Kinetic treatment of unsegmented flow systems

Pardue, Harry L.; Jordan, James M.

doi:10.1016/s0003-2670(00)80247-0

Cited by 17 publications

(5 citation statements)

References 11 publications

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“…Flow injection analysis (FIA) is among the most widely used methods for automated analysis. Its application to several fields of chemistry has been demonstrated in recent years. , Several operational modes of FIA have been realized by appropriately modifying traditional wet chemical methods (dilution, extraction, titration, fast kinetic reactions, dialyses) for use in automated flow devices. − Different types of detectors, including electrochemical, spectrophotometric, and luminescent, have been applied to FIA. , While these detectors have been shown to be effective, they can only be used for certain types of compounds. Relatively wider applicability can be achieved with detectors based on measurements of the refractive index, or rather the refractive index gradient. − Unfortunately, the sensitivity of this type of detectors is rather low.…”

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confidence: 99%

Near-Infrared Detection of Flow Injection Analysis by Acoustooptic Tunable Filter-Based Spectrophotometry

1996

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The instrumentation development of a near-infrared (near-IR) spectrophotometer based on an acoustooptic tunable filter (AOTF) and its application as a detector for flow injection analysis (FIA) are reported. In addition to being compact and all solid state, this AOTF-based instrument is very sensitive, has high resolution, and can be rapidly scanned. The latter advantage make it uniquely suited as a detector for FIA, in that it can rapidly record the whole near-IR absorption spectrum of a mixture passing through the FIA flow cell. Subsequent treatment of the recorded spectra with multivariate calibration methods makes it possible to use the FIA, for the first time, for such applications as the simultaneous determination of trace amounts of water and benzene in ethanol. Because all organic compounds absorb light in the near-infrared region, this AOTF-based near-IR detector can serve as a universal detector for FIA; as a consequence, applications of the FIA techniques can be expanded to other areas which are not possible otherwise.

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confidence: 99%

Near-Infrared Detection of Flow Injection Analysis by Acoustooptic Tunable Filter-Based Spectrophotometry

1996

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“…There are however FIA systems in which kinetic-based methods are used primarily to monitor certain chemical kinetic properties. Examples of this include fundamental studies on kinetic treatment in FIA [36,37,38,48,49], the monitoring and study of fermentation dynamics [50,51], study of reaction kinetics [52]; determination of diffusion coefficients [53,54,55,56,57], enzymatic tautomerization [58], binding [59], dissociation [60] adsorption and desorption [61] rate constants [62,63], and viscosity [53,64].…”

Section: Automatic Analysers and Kinetic Methodsmentioning

confidence: 99%

New horizons in sequential injection kinetic analysis

Staden

Stefan

2002

Analytical and Bioanalytical Chemistry

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The need to measure several quantities rapidly in the same sample has prompted the development of automated methods of analysis that in both the continuous and discontinuous modes offer the possibility of simultaneous determinations. The application of pH gradients and differential kinetic determinations dominate the simultaneous determination of two or more closely related species in mixtures without prior separation. Various options enable use of kinetic-based measurements for the simultaneous determination of different analytes in flow systems. Some possible general reactions are given and discussed. The scope of sequential injection kinetic analysis is illustrated with examples.

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“…9 . IO Both equations have been used as the theoretical basis for obtaining a linear Llt-ln C, relation ship.…”

Section: Comparison Of It Equationsmentioning

confidence: 99%

“…(2) are derived for an injected sample with no reaction and as a result of the experimental requirement that the product profile must be monitored. Slow chemical reactions tJ and diffusion effects 9 have been cited as the reasons why the assumption is not valid. The rate of the reaction is not a factor for the chemical systems studied to date.…”

Section: Comparison Of It Equationsmentioning

confidence: 99%

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Evaluation of the precision of the flow injection doublet peak method

Echols¹,

Tyson²

1994

Analyst

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The factors affecting the precision of the flow injection doublet peak method are discussed with particular reference to the contribution from the uncertainty associated with the calibration procedure. A single-line flow injection manifold was used in which the concentration gradients were generated by alternating helical reactors and the reaction products were monitored by a simple detector incorporating diodes as light source and intensity transducer. The reactions between lanthanum and Methyl Thymol Blue and between sodium hydroxide and hydrochloric acid in the presence of Bromothymol Blue were used. Optimization studies involved the method of steepest ascent, two figures of merit (the slope of the calibration and the standard deviation of a measured concentration) and two parameters (pump speed setting and the number of segments in the alternating helical reactor). The resulting minimum uncertainties, which ranged from 3 to 9%, were found to be insensitive to changes in experimental parameters. The major contribution to the uncertainty in a determined concentration was found to be the scatter of the points about the regression line fitted to the calibration data. Alternative approaches to flow injection peak width methods are discussed and it is pointed out that the doublet peak method has the unique feature of giving rise to an inherently linear calibration function, because the reference points at which the time interval is measured are not fixed at a particular value of the detector response for all concentrations.Keywords: Flow injection; doublet peak method; precision; calibration; uncertainty literature. Various other names for these methods have been proposed: 'pseudo-titrations',ll 'flow injection titrations'I2 and 'variable-time kinetic methods'.5 All methods are subsets of time-based determinations of which most are peak-width methods.The development of a comprehensive set of equations to describe the concentration-time profile of an analyte in a well stirred tank was completed by Pardue and co-workers in a series of papers.5-9 The most recent of these is a thorough review of the previous work.9 Equations were derived using a variable-time kinetic model for single-and double-line FI systems, with and without reaction. Experimental situations in which the reactant is in excess were included in the derivation. Calibration equations for time intervals on the leading edge, trailing edge and for the peak width of the FI peak were also derived; in all instances the mathematical relationship between Atrp and the logarithm of concentration is non-linear. For reference points at equal concentrations on the leading and trailing edges of a peak, Linear relationships are obtained when the reference point concentration is much less than the injected analyte concentration. All symbols used in this paper are defined in Table 1.Work by TysonlO.12 focused on the use of the time interval between doublet peaks as the analytical parameter for timebased determinations. Doublet peaks are obtained when the injected analy...

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Kinetic treatment of unsegmented flow systems

Cited by 17 publications

References 11 publications

Near-Infrared Detection of Flow Injection Analysis by Acoustooptic Tunable Filter-Based Spectrophotometry

Near-Infrared Detection of Flow Injection Analysis by Acoustooptic Tunable Filter-Based Spectrophotometry

New horizons in sequential injection kinetic analysis

Evaluation of the precision of the flow injection doublet peak method

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