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Accurate preparation of samples and standards is a fundamental starting point for any analysis, whether in analytical, quality control or testing labs. This is relevant to the pharmaceutical, chemical and food industries, to name but a few.
To prepare an accurate solution, a sample or standard must be accurately weighed on an appropriate balance for the application. Then, the precise amount of solvent must be added to make up to the required concentration.
The potential consequences of under-estimating the importance of this initial step or neglecting correct weighing protocols can be significant for the whole analysis. There is a danger that any errors or variability introduced during this first step will be carried downstream through the rest of the analytical process, leading to potential errors in the final results.
It may also mean:
- Having to repeat the work
- Sample waste
- Potential OOS investigations
However, many laboratories still rely on manual, flask-based, volumetric sample preparation, which is time-consuming and error-prone.
Sources of variability and uncertainty in the volumetric workflow include:
- Operator error
- Glassware failure
- Temperature
- Contaminants
- Data recording
What Does Gravimetric Sample Preparation Mean?
Preparing samples and standards gravimetrically leads to the concentration being expressed in mg/g, instead of mg/ml. Automated liquid dosing delivers precise concentrations every time, because solvent is added automatically based on the actual weight of solid weighed-in. This means that manual powder dosing can be approximate, and therefore much faster. Time wasted trying to precisely hit the exact target (by carefully scooping and adding powder a little at a time) can be avoided. Simply add the approximate amount of powder, but weigh it accurately, and the solvent can be added to achieve the precise desired concentration.
Download our guide and learn more about the potential sources of error during manual sample preparation, to find out why you should apply a gravimetric approach instead. We outline 10 reasons to say goodbye to inaccurate concentrations in your laboratory!
