How do you choose a spike concentration?
Choose a spiking level. For routine QC or an unknown sample concentration, choose a mid-level spike. For a specific sample of known concentration, choose a spike level that will double the sample concentration. If the known sample concentration is very low, choose a mid-level spike.
What is an acceptable spike recovery?
R&D Systems recommends an acceptable recovery range of 80-120%. Control Spike should have a recovery value within 80-120%.
What is spiking sample?
A spiked sample is a sample prepared by adding a known quantity of analyte to a matrix which is close to or identical to that of the sample of interest. Spiked samples may be used in method validation experiments to help identify matrix effects and determine the recovery of an analyte or the selectivity of the method.
What does a 100% spike recovery mean?
A spike recovery value of >100% does not mean that you added too much or the recovery process is too good. All it means is that the analytical method which is being followed “in letter and spirit” gives a positive error. There may be a bias in the method or the precision of the method is poor.
Why do we spike samples?
Spike sample – A sample to which known concentrations of specific analytes have been added in such a manner as to minimize the change in the matrix of the original sample. Every spiked sample analyzed should have an associated reference to the spike solution and the volume added.
How can I improve my spike recovery?
Correcting for poor spike-and-recovery results
- Alter the standard diluent. Use a standard diluent whose composition more closely matches the final sample matrix.
- Alter the sample matrix. If neat biological samples had been used, retest it upon dilution in standard diluent or other logical “sample diluent”.
How is Spike recovery calculated?
For example, spiking a known 1,000 unit sample with 200 units would be: (1,200 – 1,000)/200 * 100% = 200/200 * 100% = 100% recovery.
What are the two methods of spiking?
Therefore procedures for spiking of powder were tested. Two methods of material preparation were tested – spiking a bulk sample of powder and individual spiking, where radioactive solution was introduced directly into containers in which samples were being measured.
Can recovery be greater than 100%?
How can Recovery results be over 100%? While performing recovery test with an extraction method of protein precipitation, the recovery results for all QC levels are always above 100% , the area’s of Bio-analytical samples are higher than the aqueous samples .
Why is it called a spike?
The term comes from the meaning of the object — a spike allows you to go deep on a problem. A common analogy used is rock climbing. When you cannot go any further, you drive a spike in the rock.
How do you calculate spike recovery rate?
What is Spike value endotoxin?
Spike recovery: The spike is an aliquot of test sample together with a known amount of endotoxin. The spike serves as the check for interference (inhibition and enhancement). Inhibition and enhancement are conditions that adversely alter the recovery of endotoxin in a test sample.