Recovery test is a kind of “control test”. When the components of the analyzed sample are complex and not completely clear, a known amount of the measured component is added to the sample, and then measured to check whether the added component can be quantitatively recovered to determine whether there is a systematic error in the analysis process. The results obtained are often expressed as a percentage, called “percent recovery”, or “recovery” for short. The spiked recovery test is a common experimental method in chemical analysis, and is also an important quality control tool. The recovery is a quantitative indicator to determine the accuracy of the analytical results.
Spiked recovery is the ratio of the content (measured value) to the added value when a standard with known content (measured component) is added to a blank sample or some background with known content and detected by the established method.
Spiked recovery = (spiked specimen measured value – specimen measured value) ÷ spiked amount × 100%
If the added value is 100, the measured value is 85, the result is the recovery rate of 85%, known as spiked recovery.
Recoveries include absolute recoveries and relative recoveries. Absolute recovery examines the percentage of the sample that can be used for analysis after processing. This is because there is some loss of sample after processing. As an analytical method, the absolute recovery is generally required to be greater than 50% to be acceptable. It is the ratio of the measured substance added quantitatively to the blank matrix, after treatment, to the standard. The standard is directly diluted, not the same product as the same treatment. If the same, just do not add the matrix to deal with, there may be a lot of influencing factors shielded by this, and therefore lost the original purpose of the examination of the absolute recovery.
There are two types of relative recoveries strictly speaking. One is the recovery test method and the other is the spiked sample recovery test method. The former is to add the measured substance in the blank matrix, the standard curve is also the same, this kind of determination is used more, but there is a suspicion that the standard curve is repeatedly determined. The second one is to add the measured substance in the sample of known concentration to compare with the standard curve, which is also added in the matrix. The relative recoveries are mainly examined for accuracy.
Post time: Jun-02-2022