The Essentials of Recycling Rates

What is Spiking Recovery?

Spiking recovery refers to the addition of a known quantity of a standard substance into the sample matrix of the substance under analysis. Following identical sample processing steps, the obtained result is then compared to the theoretical value.

In experiments, the magnitude of spiking recovery not only signifies the quality of the test results but also reflects the technical proficiency of the operator. Furthermore, it assesses whether the analytical method is suitable for the tested matrix. Spiking recovery assists analysts in identifying potential issues during the analytical process, ensuring data accuracy and reliability.

There are two types of spiking recovery: blank spiking recovery and sample spiking recovery.

Blank Spiking Recovery:

Blank spiking recovery involves the addition of a known quantity of a standard substance into a matrix that does not contain the sample. The sample is then processed and analyzed following the same procedure. The ratio of the obtained result to the theoretical value is referred to as the blank spiking recovery.

Sample Spiking Recovery:

Sample spiking recovery typically involves taking two identical samples. One of these samples is selected, and a known quantity of the target analyte’s standard substance is added to it. Both samples are then processed and analyzed using the same procedure. The ratio of the difference between the result of the spiked sample and the result of the unspiked sample to the theoretical value of the added standard substance is referred to as the sample spiking recovery.

After understanding spiking recovery, let’s delve into the factors that can affect spiking recovery:

Sample Background

Spiking recovery is recommended to be performed using blank or negative control samples. If the sample contains a background matrix, it is essential to subtract or correct for this background before calculations. Failing to account for sample background can lead to artificially inflated recovery rates above theoretical values.
Analytical Methods and Experimental Conditions

The limitations of the analytical method can result in lower recovery rates, and variations in experimental conditions can also impact spiking recovery.

Impact of Spiking Amount

1. Excessive or insufficient spiking amounts may not ensure that the target substance in the sample and spiked sample falls within the same precision range.
2. When the standard substance is an organic solvent, excessive spiking amounts can lead to solvent effects, making it challenging to dissolve in water, potentially affecting spiking recovery due to solubility issues.
3. If the sample background content is low and the spiking amount is too low, it can result in poor recovery rates. Conversely, adding a high concentration of the standard substance may alter the determination background of the target substance in both the spiked sample and the sample.
4. When the sample background content is high, adding a high concentration of the standard substance may approach or even exceed the detection limit of the analytical method, leading to significant measurement errors.

Spiking Recovery Test Full Process Example:

• Blank

• Sample Background Solution

• 10 ng/mL Matrix Calibration Curve

• Spiking of the Sample with 10 ng/mL

After sample pre-processing and subsequent analysis on the instrument, the experimental data yielded a recovery rate within the range of 90% to 110%, meeting the national standard requirements.