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Medium Preparation: DosaPrep® X8

Technical Description

Precision Pondering Cell
A precise pondering cell assures the exact mixing ratio and the precise dispensing of the prepared medium. It works gravimetrically.

Standard Filtering
A 20 µm filter in the medium/water inlet assures retaining of particles. The filter may be exchanged easily. The instrument controls the total amount of medium/water, sets it into relation with the recommended maximum value, and suggests the replacement of the filter when this maximum value is reached.

Precise Mixing      
The instrument has two inlets: one for medium or water, and one for an additive like concentrated hydrochloric acid or buffer. The mixing ratio may be varied in a wide range.  
Alternatively ready prepared medium may be used.

Continuous Mixing

The medium is continuously mixed with a magnetic stirrer which is electronically driven and wear free. The stirrer itself is sealed and resistant against acid. This continuous mixing results in a homogeneous medium both in respect to temperature as well as in respect to the concentration.    

Precise Heating of the Medium

A specially made heater heats the medium to the desired temperature, which is continuously monitored and displayed. This helps the degassing process and saves valuable time, as the medium may be dispensed with the required temperature to the vessels. Note that the final setting of the temperature needs to be done in the dissolution station.

Effective Degassing

Effective degassing is being carried out by the following measures:

  • heating of medium;
  • vaccuum better than 200 mbar/hPa (absolute);
  • continuous mixing;
  • an additional degassing phase may be chosen at the end of the medium preparation in a wide range.  

Extra Wide Dispense Range

An extra wide range of dispensing allows to choose the appropriate dispense volume. Typically dispensing time is 30 s for 1000 ml.

Detailled Documentation
All important steps of the medium preparation are being docuemnted and can be either directly printed or sent to a PC via RS232.

Safety for Employees in the Laboratory
As the handling with concentrated acid is limited to the occasional replacement of the storage container for hydrochloric acid the safety for personnel is greatly improved.

Savings of Cost and Labour 
Rather than doing all the steps for the medium preparation manually the instrument prepares the medium with all required steps automatically. Press “Start”, and the instrument will perform all steps required to obtain the desired medium.
The medium may be then dispensed directly into the medium; no further steps are necessary. Therefore it is easy to perform a dissolution test while preparing new medium. This frees the personnel from the medium preparation work and allows for other activities. Anyhow the medium preparation for e.g. 8 l takes only approx. 15 min.