Recovery Spiked Sample

What is spiking ?

Matrix spiking is a technique used in analytical chemistry to
evaluate the performance of an analytical method for a specific
sample type (matrix). It helps ensure that the method produces
accurate and valid results for that particular sample method.

Matrix spike

A matrix spike is when a known amount of an analyte
(analytical standard) is added to a sample. This will increase the
concentration by a known amount. By testing the spiked
sample you will be able to determine if the added analyte is
recovered. Prepare six matrix spiked samples for good
recovery and reliable results.

Spike solution (analytical standard)

The spike solution is the solution that is chosen for preparing a
matrix spike. The concentration of this solution is determined
by the linearity and detection limit. Depending on the method
the spike solution should always be within the linearity
concentration range. This concentration is chosen to ensure
that the spike solution does not change the sample volume.
This makes calculating easier and avoids unknown effects from
happening.

In this example the spike solution is slightly more concentrated
than the lowest linearity standard, the linearity standards were
prepared between 0.0003 and 0.005 µg/mL. The spike solution
was chosen as 0.0005 µg/mL.

Sample Preparation

The following sample preparation was used in PCB with MS
app note;

Tap water samples were prepared in triplicate by an extraction
of 50 mL tap water with 10 mL iso-octane containing 0.003
μg/mL IS. The solution was stirred for 15 minutes with a
magnetic stirrer, two layers appeared. The top (organic) layer
was transferred into a sample container then concentrated
under N2-gas to approximately 1 mL. The extract was
transferred into an injection vial ready for analysis.

To determine the recovery, six water samples were prepared
as the water sample above and spiked with 0.0005 μg/mL PCB
standard prior to extraction. These spiked samples were used
to determine the LOQ in accordance with the method.
Blank injections of iso-octane were performed in between
samples, to ensure that the system was not contaminated
after sample injections.

Calculation

Conclusion

Compare the recovery results with the applicable validated
method requirements. When the recovery results are good
and within specification, it means that you have good
method efficiency and reliability

Download Technical Note – Recovery spiked sample v1