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The main advantage and a unique feature of the DissoPrep is, that is uses the gravimetric principle for mixing and dispensing media. The volume of a liquid differs depending on the temperature and the pressure it is exposed to. Only the weight of a liquid is not changing when it's heated and set under pressure.
Thats why the DissoPrep weighs the used media and the additive for mixing as well as it weighs the dispensed media. That's how it fullfills the requirements of the USP regarding volume precision for all kinds of media.
Example: According to the USP the volume has to be dispensed at the standard condition of 25°C. Afterwards it's heated up to 37°C. So 900mL dispensed at 37°C weigh 897,4g, which corresponds to 900 at 25°C. ???
So in accordance with the USP e.g. 900ml dispensed at 37°C into a vessel weigh 897,4g, which is the mass of 900ml at 25°C!
So it would be wrong to measure warm media in a volumetric flask or device calibrated at 20°C. And it would be also
wrong to use the specific weight (density) for gravimetric volume measuring of the media at e.g. 37°C. With this
gravimetric principle a calibration of the DissoPrep for each media and each temperature is NOT necessary!
The gravimetric dosing principle means that the dispensed media is dosed by weight and not by volume. For more information please see FAQ "What is the main advantage of the DPX?".
The content of the DPX8 (8 Liters or 8000g of media) are sufficient to fill one standard Dissolution bath with 8 positions. With the DPX15 (15 Liter/15000g) you can fill two Dissolution bathes.
Generally media should be prepared on demand rather than stockpiling, because it will shortly be saturated with gases again, so degassing would have been useless.
Additionally, the storage of media results in bacteria growth. To avoid this, the DPX is always preparing "fresh" media.
The DissoPrep is continiously stirring the medium with a magnetic stirrer. The stirrer is monitored to ensure a continious mxing.
The medium is degassed by creating a vacuum. Typically the pressure is < 100mbar. The vacuum is monitored and documented in the protocol, which is printed after every use.
The prefill volume is 1000g. It is used to fill e.g. tubings and for flushing purposes.
The DPX should be used at temperatures between 18 and 30 degrees and at a humidity of 85% max.
The tank is made of PP (Polypropylene).
The recommendation of the USP refers to the manual degassing process. For the automated process of the DPX 20µ are sufficient. Moreover our filter is made of PP, so it's acid resistant for 0,5% hydrochloric acid.
Generally it is possible to move the DPX through your lab. We offer a so called LabCart to move it safely with all its reservoirs.
But you should not move it in Prefill, Fill and Dispense state. Otherwise the load-cell would be influenced, what leads to errors in your dispensing results.
Another restriction is the power supply. The DPX must not be disconnected from power supply during operation! Otherwise it will force you to empty the system rather than dispensing. For that reason we offer an uninterruptible power supply (UPS).
The DPX offers a dilution ration between 1:3 and 1:100. Hereby the parameter "Volume Additive" must not exceed 1000g per vessel.
Example: For 1000g media per vessel the maximum dilution ratio of 1:3 means to add 333,3g Additive. (Enter "Volume Vessel" = 1000 and "Volume Additive" 0 333,3)
Yes, you can add a premixed hydrochloric acid solution instead of DI water with the Water-Inlet tubing. Please note that the maximum concentration of the hydrochloric acid is 0,5%.
Yes, surfactants can be used. There are no known issues, also if they are foaming.
Yes, basic buffers and acids can be used.
Please note the maximum concentration of 36% hydrochloric acid at the "Additive Input" line, and a maximum of 0,5% hydrochloric Acid at the "Media-Input" line and the "Output" line.
No, organic and alcoholic solvents must not be used, as the can cause an explosion when they pass the heater. Moreover some parts and tubings are not alcohol resistent.
No, the foam is on top of your medium, whereas the outlet is on the bottom of the tank. Due to the prefill volume the foam will not be dispensed.
Sampling Zone - USP found this is reliable point due to flow patterns:
“Within the time interval specified, or at each of the times stated, withdraw a specimen from a zone midway between the surface of the Dissolution Medium and the top of the rotating basket or blade, not less than 1cm from the vessel wall “
The zone is clearly interpreted as a horizontal area in the vessel. This position will therefore be different for a 900ml test from a 500ml test.