PREPARATION OF POLY(PYROMELLITIC DIANHYDRIDE-CO-THIONIN) MODIFIED VOLTAMMETRIC SENSOR FOR THE DETERMINATION OF EPICATECHIN

In this study, the electrochemical oxidation of epicatechin and its voltammetric sensing is shown at a sensitive platinum electrode modified with poly(pyromellitic dianhydride-co-thionin). The electrochemical response of the sensor was improved in the presence of both electro-inactive (sucrose, fructose, lactose) and electroactive (gallic acid, cafeic acid, ascorbic acid) interferants and displayed an excellent analytical performance for the determination of epicatechin. A linear response was obtained over a range of epicatechin concentrations from 0.05 mM to 0.30 mM and was shown to be useful for quantifying low levels of epicatechin in phosphate buffer solution, PBS, pH 7.00. Regression coefficient (R2) was found to be to be 0.9969. Limit of detection (LOD) was calculated as 1.8 × 10-5 M by using 3s/m. Where m is the slope of the calibration curve and s is the standard deviation of the calibration graph calculated using the Excel Steyx function

Sensitivity improvement for antimony determination by using in-situ atom trapping in a slotted quartz tube and flame atomic absorption spectrometry

Significant improvement has been achieved for antimony determination using a slotted quartz tube (SQT) as an atom trap (AT) for in situ preconcentration and flame atomic absorption spectrometry (FAAS). The suggested technique consists of trapping analyte species during ordinary nebulization followed by releasing the collected analyte via introducing organic solvent. Procedures and analytical figures of merit have been presented for the techniques called FAAS. SQT-FAAS and finally SQT-AT-FMS with the relevant comparisons. Analytical parameters, namely composition of the aqueous medium, sample flow rate, flame conditions, distance between burner head and SQT, sampling period and type of organic solvent and its volume have been optimized. Using SQT-AT-FAAS, a sensitivity enhancement of 369 fold has been obtained, 3 s limit of detection was 3.91 mu g L-1 when 25.0 mL of sample was collected in 4.0 min. Interference effects of some elements on antimony signal were studied

Determination of antimony by using tungsten trap atomic absorption spectrometry

35th Biennial Colloquium Spectroscopicum Internationale -- SEP 23-27, 2007 -- Xiamen, PEOPLES R CHINAWOS: 000258815800009An electrically heated tungsten coil was used as a trap in the determination of antimony. The technique consists of three steps. Initially, SbH(3) is formed by hydride generation procedure; then the analyte species in vapor form are transported to W-coil trap heated at 370 degrees C. Following the preconcentration step, the trap is heated to 895 degrees C; analyte species are revolatilized and transported to the flame-heated quartz atom cell where atornization and the formation of signal take place. The experimental parameters were optimized both for trap and no-trap studies. The most important experimental parameters are concentrations of HCI and NaBH4 solutions. H2 and At gas flow rates. and collection and revolatilization temperatures of W-coil. Accuracy was tested using a certified reference material, waste water EU-L-1. Limit of detection for the system is 16 ng 1- 1 using a sample of 36 ml collected in 4.0 min. Enhancement factor in sensitivity was 17. (c) 2008 Elsevier B.V. All rights reserved.Chinese Chem Soc, Chinese Phys Soc, Chinese Spectroscopy Soc, Natl Nat Sci Fdn China, Xiamen Municipal Govt, Xiamen Uni

Determination and interference studies of bismuth by tungsten trap hydride generation atomic absorption spectrometry

WOS: 000271055700017PubMed ID: 19782201The determination of bismuth requires sufficiently sensitive procedures for detection at the mu g L-1 level or lower. W-coil was used for on-line trapping of volatile bismuth species using HGAAS (hydride generation atomic absorption spectrometry); atom trapping using a W-coil consists of three steps. Initially BiH3 gas is formed by hydride generation procedure. The analyte species in vapor form are transported through the W-coil trap held at 289 degrees C where trapping takes place. Following the preconcentration step, the W-coil is heated to 1348 degrees C; analyte species are released and transported to flame-heated quartz atom cell where the atomic signal is formed. In our study, interferences have been investigated in detail during Bi determination by hydride generation, both with and without trap in the same HGAAS system. Interferent/analyte (mass/mass) ratio was kept at 1, 10 and 100. Experiments were designed for carrier solutions having 1.0 M HNO3. Interferents such as Fe, Mn, Zn, Ni, Cu, As, Se. Cd, Pb, Au, Na, Mg, Ca, chloride, sulfate and phosphate were examined. The calibration plot for an 8.0 ml. sampling volume was linear between 0.10 mu g L-1 and 10.0 mu g L-1 of Bi. The detection limit (3 s/m) was 25 ng L-1. The enhancement factor for the characteristic concentration (C-o) was found to be 21 when compared with the regular system without trap, by using peak height values. The validation of the procedure was performed by the analysis of the certified water reference material and the result was found to be in good agreement with the certified values at the 95% confidence level. (C) 2009 Elsevier B.V. All rights reserved.Mugla University SKV (Sitki Koqman Foundation)Mugla Sitki Kocman UniversityI Kula is grateful for the post-doc scholarship of Mugla University SKV (Sitki Koqman Foundation)

Estimation of human daily boron exposure in a boron-rich area

Although, the safe limits of human daily boron (B) exposure are not absolutely clear, there is a growing interest in B and its effects on human health. The aim of the present study was to estimate daily B exposure in 66 males in Turkey living in a B-rich area using water containing at least 2 mg/1 boron, with an average age of 38-55 (SE 1.66) years and an average number of years of residence in the B-rich area of 35-89 (SE 1.73). Another group of males (n 57), living in the city centres of Balikesir and Ankara, were taken as controls; the average age and number of years of residence for this group were 29-44 (SE 1-43) and 10-26 (SE 1.83) years, respectively. As it is assumed that the B level in urine reflects daily B exposure, the amount of urinary B of both the study and control groups was analysed by using an inductively coupled plasma optical emission spectrometry (ICP-OES) technique. The average daily B exposure value was calculated as 6.77 (SE 0.47) mg in the study group and 1.26 (SE 0-1) mg in the controls. The results of this study are expected to contribute to creating a reference value for a safe daily B exposure

From mg/kg to pg/kg Levels: A Story of Trace Element Determination: A Review

Determination of the trace elements in a variety of environmental samples is of great importance. Most elements, including iron, calcium, and selenium, are crucial for the regulation of human mechanisms, and many others, like lead and cadmium, are toxic even at trace levels. Some elements, like selenium, have a narrow margin of safety. Hence, determination of elements at trace levels is crucial in any matrix related to humans. Trace element determination requires sufficiently sensitive procedures to monitor trace levels. This review aims to highlight not only the development in instrumentation for ultratrace element determination in variety of matrices but the application of developed techniques. Advantages and disadvantages of the techniques are also discussed