As the use and applications of carbon black (CB) nanoparticles continue to rise so will the need to detect these materials in the environment, especially in water systems. Investigation into the metal impurities contained within these materials will be key in establishing new methods of detection for CB nanoparticles and other graphitic materials. The analysis of eighteen different metal impurities was conducted on six commercial varieties of CB materials. These individual collections of metal impurities, or fingerprints, were utilized for establishing possible tracers for the detection of CB in water by single particle inductively coupled mass spectrometry (spICP-MS). Of the metals identified in carbon black particles, a rare earth element (REE) impurity was chosen as tracer for spICP-MS based on the apparent concentration, low detection limits, and a lack of polyatomic interferences in mass spectrometry. For the spICP-MS detection the adhesive nature of the CB particles was a major limiting factor, therefore the use of a nonionic surfactant was vital in reducing adhesion to the introduction system while increasing dispersion of the CB particles in water. Following optimization studies for the analysis a limit of detection of 15.2 µg/L and quantification limit of 122.2 µg/L of CB exemplified the sensitivity of the current detection method. In addition, the particle sizing capability of the instrument allowed for discriminating signals from possible interfering particles in environmental samples, while natural levels of the same dissolved REE did not affect the sensitivity of this detection method. In comparison to existing technologies this method of detection has achieved competitive sensitivity, a wide dynamic working range for quantification, and ability to manage possible environmental interferences.

Targeting metal impurities for the detection of carbon black particles in water

ACS Spring 2022

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