Development of efficient digestion procedures for quantitative determination of cobalt and molybdenum catalyst residues in carbon nanotubes

Abstract

The authors are grateful to the work of Johana Pathenay from Chemistry Universitary Institute of Technology of Villeurbanne for her active participation in the method validation. Also we want to thank Evelyne Sambardier and Gernod Hudin from Anton Paar for their collaboration for MIC tests and for having provided the carbon nanotubes sample free from Co and MoInternational audienceWhatever the method used for the synthesis of carbon nanotubes (CNTs), they always contain residual catalysts in variable amount. Many methods have been proposed in the literature to purify CNTs, but their efficiency strongly depends on the experimental conditions. Although the presence of residual catalysts in small amount is generally not a problem for many applications, this can become a critical issue when a high purity is required, typically for magnetic properties or for biomedical applications (because of the intrinsic toxicity of most catalysts). Quantification of the amount of residual catalysts is usually obtained by classical chemical analysis, which requires a preliminary digestion (complete mineralisation) of the CNT samples. In this work, we systematically compared 3 different digestion protocols and optimised one, reaching 100% dissolution within a very limited time (1 h) together with the requirement of only a few milligrams of sample, and safe experimental conditions. This method can be easily transferred for use in research laboratories, making accessible the quantitative analysis of CNT samples, and has been validated following ISO/IEC 17025:2005 for linearity, specificity, intermediate precision, limits of detection and quantification

Thermal Reduction of Graphene Oxide Mitigates Its In Vivo Genotoxicity Toward Xenopus laevis Tadpoles

“…The possible presence of these compounds was checked to avoid misanalysis of toxicity-related results [44]. Quantification of metal residues in mineralized GO powder was performed as described by Ayouni-Derouiche et al [45] using ICP AES, iCAPTM 6300 analyzer (Thermo Fisher Scientific, Germany) (Crealins, Lyon, France). 32 PAHs compounds were analysed from GO dispersion in deionized water using gas chromatography-mass spectrometry (GC-MS) according to the normalized procedure NF ISO 28,540 (MicroPolluants Technologie S.A., Saint-Julien-lès-Metz, France).…”

Validation of alkaline oxidation as a pre-treatment method for elemental quantification in single-walled carbon nanotubes

“…7,8 Even though ''puried'' CNTs are available commercially, it is sometimes challenging to nd trustworthy information regarding the content of metals and/or the lot-to-lot compositional homogeneity. [9][10][11][12] While this may not constitute a critical issue in applications such as mechanical reinforcement of polymers, in other cases such as electrocatalysis, it can lead to erroneous data interpretation. 13 Historically, two of the most reliable routine tools to quantify metal elements in CNTs are optical emission spectroscopy (OES) and mass spectrometry (MS).…”

An evaluation of microwave-assisted fusion and microwave-assisted acid digestion methods for determining elemental impurities in carbon nanostructures using inductively coupled plasma optical emission spectrometry

“…Therefore, there has been much effort lately in developing metrology and standardization methods for carbon nanostructure analysis in order to implement accurate quality control checks. These are of the utmost relevance for research-grade samples just as for industrially-produced batches [17][18][19][20][21][22][23]. Unfortunately, there is a growing crisis in the field owing to the lack of affordable and sufficiently sensitive and selective analytical methods [9][10][11][12][13][14][15].…”

“…The key issue in these two techniques is the solid sample pretreatment method as it is necessary to fully dissolve the sample (including any trace impurity) and obtain a transparent homogeneous aqueous solution. The challenge concerning the determination of trace impurities in CNTs and graphene is precisely the sample preparation step for plasma based techniques since these materials are extremely difficult to bring into solution [17][18][19][20].…”