A differential pulse polarographic method for the determination of trace amounts of osmium(VIII) using a polarographic maximum wave.

Kawasaki, Mikio; Muraguchi, Tomomi; Kakizaki, Teiji; Hasebe, Kiyoshi

doi:10.2116/bunsekikagaku.46.169

Cited by 3 publications

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“…As reported in a previous paper 5 and described above, the Os, Cys and Os-Cys species are electrochemically adsorbed on the mercury electrode. Accumulative voltammetry, therefore, was applied to the Os-Cys system.…”

Section: Accumulative Voltammetry Of Osmium-cysteinesupporting

confidence: 61%

“…The electrode potential was held at a given potential for a few minutes without stirring, and then each scan was performed by DPV over the potential range of -0.3 V to -1.0 V. Voltammograms obtained by applying an accumulation potential at -0.3 V, where a slight contribution to electrochemical adsorption 5 was observed for 30 s and 60 s, are shown in Fig. 3a.…”

Section: Accumulative Voltammetry Of Osmium-cysteinementioning

confidence: 99%

“…In our previous paper 5 , we reported on the development of an analytical method for the quantification of osmium (Os) by applying Brdicka's electrode reaction using differential pulse (DP) polarography. The paper showed the following results: (1) a highly sensitive determination of Os is feasible by adding excess cysteine (Cys) into an Os solution under strongly acidic conditions, (2) the wave height depends on both the concentration of Os and Cys, (3) only S-containing compounds possessing a thiol group exhibit activity during an electrode reaction with Os(VIII), and (4) adsorption is observed around the peak potential based on the results of electrocapillary curves.…”

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confidence: 99%

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Electrode Behavior of an Osmium-Cysteine System on a Mercury Surface

Kawasaki

Kakizaki

et al. 1999

ANAL. SCI.

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Since Brdicka 1 reported a maximum wave due to an electrode reaction between sulfur-containing compounds and transition metals, such as Co and Ni, many studies utilizing such an electrode reaction have been carried out. Even now, the application of Brdicka's reaction is being used to determine 2 S-containing compounds and to characterize 3,4 the complexes formed by such compounds.In our previous paper 5 , we reported on the development of an analytical method for the quantification of osmium (Os) by applying Brdicka's electrode reaction using differential pulse (DP) polarography. The paper showed the following results: (1) a highly sensitive determination of Os is feasible by adding excess cysteine (Cys) into an Os solution under strongly acidic conditions, (2) the wave height depends on both the concentration of Os and Cys, (3) only S-containing compounds possessing a thiol group exhibit activity during an electrode reaction with Os(VIII), and (4) adsorption is observed around the peak potential based on the results of electrocapillary curves. Furthermore, we studied the valence states of Os and an interaction between Os and Cys correlated with the occurrence of the wave. 6 The following conclusions were drawn: (1) the contribution of each valency to the maximum wave height was in the order +6>+8>+4≈+3, and (2) in a strongly acidic solution, such as HCl, HNO 3 , HClO 4 and H 2 SO 4 , there were appreciable interactions between Os and Cys. However, many questions remain unsolved concerning this electrode reaction mechanism. The experimental conditions of this Os-Cys system differ from Brdicka's ordinary reaction and the applications are as follows: (1) The reduction wave occurs only when a strong acid is used as the electrolyte solution, (2) metal ions in the high valence states exhibit an activity for the occurrence of the maximum wave, and (3) an S-containing compound not possessing a thiol group, such as cystine, thiourea and thiosemicarbazide, did not yield a maximum wave in this electrode reaction with Os. Therefore, a study was carried out to further clarify this electrode reaction process.In this paper, the electrode reaction was studied using a hanging mercury-drop electrode (HMDE) and a thin mercury film electrode (TMFE), because these electrodes can easily utilize the effect of adsorption when compared with a dropping mercury electrode. Experiments Apparatus and reagentsVoltammograms were obtained using a Bioanalytical Systems incorporated (BAS) Model BAS 100W equipped with a computer. The working electrodes were a Metrohm Model E410 HMDE or a glassy carbon electrode (GCE). The electrochemical cell was equipped with a carbon rod auxiliary electrode and an Ag/AgCl reference electrode. Osmium(VIII) oxide (Os: Merck, Germany) and L-cysteine hydrochloride monohydrate (Cys: Wako Pure Chem. Ind., Ltd., Japan) were employed. All other chemicals were of analytical reagent grade and used without further purification. Nitrogen gas was used for deaeration of the electrolyte solution. The water used for all prepar...

