Facile synthesis of platinum nanoparticle-containing porous carbons,and their application to amperometric glucose biosensing

This study describes the facile synthesis of platinum nanoparticle-containing porous carbons (Pt/C) by carbonization of freeze-dried agarose gels containing potassium tetrachloroplatinate under a nitrogen atmosphere at 800 °C. By adjusting the ratio between agarose and platinate in the freeze-dried gels, the Pt content in the final Pt/C products could be systematically varied from 0–10 wt.%. Transmission electron microscopy, inductively coupled plasma atomic emission spectrometry, X-ray photoelectron spectroscopy, Raman spectroscopy, and nitrogen physisorption measurements revealed that the Pt/C materials obtained by this method possess high surface areas (350–500 m² g⁻¹), narrow Pt nanoparticle size distributions (6 ± 3 nm) and nanocrystalline graphite –like carbon character. By immobilization of glucose oxidase on the surface of a 4 wt.% Pt/C electrocatalyst prepared by this route, a very sensitive amperometric glucose biosensor was obtained (response time <2 min, sensitivity 1.9 mA M⁻¹; and a linear response with glucose concentration up to 10 mM). The simplicity and versatility of the described synthetic method suggests its application to the preparation of carbon supported noble metal catalysts including palladium/C and gold/C.

This study describes the facile synthesis of platinum nanoparticle-containing porous carbons (Pt/C) by carbonization of freeze-dried agarose gels containing potassium tetrachloroplatinate. The Pt/C materials exhibited excellent electrocatalytic activities, as demonstrated by their successful integration into amperometric glucose biosensor

     

Multielement monitoring for dissolved and acid-soluble concentrations of trace metals in surface seawater along the ferry track between Osaka and Okinawa as investigated by ICP-MS.

Multielement monitoring of the concentrations of trace metals dissolved in surface seawater collected at sampling stations along the ferry track between Osaka and Okinawa was performed by ICP-MS (inductively coupled plasma mass spectrometry). The surface seawater samples were collected by an automated sampling system for on-board sampling, which was installed on the bottom of a ferryboat. A part of each seawater sample was filtered with a membrane filter (pore size of 0.45 microm) immediately after sampling. Both filtered and non-filtered seawater samples were acidified to pH ca. 1 by adding conc. HNO3, and were subjected to chelating resin preconcentration for the determination of trace metals by ICP-MS, where the concentrations of analyte metals in the filtered and non-filtered seawater samples were referred to as the dissolved and total concentrations, respectively. According to the thus-obtained results, it was found that most trace metals, especially below the 0.01 microg l(-1) as the dissolved and total concentrations, sensitively reflected the environmental pollution in the Osaka Bay and Seto Inland Sea area, as well as near to the Bungo Canal and the outlet of Kagoshima Bay.     

Facile synthesis of platinum nanoparticle-containing porous carbons,and their application to amperometric glucose biosensing

This study describes the facile synthesis of platinum nanoparticle-containing porous carbons (Pt/C) by carbonization of freeze-dried agarose gels containing potassium tetrachloroplatinate under a nitrogen atmosphere at 800 °C. By adjusting the ratio between agarose and platinate in the freeze-dried gels, the Pt content in the final Pt/C products could be systematically varied from 0–10 wt.%. Transmission electron microscopy, inductively coupled plasma atomic emission spectrometry, X-ray photoelectron spectroscopy, Raman spectroscopy, and nitrogen physisorption measurements revealed that the Pt/C materials obtained by this method possess high surface areas (350–500 m² g^?1), narrow Pt nanoparticle size distributions (6 ± 3 nm) and nanocrystalline graphite –like carbon character. By immobilization of glucose oxidase on the surface of a 4 wt.% Pt/C electrocatalyst prepared by this route, a very sensitive amperometric glucose biosensor was obtained (response time <2 min, sensitivity 1.9 mA M^?1; and a linear response with glucose concentration up to 10 mM). The simplicity and versatility of the described synthetic method suggests its application to the preparation of carbon supported noble metal catalysts including palladium/C and gold/C. Figure

This study describes the facile synthesis of platinum nanoparticle-containing porous carbons (Pt/C) by carbonization of freeze-dried agarose gels containing potassium tetrachloroplatinate. The Pt/C materials exhibited excellent electrocatalytic activities, as demonstrated by their successful integration into amperometric glucose biosensor     

Development of a D-amino acids electrochemical sensor based on immobilization of thermostable D-proline dehydrogenase within agar gel membrane

