usos y aplicaciones potenciometria y conductimetria. La potenciometría es una técnica electroanalítica con la que se puede determinar la También se emplea la potenciometría en distintas aplicaciones como en. En estas aplicaciones, el origen y la estructura de la fibra tienen una gran Es por ello por lo que se usa la potenciometría de redisolución adsortiva, para.

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Las enzimas pueden inhibirse reversiblemente de forma competitiva y no competitiva. Para preservar la actividad fosfatasa, mantener la muestra stock potrnciometria las respectivas diluciones en hielo. A partir del preparado de potencciometria de trigo, preparar el siguiente banco de potencjometria en agua:.

Para calcular la constante de Michaelis K M de la fosfatasa para el p-nitrofenil-fosfato, se determina la actividad de la enzima en distintas concentraciones de sustrato. La mezcla resultante se neutraliza con una base y se destila. Kjeldahl method is used in analytical chemistry for the determination of nitrogen content in organic samples which is of great interest in areas such important today as food and environmental.

Today is the most widely used method for protein analysis and is performed by determining organic nitrogen. This is because different types of proteins coincide all in a similar proportion of such organic nitrogen. In most cases the following calculation factor is used:.

In this technique, proteins and other organic compounds in a food mixture are digested with sulfuric acid in the presence of catalysts. The total organic nitrogen is converted into ammonium sulfate through the digestion. The resulting mixture is neutralized with a base and distilled.

The distillate is collected in a solution of boric acid. Borate anions thus potenciomwtria are titrated with standardized HCL to determine the nitrogen content in the sample. Generally, the Kjeldahl method has the advantage of being running by unsophisticated equipments and can be performed by less experienced technicians.

The Kjeldahl method has been officially recognized by a large number of government agencies and associations such as: The method consists of three stages: This is obtained by boiling the sample in a sulfuric acid concentration. The result is an ammonium sulfate solution. Initially a steam distillation is performed by the water steam distillation method, by which distillation obtainment is accelerated.

Notas de Aplicaciones

In recent years, new equipments are being developed and improving technologies to implement these analytical techniques. The equipments for organic nitrogen determination are composed of three basic elements:. Recently, the new potenciometrka system Auto Digest 20 has been added, which optimizes speed and reliability of laboratory professionals. A number of interrelated conditions in the apljcaciones process determine the speed of reaction and the decomposition of nitrogen into ammonium sulfate, such as the amount of heat transferred, the quantity of salts to raise the acid boiling temperature, the catalyst employed and the time of digestion.

Adjustment of any of these parameters influences the rest. There are studies to determine the parameters needed applicaciones obtain optimum conditions depending on the samples matrix. For example, the amount of acid required varies depending on the fat present in the sample. The more quantity of fat, the more acid is required. It also varies with the time of digestion. The longer time, the more acid lost by evaporation. Digestion time should be determined depending on the amount of recovery by using known matrix samples.

Salts addition is helpful to raise the boiling temperature of H2SO4. There are different block sizes for 6, 12 and 20 samples. The heating element is a high electrical resistance which is controlled by an electronic device incorporating a microprocessor which allows the potencjometria to choose and memorize several programs working with fully programmable ramps and times.


Such programming capability optimizes digestions according to the material used. No deben quedar restos negros adheridos a la pared de tubo. The result is a clear transparent liquid with light blue colour, green or yellow depending on the catalyst used.

No black residues should remain attached to the tube wall. A software CD is included in the digestion unit. The software facilitates the digestion editing programs and allows you to track and record the digestor temperature. Specially designed to absorb and neutralize acid gases generated in Kjeldahl digestion processes.

It consists of a “Scrubber” unit that blocks and neutralizes the acidic condensations, and a recirculating water pump that provides a great volume of vacuum for gases suction. It is essential to place the “Scrubber” unit with the neutralizing solution between the digester and the recirculation pump.

Se suministra completo compuesto de: The equipment carries out the digestion process fully automated, with rise and fall of the rack holder. Equipment with metallic structure and automatic sample holder epoxy covered.

It is completely supplied with: Most of the NH3 is distilled and caught in the acidic solution during the first 5 to 10 minutes of boiling, but depending on the volume of digestion mixture and on the method followed, from 20 to ml of condensate can be collected to obtain a complete nitrogen collection.

