Filter/filtration absorption

Air-purifying respirator A respirator that removes airborne contaminants, such as particulates, gases, vapors and fumes, from ambient air through filtration, absorption, adsorption, or chemical reactions on the media contained in the cartridge or filter. 

The overall effect in most animals is to stimulate intestinal absorption of calcium with a concomitant increase in semm calcium and a reduction in parathyroid hormone (PTH). Modest hypercalcemia allows the glomerular filtration rate to remain stable and hypercalciuria to occur because of increased filtered load of calcium and reduction of tubular resorption of calcium with reduced PTH. However, with further increases in semm calcium, the glomerular filtration rate decreases, resulting in an even more rapid increase in semm calcium and the subsequent fall in urinary calcium. 

A powerful tool now employed is that of diode array detection (DAD). This function allows peaks detected by UV to be scanned, and provides a spectral profile for each suspected microcystin. Microcystins have characteristic absorption profiles in the wavelength range 200-300 nm, and these can be used as an indication of identity without the concomitant use of purified microcystin standards for all variants. A HPLC-DAD analytical method has also been devised for measurement of intracellular and extracellular microcystins in water samples containing cyanobacteria. This method involves filtration of the cyanobacteria from the water sample. The cyanobacterial cells present on the filter are extracted with methanol and analysed by HPLC. The filtered water is subjected to solid-phase clean-up using C g cartridges, before elution with methanol and then HPLC analysis. 

Mass concentration units for ambient measurements are mass (/xg) per unit volume (m ). Size classification involves the use of specially designed inlet configurations, e.g., PMjq sampling. To determine mass concentration, all the particles are removed from a known volume of air and their total mass is measured. This removal is accomplished by two techniques, filtration and impaction, described in Chapter 13. Mass measurements are made by pre-and postweighing of filters or impaction surfaces. To account for the absorption of water vapor, the filters are generally equilibrated at standard conditions T = 20°C and 50% relative humidity). 

Dicyclopentadiene (50 g, 0.38 mole) is dissolved in 100 ml of anhydrous ether. Platinum oxide (0.25 g) is added, and the mixture is hydrogenated in a Parr apparatus at an initial pressure of 50 psi. Initially the reaction mixture becomes warm. The absorption of 2 mole equivalents of hydrogen takes 4-6 hours. The mixture is filtered by suction to remove the catalyst, and the filtrate is distilled at atmospheric pressure through a short fractionating column. 

Hydrogenation A mixture of 27.4 g (0.20 mole) of /7-aminobenzoic acid, 200 ml of water, and 2 g of the catalyst is hydrogenated at 50 psi in a Parr apparatus. At the completion of the hydrogenation (absorption of 0.6 mole of hydrogen), the mixture is filtered and concentrated under vacuum. When crystals start to form, the mixture is diluted with 200 ml of DMF and cooled in an ice bath. The crystals are collected by filtration, washed with DMF followed by methanol, and dried. About 20 g of cis- and fr[Pg.42]

A solution of 10 g of 9 10-dihydro-9 10-ethano-(1 2)-anthracene-(9)aldehyde (made from anthracene and acrolein) and 10 g of monomethylamine in 100 cc of ethanol is heated at 80°C for 4 hours in an autoclave. The reaction mixture is then evaporated to dryness under reduced pressure to leave a crystalline residue which is dissolved in 150 cc of ethanol and, after the addition of 2 g of Raney nickel, hydrogenated at 40°C under atmospheric pressure. When the absorption of hydrogen has subsided, the catalyst is filtered off and the filtrate evaporated under reduced pressure. An oil remains which is covered with 100 cc of 2N hydrochloric acid. The 9-methylamino-methyI-9 10-dihydro-9 10-ethano-(9 10)-anthracene hydrochloride crystallizes immediately after crystallization from methanol it melts at 320°-322°C. 

After the hydrogen absorption ceases, the autoclave is cooled, vented, and the reaction mixture is filtered to separate the catalyst. The filtrate is then heated on a steam bath at 60-80 mm pressure to remove the dioxane. The less volatile residue consists of 1,933 parts of crude dithioglycerol, a viscous oil. 

