Recent Developments in Alternating Current Polarography

Smith, Donald E.; Bauer, Henry H.

doi:10.1080/10408347108542765

Cited by 37 publications

(7 citation statements)

References 142 publications

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“…The use of second harmonic alternating current polarography has had limited popularity as an electroanalytical tool (1-10). Its major use has been in kinetic studies (1)(2)(3)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23), in which the parameters (rate constant and transfer coefficient) of the electron-transfer step can often be obtained more conveniently than by faradaic impedance measurements.…”

Section: Discussionmentioning

confidence: 99%

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Excited singlet state acidity constants for hydroxy and amino substituted anthraquinones and related compounds. Comparison of excited-state pK measurement procedures

Richtol¹,

Fitch²

1974

Anal. Chem.

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that their means were equal except for 2:31Pa where the F ratio was barely significant.Additional data were obtained on precision by applying t h e procedure t o 500-ml samples of a uranium mill process waste known to contain about 3 mg of cerium and four times the 100-pg limit for the electrodeposition of 2,'3nTh. This sample was chosen to represent one of the worst cases for t,he determination of thorium. T h e results of the five replicate analyses are summarized in Table V, and an alpha spectrum of the thorium fraction is shown in Figure 4. Alpha spectra were obtained under the conditions described by Sill and Olson (31 ) to minimize recoil at~om contamination of the solid state detector. T h e counting efficiency for the ""Ac fractions was reduced to correct for the additional precipitate formed from cerium present in the sample. Thorium recoveries were determined with ','j4Th tracer and ranged from only 8 t o 25% because of large losses in the electrodeposition.In spite of the large thorium losses. the relative deviation of an individual result from the mean was only 4')/0 for r:ioTh, but 9, 16, and 5% for 2:iaTh, ?.STh, and "25Th, respectively. A major factor in the variance of the ?;'"Th results was the large correct,ion applied for the contribution of degraded ':ioTh alpha particles in the ';"'Th energy region. T h e relative uncertainties of just the numbers of counts were approximately 8 to 12% and 2 to 4% in the ' "Th and 22TTh energy regions, respectively. T h e wide variance of the results for '2,'i1Pa was due to its large and erratic losses on silica from the process waste sample and also in the electrodeposition. In such cases, thorium recoveries are not reliable estimates of ',jlPa recoveries. and the results were included in Table V merely to emphasize this point. T h e relative deviations of individual results about (31) C. W . Sill and D. G. Olson, Anal. Chem. , 42, 1596 (1970) the means for 2 2 7 A~, 228Ra, and 2zsRa were 2 to 4%, about the same as the precision for 2 2 7 A~ and 22sRa in the series of pitchblende ore analyses.Sensitiuity. T h e following detection limits for 500-ml liquid and 100-m" air samples were calculated for paired observations (32) and are merely intended t o illustrate the sensitivities of the procedure under the conditions specified.T h e blank activity for the determination of 2zsRa by either gross-alpha counting' or the emanation method is about 25 cph, which results in detection limits for gross counting and emanation counting, respectively, of 1 X 10-9 and 3 X 10-lo pCi/ml for liquid samples and 4.5 X 10-15 and 1.4 X pCi/ml for air samples. T h e 228Ra blank of about 195 counts per 50 minutes is equivalent to a detection limit of 2.5 X 10-9 pCi/ml for a liquid sample and 1.2 X pCi/ml for a n air sample. However, decay of the 6.13-hour 228Ac used for the indirect determination of 2L'xRa results in a practical detection limit 1.5 to 2 times these values. T h e blank for ";Ac is about 7 cph, and the detection limit is 6 X pCi/ml for air samples. Gross alpha blank...

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Section: Discussionmentioning

confidence: 99%

“…Buffer solutions of 33% dioxane-water in the pH range [1][2][3][4][5][6][7][8][9][10][11][12][13][14] were prepared by using appropriate mixtures of the following in deionized water solutions: HC1, HOAc, NaOAc, KH9PO4, NaOH, H;iBO:¡. Each buffer was brought up to constant ionic strength by adding an appropriate amount of KC1.…”

Section: Methodsmentioning

confidence: 99%

Excited singlet state acidity constants for hydroxy and amino substituted anthraquinones and related compounds. Comparison of excited-state pK measurement procedures

Richtol¹,

Fitch²

1974

Anal. Chem.