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Section: Accumulative Voltammetry Of Osmium-cysteinesupporting

confidence: 61%

Section: Accumulative Voltammetry Of Osmium-cysteinementioning

confidence: 99%

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confidence: 99%

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Electrode Behavior of an Osmium-Cysteine System on a Mercury Surface

Kawasaki

Kakizaki

et al. 1999

ANAL. SCI.

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“…This communication examines the interaction between osmium and cysteine, and the electrochemical behavior of the system in various acids such as hydrochloric, nitric, perchloric and sulfuric acid. All of the experimental procedures were similar to the previous study [2].Polarograms of 100 mmol/L osmium(VIII) tetraoxide in various acid solutions (1 M) were obtained by direct current polarography (DC) and shown in Figure 1. In 1.0 mol/L hydrochloric acid three reduction waves at ¹0.50, ¹0.80 and ¹1.20 V are observed (Fig.…”

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confidence: 97%

“…In our previous article [2], we describe the fact that osmium(VIII) tetraoxide, in the presence of cysteine in hydrochloric acid, also results in an unusual polarographic wave. The article showed the following results for the electrode reaction:…”

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A Catalytic Hydrogen Wave of the Osmium-Cysteine System

Kawasaki

Kakizaki

et al. 1998

Electroanalysis

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In the presence of cysteine, osmium(VIII) in hydrochloric acid exhibits a well-defined maximum wave at ¹0:85 V (vs. SCE). Effects of the osmium's valence states and the coexisting anions on the reduction wave have been studied polarographically in acidic solution. The high oxidation states (e.g., osmium(VIII) and (VI)) in comparison with low oxidation states have an influence on the height of the hydrogen wave.Keywords: Osmium, Cysteine, Maximum wave, PolarographySince Herles and Vancura's [1] first observation in 1930 of an unusual wave during the polarographic analysis of blood serum solutions in ammonia buffer, the study of a catalytic wave arising from the electrode reaction that contains sulfur compounds has been the objective of numerous studies. In our previous article [2], we describe the fact that osmium(VIII) tetraoxide, in the presence of cysteine in hydrochloric acid, also results in an unusual polarographic wave. The article showed the following results for the electrode reaction:• in acidic solution, the osmium-cysteine yields a maximum wave; • the peak current reaches a maximum when the concentration ratio of osmium/cysteine is about 2000;• the peak current is enhanced by adding cysteine more than 1000 times compared to the case where no cysteine exists;• in the presence of disulfide compounds, the wave does not occur;• the adsorption at the peak potential is observed from the result of the electrocapillary curves.However, several important questions relevant for the chemical reaction in bulk solution and the electrode reaction on the electrode surface have remained unanswered. Different experimental conditions were used because this osmium-cysteine system is different from other studies. Many studies of the 'Bridicka's current' had been carried out in the pH range of 4 to 9 and metal ions such as Co 2þ or Ni 2þ were employed. Prior studies using platinum metal also used low valence state ions in mixed solvent [3]. In our study, however, a high valence state of osmium ions was used in acidic solution. It is supposed that the chemical, nonelectrochemical, redox reaction which turns the valence state into the low state of osmium takes place in the bulk because osmium tetraoxide and cysteine are oxidizing and reducing agents, respectively. Therefore, it is unknown whether the high or low states of osmium are concerned with the appearance of a maximum wave. Kadlecek et al.[4] studied the catalytic activity of structural similar thiols and found that the activity decreases with the stability decrement of their complexes with Co II ions. Few studies [5] associated with complexing between platinum metals and low molecular weight thiols have been carried out. With respect to osmium, Medyantseva et al. [3] determined Os III with 8-mercaptoquinoline in a mixture of dimethylformamide with an acetate buffer. Aliphatic thiol compounds such as cysteine, however, have not been investigated. This communication examines the interaction between osmium and cysteine, and the electrochemical behavior of the sys...

