Multi-parameter analysers

The legislation on water pollution and quality control necessitates analyses for an Increasingly larger number of parameters. These demands have been met by commercial firms with the manufacture of muiti-parameter analysers. The Philips Environmental Protection range Is representative of this type of instrument. 

The electronic unit Is completed by recording equipment which can be from a muiti-channel recorder to up to four dual-line recorders. Data transmission is achieved by mounting the appropriate equipment In the recorder section. It Is also possible to mount a microcomputer-based pollution data reductor. 

Comber and Nicholson [43] reported a home-made design for the continuous 

The principle behind the FIA technique (reversed mode) has been exploited to develop a completely automated instrument [44] (Fig. 15.15) in which the sample is continuously pumped along the system and in which different injection valves [45] or a single injection valve aided by a selecting valve [46] are used to introduce the reagents required for the determination of each analyte in the appropriate sequence and at the required time intervals. The reacting plug is driven to the fiow-ceii of a photometric detector, and the 

An rFIA-asynchronous merging zones configuration has be used for the speciation of up to nine different chromium forms —aquo complex, mono-, di- and tetrahydroxylated Cr(III) and molecular, anionic and dimeric Cr(VI). It Includes a glass-calomel microelectrode Inserted In the sample stream prior to the merging with the reagents, and a microcomputer which acquires the measured pH and chromium concentrations —Cr(VI) and total Cr. These data are pro-cesssed by a computation program In which the equilibrium constants of the 

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These are often multi-parameter analysers and enable several determinations to be carried out on the same sample furthermore, the number of determinations can be programmed for each individual sample. An aliquot of the sample is placed in a transparent measurement cuvette following addition of the reagents, a colorimetric measurement is then carried out directly on the cuvette. The analysis rate varies from 50 to 1000 determinations per hour, and the principal applications are carried out either by chemical or enzymatic analysis. The volumes of reagent required for sequential analysis are small by comparison with FTA which substantially reduces the cost per analysis, particularly for enzymatic determinations. 

Even more complex and powerful than the Technicon RA-100 is the Hitachi Model 705, a multi-parameter analyser capable of analysing for up to 19 analytes per sample. As can be seen from Fig. 8.9, it consist of the following elements ... 

To follow the trend of the automation of the potentlometrlc technique, various manufacturers have launched a series of single- and multi-parameter analysers for the determination of gases and liquids, which are discussed below. 

The joint use of single- and multi-parameter analysers permits the monitoring of a variety of analytes. The instrument depicted in Fig. 15.24b is... 

The most complex fashion of performing environmental sampling, analysis and control is probably that used by automatic water and atmospheric pollution survey networks. A survey network consists of a series of stations, each of which has a modular multi-parameter analyser transmitting data to and receiving commands from a central computer that controls and organizes all the stations making up the network. The scheme of one such network for water control is depicted in Fig. 15.27. 

Rates of the alkaline hydrolysis of 12 ortho-, meta- and ) ara-X-substituted phenyl tosylates, 4-MeC6H4S02C6H4X, in aqueous 0.5 m Bu4NBr over a wide temperature range have been analysed using the modified Fujita-Nishioka multi-parameter equation. It was concluded from both these and previously reported data by the same group that solvent electrophilicity was the main factor responsible for changes in the ortho, meta and para polar substituent effects with medium.60... 

The spectrum is scanned repetitively and accumulated until the signaknoise ratio is adequate. Depending on the count-rate, i.e. the strength of the source, this may take a few minutes or several hours. Accumulation is normally in a multi-channel analyser, so that the spectrum is obtained in digitized form and may be transferred directly to a computer which fits a calculated spectrum to the data points modern spectrometers are effectively PCs with built-in data processing. The fitting programme takes estimates of the parameters supplied by the user, from which a trial spectrum is calculated, and an iterative process optimizes the parameters. 

F. Laborda, M. J. Baxter, H. M. Crew, J. Dennis, Reduction of polyatomic interferences in inductively coupled plasma mass spectrometry by selection of instrumental parameters and using an argon-nitrogen plasma effect on multi-element analyses, J. Anal. Atom. Spectrom., 9 (1994), 727-736. 

