Micro solubility test

The toxicity of PGM and their compounds depend mainly on their solubility (Moldovan etal. 2002). Experimentally, soluble PGM salts are much more toxic than compounds with a low solubility. Micro toxicity tests... 

When the correct solvent for recrystallisation is not known a procedure similar to that given on pp. 15-16 should be followed, but on the semi-micro scale not more than 10 mg. of the solid should be placed in the tapered-end test-tube (Fig. 29(B)) and about o i ml. of the solvent should be added from the calibrated dropping-pipette (Fig. 30(B)). If the compound dissolves readily in the cold, the solvent is unsuitable, but the solution should not be discarded. [In this case recourse should be had to the use of mixed solvents (p. 18). For example if the substance is very soluble in ethanol, water should be added from a calibrated pipette with shaking to determine whether crystallisation will now take place, indicated by a cloudiness or by the separation of solid.]... 

The application of fullerene on the surfaces has an essential advantage in the studies with cell cultures as in this case we can obtain the maximum contact of cells with fullerene - cells adhere on the surface and colonize it as a confluent monolayer. That is the basic difference from the water-soluble complexes and micro-dispersed suspensions of fullerene C60. The pro-/antioxidant activities of fullerene were tested in chemical and biological systems. 

To find a suitable solvent for recrystallization you must carry out a series of tests measuring the solubility of your crude compound in a series of solvents (cold and hot) of varying solvent polarity. This series of tests is called solvent selection and is carried out on a test tube scale but, as your technique improves, you can carry out the tests using semi-micro scale since you will use less of your compound during the process. The procedure for solvent selection at the test tube scale is described in Box 13.1 and modification of the procedure to semi-micro scale requires only a corresponding reduction of the quantities of solvent and solute used. 

Identification and characterization of the structures of unknown substances are an important part of organic chemistry. It is often, of necessity, a micro process, e.g., in drug analyses. It is sometimes possible to establish the structure of a compound on the basis of spectra alone (ir, uv, and nmr), but these spectra must usually be supplemented with other information about the unknown physical state, elementary analysis, solubility, and confirmatory tests for functional groups. Conversion of the unknown to a solid derivative of known melting point will often provide final confirmation of structure. 

MARA is an innovative bioassay devised for the evaluation of toxicity of chemicals and environmental samples. The assay utilizes a taxonomically diverse array of ten bacterial species (prokaryotes) and a yeast (eukaryote). The assay is performed in a 96 well micro titre plate and involves exposure of the microorganisms provided in a freeze-dried state. The toxicity of the test sample using a concentration gradient is determined with the employment of the redox dye tetrazolium red (TZR). The dye is transformed from a soluble colourless state to a red insoluble form upon reduction. The dye is a growth indicator and detects enzyme systems by acting as an electron acceptor. 

As even in the world of the micro-units the production of crystals does not always provide a guarantee of the purity of the substance separated, so is this the case to a higher degree in the domain of colloid crystals. We then have as the criterion that a protein has been obtained crystalline in a pure state that the so-called phase rule test 2 should apply, in which the solubility of the preparation is investigated... 

The objective of this research Is the examination of the effects of ion bombardment on the structure of thin ceramic films on ceramic substrates. The material combinations will Include oxide films that have (a) no solid solubility, (b) limited solid solubility, and (c) complete solid solubility with the substrate material (also an oxide). Techniques for determination of elastic and plastic properties of thin films or coatings on ceramic substrates and for the determination of the strength of the bond between the film and substrate, which are currently being developed, will be used to determine the hardness, elastic modulus, and adherence of each material combint tion. The main testing techniques will be the ultra-low load micro-indentation tester (Nanaindenter) and thermal cycling tests. 

Many of the qualitative tests may be applied to the quantitative determination of sugars. The color developed in the presence of acids and phenols or the amount of metal or metallic oxide formed by the reduction of the salts of heavy metals by the sugars can be measured. Some of these methods can also be used on a micro-scale to determine quantitatively the sugar eluted from paper chromatograms. In some cases, difficultly soluble derivations such as the osazones or hydrazones can be weighed directly. Because of the absence of a stoichiometric relation for the methods, they are not completely satisfactory. Complete descriptions of many of the methods described will be found in the article by Bell 6). 

Isonitrosobenzoylmethane reacts with iron i salts to yield a blue inner complex salt that is soluble in benzene. One drop of the test solution is placed on filter paper and spotted with a 1 % alcoholic solution of the reagent. When held over ammonia, a green fleck appears Idn. Limit 0.02 y Fe). The test may be conducted likewise on a spot plate or in a micro crucible. In the latter case, benzene extraction is possible. Copper, cobalt, nickel interfere silver, lead, zinc, manganese, chromium lower the sensitivity. 

Procedure. The test is conducted in a micro test tube. A drop of the test solution is treated with a drop of a 1 1 mixture of 1 % barium chloride and 10 % sodium nitrite, and a arop of dilute hydrochloric acid. If aminosulfonic acid is present, a precipitate or turbidity of barium sulfate will appear. With slight quantities of sulfamic acid, the BaS04 can be brought down almost immediately by adding several drops of ether and swirling the test tube. This effect is due to the considerable solubility of ether in water which thus accelerates the normally sluggish separation of small amounts of barium sulfate. 

Procedure. A drop or two of the test solution is placed in a micro crucible and treated with a like volume of reagent solution and a little solid sodium sulfite and sodium chloride. A pink color appears at once if small amounts of iron are present. The function of the sodium chloride is to form the soluble complex NagLHgClJ and thus prevent the precipitation of the white insoluble double salt of HgClg and a,a -dip3rridyl. Sometimes a red precipitate of [Fe(a,a dip)g] [HgClJ is formed instead of a red color. 

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