AutoAnalyzer

AutoAnalyzer is an automated analyzer using a special flow technique named "continuous flow analysis (CFA)" first made by the Technicon Corporation. The instrument was invented 1957 by Leonard Skeggs, PhD and commercialized by Jack Whitehead's Technicon Corporation. The first applications were for clinical analysis, but methods for industrial analysis soon followed, and by the time Technicon sold its business to separate clinical (Bayer) and industrial (Bran+Luebbe) buyers in 1987 industrial applications accounted for about 20% of CFA machines sold.

Instruments

USA

The best known of Technicon's CFA machines are the AutoAnalyzer II (introduced 1970), the Sequential Multiple Analyzer (SMA, 1969), and the Sequential Multiple Analyzer with Computer (SMAC, 1974). After Technicon was dissolved in 1987 Bayer did not manufacture any new CFA instruments, but Bran+Luebbe continued to manufacture the AutoAnalyzer II and TRAACS, a micro-flow analyzer for environmental and other samples, and went on to develop the AutoAnalyzer 3 in 1997 and the QuAAtro in 2004.

Today there are other manufacturers of CFA instruments. Astoria-Pacific International, for example, was founded in 1990 by Raymond Pavitt, who owned another CFA manufacturing company in the past. Based in Clackamas, Oregon, U.S.A., Astoria-Pacific manufactures its own micro-flow systems. Its products include the Astoria Analyzer lines for Environmental and Industrial applications; the SPOTCHECK Analyzer for Neonatal screening; and FASPac (Flow Analysis Software Package) for data acquisition and computer interface. FIAlab Instruments, Inc., in Bellevue Washington, also manufactures several analyzer systems.

Europe

CFA machines were made in the UK by Chemlab Instruments and are still made in Holland by Skalar.

Clinical analysis

AutoAnalyzers were used mainly for routine repetitive medical laboratory analyses, but they had been replaced during the last years more and more by discrete working systems which allow lower reagent consumption. These machines typically determine levels of albumin, alkaline phosphatase, aspartate transaminase (AST), blood urea nitrogen, bilirubin, calcium, cholesterol, creatinine, glucose, inorganic phosphorus, proteins, and uric acid in blood serum or other bodily samples. AutoAnalyzers automate repetitive sample analysis steps which would otherwise be done manually by a technician, for such medical tests as the ones mentioned previously. This way, an AutoAnalyzer can analyze hundreds of samples every day with one operating technician. Early AutoAnalyzer instruments each tested multiple samples sequentially for individual analytes. Later model AutoAnalyzers such as the SMAC tested for multiple analytes simultaneously in the samples.

Industrial analysis

The first industrial applications - mainly for water, soil extracts and fertilizer - used the same hardware and techniques as clinical methods, but from the mid 1970s special techniques and modules were developed so that by 1990 it was possible to perform solvent extraction, distillation, on-line filtration and UV digestion in the continuously flowing stream. In 2005 about two thirds of systems sold world-wide were for water analysis of all kinds, ranging from sub-ppb levels of nutrients in seawater to much higher levels in waste water; other common applications are for soil, plant, tobacco, food, fertilizer and wine analysis.

Operating Principle

Segmented Flow Analyzer

In a continuous flow analyzer, a peristaltic pump contains several tubes including one for the sample, one or more for various reagents and one or more to generate air bubbles. The pump tubes deliver into the "manifold" of junctions, coils and tubing where the reactions take place. In Segmented Flow Analyzers (SFA), the sample is mixed with small reproducible volumes of the required reagents and air bubbles are introduced into the flow, creating about 20 - 100 segments of liquid for each sample, keeping them separated as they flow sequentially through the tubing. The inlet side of the sample pump tube is connected to the sample probe in an autosampler. The sample probe moves between the small cups holding liquid samples and a reservoir of wash solution, normally pure water, which also serves to generate a baseline response. The sample / reagent mixture flows through mixing coils, and depending on the method a heated coil for elevated reaction temperature or other modules to develop a color proportional to the amount of analyte in each sample. The samples with developed color flow through a colorimeter to measure the color. Other detectors such as a flame photometer, a fluorometer or an ISE module are used for some applications.

