Connection of Balances

Almost for every measurement that is performed by HPLC or GC systems, sample weightings need to be performed in advance. No matter if a sample weighting or if a solution for a reference solution is prepared, always measuring values from a balance are involved. 

For a laboratory with a paperless workflow, these values are kept in the Laboratory Information and Management System (LIMS) and will be transferred to the CDS. Without this cross-hnking, the manual input of weightings into the CDS would signify an enormous effort and the risk of transcription errors would exist. To avoid this, two approaches for the transfer of balance data to the CDS are thinkable  

First instrument driver of a balance could be connected directly to the CDS and transfer the values through this interface, for example, into the sample table of a CDS. However, although this seems to be a simple solution, there is a little pitfall standard solutions are often prepared for the use of a defined period. The measuring value of a standard that was prepared on a Monday still needs to be available on a Tuesday. Does the expiry end after 3 days, this value must not be used on Friday. An administration of standard values, therefore, needs to be provided. Where solutions are available for later measurements until their expiry date. 

If a weighting consists of several steps, the measuring value from the balance is not the value that should be used in the CDS. For example, 12 mg of substance A are weighed and 15 mg of substance B are added, the actual balance displays a value of 27 mg. Before transferring the values to the CDS, a difference between weighing A and weighing B needs to be calculated. 

For this reason, a direct interface between the balance and the CDS is only productive for easy processes. The second solution should, therefore, be preferred  

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