Matrix Interference
An electrochemical or spectroscopic disruption arises when high concentrations of negative ions compete with the target analyte during measurement. In the context of textile testing for perfluorinated substances, fluoride ion interference can suppress the signal of carboxylic acids or sulfonates. This specific problem occurs most frequently when fabric samples have been treated with high levels of inorganic salts or when the extraction solvent contains hydrofluoric acid residues.
Signal Suppression
Charged particles in the ion source reduce the efficiency with which the mass spectrometer captures the target molecules. Because fluoride ions are highly electronegative, they dominate the ionization process and prevent the formation of the required ions for the substances being measured. Laboratories often observe a drop in the recovery rate of internal standards when this interference is present.
Mitigation Step
Sample dilution or solid phase extraction removes the excess salts before the extract reaches the detector. These steps lengthen the preparation time but ensure the accuracy of the final concentration reading.
Quantitative Accuracy
Failure to account for this suppression leads to underreporting the true level of hazardous chemicals in a garment. Regular use of matrix matched calibration curves helps the laboratory quantify the extent of the suppression. The presence of these ions is a common barrier to achieving the low detection limits required by modern green chemistry standards.