Flow Injection Analyzer

Flow Injection Analysis (FIA), conceived in 1975 by Ruzicka and Hansen, has been described in over 16,000 scientific papers^[1] and almost 20 monographs. The Japanese Society for Flow Injection Analysis (JAFIA) has been in existence for 20 years and publishes a scientific journal devoted to research in this rapidly growing field of automated chemical analysis, now closely related to microfluidics.

The first generation of FIA technology, termed Flow Injection (FI), was indeed inspired by the AutoAnalyzer technique invented by Skeggs in early 1950s, yet it is principally different in its underlying principles. While Skeggs' AutoAnalyzer uses air segmentation to separate a flowing stream into numerous discrete segments to establish a long train of individual samples moving through a flow channel, FIA systems process one sample at a time, making air segmentation unnecessary. While the AutoAnalyzer mixes sample homogeneously with regents, in all FIA techniques sample and reagents are merged to form a concentration gradient that yield analysis results. Removal of air segmentation, previously viewed as impossible, opened the door to instrument miniaturization and inspired further progress towards analytical microfluidics, sometimes termed as "lab-on-chip".

The second generation of the FIA technique, called Sequential Injection Analysis (SI), was conceived in 1990 and has been further developed and miniaturized over the course of the following decade. It uses flow programming instead of the continuous flow regime (as used by CFA and FI), that allows the flow rate and flow direction to be tailored to the need of individual steps of analytical protocol. Reactants are mixed by flow reversals and a measurement is carried out while the reaction mixture is arrested within the detector by stepping the flow. Microminiaturized chromatography is carried out on microcolumns that are automatically renewed by microfluidic manipulations. Continuous flow analyzers were designed at a time when environmental awareness did not exist, and chemical were inexpensive to buy and easy to dispose of. Therefore, all CFA systems produce hazardous waste continuously.^{[citation needed]} In contrast, the discrete pumping and metering of microliter sample and reagent volumes used in SI is far more economical and environmentally friendly. The enormous volume of FI and SI literature documents the versatility of FI and SI and their usefulness for routine assays (in soil, water, environmental, biochemical and biotechnological assays) has demonstrated their potential to be used as a versatile research tool.

Dialyzer module

In medical testing applications and industrial samples with high concentrations or interfering material, there is often a dialyzer module in the instrument in which the analyte permeates through the diaphragm into a separate flow path going on to further analysis. The purpose of a dialyzer is to separate the analyte from interfering substances such as protein, whose large molecules do not go through the dialysis membrane but go to a separate waste stream. The reagents, sample and reagent volumes, flow rates, and other aspects of the instrument analysis depend on which analyte is being measured.

Recording of results

Previously a chart recorder and more recently a data logger or personal computer records the detector output as a function of time so that each sample output appears as a peak whose height depends on the analyte level in the sample.

Current Uses

AutoAnalyzers are still used for a few clinical applications such as neonatal screening or Anti-D, but the majority of instruments are now used for industrial work. There exist standard methods published by the American Society of Testing Materials (ASTM), the US Environmental Protection Agency (EPA) as well as ISO for parameters in environmental analysis such as nitrite, nitrate, ammonia, cyanide, and phenol, and also for vegetable and tobacco leaf analysis. The main reasons for using an AutoAnalyzer for these applications are the convenience of integrating difficult sample preparation and cleaning steps like distillation or ultrafiltration (dialysis); the low detection limits, which make CFA still the most widely used technique for the determination of nutrients in seawater; and the high analysis rate, typically between 30 and 100 samples per hour.

Method sheets

Technicon published method sheets for a wide range of analyses and a few of these are listed below. These were for the AutoAnalyzer I, which was rather like a Meccano set and could be assembled by the user. This gave great flexibility for the user to modify the machine for new analyses.

Sheet no.	Determination	Sample	Main reagent(s)	Colorimeter
N-1c	Urea nitrogen	Blood or urine	Diacetyl monoxime	520 nm
N-2b	Glucose	Blood	Potassium ferricyanide	420 nm
N-3b	Kjeldahl nitrogen	Foodstuffs	Phenol & hypochlorite	630 nm
P-3b	Phosphate	Boiler water	Molybdate	650 nm

References

↑ E. H. Hanson's database of FIA research publications

External links

[1] E. H. Hanson's database of FIA research publications

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