Chemical composition of felt-tip pen inks

Felt-tip pens are frequently used for the realization of sketches, drawings, architectural projects, and other technical designs. The formulations of these inks are usually rather complex and may be associated to those of modern paint materials where, next to the binding medium and pigments/dyes, solvents, fillers, emulsifiers, antioxidants, plasticizers, light stabilizers, biocides, and so on are commonly added. Felt-tip pen inks are extremely sensitive to degradation and especially exposure to light may cause chromatic changes and fading. In this study, we report on the complete chemical characterization of modern felt-tip pen inks that are commercially available and commonly used for the realization of artworks. Three brands of felt-tip pens (Faber-Castell, Edding, and Stabilo) were investigated with complementary analytical techniques such as thin-layer chromatography (TLC), VIS-reflectance spectroscopy, micro-Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS), pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), GC-MS, and Fourier transform infrared (FTIR) spectroscopy. The use of TLC proved to be very powerful in the study of complex mixtures of synthetic dyes. First derivatives of the reflectance spectra acquired on the TLC spots were useful in the preliminary identification of the dye, followed by Raman spectroscopy and SERS, which allowed for the unambiguous determination of the chemical composition of the pigments (phthalocyanines, dioxazines, and azo pigments) and dyes (azo dyes, triarylmethanes, xanthenes). FTIR spectroscopy was used especially for the detection of additives, as well as for confirming the nature of solvents and dyes/pigments. Finally, (Py-)GC-MS data provided information on the binders (styrene-acrylic resins, plant gums), solvents, and additives, as well as on pigments and dyes

Carbon based materials for electronic bio-sensing

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The detection of drugs of abuse in biological matrices using enzyme-linked immunosorbent assay and liquid chromatography-tandem mass spectrometry

The aim of this study was to investigate the potential use of ELISA and LC-MS-MS in combination and as individual techniques, for the detection of drugs of abuse in biological matrices. Overall the LC-MS-MS method showed good correlation results for opiates compared to the GC-MS method. 6-MAM was however detected in more root segments and segments excluding roots by LC-MS-MS. Morphine was detected in a greater number of root segments by LC-MS-MS compared to GC-MS. However, morphine was detected in a greater number of segments excluding roots by GC-MS. Codeine and dihydrocodeine were also detected in a greater number of root segments and segments excluding roots by GC-MS. The cocaine results showed excellent qualitative correlation between the LC-MS-MS and GC-MS methods for cocaine and benzoylecgonine. The GC-MS method did not however extract greater concentrations of cocaine and its metabolites compared to LC-MS-MS due to the higher recovery of the drug group specific GC-MS method. Cocaethylene and EME were detected in some samples by LC-MS-MS method for opiates and cocaine and its metabolites compared to the GC-MS method; there may be some cases where the GC-MS method would detect the analytes where the LC-MS-MS method would not. This has been demonstrated in 3 samples for morphine and in 6 samples for codeine. The LC-MS-MS method analysed for and detected amphetamines in samples that were not tested for amphetamines by GC-MS. In one sample that was tested by both methods, amphetamine was detected in the root sample by LC-MS-MS where GC-MS failed to detect it. Also a greater concentration of amphetamine was extracted using the LC-MS-MS method in the segment without roots. The LC-MS-MS method was useful for the analysis of 17 drugs of abuse in post-mortem hair samples in forensic toxicology cases. Using this method, it is possible to obtain maximum information from one hair sample which is extremely useful when the sample weight is limited. The ability of the LC-MS-MS method to extract and analyse a greater number of drug groups from one hair sample highlights the advantages of using this method over GC-MS which targets individual drug groups and requires splitting of the sample. This method is particularly applicable for implementation in the forensic toxicology laboratory at the University of Glasgow where currently GC-MS methods that target individual drug groups are used for routine hair screening and confirmation.EThOS - Electronic Theses Online ServiceGBUnited Kingdo