Undissolved substances

Amongst the undissolved substances, a distinction may be made between 

Filter 1 litre of a thoroughly mixed water sample. The paper or membrane filters should be washed with distilled water beforehand and dried at e.g. 103 C for 2 hours, cooled in the desiccator and weighed. Rinse the filtered residue with about 10 ml of distilled water and vacuum-dry. Lift the 

In order to prevent errors due to subsequent flocculation, as soon as 

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Undissolved substances were removed by filtration and the filtrate was concentrated on a steam bath to a volume of about 125 ml and cooled to effect crystallization. After 20 hours at room temperature the crystals that had formed were recovered, washed with isopropyl alcohol, and dried, yielding 15.61 grams (46.2%) of crystalline 5-[bis(2-hydroxy-ethyl)amino] uracil having a MP of 157° to 163°C. An analytical sample, obtained by several recrystallizations from isopropyl alcohol, melted at 166° to 168°C. 

Particulate matter is defined in the USP as extraneous, mobile, undissolved substances, other than gas bubbles, unintentionally present in parenteral solutions. Test methods and limits for particulates are stated in the USP for large-volume injections and small-volume injections. 

When it is desired to accelerate a reaction in solution or with undissolved substances at a temperature above their boiling point, the reactants must be shut off from the external atmosphere either by sealing in a glass tube in which they are then heated, or in a closed metallic vessel (autoclave). This is obviously necessary even when we wish a reaction to take place in alcoholic solution at 100° or in aqueous solution at about 120°. Thus the aim is entirely to increase the temperature of the reaction the accompanying increase in pressure has no effect on the reaction velocity, for as a rule it is unaccompanied by any significant change in the concentration. 

Dithiocyanato-diethylenediamino-chromic Chloride, [Cr en2 (SCN)2]C1.HC1, is prepared from the thiocyanate on treatment with concentrated hydrochloric acid, filtering off undissolved substance, and cooling the filtrate, when a crystalline powder separates. This is recrystallised from water and obtained in ruby-red glistening needles. From a solution of this salt may be precipitated the nitrate, sulphate, bromide, or dichromate by means of the corresponding acid or potassium dichromate. 

Strychnine.—Treat 0.5 gm. of brucine with 5 gm. of absolute alcohol at the ordinary temperature for one hour, with frequent shaking. Filter, transfer a portion of the undissolved substance to a watch glass, allow it to dry thereon, and then dissolve it in a few drops of concentrated sulphuric acid. To this solution add a small crystal of potassium dichromate. A play of colors, from blue through violet and. red into green, is evidence of the presence of strychnine. 

Environmental Aspects of Cooling Tower Operation. Accumulation and Escape of Dissolved and Undissolved Substances... 

The simplest deLnition of solubility is that the solubilfy, of a substance is the molarity of that substance (counting all its solution species) in a solution that is at chemical equilibrium with an excess of the undissolved substance. This implies that there must also be a uniform temperature throughout the system, becaifiteis typically temperature dependent (Ramette, 1981). 

When a substance is dissolved in water to form a saturated solution (see Types of Solutions in Chapter 2), some of the substance remains undissolved, so we know we have reached the saturation point. Present in the solution would be the dissolved ions and a small portion of the undissolved substance. When all these substances are present, we can say that we have reached equilibrium. To have equilibrium, the rate of the substance dissolving has to equal the rate of the dissolved ions reforming the original substance. To show that a system is at equilibrium, we use a double arrow in the equation. When sodium... 

Note 1. If the residue on evaporation does not redissolve after warming it 10 minutes with 60 cc. of water, it contains arsenious oxide either from incomplete oxidation by nitric acid, or from a decomposition of arsenic pentoxide by overheating. Test 1 cc. of the suspension containing the undissolved substance by adding 10 cc. of water, then solid sodium bicarbonate until no more effervescence occurs, and then a considerable quantity in excess. Add to this a solution of iodine, drop by drop. The amount of the latter which is decolorized (if any) corresponds to the amount of arsenious acid (As203), which was in the sample. 

SOLUBILITY PRODUCT The saturated solution of a salt, which contains also an excess of the undissolved substance, is an equilibrium system to which the law of mass action can be applied. If, for example, silver chloride precipitate is in equilibrium with its saturated solution, the following equilibrium is established ... 

The classical measurement of LogP is the shake flask method [17]. A known amount of drug is dissolved in a flask containing both octanol phase and aqueous buffer at controlled pH to ensure the existence of only nonionic form (at least two units from the drug pA) ). The flask is shaken to equilibrate the sample between two phases. There must be no undissolved substance present in both phases. After the system reaches its equilibrium, which is time- and temperature-dependent, the concentration of drug is analyzed by HPLC in both phases. Partitioning coefficient is calculated as... 

Reactions between solids and solutions may be treated in a similar manner. Every solid has a definite solubility in every solvent, just as it has a definite vapour pressure at a given temperature. The solubility depends on the nature of the solvent and on the temperature, but is independent (in dilute solutions at least) of the presence of other dissolved or undissolved substances. So-called insoluble substances differ from soluble substances only in that their solubility is exceedingly small. 

For comparison, a sample containing 10 ml water as well as the substance (extract etc.) is stored at 80 °C. After the predetermined storage time, the samples are worked up, i.e. undissolved substance must be brought into solution and acidic and basic solutions must be neutralized. Drugs and extracts are usually subjected to an often complex sample preparation before the preparations for TLC can be started. 

There is substantial evidence (much from the literature on drug abuse) indicating that particulate matter (undissolved substances) is a health hazard in parenteral products [21], The precise hazards depend very much on the physical and biological properties of the particles, and their site of lodgement in the vascular system. Phlebitis and pulmonary infarctions are the most significani problems associated with particulate matter. Particulate matter is an unwanted and unnecessary addition to parenteral therapy. 

For wastewaters polluted mainly by undissolved inorganic substances (e.g. from metallurgical and mining operations) the population equivalents can be calculated in such a way that the value of specific production of undissolved substances per capita per day (90 g) is substituted into the above formula. 

Water solubility (5 ) is defined as the maximum amount of a compound that will dissolve in pure water at a specified temperature. Addition of further amounts of the chemical, which may be either solid or liquid, will result in a two-phase system at the defined temperature the saturated aqueous solution and the solid or liquid phase of the undissolved substance (Lyman, Reehl and Rosenblatt, 1990). Under these conditions, water solubility can also be... 

If the water contains undissolved substances, either the total activity of... 

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