LABORATORY PROFILE On-Site Analysis Made in Germany Although on-site chemical analysis is a topic of growing interest in the United States, it is just a wallflower in Europe. Johannes Flachowsky heads one of the few European research groups engaged in this work. Flachowsky's group is located at the Centre for Environmental Research Leipzig-Halle in what was formerly East Germany and is affiliated with the national Helmholtz Society—institutions founded and paid for by the German Federal Government. "On-site analysis is cheaper than the usual approach, where environmental samples are brought to the laboratory," Flachowsky says. "Misleading information can be avoided; the samples do not undergo alteration or contamination; and the analyst gets an immediate feedback, which allows us to probe those sites that are the most interesting ones. Even a quick, qualitative analysis can yield information of utmost importance." In 1991, Flachowsky's team equipped a Mercedes van with an energy supply and some state-of-the-art analytical instrumentation to perform a wide number of assays in thefield.The van carries a built-in GC/MS and an X-ray fluorescence spectrometer, plus all the equipment needed for the determination of field parameters such as pH, redox potential, dissolved oxygen, and ion concentrations. If nee-
voltammetry (to measure metals) can be carried on board. Most of the analytical equipment comes from commercial sources. The vehicle also includes a computer, a refrigerator, laboratory bench space, and a powerful energy supply (380-Ah battery, 60-A charger, 1.2-kW inverter for 220-V and 3-kW emergency power unit). Flachowsky's groupfitsthe GC/MS with various probe heads. Commercial probe heads are used for the soil analysis (utilizing a quasi-open headspace technique with a heated sampler head and silicone rubber membrane) or for air samples. For aquatic samples, Flachowsky's group has developed a spray-and-trap probe device that allows the enrichment of volatile organic compounds (VOCs) without loss. Typically, water is sampled at 425 mL/min for 4 min and the VOCs are trapped on Tenax TA. This sampling technique even works in groundwater at depths of 70 m Probing directly at the site of interest even if it is well below the surface prevents sample degassing and the loss of volatile analytes says Flachowsky Flachowsky's team is now developing a sampling head for horizontal probing of soil below the surface. Vertical probing is regularly performed using a penetrometer, a drilling head equipped with various sensors. Horizontal probing, on the other hand, is a new approach that promises to yield a pattern of information not easily available by other means, he says. When he analyzes samples, Fla-
pssurv
additional equipment for nondispersive infrared spectroscopy (to detect for example contamination by mineral oil hydrocarbons) or
No wallflower. Johannes Flachowsky demonstrates the analytical equipment used for on-site analysis.
chowsky's approach is to obtain as many results as possible. He argues that it makes no sense to commit time to improving precision, given the heterogeneity of the samples, but instead focus on producing accurate results. As a result, a typical analysis run takes just 1 or 2 min, and sample preparations are fast and simple. The GC analyses are performed in many cases on a short column only 3 m long, and the resulting chromatograms are poorly resolved. (Fast HPLC would also be a valuable technique, but that instrumentation has not been used thus far because of its high cost, he says.) Data are analyzed by fuzzy logic routines, and the group includes a software specialist involved in cluster analysis. Flachowsky says that his work is heading toward the development of new "effect-specfiic indicators"—responses that can be used to represent the sum of ecotoxic load on humans or other organisms. The indicators available thus far, such asfishtoxicity or halobacteria tests, do not correlate well with analyses that show toxic chemicals in the environment. Currently, there is little funding for on-site analysis in Europe as compared to the U.S. where such research is supported by federal organizations such as the Department of Defense's Strategic Environmental Research and Development Program and the Environmental Protection Agency. Moreover, the U.S. programs are involved in the validation of on-site analytical methods. However, there are signs that European scientists are becoming increasingly active in thisfield.The First International Conference and Industrial Exhibition, "Field Screening Europe," will be held at the University of Karlsruhe (Germany) Sept. 29-Oct. 1. The conference is expected to bring together European analytical chemists, engineers, and geologists to discuss the state of the art in on-site analysis Veronika Meyer
Analytical Chemistry News & &eatures, July 1, 1,97
799 A
