A software package for the orthogonal polynomial approximation of analytical signals, including a simulation program for chromatograms and spectra

Scheeren, P.J.H.; Klous, Z.; Smit, H.C.; Doornbos, D.A.

doi:10.1016/s0003-2670(00)84183-5

Cited by 20 publications

(5 citation statements)

References 19 publications

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“…For Gaussian function 6-7 points are sufficient to describe it Calculates 7 points per peak for less than 0.1% error in peak area (uses Shannon's theorem) [18] 10 data points across 2.355 σ G Provides a "good guideline" for fast peaks [48] 8 data points across baseline width of a Gaussian 8σ G No criterion provided [52] 36 data points per peak Approximation derived from the inverse relationship between standard deviation of the Gaussian function and its Fourier transform [17] 14 data points per peak Analysis based on allowed maximum error (0.001%) in the peak height [14] sampling frequency = CQ√N 4V e 1 + k C= no. of data points desired per peak, Q= volumetric flow rate, N = plates, V o = void volume, k= retention factor [53] Real time oversampling (up to MHz) and data averaging Shows the advantage of oversampling points into one recorded data and averaging to improve the signal to noise ratio [19] 15 data points for a Gaussian peak 15 data points for < 0.1 % error in peak area; Simpson's rule: 6 x base width [15] Data acquisition rate has no influence on band broadening and resolution Also shows an example of "hidden features" in the software causing peak distortion [21]…”

Section: Suggestions For Practitioners and Manufacturersmentioning

confidence: 99%

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Sampling frequency, response times and embedded signal filtration in fast, high efficiency liquid chromatography: A tutorial

Wahab

Dasgupta

Kadjo

et al. 2016

Analytica Chimica Acta

118

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With increasingly efficient columns, eluite peaks are increasingly narrower. To take full advantage of this, choice of the detector response time and the data acquisition rate a.k.a. detector sampling frequency, have become increasingly important. In this work, we revisit the concept of data sampling from the theorem variously attributed to Whittaker, Nyquist, Kotelnikov, and Shannon. Focusing on time scales relevant to the current practice of high performance liquid chromatography (HPLC) and optical absorbance detection (the most commonly used method), even for very narrow simulated peaks Fourier transformation shows that theoretical minimum sampling frequency is still relatively low (<10 Hz). However, this consideration alone may not be adequate for real chromatograms when an appreciable amount of noise is present. Further, depending on the instrument, the manufacturer's choice of a particular data bunching/integration/response time condition may be integrally coupled to the sampling frequency. In any case, the exact nature of signal filtration often occurs in a manner neither transparent to nor controllable by the user. Using fast chromatography on a state-of-the-art column (38,000 plates), we evaluate the responses produced by different present generation instruments, each with their unique black box digital filters. We show that the common wisdom of sampling 20 points per peak can be inadequate for high efficiency columns and that the sampling frequency and response choices do affect the peak shape. If the sampling frequency is too low or response time is too large, the observed peak shapes will not remain as narrow as they really are - this is especially true for high efficiency and high speed separations. It is shown that both sampling frequency and digital filtering affect the retention time, noise amplitude, peak shape and width in a complex fashion. We show how a square-wave driven light emitting diode source can reveal the nature of the embedded filter. We discuss time uncertainties related to the choice of sampling frequency. Finally, we suggest steps to obtain optimum results from a given system.

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Section: Suggestions For Practitioners and Manufacturersmentioning

confidence: 99%

“…It should be noted that many of the suggestions differ because the focus of the investigations differed. For example the goal some workers was to accurately render peak heights [14] or while others considered peaks areas [15,16] and some focussed on the minimum number of points needed to describe a Gaussian function [17,18].…”

Section: Introductionmentioning

confidence: 99%

Sampling frequency, response times and embedded signal filtration in fast, high efficiency liquid chromatography: A tutorial

Wahab

Dasgupta

Kadjo

et al. 2016

Analytica Chimica Acta

118

View full text Add to dashboard Cite

show abstract

“…It has been shown [19] that a Gaussian function can be described if the distance between two sample points is equal to (or smaller than) the standard deviation o of the peak. If the width of an injection is small compared to the standard deviation, a width of one point (w = 1) will be sufficient, because then the distance between two sample points is smaller than the standard deviation of the peak.…”

Section: Theorymentioning

confidence: 99%

Correlation capillary zone electrophoresis, a novel technique to decrease detection limits

et al. 1995

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General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. SummaryThe application of multiple injections and correlation techniques in capillary zone electrophoresis, a method known for its high detection limits, is described. An experimental electrokinetic injection device, particulary suited for fast and reproducible multiple injections is used in combination with a conventional CZE system. The results show a considerable reduction of the detection limit, in agreement with the experience in the already fully developed correlation chromatographic methods, and in agreement with the theoretical predicted values.

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“…Stated simply, there must be enough IMS measurements taken to constitute a definable Gaussian peak eluting from the separation device. The reconstruction of an ideal Gaussian peak with an error of 0.1% requires a minimum sampling rate to establish seven data points across the peak’s full width at half-maximum (FWHM). , For a lower margin of error, more data points are required. As an exercise to illustrate the determination of the maximum measurement time for an IMS spectra, a peak elutes from a gas chromatogram with a minimum peak width (FWHM) of 7 s results in a minimum sampling rate of .…”

Section: Introductionmentioning

confidence: 99%

Miniaturized Drift Tube Ion Mobility Spectrometer with Ultra-Fast Polarity Switching

et al. 2022

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Ion mobility spectrometers (IMS) are well suited for detecting trace gases down to levels at ppb v and even ppt v within 1 s of analysis time when using chemical ionization. The measuring principle is based on the separation and detection of the ionized constituents of a sample. Depending on the sample composition, certain ionization sources create both positive and negative analyte ions, but the simultaneous detection of both ion polarities usually requires two drift tubes. Contained within this effort, we present an alternative approach for detecting both ion polarities using one single drift tube that can switch the polarity of the drift tube within 12 ms. This technique allows for generating one positive and one negative ion mobility spectrum, each with a drift time range of 13 ms (minimum reduced ion mobility of K 0 = 0.72 cm 2 V −1 s −1 ), within a total experiment time of 50 ms. Additionally, ions are continuously generated in the ionization region during both the polarity switching and the analysis of one of the polarities, which allows for an effective ionization/reaction time of 25 ms. Comparable to the performance of similar instrument designs we reported previously, the presented device has a high resolving power of R P = 70 with a drift length of 51 mm. The limits of detection are for the monomers between 70 and 370 ppt v and for the dimers between 450 and 800 ppt v for 1 s of averaging for various ketones, methyl salicylate, and chlorinated hydrocarbons. Although this work focuses on applying ultra-fast polarity switching to an existing IMS, the techniques shown here may be applied to other IMS implementations for different applications.

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A software package for the orthogonal polynomial approximation of analytical signals, including a simulation program for chromatograms and spectra

Cited by 20 publications

References 19 publications

Sampling frequency, response times and embedded signal filtration in fast, high efficiency liquid chromatography: A tutorial

Sampling frequency, response times and embedded signal filtration in fast, high efficiency liquid chromatography: A tutorial

Correlation capillary zone electrophoresis, a novel technique to decrease detection limits

Miniaturized Drift Tube Ion Mobility Spectrometer with Ultra-Fast Polarity Switching

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