Small variations with ZrO2 on a graphite surface improve the retention and subsequence detection of fluorinated contaminants at trace levels
Source: BAM Divisions Surface Analysis and Interfacial Chemistry, Inorganic Trace Analysis, Inorganic Reference Materials, Structure Analysis
Maybe you know fluorine as a beneficial element for caries prevention: it can be found in toothpaste and even some countries fluoridate their tap water. However, excessive fluorine ingestion produces a disease, called fluorosis. This disease is characterized by hypermineralization of tooth enamel and bones, and consequently, they become fragile. Dental prophylactics is not the only anthropogenic fluorine source. Fluorine substituents have been introduced in many functional polymers and pharmaceutical products in order to enhance their chemical stability, resistance, and solubility. Unfortunately, many of these products are toxic and can pollute the environment.
For health authorities, pharmaceutical companies, and public, fluorine quantification is a need. However, fluorine analysis is not that simple. Fluorine is a unique element due to its extremely high electronegativity and reactivity. Therefore, it is almost invisible for most traditional analytical methods. However, there is a chemical trick: the reaction of fluorine with specific elements to produce a small molecule that we can see and measure.
This research deals with the trace analysis of fluorine and how to improve a current analytical method, called High-Resolution Continuum-Source Molecular Absorption Spectrometry (HR-CS-MAS). In recent investigations, calcium was added to a sample containing fluorine and heated at temperatures higher than 2300 °C inside a graphite furnace. Thus, for a few seconds, a transient diatomic molecule CaF is generated and measured. Contrary to fluorine, the CaF molecule can be detected photometrically. Therefore, the concentration of fluorine can be indirectly determined by quantifying the CaF signal. However, how can we improve this method? It is necessary to understand the chemical reaction between all the components in order to enhance the CaF signal. As results, we finally understood the mechanism in how the CaF molecule is formed. In this case, the reaction occurred on the graphite furnace. By introducing small variations and fine tuning the surface with solid catalysts, the indirect determination of fluoride was drastically improved. With this knowledge, we could develop a robust and sensitive method for the trace analysis of fluorine.
Zirconium permanent modifiers for graphite furnaces used in absorption spectrometry: understanding their structure and mechanism of action
Carlos Abad, Stefan Florek, Helmut Becker-Ross, Mao-Dong Huang, Ana Guilherme Buzanich, Martin Radtke, Andreas Lippitz, Vasile-Dan Hodoroaba, Thomas Schmid, Hans-Joachim Heinrich, Sebastian Recknagel, Norbert Jakubowski and Ulrich Panne
JAAS, Journal of Analytical Atomic Spectometry, 2019, Volume 33, No. 12, 2018, pages 2023-2220
BAM Fachbereiche Oberflächenanalytik und Grenzflächenchemie, Anorganische Spurenanalytik, Anorganische Referenzmaterialien, Strukturanalytik