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Highly Sensitive Determination of Paraquat and Diquat in Human Blood with Tetrabromophenolphthalein Ethyl Ester by Ion-Pair Extraction/Spectrophotometric Method

et al. 1999

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Paraquat (1,1′-dimethyl-4,4′-dipyridinium, PQ), which is toxic to humans, has been widely used as a herbicide. Poisoning cases are occasionally encountered due to accidental and intentional ingestion. Many methods such as spectrophotometry [1][2][3][4][5][6] , liquid chromatography 7-10 , flow-injection 11 , gas chromatography 12 , and electrochemistry 13,14 for the determination of PQ in biological samples have been reported.Most of these methods require a complicated and time-consuming sample pretreatment. Furthermore, most spectrophotometric methods are based on its reduction to a blue radical with alkaline sodium dithionite.2 The blue-color development, however, is unstable.Since the commercially available PQ herbicide is a mixture of PQ and DQ, it is worth developing a simple spectrophotometric method for a highly sensitive determination of PQ and DQ for forensic and clinical purposes as preliminary screening. PQ reacts with TBPE to provide an organic solvent extractable, blue-color PQ-TBPE. 15 We found that DQ can be extracted with TBPE into dichloromethane as well as PQ, and that PQ-TBPE gives a slightly different absorption spectrum from that of DQ-TBPE. In this work, an ion-pair extraction/spectrophotometric determination of the total amounts of PQ and DQ in human blood sample using TBPE was developed. Experimental ReagentsThe PQ and DQ used as standards were biochemical reagents from Wako Chemical Industry. TBPE was supplied by Kanto Chemical Co. Ltd. A standard solution of 3.00×10 -3 M (1 M=1 mol dm -3 ) TBPE was prepared by dissolving 52.5 mg of TBPE in a waterethanol (50:50(v/v)%) solution. Sodium tetraborate (0.2 M)-sodium hydroxide (0.1 M) buffer solutions were used to adjust the pH. The concentration of tetraborate was fixed at 0.02 M. A Sep-Pak C 18 cartridge (500 mg) was obtained from Waters Associates (Milford, MA, USA). Water was distilled and deionized with a Milli-Q system (Milli-Q SP. TOC., Millipore). All other chemicals were of reagent grade and were used without further purification. ApparatusThe absorption spectra and absorbances were measured by a JASCO V-560 UV/VIS spectrophotometer using a quartz cell with an optical path length of 1.0 cm. The pH measurements were carried out using a Radiometer PHM 93 pH meter. A mechanical shaker (Iwaki) was used to equilibrate the extraction vials. All of the experiments were carried out at 25˚C in a thermostated room. Extraction procedure of PQ and DQPrior to the extraction of PQ and DQ in human blood with TBPE into dichloromethane, each blood sample was deproteinized with 0.23 M perchloric acid, followed by an ultrasonic treatment. PQ and DQ in the sample solution were extracted with a Sep-Pak C 18 cartridge according to an almost similar procedure to that discussed in a reference. 16 The pH of the deproteinized sample solution (1 ml) was adjusted to about pH 11 with a sodium hydroxide solution. The sample was injected into a Sep-Pak C 18 cartridge pre-conditioned with 5 ml of water, 5 ml of methanol and 20 ml of water. Three milliliters of dist...

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A differential pulse polarographic method for the determination of trace amounts of osmium(VIII) using a polarographic maximum wave.

Cited by 3 publications

References 0 publications

Electrode Behavior of an Osmium-Cysteine System on a Mercury Surface

Electrode Behavior of an Osmium-Cysteine System on a Mercury Surface

A Catalytic Hydrogen Wave of the Osmium-Cysteine System

Highly Sensitive Determination of Paraquat and Diquat in Human Blood with Tetrabromophenolphthalein Ethyl Ester by Ion-Pair Extraction/Spectrophotometric Method

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