arium® pro UV Ultrapure Water for ICP-MS

arium® pro UV Ultrapure Water for ICP-MS

Introduction

Inductively coupled plasma mass spectrometry (ICP-MS) is a highly sophisticated multi-element analytical technique that is increasingly being used for trace analysis in the pharmaceutical, food and beverage and environmental industries as well as in analytical laboratories. The ICP-MS technique is capable of analysis down to sub-ppt (parts per trillion) detection limits, whereby the lowest detection limits can be achieved only in a clean room environment.

Because water is used early in tests for trace elemental analysis with ICP-MS, it is obvious that any contamination from the water can compromise an entire analysis. Therefore, the water used must be of a high analytical grade quality, e.g., ASTM Type I water. The objective of the analytical test series described below is to ensure that the ultrapure water generated by the arium® pro UV water systems has a high purity level (in this case free of metal elements respectively metal elements not detectable) and can be used without any problems for trace analysis of elements performed with ICP-MS devices.

Principle of ICP-MS Technology

ICP technology was built on the principles of atomic emission spectroscopy. Samples are decomposed into positive charged ions based on their mass-to-charge ratio in a high temperature argon plasma followed by a passage through a mass spectrometer for detection. In principle, ICP-MS consists of the following steps: sample preparation and introduction, aerosol generation, ionization by an argon plasma source, mass discrimination, and identification by the detection system, including data analysis (according to Worley and Kvech , (1))

Description of the arium® pro UV Ultrapure Water System

Fig. 1 Photograph of the arium® pro UV pure water system (photo Sartorius)

The arium® pro UV system (Figures 1 and 2) is designed to produce ultrapure water from pre-treated water sources by removing trace levels of residual contaminants. For general water purification, various technologies (distillation, reverse osmosis, deionization and electrodeionization) are used. The production of ultrapure water with arium requires continuous recirculation and constant flow. This is carried out by a pump system with pressure regulation. The conductivity of the water is measured at the water feed inlet and the water outlet (downstream product). The total organic carbon content (TOC) is measured by a special TOC analyzer.

The actual purification process depends on the arium® type and technology used. The arium® pro UV system works with two different cartridge kits. These cartridges are filled with a special active carbon adsorber and a special mixed bed exchange resin designed to deliver high-purity water with low extractables. In the arium® pro UV system, a UV lamp, which operates at 185 and 254 nm is used as germicidal and oxidizing agent. A final microfilter at the outlet is normally installed to remove any particles or bacteria from the ultrapure water as it is dispensed.

The general process described for water purification with arium® pro UV is depicted in Figure 2.

Fig. 2: Schematic drawing of the arium® pro UV pure water system

Test Method

The tests were carried out with the Sartorius arium® pro UV pure water system in a Class 1 clean hood. Samples were taken from the product water side (without a final microfilter capsule installed) and were analyzed with the Agilent ICP-MS system 7500cs (2).

Results

Trace element analysis requires reagents and /or solvents and water of high purity to ensure that the accuracy of the ICP-MS instrument is not negatively influenced. For example, pure water is necessary to create instrument blanks, calibration curves and standard solutions. Purified water is also necessary for sample preparation and must thus be free of those elements under investigation.

Standard solutions of the elements mentioned below were injected together with an instrument blank (zero value) into the Agilent ICP-MS system 7500 cs to generate calibration curves. Figures 3 and 4 below show examples of the calibration curves of lead (Figure 3) and chromium (Figure 4) as a function of signal value plotted against the concentration of the element expressed in ppt. The concentrations of each element in the samples tested were calculated from the corresponding calibration curves and are shown in Table 1 below.

Fig. 3 Typical calibration curve for lead Pb (CPS = counts per second)

Fig. 4 Typical calibration curve of chromium Cr (CPS = counts per second)

Table 1: Trace analysis in arium® pro UV product water

Conclusion:

It can be clearly seen that under the given test conditions, the ng/l (ppt) quantities of the different elements, specified above, in water produced by the arium® pro UV system are below the detection limits. To achieve such high quality water, all system parts including the tubing have been specially designed for the ICP-MS application and are used for serial production of arium® pro UV devices. The results obtained clearly illustrate the fact that ultrapure water produced by arium® pro UV is exceptionally well suitable for use in ICP-MS technology because error sources or risks of inaccuracies due to the presence of the trace elements mentioned above are prevented. Such conditions are prerequisite to trace analysis of these elements in pharmaceutical and environmental industries as well as in analytical laboratories.

References/Further Information

1. Information published by Worley, Jenna and Kvech, Steve on the Internet. No date of publication specified: http://www.cee.vt.edu/ewr/environmental/tweach/smprimer/icpms/icpms.htm#References
2. Reinstwasseranalyse am Auslauf der “arium® pro UV Anlage“ATU GmbH-Analytik für Technik und Umwelt, Herrenberg, 2011 ,Dr. Elmar Herbig , Sartorius Goettingen, Germany; M. Reutz and R. Braitmayer, ATU GmbH, Herrenberg, Germany Oct. 2011

Acknowledgements