What are 3 possible reasons why a percentage recovery might be low? And what are 3 possible reasons why a percentage recovery might be well over 100%?
You can't possibly answer this without knowing what procedure is under discussion.
Three possible reasons why a percentage recovery might be low are:
1. Incomplete extraction: If the process of extracting a substance from a sample is not efficient, a low percentage recovery could occur. This can happen if the extraction conditions are not optimal, such as using insufficient solvent or inadequate mixing. Incomplete extraction means that not all of the desired substance was successfully separated from the sample.
2. Loss during purification: Another reason for low recovery could be the loss of the substance during the purification process. For example, if the substance is volatile and easily evaporates, it may be lost during heating or evaporation steps. Similarly, if the substance is adsorbed onto filter paper or absorbs onto glassware, it may be difficult to recover it completely.
3. Sample contamination: Low recovery may also be due to contamination of the sample with impurities. Contaminants can interfere with the separation process, causing loss or incomplete recovery of the desired substance. This can happen if the sample is not properly handled, stored, or protected from external contaminants.
On the other hand, it is not possible for a percentage recovery to be well over 100% in a typical recovery calculation. A recovery percentage greater than 100% would imply that more of the desired substance was recovered than was actually present in the original sample. Such a result would indicate an error or inaccuracy in the analysis or measurement process. Potential reasons for a recovery percentage falsely exceeding 100% could include:
1. Calculation error: The recovery calculation involves comparing the amount of substance recovered to the initial amount present in the sample. If there is a mistake in the calculations, such as incorrect units or decimal point placement, it could lead to an erroneously high recovery value.
2. Experimental error: Any errors in measurement, sample preparation, or analysis techniques can contribute to inaccuracies in the recovery calculation. For example, inaccurate weighing of the sample or a miscalibrated instrument could result in an overestimation of the recovery.
3. Contamination: If the recovered substance is contaminated with additional material during the process, it could contribute to an inflated recovery percentage. The contamination may arise from external sources or originate from reagents and equipment used in the analysis. It is important to ensure proper controls and precautions to minimize contamination effects and obtain accurate results.
In summary, low recovery percentages can be attributed to incomplete extraction, loss during purification, or sample contamination. However, recovery percentages well over 100% are generally not possible and may indicate errors or inaccuracies in the analysis process.