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A membrane-based optical flow-through sensor is described which can be alternatively used for absorbance and reflectance detection within the receiver channel of a sandwich-type gas-diffusion separation cell. Using the common spectrophotometric detection scheme for nitrite based on azo-dye formation, the principle features of the flow-through sensor are investigated and the performance is characterised...
Addition of a sodium hypochlorite solution (9.2% (w/v)) was effective to reduce a sulfide interference in determination of organic mercury, including methylmercury and phenylmercury, as well as a previously reported determination of inorganic mercury by cold vapor atomic absorption spectrometry (CVAAS) in an alkaline medium. Total mercury ranging from 0.17 to 33μgL -1 in 15mL of sample...
The use of 3-indoxyl phosphate (3-IP) as an electrochemical substrate for ELISAs with voltammetric detection was investigated. Indirect measurements of alkaline phosphatase (AP) and horseradish peroxidase (HRP) activity in solution were carried out. Picomolar levels of both enzymes can be detected, which enables the design of electrochemical immunoassays using this substrate. The enzymatic turnover...
A highly sensitive and virtually specific method has been developed for the trace and ultra trace 5ngml -1 -1μgml -1 fluorimetric analysis of nitrite. The method is based on the quenching action of nitrite on the native fluorescence of murexide (ammonium purpurate) [λ ex =349.0nm, λ em =444.5nm] in the acid range of 0.045-0.315 (M) H 2 SO...
The spectral distribution for the chemiluminescent oxidation of ammonia with hypobromite is significantly different to that for the oxidation of ammonia with N-bromosuccinimide. Therefore, in contrast to the assumptions of several authors, the action of N-bromosuccinimide is not solely derived from the in situ formation of hypobromite. Neither the oxidation of urea with hypobromite nor the oxidation...
Qualitative and quantitative analysis of organophosphorus pesticide residues (acephate and trichlorphon) using temperature modulated SnO 2 gas sensor were studied. The testing method employed only a single SnO 2 -based gas sensor in a rectangular temperature mode to perform the qualitative analysis of pure pesticide vapor and a binary vapor mixture in the air. Experimental results...
This study was undertaken to establish one of the most reliable sampling methods and to precisely evaluate the bias involved in the collection of airborne pollutant samples. For the purpose of our study, we investigated the performance of three different types of sampling techniques by measuring major aromatic volatile organic compounds (VOC) in outdoor air; the target analytes specifically include...
Flow injection hydride generation atomic absorption spectrometry (FI-HGAAS) was used for determination of lead in dialysis concentrates. The parameters such as acidity, concentration of oxidising and reducing agents and argon gas flow rate were investigated to reach the best peak height sensitivity. No significant background signal was observed at high salt concentrations. The detection limit, concentration...
In this paper, the solid-phase spectrophotometric concept is critically examined in flow systems exploiting a dedicated microcolumn-based optical sensor packed with octadecyl chemically-modified silica gel. The flow configuration integrates matrix separation with pre-concentration and on-column sensing of non-polar complexes resulting from analyte derivatization. The design criteria for optimum performance...
Extraction of dry cured ham volatile compounds by solid-phase microextraction (SPME) was optimized. Different fiber coatings (carboxen/polydimethylsiloxane (CAR/PDMS), divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS), polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB)), times of extraction (15, 30, 60min) and sample preparation (ground samples and homogenates with...
A novel multi-walled carbon nanotubes/(3-mercaptopropyl)trimethoxysilane (MPS) bilayer modified gold electrode was prepared and used to study the electrochemcial behavior of fluphenazine and determine it. Fluphenazine could effectively accumulate at this electrode and produce two anodic peaks at about 0.78V and 0.93V (versus SCE). The peak at about 0.78V was much higher and sensitive, thus it could...
The formation of open chain polyammonium cation-fluoride and -carbonate complexes was studied by potentiometric and calorimetric techniques at t=25 o C. Several species of H i AL (A=amine; L=F - , CO 32- ) are formed in both systems with a mean stability logK=1.0ζ (ζ=|z anion xz cation |) and logK=2...
The aim of this work is the application of Stocks and Miller capillary electrophoresis (CE) method in order to evaluate the human LDL susceptibility to Cu 2+ -induced oxidation. Lipid peroxidation determines a change in the relative electrophoretic mobility (REM) of lipoprotein that can be monitored by capillary electrophoresis using uncoated fused silica capillaries and tricine-methylglucamine...
The use of natural and synthetic anabolic steroids in animal fattening has been prohibited in Taiwan and many countries because of their potential toxic effect on public health. This paper describes a newly developed gas chromatography-ion trap-mass spectrometry (GC-IT-MS) method for the quantitative determination of various residual anabolic steroids in meat. Anabolic steroid was derivatized with...
A glucose biosensor using an enzyme-immobilized eggshell membrane and oxygen electrode for glucose determination has been fabricated. Glucose oxidase was covalently immobilized on an eggshell membrane with glutaraldehyde as a cross-linking agent. The glucose biosensor was fabricated by positioning the enzyme-immobilized eggshell membrane on the surface of a dissolved oxygen sensor. The detection scheme...
Inorganic arsenic, a term which encompasses both As (III) and As (V) species, constitutes the highest toxicological risk associated with arsenic in water in contrast to the organic arsenic species. Different determination methods of inorganic arsenic have been developed over 40 years providing timely and efficient risk assessments of inorganic arsenic contamination world wide. The current report gives...
In this work, methodologies were developed to determine aluminum (Al), cadmium chromium and lead in drinking water by electrothermal atomic absorption spectrometry using permanent modifiers. No use of modifier, iridium, ruthenium, rhodium and zirconium (independently, 500μg) were tested to each one analyte through the pyrolysis and atomization temperatures curves. As the matrix is very simple, did...
In this work the viability of a fluorescent technique for the determination of quinolones is studied. This analytical technique allows one to analyze the effect of the increasing order of the analytical signal from a univariate calibration (zero order data) to partial least squares (PLS) calibration (first order). The comparison has been done through the figures of merit of the analytical procedure...
A new HPLC-UV-Vis method for identification of drying oils from binding media or protective film used in pictorial works of art prior to conservation or restoration is proposed. Chromophore derivatization of fatty acids released by hydrolysis of structural drying oils is studied. The derivatization reagent selected was 2-nitrophenylhydrazine with 1-ethyl-3-(3-dimethyl animopropyl)carbodiimide hydrochloride/pyridine...
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