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36 Environmental Analysis

Standards Compared in Moisture Measurement at Leading Institutes

When four of the world’s leading national metrology labs took the bold step of comparing their primary moisture standards, the tool of choice --a Tiger Optics LaserTrace --performed admirably. Measurements deviated less than 2 percent over the course of the three-year, multinational inter-comparison, thereby permitting the facilities to establish a much-needed baseline for future work. The groundbreaking study --undertaken by the European Association of National Metrology Institutes (EURAMET) --relied solely upon the company’s LaserTrace, along with a back-up compact HALO instrument, also from Tiger Optics (USA).

The performance of the Tiger Optics instruments permitted scientists to compare standard generation facilities by shipping the analytical instruments --in lieu of cumbersome standards --to the participants in the United Kingdom (National Physical Laboratory), the United States (National Institute of Standards and Technology), Japan (National Metrology Institute of Japan), and Germany (Physikalisch-Technische Bundesanstalt).

The measurement of trace amounts of moisture contamination is of utmost importance to a number of manufacturers and suppliers of purge and process gases. The semiconductor industry, for example, regards moisture as one of the most difficult impurities to measure and to control. As manufacturers develop moisture analysers to detect ever-smaller amounts of contaminants, there is an equally pressing need for traceable calibration. Hence, EURAMET’s desire to compare facilities and quantify the variability among the standards and their accuracy at fraction amounts.

Until this study, an inter-comparison of such facilities was untenable, due to the characteristics of trace water-vapour standards. Such standards are produced via a dynamic method, for example; gravimetrically, or a frost-point generation, involving large, weighty, and complex pieces of equipment that are not readily brought together for comparison purposes. To resolve that problem, EURAMET elected to transport instruments, rather than standards.

The study was designed to compare the performance of each of the national metrology institute’s facilities over the range of 10 ppb to 2000 ppb. For the first time, participating laboratories were able to quantify the comparability of their trace water-vapour standard generation facilities, which proved to be excellent across the full range of measured amount fractions, as the graph illustrates.

“While we learned that such studies take considerably longer than anticipated, the chance to support the noble aim of achieving a comparable moisture standard worldwide was well worth it,” said Lisa Bergson, Tiger Optics’ founder and chief executive, adding, “Beyond that, we are proud of our analysers’ precision and robust performance. It’s great to be in a position to offer them to our friends in the institute community.”

Reader Reply Card No. 99

HPLC Method Development Calculator for Chromatographers

Thermo Fisher Scientific (USA) provides invaluable assistance with the HPLC Method Development Calculator to chromatographers looking to optimiSe methods with the latest column technologies. This interactive range of online tools is hosted on the Thermo Scientific Chromatography Resource Center and helps calculate initial conditions for gradient and isocratic methods. In addition, an LC column selection tool is provided to assist in the choice of the appropriate column for any application.

With the ability to significantly reduce the time spent in experimentally defining optimal analysis condition, the HPLC Method Development Calculator provides users with quick and easy access to the technical expertise of chromatographers at Thermo Fisher Scientific.

Reader Reply Card No. 100

Compact, High Efficiency Cold Trap & Freeze Dryer

Genevac (UK) has announced a new version of its miVac SpeedTrap™ frost-free cold trap that not only provides unmatched volatile solvent recovery but now also enables freeze drying of up to 250ml of aqueous samples.

The new generation SpeedTrap™ is suitable for use with a wide range of solvents, from volatile organic solvents through to water and even higher boiling point solvents including 1,4-dioxane, tertiary butanol, and cyclohexane. While it is designed to complement the miVac series of concentrators it can also be used with other manufacturer's concentrators, provided that the solvents concentrated are compatible.

The SpeedTrap can be used with a high vacuum pump as a stand-alone small volume freeze dryer, or can be used with a concentrator to become a combined concentration and freeze drying system.

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The new SpeedTrap is radically different. It is very small in size and requires little bench space, being only 212mm (8.3 inches) wide. The SpeedTrap operates with the cold condenser coils suspended directly in the vapour path, so that solvent vapours condense directly on to the coils and run off into the collection vessel below. There are many benefits to this method including it is highly efficient, with more than twice the condensing power of similar cold trap systems ; users can quickly see the solvents in the trap and emptying the trap is easy, requiring no defrosting. An automatic defrost mode ensures that the user does not need to spend time defrosting the system, even when using water. The collection vessel is removed with a simple quarter turn, allowing safe disposal of the solvents.

Reader Reply Card No. 101

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