University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Signal noise

Classification: Signal processing -> Signal noise

Citations 11

"Extraction Of Non-stationarity Information From Correlation Noise"
Anal. Chim. Acta 1985 Volume 177, Issue 1 Pages 15-22
Scott Frazer and Michael F. Burke

Abstract: A method is described to minimize noise due to fluctuations in input concentration. or system response during data collection. Single-component samples of heptane were injected by a computer-controlled auto-injector into a gas chromatograph modified to accept multiple injections. A Durapak C18 column (60 cm x 3.2 mm) operated at 91°C was used with a flow rate of 20 mL min-1 and FID. Output data was fed to a computer and processed by an inverse FT deconvolution equation. The method is also applicable to process-stream control, flow injection analysis and other continuous monitoring devices.
GC

"Use Of The Hunt Filter To Optimize The Determination Of Impulse Response Functions Of Individual Component Parts Of Flow Injection Manifolds"
Anal. Chim. Acta 1989 Volume 222, Issue 1 Pages 151-157
I. C. Van Nugteren-Osinga, M. Bos and W. E. Van der Linden

Abstract: The dispersion behavior of the various individual parts making up a flow-injection manifold can be expressed by means of impulse-response functions. These functions can be determined by deconvolution of the response curves obtained with and without the part concerned. Special attention is paid to a procedure to decrease the influence of noise. It is shown that good results can be obtained with a Hunt filter which operates in the Fourier domain.

"Signal Analysis And Data Processing For Inductively Coupled Plasma-atomic Emission Spectrometry With Microliter Sample Introduction. 1. Introduction, Signal And Noise Characteristics"
Anal. Chim. Acta 1989 Volume 226, Issue 1 Pages 53-72
P. J. H. Scheeren, P. J. H. Seeverens, F. J. M. J. Maessen and H. C. Smit

Abstract: The introduction of microlitre samples has found widespread applications when inductively coupled plasma-atomic emission spectrometry (ICP-AES) is used for detection in liquid chromatography or in flow-injection systems. This technique for introducing small samples is poorly characterized. The properties of the transient signals and the noise associated with 'plug' sample introduction are examined here to establish guidelines for improving the technique. The analytical performance is characterized by parameters deduced from the signal-to-noise power ratio. The influence of the operating conditions of ICP-AES on the technique is described for cross-flow, concentric and high-solids nebulizers. The performance of microlitre sample injection proved to be similar to that of continuous sample introduction for the cross-flow and concentric nebulizers.
Spectrophotometry

"Real-time Digital Filters For Signal Processing In Flow Injection Analysis. 1. General Considerations And Simulation Study"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 509-519
Bogdan Szostek and Marek Trojanowicz*

Abstract: The fundamentals of digital filtering are presented, and infinite and finite impulse response filters are described theoretically. The frequency response characteristics of real-time digital filters are shown graphically. Several filtering procedures are compared by using simulated data corresponding to signals commonly observed in routine flow injection analysis with various detection methods and artificially added h.f. noise, and the effectiveness of each is estimated numerically. It is concluded that infinite impulse response filters provide the most effective means for removal of h.f. noise. Theoretical description and frequency response characteristics of selected real-time digital filters is presented, including infinite impulse response (IIR) and finite impulse response filters. The application of different filtering procedures to computer-simulated noisy signals, corresponding in shape to a common asymmetric flow-injection response, suggests that the use of IIR filters is the most effective for the removal of high-frequency noise.

"Deconvolution Techniques For Rapid Flow Injection Analysis"
Talanta 1985 Volume 32, Issue 8B Pages 807-810
James T. Dyke and Quintus Fernando*

Abstract: Techniques of FT deconvolution and of iterative-convolution curve-fitting (Vanderslice et al., Ibid., 1981, 28, 11) were investigated, the variables being the effect of random noise and the signal-to-noise ratio. Use of these techniques in spectrophotometric flow injection analysis to separate overlapping peaks permits the sampling rates to be increased. The iterative method is less sensitive to random noise than is FT deconvolution.
Spectrophotometry