Depending on the number of analytes that can be assayed per sample, analysers can be classified Into one-parameter (e.g. centrifugal and flow-injection analysers) and multi-parameter. The latter are of special use In clinical assays, usually requiring the determination of several parameters In blood or urine —the SMAC, an extremely powerful analyser manufactured by Technlcon allows the determination of up to 20 parameters (analytes) per sample. Because of reminiscences of former times, some workers still use a parallel nomenclature (single-channel and multi-channel) to refer to these analysers. This Is acceptable as the earliest commercially available continuous segmented flow analysers (Technlcon AutoAnalyzers) carried out one determination per channel Into which the sample was spilt. Hence the equivalence between channel and parameter , exclusive to this type of analyser. 

The determination of several analytes in the same sample is commonplace in some areas, particularly in clinical chemistry. Multi-parameter designs are thus of great Interest to the automation of laboratory procedures, to which commercially available analysers, with the exception of some rather specific examples, are perfectly suited. In continuous segmented analysers, the term... 

Fig. 8.3 Scheme of the commonest configurations of (a) continuous and (b) batch analysers for multi-parameter determinations. 

FP-901 analyser proper is a semi-automatic nine-channei photometer with vertical parallel light paths unlike conventional photometers. It has nine light sources and as many photodetectors. Measurements are carried out simultaneously, which makes this a parallel batch system. However, despite its apparent multi-parameter character, it can only determine one parameter in each batch of operations. It allows for Incubation at 30 or 37 C and for mixing within each cuvette. Its functioning is controlled by a microprocessor. 

The instruments with which continuous techniques of clinical analysis are carried out belong to the group of flexible analysers. Segmented-flow instruments used in this field are multi-parameter and allow the simultaneous determination of the different species by means of systems splitting the aspirated sample into as many lines as parameters are to be determined (see Chapter 5). The adaptation for analysis of a new parameter Is readily accomplished by simply changing the corresponding analytical cartridge. Thanks to Its versatility, the FIA technique is adaptable to any type of analysis, whether for one... 

Fig. 15.24 (a) Analyser with IR detector for the determination of CO and CO2. Analyser with single- and multi-parameter detectors for blast furnace (b) and basic oxygen process (c). (Reproduced with permission of Academic Press). 

Sakai T, Hamano T, Kamiya T, Murozono K, Inoue J, Matsuyama S, Iwasaki S, Ishii K (1998) Development of a fast multi-parameter data acquisition system for microbeam analyses. Nucl Instrum Methods Phys Res B 136-138 390-394... 

Advanced EMR methods may be used to conduct quantitative measurements of nuclear hyperfine interaction energies, and these data, in turn, may be used as a tool in molecular design because of their direct relation to the frontier orbitals. The Zeeman field dependence of hyperfine spectra enables one to greatly improve the quantitative analysis of hyperfine interaction and assign numeric values to the parametric terms of the spin Hamiltonian. Graphical methods of analysis have been demonstrated that reduce the associated error that comes from a multi-parameter fit of simulations based on an assumed model. The narrow lines inherent to ENDOR and ESEEM enable precise measures of peak position and high-resolution hyperfine analyses on even powder sample materials. In particular, ESEEM can be used to obtain very narrow lines that are distributed at very nearly the zero-field NQI transition frequencies because of a quantum beating process that is associated with... 

The kinetics of the oxidation of ort/io-substituted benzaldehydes by pyridinium chlorochromate have been analysed in terms of a multi-parameter equation, to allow separation of the ortho or steric effect from the inductive and resonance effects. 

The current version of CalTOX (CalTOX4) is an eight-compartment regional and dynamic multimedia fugacity model. CalTOX comprises a multimedia transport and transformation model, multi-pathway exposure scenario models, and add-ins to quantify and evaluate variability and uncertainty. To conduct the sensitivity and uncertainty analyses, all input parameter values are given as distributions, described in terms of mean values and a coefficient of variation, instead of point estimates or plausible upper values. 

These force versus deflection relationships are usually nonlinear (due to materials or geometry) and are called resistance functions. They are an essential input parameter for the analysis of equivalent single degree of freedom (SDOF) systems, Resistance functions are not usually needed for analyses of multi-degree of freedom (MDOF) systems. Material models employing nonlinear stress versus strain data, as discussed in Chapter 5, are used in MDOF systems. 

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