Sometimes distillation is required to be extended, which produces more water but this does not alter the results when making the titration. The distillation speed varies with the condenser cooling capacity and with the capacity of generating heat from the heater. The system of heating by water steam accelerates the obtaining of distillation. Using a recipient solution made of boric acid, dosing is not required with accuracy, as titration measures exactly the amount of ammonia by neutralizing 1: In fact, quite boric can be added to ensure the complete absorption of ammonia.

Pronitro M is a Kjeldahl with an automation level that provides a simple and safety operation.

POTENCIOMETRÍA by Salvador Gómez Fuentes on Prezi

It is suitable for a laboratory with a small or medium samples volume. Se procede de la siguiente forma:. Peso de la muestra mg. Adecuado para un laboratorio con un volumen de muestras mediano o grande. Boric acid captures ammonia gas and forms a boric ammonia complex. When ammonia is captured, colour of the recipient solution changes.

Actually, different indicators can be used to get a turn as clean and sharp as possible. If it becomes difficult to detect the turning point, it may be useful to use a white reference solution.


When making calculations, we must take into account the recipient solution and the dilution factors used in the distillation process.

References may be taken potenciometia the published reference methods. Kjeldahl distiller is fully automatic and with a titration system “on-line” real-time titration. Equipment for a systematic analysis, highly accurate, and with minimal staff, easy and safe.

Suitable for laboratory with medium or large sample volume. This type of titration provides an additional advantage: The colorimetric evaluation is accepted by the AOAC and needs no periodic calibration. The method consists of mineralizing the sample with a concentrated sulfuric acid and alkalinizing with sodium hydroxide. The ammonia released is carried by distillation and collected on boric acid.

Subsequent titration with hydrochloric acid allows calculation of the amount of protein initially present in the sample. It is important that all reagents are completely free from nitrogen. Dose 50 ml of boric acid in an Erlenmeyer flask and some drops of mixed indicator.

Place the Erlenmeyer flask in the refrigerant extension taking care it has to be submerged in the boric acid. Once the sample tube and the Erlenmeyer with boric acid are placed, dose 50ml of NaOH and start distillation. Distillation should be extended long enough to distillate at least ml, approximately from 5 to 10 minutes. After distillation of a sample, perform a blank test aplicacilnes using the above described method, but using 5 ml of distilled water.


Titrate the obtained distillate with 0. For crude protein a value of 6. For greater accuracy, other conversion factors can be used by distinguishing the protein quality according to the sample nature. From the first day of its activity, J.

Selecta has tried to be aware of the latest technologies and methodologies in the field of laboratory equipments. Continuing with this innovative eagerness, as soon as the new electronic elements to produce both heat and cold through the principle called Potenciiometria were known, a series of research projects aimed at creating a new refrigerated incubator based on this system started. Early work with Peltier elements for knowing technology started in the early 80’s but it was not until when the first incubator finally hit the market as a world premiere, running only by Peltier elements.

Over these 32 years that we have had our incubators cooled with Peltier system on the market, effectiveness and utility have been proven, being this line of ovens the most prestigious of our brand. Particularly potenciomeria is worth mentioning a long list of advantages if compared potenciommetria traditional ovens made with conventional heating elements and cold groups:.

With Peltier technology, heating and cooling processes are conducted into one compact system.

Both the excellent adjustment level and the oscillation reduced to the minimum of the temperature obtained occur thanks to the perfect development of refrigeration and heating technique, with a considerable energy saving and environmentally friendly.

Models Most important aspects: Peltier System Background The discovery of thermoelectric phenomenon two centuries ago, and the search for new alternative energy generation, has allowed continued progress in thermoelectric technology in recent years. Since this is known as the Peltier effect; however, its practical application needed the development of semiconductor materials. The Peltier effect is characterized by the occurrence of a temperature difference between two sides of a semiconductor when a current flows through it.

Generally such cells are made with Bismuth for the P type semiconductor face and with Tellurium for the type N face. The establishment of a heat flow, opposite to the thermal diffusion, when a material subjected to a temperature gradient is crossed by an electric current, suggests thermoelectric cooling applications. This alternative solution to the traditional refrigeration that uses compression-expansion cycles does not need moving parts, which increases its reliability.

Besides being totally quiet, they have a very small size and weight, and they can easily handle bumps and vibrations, they can be used in any position, vertical, horizontal, inclined and also, thanks to them, cooling capacity can be adjusted by simply varying the feed stream.

What makes them even more interesting is the fact that, when reversing the supply polarity, their operation is also reversed, that is to say: These properties are essential in applications where the temperature must be controlled very precisely and reliably, such as in the containers used in transporting organs for transplantation or in those in which vibrations are serious disadvantages, for example: