by a distillation head. The excess propionaldehyde (119 g.) is distilled under atmospheric pressure, b.p. 48-49°. Succinate 1 is distilled under reduced pressure. The main fraction, b.p. 145-151.5° (15-16 mm), provides 417-449 g. (75-81%) of product having sufficient purity for use in the next step (Note 4). 

The method just described is not usually applicable in the ultraviolet because ultraviolet lamps of known spectral distribution are not readily available at present. The spectral sensitivity caii be calculated directly if the values of B L and P, are known. The first of these is obtained from the dispersion curve of the monochromator the second is somewhat difficult to measure—for prism instruments over restricted wavelength regions above 250 m t it is often reasonably constant. The photomultiplier sensitivity, P can be determined by comparison with a thermopile or with the ferrioxalate actinometer.11 12 Direct calculation of S, is subject to inaccuracies due to the accumulation of errors in the measurement of the three separate quantities B L and P,. A more convenient... 

The mineral fluorite, CaF2, in Figure 13-5 has a cubic crystal structure and often cleaves to form nearly perfect octahedra (eight-sided solids with equilateral triangular faces). Depending on impurities, the mineral takes on a variety of colors and may fluoresce when irradiated with an ultraviolet lamp. 

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