Versatile instrument for pulse width measurement

Dasgupta, Purnendu Κ.; Loree, Ellis L.

doi:10.1021/ac00293a059

Cited by 9 publications

(5 citation statements)

References 29 publications

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“…As a measure of the peak width, we use the time necessary for the current to decay to half that of the starting value, termed 1/2. This quantity is easily and precisely measured by a voltage activated timer such as that described in ref 21. The values of /2 for 56 anions under specified operating conditions are presented in Figure 7; the width indicates the 95% confidence limit.…”

Section: Resultsmentioning

confidence: 99%

Identification of ions in anion chromatography by stopped flow chronoamperometry

Okada¹,

Dasgupta²,

Qi³

1989

Anal. Chem.

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Section: Resultsmentioning

confidence: 99%

Identification of ions in anion chromatography by stopped flow chronoamperometry

Okada¹,

Dasgupta²,

Qi³

1989

Anal. Chem.

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“…The pulse width counter described earlier [9] is essentially a signal-switched stopwatch of 10 ms resolution that starts counting the time when the input signal rises above some preset (0.1--1 V) value and stops counting as the input signal falls below some other, independently preset, value. can Instruments, Santa Clara, CA) produces an analog output voltage linearly related to the conductance (a sensitivity setting of 1 mS/ volt was used in this work); large amounts of positive or negative offset can be applied to the output voltage.…”

Section: Methodsmentioning

confidence: 99%

“…The input stage functions as a unity-gain inverting amplifier; it is directly connected to the detector output. As soon as the flip-flop senses that the input to it has changed from high to low, its output flips to high (5 V) and the pulse counter [9] connected to the output begins to count. An adjustable reference voltage is supplied to the comparator; this is the signal threshold voltage at which the comparator output changes.…”

Section: All All Determination Systemmentioning

confidence: 99%

Measurement of total alkali and phenol in process liquor by FIA

Sweileh¹,

Dasgupta²,

López³

1986

Mikrochim Acta

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Flow injection analysis (FIA) has been applied to the determination of total phenol and total alkali in high concentration alkaline phenoxide liquors as it occurs in industrial process streams. The total alkali content and total phenol content in samples containing 20--50% (w/v) sodium phenoxide can be directly measured without mutual interference. The first is measured by peak width measurement based FIA with conductimetric detection utilizing an electronic circuit to permit automatic measurement from minima to minima. The total phenol is measured by the Berthelot reaction using NaOC1 and ammonia to form indophenol blue, monitored at 660 nm with a light emitting diode-based detector.Phenol is used for a great variety of products: dyes, plastics, explosives, medicines and perfume. Concentrated aqueous phenol liquors (20--50% w/w) are involved in its manufacturing [1]. These solutions typically contain up to a 10% stoichiometric excess or deficit of sodium hydroxide. Other compounds generally occur only in traces. Reliable routine determinations of total alkali (sodium phenoxide and free sodium hydroxide, if any) and total phenol (phenoxide + free phenol, if any) are necessary in this caustic, corrosive, and odorous liquor. Direct photometric measurements in the UV to determine total phenol suffers from errors due to pH variation; the absorbance at the phenol-phenoxide isosbestic point is too high for convenient measurement.

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“…If the assumption is made that dispersion oc curs only in the mixing chamber of the manifold, in accordance with that of a single well-stirred tank, the time between the two peaks, !J.t, can be related to a number of system parameters by the following equation: Dasgupta and Loree [6] have developed instru mentation for peak width measurements in FIA and liquid chromatography (LC). Previous work by our group involved the development of a sim ple instrument for doublet-peak measurements suitable for use in teaching laboratories [7].…”

Section: Introductionmentioning

confidence: 99%