A novel biosensor for determination of d-amino acids (DAAs) in biological samples by using an electrode based on immobilization of a thermostable d-Proline dehydrogenase (d-Pro DH) within an agar gel membrane was developed. The electrode was simply prepared by spin-coating the agar solution with the d-Pro DH on a glassy carbon (GC) electrode.An electrocatalytic oxidation current of 2,6-dichloroindophenol (DCIP) was observed at −100 mV vs. Ag/AgCl with the addition of 5 and 20 mmol L⁻¹d-proline. The current response and its relative standard deviation were 0.15 μA and 7.6% (n = 3), respectively, when it was measured in a pH 8.0 phosphate buffer solution containing 10 mmol L⁻¹d-proline and 0.5 mmol L⁻¹ DCIP at 50 °C. The current response of d-proline increased with increase of the temperature of the sample solution up to 70 °C. The electrocatalytic response at the d-Pro DH/agar immobilized electrode subsequently maintained for 80 days. Finally, the d-Pro DH/agar immobilized electrode was applied to determination of DAAs in a human urine sample. The determined value of DAAs in the human urine and its R.S.D. were 1.39 ± 0.12 mmol L⁻¹ and 8.9% (n = 3), respectively.     

Characterization of a glucose sensor prepared by electropolymerization of pyrroles containing a tris-bipyridine osmium complex.

A glucose sensor was developed by electrocopolymerization using pyrroles containing a tris-bipyridine (bpy) osmium complex (Os-py), pyrrole (py), pyrrole propanoic acid (PPA) and glucose oxidase (GOx) to improve the key performance characteristics, such as the sensitivity, selectivity, and long-term stability. Tris-bipyridine osmium pyrrole complexes with four different methylene moieties were utilized to correlate the methylene length with the glucose sensor performance. The electrocatalytic response of glucose was clearly observed at electrodes modified with Os-py, except for the electrode immobilized with the Os-py complex containing the shortest methylene moiety. The current response to glucose increased up to a concentration of 100 mmol dm(-3). The electrocatalytic response to glucose at the [Os(bpy)(2)(py(6)-bpy)](2+/3+)/py/PPA/GOx electrode was stable for more than 100 days. Dissolved oxygen and potential interference compounds (ascorbic acid, uric acid, and acetaminophen) minimally perturbed the current response to glucose at the [Os(DM-bpy)(2)(py(6)-bpy)](2+/3+)/py/PPA/GOx electrode. Based on these results, a longer methylene moiety appears to improve the performance characteristics of a glucose sensor fabricated via the electropolymerization of tris-bipyridine osmium pyrrole complexes.     

Simultaneous determination of trimethyl-and triethyllead in urban dust by species-specific isotope dilution/gas chromatography-inductively coupled plasma mass spectrometry

Both (206)Pb-labeled trimethyllead (TML) and triethyllead (TEL) were synthesized from (206)Pb-enriched metallic Pb certified reference material (NIST SRM 983) and iodomethane or iodoethane through a one-process reaction in a closed system using centrifuge tubes, respectively. Organolead compounds in an urban dust reference material (BCR CRM 605) were extracted with an acetic acid/methanol (1:1) solution, which was mechanically shaken for 24 h. After adjusting the pH of the extracted solution to pH 5, the extracted organolead compounds were derivatized by tetrabutylammonium tetrabutylborate (TATB) and measured with GC-ICPMS. The analytical results of TML and TEL for BCR CRM 605 were 8.22 +/- 0.04 microg kg(-1) (mean +/- standard deviation, n = 3) and 1.12 +/- 0.06 microg kg(-1), respectively. The analytical results of TML agreed well with the certified value (7.9 +/- 1.2 microg kg(-1)).     

A multielement masking method using magnesium hydroxide coprecipitation for the selective determination of lead in water samples by differential pulse anodic stripping voltammetry.

We present a new multielement masking method using magnesium hydroxide coprecipitation for the selective determination of Pb by differential pulse anodic stripping voltammetry (DPASV). The recovery of Pb in the masking method was over 95%, while interfering ions (Cd(2+), Co(2+), Cu(2+), Fe(3+), Mn(2+), and Ni(2+)) could be removed at 100% from the analytical sample. A linear regression was obtained in the Pb concentration from 10 to 1000 microg kg(-1) in the existence of 100 microg kg(-1) of the interfering ions. When this method was applied to the determination of Pb in a natural water-standard reference material (NIST 1640), the determined value for Pb in this work (25.4 +/- 4.1 microg kg(-1)) almost agreed with the certified value (27.89 +/- 0.14 microg kg(-1)).