"Neural Network-based Recognition Of Flow Injection Patterns"
Analyst 1993 Volume 118, Issue 4 Pages 347-354
Margaret Hartnett, Dermot Diamond and Philip G. Barker

Abstract: The choice and application of artificial neural networks is described in study of problems of ion-selective electrode detection in flow injection analysis. These problems include noise pickup, baseline shift and mutual interference by other ions present. A back-propagation training algorithm has been applied to a feed-forward network for pattern recognition and identification in response profiles in a system containing three selective electrodes for Ca, K and Na and pattern distortion previously unobserved were recognized and studied.
Calcium Potassium Sodium Electrode Electrode Electrode

"Hazards Of A Naive Approach To Detection Limits With Transient Signals"
Anal. Chem. 1988 Volume 60, Issue 7 Pages 725-727
T. W. Williams and Eric D. Salin

Abstract: Detection limits were calculated for transient signals (as generated in flow injection, chromatographic and atomic spectrometric methods) taking into consideration the time window in which a peak would be expected to appear. Procedures used for computerized smoothing of noisy signals are outlined. It is shown that a 99.9% confidence limit would not be correctly obtained by a simple standard deviation calculation, and that the window size and degree of smoothing affect the calculated detection limit.

"Improvements In The Signal-to-background Ratio With Hydride Generation Inductively Coupled Plasma Atomic Emission Spectrometry"
Spectrochim. Acta B 1993 Volume 48, Issue 11 Pages 1339-1345
Hiroaki Tao*, Victor J. Boyko and James W. Mclaren

Abstract: An investigation of the effects of torch position and of diameter of the central tube of the ICP torch on signal-to-background ratio and reflected power in hydride generation inductively coupled plasma atomic emission spectrometry has identified conditions under which a stable plasma can be sustained at only 0.5 kW with a five times better signal-to-background ratio for Se than could be obtained at 1.4 kW. The improved performance is attributed to a more efficient introduction of hydrogen to the central channel of the plasma. [References: 15]
Selenium Spectrophotometry

"Factors Affecting Detection Limit In Flow Injection Solution Spectrophotometry"
Anal. Proc. 1988 Volume 25, Issue 3 Pages 89-90
Andrew B. Marsden, Julian F. Tyson

Abstract: Strategies for minimization of baseline noise in flow injection - spectrophotometric systems are discussed and tested. Devices used included dampers to lessen pump roller noise, optimized design of the confluence junction of merging streams, and the introduction of intervening mixing stages, e.g., a packed-bed reactor and/or a reaction coil between the noise sources and the detector. Best results were achieved with packed-bed and open-tube coil reactors both included between the confluence point and the detector.
Chloride Spectrophotometry

"Noise And Drift Phenomena In Amperometric And Coulometric Detectors For HPLC And Flow Injection Analysis"
J. Liq. Chromatogr. Relat. Technol. 1983 Volume 6, Issue 12 Pages 2231-2254
H. W. Van Rooijen; H. Poppe

Abstract: The cited phenomena in electrochemical detectors with solid electrodes are investigated. A relationship between the capacity of the working electrode and detector noise is demonstrated by direct correlation, measurement of time correlation functions, and electrical simulation of cell properties. Means of improving detection limits are indicated, e.g., appropriate choice of electronic equipment and the material and effective area of the electrode.
Amperometry Coulometry HPLC Electrode

"Computerized Methods In Electroanalytical Chemistry"
J. Anal. Chem. 1988 Volume 43, Issue 3 Pages 541-554
Gratzl, M.;Pungor, E.

Abstract: A review is presented, with 35 references, of computerized methods for carrying out noise treatment, feature selection and pattern recognition in electrochemical analysis. Problems discussed include noise in turbulent voltammetric cells, acceleration of measurement with ion-selective electrodes (ISE), evaluation of potentiometric and amperometric flow-through titration curves, automated evaluation of polarograms and potentiometric flow injection peaks, automated calibration of ISE and automation of the potentiometric in vivo analysis of biological materials.
Biological material Amperometry Electrode Electrode Potentiometry