Preliminary tests solution

It is assumed that the best solvent and the approximate proportions of solute and solvent have been determined by preliminary tests as described in the previous Section or have been obtained from reference... 

A. Carry out the following preliminary test. Dissolve a drop or a few small crystals of the compound in 1 ml. of rectified spirit (95 per cent, ethanol) and add 1 ml. of iV hydrochloric acid. Note the colour produced when 1 drop of 5 per cent, ferric chloride solution is added to the solution. If a pronounced violet, blue, red or orange colour is produced, the hydrox amic acid test described below is not applicable and should not be used. 

A preliminary test for the biodegradability of the 3-phenyl- and 3-carbamoyl-2(lH)pyridones was conducted in a barnyard humus suspension. The analysis by HPLC showed some loss, and the fluorescent compounds seemed to be adsorbed onto the solid. The 3-carbamoyl-2(lH)pyridone (II) also hydrolyzed to 3-carboxylic acid-2(lH)pyridone both in the slurry test and in water solutions that had been left standing 1-2 weeks. In preliminary tests both the 3-phenyl- and the 3-carbamoyl-2(lH)pyridones apparently adsorbed to some extent on silica sand columns. In addition, the solubility of both 1-H compounds was somewhat low, 1.3 x 10 M for II, and 1.0 x 10 M for IV. 

Preliminary Cytotoxicity Testing. An essential first step is to carry out a preliminary study to evaluate the toxicity of the test material to the indicator cells, under the conditions of the main mutagenicity test. When selecting dose levels, the solubility of the test compound, the resulting pH of the media, and the osmolality of the test solutions all need to be considered. The latter two parameters have been known to induce false positive effects in in vitro mammalian tests (Brusick, 1986). The experimental procedure is carried out as follows. 

Small amounts of easily evaporated liquids can be removed directly from a test tube or a small flask heated on the water bath. On each occasion the test tube is filled to a depth of 2-3 cm. only, and is replenished from time to time during the boiling on the water bath it must be shaken continuously or stirred with a thin glass rod. All preliminary tests with solutions are carried out in this simple way previous to an examination of the residues. For the latter purpose solutions of substances liable to decompose are left exposed to the air in watch-glasses or small crystallising basins so that the solvent may evaporate. 

Prior to the advent of DDT, no highly successful chemical control of tsetse flies had been accomplished. In 1945 duToit, Graf, and Theiler of the Onderstepoorte Staff began their investigations on aircraft-distributed DDT for the control of adult tsetses. The site selected was a belt 30 square miles, comprising the Mkuzi Reserve in Northern Zululand, an area well populated with G. pallidipes. In the preliminary tests a 5% solution of DDT in furnace oil was applied as a spray at the... 

Handa et al. reported the synthesis of a phosphorus equivalent of Barthel s salts in which the hexavalent phosphorus(V) was coordinated by three bidentate ligands. 1.2-benzenediolato-O.C7. Its thermal stability is similar to that of its boron counterparts, and moderate ion conductivity was achieved in nonaqueous media. The authors attributed the less-than-satisfactory ion conduction to the large size of the anions, which increased the viscosity of the resultant electrolyte solutions. The anodic stability limit, as measured by voltammetry on a Ni electrode, was below 3.7 V. A preliminary test of this salt in EC/ THF was conducted in a lithium cell using the low potential cathode. V2O5. and the authors believed that this salt could be a superior electrolyte solute, judging from the utilized cell capacity that was close to the theoretical value. 

The incubation conditions for trypsin and pepsin were chosen after preliminary tests showed that measurable amounts of collagen were released into the incubation solutions. In trypsin incubations, degradation is fastest on day 1 and decreasing in velocity thereafter. Slices digested extensively by pepsin were fragile. Infermittent changes of pepsin solutions were therefore avoided. 

Because cryosolvents must be used in studies of biochemical reactions in water, it is important to recall that the dielectric constant of a solution increases with decreasing temperature. Fink and Geeves describe the following steps (1) preliminary tests to identify possible cryosolvent(s) (2) determination of the effect of cosolvent on the catalytic properties (3) determination of the effect of cosolvent on the structural properties (4) determination of the effect of subzero temperature on the catalytic properties (5) determination of the effect of subzero temperature on the structural properties (6) detection of intermediates by initiating catalytic reaction at subzero temperature (7) kinetic, thermodynamic, and spectral characterization of detected intermediates (8) correlation of low-temperature findings with those under normal conditions and (9) structural studies on trapped intermediates. 

Coupling of an aryl 1-S-cellobioside to an affinity carrier was therefore expected to be useful in the chromatographic fractionation of endo and exo enzymes, e.g., from Tr. r. Preliminary tests indicated that CBH I and CBH II (prepurified by ion-exchange chromatography) were completely retained by the affinity support (4 -aminobenzyl 1-S-cellobioside coupled to Affigel-10 from Biorad). Desorption was achieved differentially by 0.1M lactose (elutes CBH I) and 0.01M cellobiose (elutes CBH I and CBH II). Attempts to elute the enzymes with 1M KC1, ethyleneglycol or glucose solutions were unsuccessful (11). 

The above conditions were found by varying, in preliminary tests, the concentration of the alkylaluminum solution and the contact time. 

A finished propellant block (of precisely known properties) was then cut into strands 0.25 in. square and approximately 4 in. long. All strands were inhibited by leaching in water for 10-15 sec. When the burning surface could not be made to burn straight and perpendicular to its direction of travel, the strands had to be inhibited with three coats of 5% vinyl plastic (VYLF) in dichloromethane solution in addition to leaching in water. Preliminary tests showed that this inhibition had no significant effect on the burning rate but did increase the extinction pressure from 0.045 to 0.060 atm. 

Preliminary experiments resulted in the formation of a precipitate due to the presence of inorganic salts when the pH of the test solution was raised to 10 for the first passage through the XAD-8 column to isolate the hydrophobic base fraction. Initially, desalting the solution with a cation-exchange resin (i.e., AG-50-X8, Na+ form) was tried before... 

To obtain the prescribed concentration, a preliminary test must be made if there is no indication of the approximate content of tannin in the substance. In general this concentration is obtained approximately by weighing out, for each litre of solution, the following quantities of the different tanning materials (see Joum. Soc. Chem. Indus-... 

Tannic and Gallic Acids.—A preliminary test for these two adds may be made by diluting the ink with water, acidifying slightly with dilute sulphuric add and extracting with ethyl acetate. The ethereal liquid is evaporated and the residue dissolved in water, the solution being tested as follows ... 

When the best solvent or solvent mixture and the appropriate proportions of solute and solvent have been determined by these preliminary tests or have been obtained from reference books containing solubility data,39,40 the solid substance is placed in a round-bottomed flask of suitable size fitted with a reflux condenser (Fig. 2.54) and slightly less than the required quantity of solvent is added together with a few pieces of porous porcelain to prevent bumping (see... 

CSSX that hydrogen-bond donor modifiers were most effective for Cs extraction, TBP being a poor modifier by comparison (413). The results of preliminary tests showed that the process is effective at selectively extracting Cs and Sr from solutions of nitric acid concentration between 0.5 and 2.5 M. Cesium and Sr can be stripped from the solvent with 0.01 M HN03 solution. 

---