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Home > Technical Articles > Sampling
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Home > Technical Articles > Sampling
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| Recently we read an excellent article entitled "Correct Sampling" by Robert S. Green, president of Integrated Biomolecule Corp., published in the Natural Products Industry Insider (6/28/99), p 18. Some of the points made in that article are that (1) for the test results to be representative of the batch, the sample must also be representative, (2) samples can be affected by storage conditions, and (3) USP states that samples should be taken from the upper, middle, and lower sections of the container. We thought we might add our own $0.02. | One common problem is sampling for moisture content, particularly with materials that are hygroscopic (adsorb moisture). If the material is stored refrigerated, you should let the container warm to room temperature before sampling. A cold, dry powder will adsorb moisture very fast. The container must be tightly sealed to prevent exposure to atmospheric moisture. Solvents such as anhydrous methanol and DMSO and hygroscopic materials may need to sampled in a dry box. If this is not possible, you might want to consider sending the sample to us in an unopened, original bottle. |
Another problem we often see is insufficient sample for compendial testing (USP, etc.). While most tests can be modified to work with smaller amounts and you may not have to follow the method exactly if you are only "QC-ing" raw materials, you should definitely follow the compendial method exactly for finished products. Deviations can only lead to problems. For the lab to have sufficient sample for there own QC (duplicates and spikes), a good rule of thumb is to double the amount specified in the monograph.
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