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“…In addition, small amounts of a third apolipoprotein which probably also belongs to the lipoprotein A family could be found in subfraction 3 and was therefore designated as ApoAIII [7]. The protein part of lipoprotein B, the major family of low-density lipoprotein subfraction 3 has not been characterized entirely, and there seems to be some disagreement concerning the amount, type and molecular weight of the polypeptides found in this lipoprotein [8,9]. Apolipoprotein C, first demonstrated in very-low-density lipoprotein as a third class of apolipoproteins [lo], was found to be composed of four different polypeptides [ll].…”

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confidence: 99%

Polypeptide Distribution of the Main Lipoprotein Density Classes Separated from Human Plasma by Rate Zonal Ultracentrifugation

et al. 1974

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The polypeptide distribution of lipoprotein density fractions isolated from normal human serum by rate zonal ultracentrifugation was investigated by polyacrylamide gel electrophoresis and qualitative and quantitative immunochemical methods. I n very-low-density lipoproteins all known apoA and apoC peptides were present in amounts similar to these preparations from fixed-angle rotors. Low-density apolipoproteins consisted primarily of apoB (98 Oi0) but some small amounts of apoAIII and apoCIII were also present. No region of 100 apoB, uncontaminated by A and C peptides could be isolated by subfractionation of the low-density peak. There were marked differences in thc protein part of the high-density lipoprotein subfractions 2 and 3, as compared to these subfractions separated in the angle-head rotor. The weight ratio apoAI : apoAII was found to be approximately three times as high for subfraction 2 as for subfraction 3. I n addition, apoAIII was detectable only in subfraction 3. Of the known apoC peptides, apoCII was present in both fractions only in trace amounts, while the concentration of apoCI was in the order of I o/o and that of apoCIII, and of apoCIII, in the order of 1.5 O i 0 . Apolipoprotein B was not detectable in subfraction 2 . Two density regions were found with small amounts of lipoproteins consisting only of apoAI polypeptides. A peak corresponding to subfraction 1 of the highdensity lipoprotein from fixed-angle rotor preparations could not be detected in the eluate of zonal rotors after 24-h runs; the low-density lipoprotein peak was symmetrical in all experiments. Lipoproteins present in the bottom fraction amounted to about 2.5-4O/, of the total lipoprotein content. The only apolipoprotein found in this fraction was apoA1.It now seems to be widely accepted that individual lipoprotein density classes are composed of several lipoprotein families, i.e. separate entities with identical prot,ein moities [l -41. Although from analytical isoelectric focusing experiments a minimum of 8 different lipoprotein subpopulations can be expected [5], only three main lipoprotein families could be isolated from human plasma on a preparative scale and characterized by chemical and physicochemical means. Lipoprotein A represents the major family in high-density lipoprotein subfractions 2 and 3 and consists of two major nonidentical polypeptides, ApoAl and ApoII [2,6]. In addition, small amounts of a third apolipoprotein which probably also belongs to the lipoprotein A family could be found in subfraction 3 and was therefore designated as ApoAIII [7]. The protein part of lipoprotein B, the major family of low-density lipoprotein subfraction 3 has not been characterized entirely, and there seems to be some disagreement concerning the amount, type and molecular weight of the polypeptides found in this lipoprotein [8,9]. Apolipoprotein C, first demonstrated in very-low-density lipoprotein as a third class of apolipoproteins [lo], was found to be composed of four different polypeptides [ll]. These polypeptides, which w...

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“…The former approach is pulse voltammetry [16][17][18], differential pulse [19,20] and square-wave [21][22][23] versions being the most effective. Current selection by phase is implemented in alternating current voltammetry [24][25][26][27], and sinusoidal voltammetry [28][29][30] in particular. Various stripping techniques are also powerful tools for sensitivity enhancing as the faradaic current is increased due to analyte preconcentration [31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Interrupted amperometry: An ultrasensitive technique for diffusion current measuring

Belebentseva

Navolotskaya

Ermakov

et al. 2016

Electrochimica Acta

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Recent Developments in Alternating Current Polarography

Cited by 37 publications

References 142 publications

Excited singlet state acidity constants for hydroxy and amino substituted anthraquinones and related compounds. Comparison of excited-state pK measurement procedures

Excited singlet state acidity constants for hydroxy and amino substituted anthraquinones and related compounds. Comparison of excited-state pK measurement procedures

Polypeptide Distribution of the Main Lipoprotein Density Classes Separated from Human Plasma by Rate Zonal Ultracentrifugation

Interrupted amperometry: An ultrasensitive technique for diffusion current measuring

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