Calculation Method
Analytical technique used to improve the accuracy of chemical measurements involves removing the background signal detected in a control sample from the total signal of the test sample. In the testing of paper packaging, procedural blank subtraction ensures that any contaminants introduced by solvents, glassware or the laboratory environment are not wrongly attributed to the board. This step is mandatory in trace analysis where the concentrations of interest are near the detection limit.
It provides a more honest representation of the material’s purity.
Background Noise
Solvents used for extraction often contain minute amounts of hydrocarbons that can interfere with the results. By running a blank through the entire process, the chemist identifies this external contribution.
Accuracy Protocol
Quantification of mineral oils in recycled board relies on this subtraction to avoid over-reporting the contaminant levels. If the blank value is high, it indicates a contamination problem in the laboratory that must be resolved before proceeding. Standard methods specify that the blank value should not exceed a certain percentage of the target limit.
Proper documentation of this subtraction is required for compliance reports. It allows for the comparison of results between different labs by normalizing the background interference. Careful execution of this step is vital for the legal defense of a product’s safety.
Technicians must treat the blank exactly like the sample to ensure the correction is valid.
