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- 2015 (2) (entfernen)
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Hydrophilic interaction chromatography (HILIC) coupled with inductively coupled plasma mass spectrometry (ICP-MS) were optimised for the direct determination of gadolinium-based contrast agents in tap water. In comparison to our previous work, a new developed zwitterionic HILIC column (ZIC-cHILIC) was used for speciation of Gd-containing contrast agents. The limit of quantification (LOQ) for the five contrast agents Gd-BOPTA, Gd-DPTA-BMA, Gd-BT-DO3A, Gd-DOTA and Gd-DTPA are in the range of 512 ng Gd per litre. Additionally, a new internal standard, Pr-DOTA, was investigated to correct intensity drifts, minor and major changes in the sample volumes and possible matrix effects. With the speciation method described, tap water samples from the area of Berlin were analysed and for the first time, three Gd species, Gd-BT-DO3A, Gd-DOTA and Gd-BOPTA, were found in tap water samples at concentrations of about 10–20 ng Gd per litre. These are the same Gd species which have been previously detected predominantly in surface waters of the Berlin area.
In this work the determination of Cd, Cu, Cr, Fe and Sb as organic and inorganic additives in in-house plastic materials (ABS, LDPE) using electrothermal vaporization combined with inductively coupled plasma optical emission spectroscopy is described. The influence of CCl2F2 as gaseous halogenation modifier was investigated. Especially for the carbide forming elements the sensitivity was improved and the memory effects were significantly reduced. Calibration was performed by external calibration and standard addition with aqueous standard solutions added directly into the sample boats. Absolute limits of detection (3s-criterion) range between 0.1 ng (Cd) and 9 ng (Fe) which corresponds to relative values of 0.1 mg kg-1 and 1.6 mg kg-1, respectively, taking 5 mg as typical sample mass. The detection limits are sufficient to monitor the element contents of plastic materials according to European directives such as European directive on the safety of toys. The developed ETV-ICP-OES method allows a fast analysis with a high sample throughput (3 minutes per analysis), low sample consumption and good trueness and precision for the analyzed elements. Sample preparation is reduced to ashing the samples in a muffle furnace. Furthermore, measurements are possible regardless of the chemical form in the additives. For verification the results obtained with the developed method were compared with measurement results of independent methods ICP-MS/OES after digestion. In addition Cd, Cr and Pb were determined in a solid plastic reference material BAM-H010 to confirm the applicability and accuracy of the method.