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Monitoring of Iodine- and Gadolinium-Containing Contrast Media in Aqueous Matrices
Combustion Ion Chromatography – Straightforward Determination of Halogens and Sulphur in Solid and Liquid Samples
The cooperation between Metrohm and Mitsubishi opens up new possibilities in analysis. Solids and highly viscous samples can now be analysed fully automatically, whereas in the past, e.g. with the oxygen bomb, a good deal of manual work was required. The advantages of Combustion IC include the fully automated simultaneous determination of halogens and sulphur. Combustion IC works very precisely and with optimised timing, allowing a high sample throughput. In a fully automated process the samples are thermally digested under argon in the furnace unit and then com-busted with oxygen. The resulting gaseous compounds are passed into an absorption solution, which is then transferred inline to a Metrohm ion chromatography system.
With the help of the appropriate autosampler it is possible to save time when measuring both liquid and solid samples: at the same time as a chromatogram is being recorded, the next sample is already being digested. Among other possible fields, Combustion IC can be highly useful in quality control of raw materials, intermediates and finished products. In the environmental field Combustion IC can be used to monitor compliance with standards such as ASTM D 7359-08, DIN EN 228, IEC 60502-1, RoHS, WEEE and others.
Circle no. 47
Metrohm is pleased to present a method for the rapid, reliable, and sensitive analysis of free and complexed gadolinium and iodine-containing compounds in aqueous matrices by ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP/MS). The method proceeds without costly sample preparation and provides substantial information on the entry, degradation, and fate of contrast agents in (waste)water.
Biologically inert iodinated X-ray contrast media (ICM) and gadolinium chelates are used as contrast agents in diagnostic radiology. These contrast media are applied extensively and are excreted in unmetabolised form via urine into wastewater. ICMs are suspected to be nondegradable in most conventional water treatment plants and ultimately accumulate in drinking water. As their effects on the environment are still unknown, they are removed by water treatment technologies using either ozonation or floculation.
Ozonation gives origin to a range of unidentified iodine- containing ozonation by-products (OBPs) of unknown toxicity. Similarly, the addition of competitive Fe3+
ions in
the flocculation step enhances the displacement of gadolinium from its chelate complexes, which gives origin to highly toxic Gd3+
ions.
In laboratory studies, the effects of ozonation and flocculation were evaluated, respectively, for iodine- containing (e.g., Iomeprol, Amidotrizoic Acid) and gadolinium-containing (e.g., Gadovist® contrast media.
, Magnevist® Circle no. 48
Ion Chromatography and Voltammetry to Determine Chromium(VI)
High levels of toxic chromium(VI) in environmental samples have recently stirred up public attention in the US to focus on the impact of industrial pollution on humans and the environment. With ion chromatography and voltammetry, Metrohm provides state-of-the-art analytical techniques as well as the required instrumentation to help authorities to get a better picture of the hazards to public health.
With ion chromatography, chromium(VI) is detected with high sensitivity as a violet chromium-diphenylcarbazone complex at 540 nm after separation on a polyalcohol anion-exchange column and subsequent post-column derivatisation with 1,5-diphenylcarbazide. When using a 1000 µL sample loop, the chromate detection limit determined in compliance with DIN 32654 is less than 10 ng/L. For the fully automated determination of chromium(VI) Metrohm recommends the combination of a Professional IC with the 887 Professional UV/VIS Detector and the 886 Professional Reactor.
Alternatively, chromium(VI) can be determined by voltammetry on the 797 VA Computrace. Unlike spectroscopic methods, voltammetry is able to distinguish between different oxidation states of metal ions (speciation) as well as between free and bound metal ions. This provides important information regarding the bioavailability and toxicity of heavy metals. When analysing drinking or ground water samples, voltammetry enables direct determination of the target analytes without prior sample preparation. If organic compounds are present in the sample they are reliably removed by UV photolysis within 60 minutes using the 705 UV Digester.
Circle no. 49 ) Precision – It’s all about the right people
«By titration alone we determine 10.000 different chemicals. 75% of those applications are covered by our Metrohm ProcessLab in the minimum of space.»
Dr. H. George, Sigma-Aldrich
10.000 different chemicals are determined by titration alone by Sigma-Aldrich in their laboratories in Steinheim, Germany. 75% of those applications are done on a Metrohm ProcessLab. This system was designed by the specialists of Deutsche Metrohm Prozessanalytik to exactly meet the requirements of Dr. George and his team. Just to mention it, Metrohm’s ap- plication chemists share their know-how with Sigma-Aldrich and any other cus- tomer – for free.
Metrohm. People you can trust.
testimonials.metrohm.com
Circle no. 50
INTERNATIONAL LABMATE - AUGUST/SEPTEMBER 2011 - ADVERTORIAL
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