Agilent Technologies has produced an application note describing the direct analysis of selected iodinated contrast media (ICMs) in water samples at low ng/L (ppt) levels. Direct injection of water samples without any pretreatment except filtration was applied.
ICMs are globally used for medical X-ray imaging. Significant levels can be found in various aqueous matrices (hospital wastewater, surface water, ground water, and even drinking water), and soil.
In this application, direct injection of water samples without any pretreatment except filtration was applied. Relatively large volumes need to be injected, requiring adequate control of the separation conditions. State-of-the-art mass spectrometry offers high sensitivity, allowing direct analysis of trace contaminants in water. This reduces time and cost per analysis, and minimizes errors that can be made during sample pretreatment.
An Agilent 1290 Infinity II LC and an Agilent 6495 Triple Quadrupole MS with an Agilent Jet Stream technology source were used.
Results and Discussion
The selected ICMs are highly polar, and the analytical conditions had to be carefully chosen to obtain adequate retention, acceptable peak shape, and good efficiency. Moreover, care had to be taken so that the sensitivity of the mass spectrometer was not affected by the choice of the mobile phase. All LC parameters were carefully optimized, and reversed-phase LC with a mobile phase of acetic acid in water and acetonitrile proved to give the best overall results in terms of chromatography and detection.
Direct injection of water samples was carried out for the analysis of low ng/L (ppt) levels of iodinated contract media. The Agilent 1290 Infinity II Multisampler equipped with a 100 μL loop and analytical head allowed efficient loading of 100 μL of sample with no detectable carryover. High sensitivity was achieved by using the Agilent 6495 Triple Quadrupole MS with Agilent Jet Stream Technology.