Dilution appears to be a simple laboratory operation but it is highly critical for accuracy of your results. From your school days you have been carrying out dilutions in the chemistry laboratory using a graduated cylinder or a pipette.As you moved on to the university you would have been exposed to use of micro- pipettes for precise volume deliveries.
Mostly dilutions are necessary for laboratory operations such as:
- Dilutions of stock solutions
- Preparation of reference standard solutions over a range of concentrations
- Preparation of reagents and titrants
- Dilutions of concentrated sample solutions to bring the concentration levels within the observable range of the instrument
Dilutions form the basis for quantitative estimations. Dilutions errors lead to errors in final results as such errors are multiplicative in sequential dilutions. Subsequent stage dilution errors also contribute in the same manner in serial dilutions. This explains why it is necessary to carry out dilutions as accurately as possible.
With experience you acquire sufficient skills to accurately measure and transfer volumes by manual techniques but even then there is scope for personal errors. Apart from such errors there is always a risk of contamination from earlier dilutions.
The highlighted problems are reduced to a great extent by use of micropipettes for dilutions. For better precision and accuracy micropipettes are available for delivery of a range of volumes ranging from sub – μl to ml volumes. However, even dilutions using micropipettes require adherence to recommend handling practices to avoid errors.
Looking forward automated dilutions systems overcome most of the drawbacks of manual dilutions and give you sufficient time to engage in other laboratory activities. The dilution volume, wash cycles and sequence can be programmed at the start and the process continues unattended. Automated dilution systems are capable of delivering highest levels of accuracy and freedom from contamination. Your role is limited to ensuring that the receiving vials or volumetric vessels are sufficiently clean.
To summarise the benefits of automated dilutions are:
- Saving of time in comparison to time consuming manual dilutions
- Elimination of personal errors
- Reduction of errors due to use of not properly cleaned glassware.
Information on some renowned suppliers of automated dilutions systems are provided in the links below:
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