Discrete automated systems

Positive-liquid-displacement pipettes are used for specimen handling in most discrete automated systems. With them, specimens, calibrators, and controls are delivered by a single pipette to the next stage in the analytical process. 

Discharge lamps, electrodeless, 239 Discrete automated systems, 931. 942... 

Compare and contrast continuous flow and discrete automated systems. Give the advantages and disadvantages of each type of automated system. 

A system based on grafted polymer synthetic objects (lanterns) is available from Mimotopes Pyt. Ltd.12 The system is composed of the synthetic objects (lanterns), RF-Tags (Transtems), software to track the synthesis (TranSort), and a cleavage system. Additional systems that are not commercially available have been reported. Workers at Aventis have developed a highly automated system based on the Mimotope lanterns.13 Recently workers at Millenium Pharmaceuticals reported the St AC system (Stratified Adressable System), a three-dimensional spatial array that allows discrete compounds to be synthesized using the same efficiency as the directed sorting approach.14... 

Several recent reviews (84-88) cover the characterization of discrete libraries from parallel synthesis with automated systems and using different analytical and/or detection methods their perspective may help the reader to expand his or her knowledge of... 

Manufacturing automation system is a value-added system. The material flow and information flow come together in MAS. For a discrete manufacturing company, MAS consists of a number of manufacturing machines, transportation systems, high-bay stores, control devices, and computers, as well as MAS software. The whole system is controlled and monitored by the MAS software system. For the process industry, MAS consists of a number of devices controlled by DCS, the monitor system, and the control software system. The objectives of MAS are to increase productivity, reduce cost, reduce work-in-progress, improve product quality, and reduce production time. 

The advantage of discrete analyzers is that sample crossover in the system itself is the lowest possible. Volumes of 75 pi of reagent and sample volumes as large as 100 pi are sufficient. In an automated system with a throughput of 200 determinations per hour in the same sample 6 to 10 components (such as ammonium, alkalinity, aluminum, boron, bromide, calcium, chloride, chromium(VI), cyanide, fluoride, iron, magnesium, nitrate, nitrite, phosphate, etc.) can be determined. In discrete analyzers normally conventional spectrophotometric methods are used. These methods are prone to interference of the matrix of the sample. As a good concept for interference studies still is not available, interferences are as yet not sufficiently studied systematically even for routine analyses. 

A group of computers can become networked once intercomputer communication is established. Prior to the 1980s, all system suppHers used proprietary protocols to network their systems. The recent introduction of standardized protocols is based on the ISO-OSI seven-layer model. The manufacturing automation protocol (MAP), which adopted the ISO-OSI standards as its basis, specifies a broadband backbone local area network (LAN). Originally intended for discrete component systems, MAP has evolved to address the integration of DCSs used in process control as well. TCP/IP (transmission control protocol/internet protocol) has been adopted for communication between nodes that have different operating systems. 

Woodruff and co-workers introduced the expert system PAIRS [67], a program that is able to analyze IR spectra in the same manner as a spectroscopist would. Chalmers and co-workers [68] used an approach for automated interpretation of Fourier Transform Raman spectra of complex polymers. Andreev and Argirov developed the expert system EXPIRS [69] for the interpretation of IR spectra. EXPIRS provides a hierarchical organization of the characteristic groups that are recognized by peak detection in discrete ames. Penchev et al. [70] recently introduced a computer system that performs searches in spectral libraries and systematic analysis of mixture spectra. It is able to classify IR spectra with the aid of linear discriminant analysis, artificial neural networks, and the method of fe-nearest neighbors. 

In basic terms, all automated analyses of samples in the hquid state are performed by one of two methods, discrete or continuous, and occasionally by a combination of the two. There are several basic subdivisions in each group and some examples will be described here and throughout the other chapters of the book to provide a starting platform for the systems designer. 

The philosophies for automation have been described in the foregoing sections. However, to solve an analytical problem there may well be more than one approach that offers potential. The Hterature abounds with methods that have been automated by flow-injection and by continuous-flow methodologies. Also, very often a procedure which involves several stages prior to the actual measurement can be configured by combining two of the approaches. An example of this is the automated Quinizarium system described by Tucker et al. [46]. This was a continuous extraction followed by a hatch extraction which is finally completed by a batch measurement on a discrete sample for quantification and measurement. Whereas sample preparation is almost always required, there is no doubt in my mind that the best approach to this area of activity is to avoid it totally. The application of near infra-red spectroscopy is an example of this strategy. 

Fig. 4 Illustration of (a) Chemspeed automated synthesizer and (b) Symyx batch polymerization system for synthesis of discrete polymer libraries. Reprinted with permission from [90], (Copyright 2007 Taylor Francis Group, http //www.informaworld.com)...

The advantages of the bipolar pulse technique include speed (discrete measurements at a rate as high as 30 kHz), accuracy, and signal-to-noise ratio. The system has been employed as a detector in automated conductometric titrations and in stopped-flow mixing systems with excellent results. 

Coughanowr, D. R. Process Systems Analysis and Control, 2nd edn. (McGraw-Hill, New York, 1991). Kuo, B. C. Discrete Data Control Systems (Prentice-Hall, Englewood Cliffs, New Jersey, 1970). Landau, Y. D. Adaptive Control—The Model Reference Approach (Marcel Dekker, New York, 1979). Popovic, D. and Bhatkar, V. P. Distributed Computer Control for Industrial Automation (Marcel Dekker, New York, 1990). 

The GPIB or IEE-488 cable is a bidirectional serial cable carrying module addressing information lines as well as signal and housekeeping lines. It can be used to send and collect information from different instruments on a cable bus. It is often used in instrumentation to automate a series of discrete instrument modules connected through a system controller. 

One of the most successful applications of microsystem technology is the use of pTAS in diagnostics [332-335]. Microreactors have been integrated into automated analytical systems, which eliminate errors associated with manual protocols. Furthermore microreactors can be coupled with numerous detection techniques and pretreatment of samples can be carried out on the chip. In addition, analytical systems that comprise microreactors are expected to display outstanding reproducibility by replacing batch iterative steps and discrete sample treatment by flow injection systems. The possibility of performing similar analyses in parallel is an attractive feature for screening and routine use. 

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