The sampling of solution for activity measurement is carried out by filtration with 0.22 pm Millex filter (Millipore Co.) which is encapsuled and attached to a syringe for handy operation. The randomly selected filtrates are further passed through Amicon Centriflo membrane filter (CF-25) of 2 nm pore size. The activities measured for the filtrates from the two different pore sizes are observed to be identical within experimental error. Activities are measured by a liquid scintillation counter. For each sample solution, triplicate samplings and activity measurements are undertaken and the average of three values is used for calculation. Absorption spectra of experimental solutions are measured using a Beckman UV 5260 spectrophotometer for the analysis of oxidation states of dissolved Pu ions. 

Test 1. Mix a quantity containing 40 mg of miconazole nitrate with 20 mL of a mixture of 1 volume of 1 M sulfuric acid and 4 volumes of methanol and shake with two 50 mL quantities of hexane, discarding the organic layers. Make the aqueous phase alkaline with 2 M ammonia and extract with two 40 mL quantities of chloroform. Combine the chloroform extracts, shake with 5 g of anhydrous sodium sulfate, filter, and dilute the filtrate to 100 mL with chloroform. Evaporate 50 mL to dryness and dissolve the residue in 50 mL of a mixture of 1 volume of 0.1 M hydrochloric acid and 9 volumes of methanol. The light absorption of the resulting solution, Appendix II B, in the range 230-350 nm exhibits maxima at 264, 272, and 282 nm. 

Berndt et al. [740] have shown that traces of bismuth, cadmium, copper, cobalt, indium, nickel, lead, thallium, and zinc could be separated from samples of seawater, mineral water, and drinking water by complexation with the ammonium salt of pyrrolidine- 1-dithiocarboxylic acid, followed by filtration through a filter covered with a layer of active carbon. Sample volumes could range from 100 ml to 10 litres. The elements were dissolved in nitric acid and then determined by atomic absorption or inductively coupled plasma optical emission spectrometry. 

Livingston and Cochran [50] collected large seawater samples by using a cable-supported electrical pumping system for subsequent determination of thorium, americium, and plutonium isotopes. Particles were removed by filtration and actinides were collected by absorption on manganese dioxide-coated filters. The samples were then analysed by standard radiochemical and a spec-trometric techniques. 

D. 2,3-Diamino pyridine (Note 12). In an apparatus for catalytic hydrogenation (Note 13) 56.4 g. (0.3 mole) of 2,3-diamino-5-bromopyridine suspended in 300 ml. of 4% sodium hydroxide solution is shaken with hydrogen in the presence of 1.0 g. of 5% palladized strontium carbonate (Note 14). When absorption of hydrogen is completed, the catalyst is removed by filtration, and, after saturation with potassium carbonate (about 330 g. is required), the resulting slushy mixture is extracted continuously with ether until all the precipitate completely disappears (usually about 18 hours, but this depends on the efficiency of the extraction apparatus). The ether is removed by distillation, and the residue of crude 2,3-diaminopyridine is recrystallized from benzene (about 600 ml. is required) using 3 g. of activated charcoal and filtering rapidly through a preheated Buchner funnel. The yield of 2,3-diaminopyridine, obtained as colorless needles, m.p. 115-116°, pKa 6.84, is 25.5-28.0 g. (78-86%) (Note 15). 

Salicylic Acid Absorption. The apical 5 cm of the primary and two seminal roots from each of three plants were out into 1-cm segments to form an experimental unit (ca. 0.08 g). Incubation solution cc ijjtalned 0.5 mM KCl, 0.25 mM CaSOjj, 0.5 mM salicylic acid, 10 nCl/mL [ C]-sallcyllc acid, with 25 mM Tris and 25 mM Mes buffers mixed to obtain pH 6.5. Because the salicylic acid was dissolved in absolute ethanol, the final concentration of ethanol in the incubation solution was 1 (v/v). Root segments were transferred to test tubes containing 10 mL continuously aerated incubation solution. After the predetermined absorption time, segments were collected from the incubation solution by rapid filtration on Whatman No. 2 filter paper. 

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