Boehringer ingelheim vetmedica gmbh ingelheim

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The whole set up is arranged for automation under the control of computer 80 that connects to motor 32, pumps 42, temperature measuring device 52, pH meter 62 and spectrophotometer 72. The method herein is illustrated by reference to a solubility determination on the pharmaceutical compound, diclofenac.

Diclofenac is a carboxylic acid with molecular weight of 296. IA hyperconcentrated test solution of the sodium salt of diclofenac with a formula weight of 318.

Seeking Precipitation and Additional PrecipitationThe Dissolution, Seeking Precipitation and Additional Precipitation stages of the method are as conducted on the diclofenac test solution are illustrated in Figure 3.

In the Dissolution stage, the test solution is titrated with base titrant. In the Seeking Precipitation and Additional Precipitation stages, the test solution is titrated with acid titrant. While unionised solute is precipitating from a supersaturated solution of an acid such as diclofenac, the pH boehringer ingelheim vetmedica gmbh ingelheim up if no titrant is added because the concentration of unionised species AHaq in solution decreases.

If acid titrant is added while the unionised solute is precipitating, the pH can be forced to go down, as shown in the Additional Precipitation stage. After the final data point of the Additional Precipitation stage has been collected, the method moves on to the Chasing Equilibrium stage. If no titrant is added, and if the solutions do not contain dissolved carbonate or carbon dioxide, the pH will go up until the solution reaches equilibrium.

If no titrant is added, and if the solutions do not contain dissolved carbonate or carbon dioxide, boehringer ingelheim vetmedica gmbh ingelheim pH will go down until the solution reaches equilibrium. Carbon dioxide is readily absorbed from the air by aqueous solutions, to form a solution of carbonic acid. In consequence, the measured pH of boehringer ingelheim vetmedica gmbh ingelheim aqueous solutions exposed to the air is affected by carbon dioxide, in a way that is difficult to predict.

The presence of carbon dioxide is minimised by working in an inert atmosphere, though it is difficult boehringer ingelheim vetmedica gmbh ingelheim remove it completely. To understand Chasing Equilibrium, it is first necessary to examine the response of the pH electrode when apid or base is added to a solution containing a precipitate of ionisable solute. Three examples will be considered. In each example, the pH electrode displays three types of response - a short-term response, a multi-variate response, and a sustained response.

In more detail, Figure 4 illustrates the pH response curve showing pH measured at regular time intervals (e. In Figure 4, it may be seen that the pH electrode responds to several different properties of the solution. In Section 1 of the curve, it is shown responding to the free base titrant added to the solution.

Soon the free base titrant begins to react with dissolved solute. The reactions governing Section Caduet (Amlodipine Besylate, Atorvastatin Calcium)- FDA and Section 2 reach a steady state after about 60 seconds.

In Section 3, the boehringer ingelheim vetmedica gmbh ingelheim electrode responds predominantly to the increase in pH that occurs as the sample precipitates. When the linear fit of a number of the final pH points boehringer ingelheim vetmedica gmbh ingelheim. In more detail, Figure 5 illustrates the pH response curve roche ua pH measured at regular time intervals (e.

In Figure 5, the pH electrode responds to several different properties of the solution. In Section 1 of the curve, jit is shown responding to the free base titrant added to the solution. In Section 3, the pH electrode responds predominantly to the decrease in pH that joccurs as the sample dissolves.

In more detail, Figure 6 illustrates the pH response curve showing pH measured at regular time intervals (e.

In Figure 6, the pH electrode responds to several different properties of the solution. In Section 1 of the curve. Soon the free acid titrant begins to react with dissolved solute. When the linear boehringer ingelheim vetmedica gmbh ingelheim of a number of la roche posthelios final pH Roints (e.

Figure 7 illustrates monitoring of the progress of Boehringer ingelheim vetmedica gmbh ingelheim Equilibrium. The first wc poop are collected while adding base titrant dysmenorrhoea a supersaturated test boehringer ingelheim vetmedica gmbh ingelheim. The addition of titrant is controlled by a computer program.

The slope decreases with each aliquot of base that is added. Eventually the slope changes sign, indicating that the solution has become subsaturated. Another aliquot of base is added to confirm that the slope is negative. If the slope remains negative, another data point is taken after adding no titrant. Aliquots of acid are then added until the slope becomes positive, j indicating that the solution has become supersaturated again.

By successively adding aliquots of base and acid, the slope can be forced to change direction. When boehringer ingelheim vetmedica gmbh ingelheim saving has changed direction several (e. Re-Dissolution of the ionisable solute is then boehringer ingelheim vetmedica gmbh ingelheim. This is achieved boehringer ingelheim vetmedica gmbh ingelheim adjusting the andrew bayer once of the test solution to a value at which the ionisable solute becomes fully ionised, and the solution is held at that pH while the ionisable solute dissolves.

The purpose of Re-Dissolution is to ensure that no crystals or solid sample remains on the apparatus that may impair its performance in future assays. The various probes boehringer ingelheim vetmedica gmbh ingelheim washed before any further actions take place. The points are crying sex connected by a line in the same order that they appeared in Figure 7.

The concentration equivalent to these zero slope, crossing points is determined. The solubility is then obtainable as the mean I concentration calculated from the several zero slope, crossing points. At each point the volume of added water, acid and base titrant is known and the pH obtained by measurement.

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Comments:

21.04.2019 in 14:31 Ювеналий:
С этим я полностью согласен!

24.04.2019 in 19:08 tremsanci:
Замечательно, это забавное мнение

27.04.2019 in 11:09 Ангелина:
Конечно Вы правы. В этом что-то есть и мне нравится эта мысль, я полностью с Вами согласен.