Shaking agitation procedure

Under normal circumstances the acetone will be removed from the extract by shaking the total extract with a large surplus of water, at least four times the volume of the acetone should be applied. Therefore, the amount of hydrocarbon 

Examples of the shaking procedure can be found in several ISO standards for the determination of organic micro-pollutants in soil, such as PAH, OCB and PCB, mineral oil and herbicides. 

Super critical fluid extraction enlarges the range of solvents. Using super critical carbon dioxide has the advantage that the final extract is automatically concentrated to dryness. The polarity of supercritical carbon dioxide is rather low therefore, small amounts of methanol are added as modifier to increase the polarity of the extractant. The solvents also have a large penetrating power because of their low viscosity. The invention of ASE has reduced the interest in SFE due to the more versatile applicability and robustness of ASE. 

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The classical methods of solvent extraction of polymers can be conveniently divided into those for which heat is required (Soxhlet/Soxtec ), and those methods for which no heat is added, but which utilise some form of agitation, i.e. shaking or sonication (Table 3.3). Other LSE procedures consist in soaking the polymer in boiling solvents [84,85] and cold LSE [80,86]. These methods are also time-consuming, use large amounts of solvents which are scheduled to be restricted in the future, and exhibit other limitations when analytes are present in small quantities, where they may actually be lost in concentration steps following extraction. Many norms are still based on such standard procedures [87,88],... 

Preparation of Thiocyanogen Solutions. To a suspension of 30 g. of plumbous thiocyanate in 300 ml. of the acetic acid is added 5 ml. of the bromine solution. The mixture is agitated vigorously on a shaking machine until it is practically colorless, and another portion of the bromine solution is added. This procedure is continued until all the bromine solution has been added. The mixture is then rapidly filtered through a dry fluted filter paper. ... 

The third major improvement is to use a vial-roller for 90 min for the equilibration procedure (see Fig. 12.2). The gentle rolling ensures that adequate mixing is achieved, but more importantly an octanol emulsion is not formed, which is usually associated with the severe agitation achieved with the traditional shake-flask technique. This negates the need for a centrifugation step. 

Preparation. Zinc dust (400 g.) is amalgamated by shaking with a solution of 32 g. of mercuric chloride and 20 ml. of coned, hydrochloric acid in 400 ml. of water. The aqueous phase is decanted, and 800 ml. of water, 80 ml. of coned, hydrochloric acid, and 200 g. of chromic chloride hexahydrate are added. Carbon dioxide from a dry ice generator is bubbled through the mixture to provide agitation and prevent reoxidation by air. When the solution turns light blue it is ready for use. A procedure for preparation of an alcoholic solution using a Jones reductor is also described. ... 

Agitation is the easiest way of producing foam, but the results are very dependent on the details of the shaking procedure. Foam height, or for more viscous fluids specific gravity changes, are usually measured. 

After complete drying, the glass slide is gently dipped into a bath of xylene during 5 min. This procedure is repeated two times. No agitation or shaking is needed. 

Adsorption from solution measurements are obviously facilitated if an instrumental technique (e.g. a spectrophotometer or refractometer) can be used to follow the change in solute concentration. However, it is not always easy to achieve high accuracy and reproducibility, and it is therefore necessary to take account of a number of practical considerations and precautions The traditional experimental method is to add a known mass of the solid to a measured amount of solution of known composition. The container is then sealed and subjected to some form of agitation (shaking or preferably tumbling), whilst being held at constant temperature. Samples of the supernatant liquid are withdrawn and analysed. In such an experiment it is not easy to establish whether equilibrium has been established and in fact this may take from one hour to a few days Problems may also arise in the separation of the adsorbent and the supernatant liquid. The procedure is laborious and cumbersome, because a fresh sample is required for the determination of each point on the isotherm. 

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