Discrete analyzers: a force in environmental analysis.

For nearly two decades now, discrete analyzers have played a major role in the evolution and automation of clinical laboratory analysis. Offering faster, more reproducible results with less sample waste and greater automation than previous automatic analyzers, discrete analyzers have become a formidable force in clinical laboratories worldwide, and ultimately a valuable alternative to continuous flow analyzers (CFA). By 2002, discrete analyzers had started to be used in environmental laboratories, promising similar benefits for applications dominated by CFA instruments, such as the analysis of nutrients and chemicals in water and soils.

Today's discrete analyzers, with more automated and programmable features, higher sample throughput and less reagent consumption than segmented flow analysis (SFA) or flow injection analysis (FIA) systems, have only scratched the surface of their potential for environmental and industrial applications. And while no concrete evidence can predict the future of discrete analysis within the environmental market, perhaps the best evidence of the future is found in the success of discrete analyzers in clinical laboratories--especially when only one representative from a short list of discrete analyzer companies chose to answer IBO's questions.

When EST Analytical began marketing its Konelab discrete analyzers to environmental laboratories in 2002, it found an industry unfamiliar with the technology. At that time, said Larry Anderson, product manager for EST Analytical, education was an important tool in breaking into the market. "We sold only nine units that first year," Mr. Anderson said, "Since then we can say we've seen about a 400% increase in yearly sales." Three years later, the environmental market is now EST's strongest market for its Konelab line of analyzers, which perform the same colorimetric chemistries and methods used for SFA and FIA systems, with less man-power and lower laboratory costs. "If an analysis can be done colorimetrically or enzymatically," he said, "it can be done on the Konelab."

Unlike SFA and FIA, in which reactions occur within tubing in a continuous flow, discrete analyzers employ individual wells, enabling multiple testing of one sample as well as automated sample preparation of new samples while analyses are being performed. Sample and reagent addition and mixing are also automated (see IBO 11/15/03).

When compared to SFA or FIA, discrete analyzers offer several advantages. One advantage is higher sample throughput. Lachat Instruments' benchtop AP 300 Discrete Analyzer can perform 300 tests per hour. SEAL Analytical's fourth-generation colorimetric analyzer, the floor-standing Aqua 900, has a throughput of 800 tests per hour. Discrete analyzers also require less reagent volume, typically 1-250 microliters due to more accurate reagent dispensing. Automated features include preprogrammed methodologies, making discrete analyzers easy to use. OI Analytical's DA 3500 Discrete Analyzer offers preprogrammed methods for analyses of ammonia, nitrate and nitrite, among other analyses.

Relatively few companies make discrete analyzers for environmental applications, yet nearly all of them also offer CFA systems. EST Analytical, SEAL Analytical, whose AQ2+ discrete analyzer is distributed by Bran+Luebbe, and Westco Scientific Instruments were the first wave of companies to manufacture dedicated discrete analyzers for the environmental testing market. Lachat, a division of Hach, entered the market in 2004, and OI introduced its first product this year (see IBO 11/15/05).

Despite the relatively few manufacturers, a range of product types are available. One differentiating feature is the detector. The AQ2+ from SEAL Analytical features a photometer and filter wheel for a wavelength range of 400 nm-900 nm. Lachat's AP 300 optical system includes a multiple filter photometer with eight wavelengths. OI's DA 3500 features a diode array spectrophotometer for measurement of 27 wavelengths. Curvette features also differ among systems. The Lachat system employs quartz curvettes that are automatically cleaned, while OI's system features disposable curvettes. In comparing benchtop to floor standing models, SEAL's Aqua 900 analyzes six reagents per test, while its AQ2+ benchtop analyzes four reagents per test.

Capable of tests for water, soils, plants, beverages, pharmaceuticals and more, and an increasing number of automated and testing capabilities, discrete analyzers could be extremely competitive with the CFA systems used most often by environmental laboratories. In January, the EPA issued a memorandum for the "Guidance on the Use of Discrete Analyzers Under EPA Clean Water Act Programs" that concludes that discrete analyzers achieve results equal to EPA-approved methods, an important development that could make discrete analyzers even more competitive with FIA and SFA for environmental applications. Mr. Anderson said that, although discrete analyzers do not replace FIA and SFA, "The technology is 30-plus years old. It's time for something new." Of course, old technology or not, FIA instruments are able to automate distillation and digestion and to manipulate matrices, tasks which discrete analyzers can only perform manually. But, with a few innovations aimed at those specific drawbacks, discrete analyzers could do for the environmental field what they did for clinical laboratories in the past.

EST Analytical has already ventured into other areas for discrete analyzers, such as wine, enzymes, proteins, fertilizer and tobacco, but Mr. Anderson promised, "We will continue to serve our customers in [the environmental] industry for years to come." When asked where the biggest opportunities for the sale of discrete analyzers in the near future will be, he replied, "The food industry is going to be huge. Everyone in that industry uses a spectrophotometer in [the] QC process. We are actively pursuing this industry."