共查询到20条相似文献,搜索用时 0 毫秒
1.
Cross-correlation was implemented for flow-injection analysis by using two parallel flow lines, each with amperometric detectors, and driven by peristaltic pumps. One flow line was used to generate the reference signal for an analog correlator circuit and the other to generate the analyte signal. Cross-correlation was performed by multiplying these signals together at a time delay of zero, followed by low pass filtering. Using dopamine as a test system, improvements in signal-to-noise ratios of about two orders of magnitude were found for the correlation signal over the direct measurement of the electrode current. 相似文献
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For the determination of total phosphorus in waters by flow-injection analysis, a continuous microwave oven decomposition with subsequent amperometric detection of orthophosphate is proposed. The percentage digestion was examined for two different decomposition reagents and by varying the pH of the carrier and the length and diameter of the digestion coil. With potassium peroxodisulphate decomposition the recoveries of phosphorus vary from 91 to 100% for organic phosphorus compounds, and with perchloric acid decomposition the recoveries vary from 60 to 70% for inorganic polyphosphates. Calibration graphs are linear for up to 30 mg P l?1, the determination limit is 0.1 mg P l?1 and the precision of the method is 3% (relative standard deviation) (n = 5) at 5 mg P l?1. The sampling rate is 20 h?1. Good recoveries of phosphorus after addition to domestic waste water sample are obtained. 相似文献
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Two FIA methods for the determination of pentachlorophenol, based on its oxidizing-condensation reaction with 4-aminoantipyrine in aqueous medium and spectrophotometric detection in the conventional and stopped-flow modes, are described. In both cases the calibration graphs are linear in the range from 1.0 to 60.0 mug/ml pentachlorophenol, with sampling rates of 48 and 28 samples/hr for triplicate analysis, respectively. Interferences from phenol and other chlorophenols have been evaluated. The stopped-flow method is particularly useful for determining pentachlorophenol in commercial formulations containing no more than 15% of other chlorophenols. 相似文献
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Flow-injection analysis for the determination of hydrazine derivatives based on their nucleophilic substitution reaction with 4-chloro-5,7-dinitrobenzofurazan in aqueous medium, and spectrophotometric detection has been described. The calibration graphs were linear in the range from 0.15 to 4.0 mug ml(-1) of hydrazine derivatives, with sampling rates of up to 28-32 samples h(-1). Interferences from amino compounds, benzoic acids, aliphatic amines and ammonia have been evaluated. The procedure has been applied to the determination of hydrazine derivatives in serum, urine, appressin drugs and artificial mixtures. 相似文献
5.
Optimisation of the electrodeposition of Prussian Blue onto mirrored glassy carbon electrodes yielded a modified electrode practically insensitive to oxygen reduction. At the same time the electrode activity towards hydrogen peroxide reduction was extremely high. This allowed the detection of hydrogen peroxide by electroreduction over a wide potential range. Flow-injection investigations of this electrode inserted into a flowthrough electrochemical cell of the confined wall-jet type showed that the response for hydrogen peroxide is limited by diffusion. Glucose and alcohol biosensors were made by immobilisation of glucose oxidase and alcohol oxidase respectively, within a Nafion layer, onto the top of the Prussian-Blue-modified electrodes. By increasing the density of Nafion and decreasing the measuring potential the glucose biosensor was made completely insensitive to both ascorbate and acetominophes. 相似文献
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Bo Olsson György Marko-Varga Lo Gorton Roger Appelqvist Gillis Johansson 《Analytica chimica acta》1988
A selective and sensitive flow-injection system for the determination of myo-inositol (hexahydroxycyclohexane) is described. Inositol dehydrogenase, IDH, lactate dehydrogenase, LDH, and lactate oxidase, LOD, are co-immobilized on porous glass and used in a packed-bed enzyme reactor. myo-Inositol reacts to produce an equivalent amount of hydrogen peroxide, which oxidizes hexacyanoferrate(II) to hexacyanoferrate(III) in a second reactor containing immobilized peroxidase. The hexacyanoferrate(III) is then detected amperometrically at 0 mV vs. SCE in a flow-through detector. The system responds linearly to injected samples of myo-inositol (25 μl) in the concentration range 1–300 μM. The maximum throughput was 90 samples per hour. The IDH/LDH/LOD reactor was stable for at least 5 weeks. 相似文献
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The change in peak current resulting from the reaction of Fe(II) with nitroso-R salt in a flow-injection system is used to quantify Fe(II) with either single- or dual-electrode amperometric detectors. The current change varies linearly with Fe(II) concentration from 0 to 200 mg 1?1. The relative standard deviation was about 5% with the single-electrode detector and about 10% with the dual-electrode detector. The method is evaluated for the determination of iron in dietary supplements. 相似文献
8.
Sulphur dioxide can be determined at a sampling rate of 120 h?1, with amperometric detection after separation in a diffusion cell with a teflon membrane. At 25°C, the calibration graph shows two linear ranges, between 0.06 and 6 mg l?1 and 12 and 110 ml l? sulphur dioxide, with a detection limit of 0.03 mg l?1. At 50°C, the liner range is 04–5 mg l?1, with a detection limit of mg of l?1. The procedure has been applied to the determination of sulphur dioxide in wines. 相似文献
9.
Fanjul-Bolado P González-García MB Costa-García A 《Analytical and bioanalytical chemistry》2006,385(7):1202-1208
p-Nitrophenyl phosphate is one of the most widely used substrates for alkaline phosphatase in ELISAs because its yellow, water-soluble
product, p-nitrophenol, absorbs strongly at 405 nm. p-Nitrophenol is also electroactive; an oxidative peak at 0.97 V (vs. an Ag pseudoreference electrode) is obtained when a bare
screen-printed carbon electrode is used. When an amperometric detector was coupled to a flow-injection analysis system the
detection limit achieved for p-nitrophenol was 2×10−8 mol L−1, almost two orders of magnitude lower than that obtained by measuring the absorbance of the compound. By use of this electrochemical
detection method, measurement of 7×10−14 mol L−1 alkaline phosphatase was achieved after incubation for 20 min. The feasibility of coupling immunoassay to screen-printed
carbon electrode amperometric detection has been demonstrated by performing an ELISA for detection of pneumolysin, a toxin
produced by Streptococcus pneumoniae, which causes respiratory infections. The method is simple, reproducible, and much more sensitive than traditional spectrophotometry. 相似文献
10.
A sensitive,selective,rapid,simple,and convenient method for the determination of thoriumwas developed.The method was based on the color reaction of thorium with DBF-arsenazo in astrong acidic medium (4 mol/L HCI).The flow-injection technique was used with an automated flow-injection analyzer.Beer's law was obeyed in the range of 0—1.4 μg/mL.The relative standarddeviations were less than 1%. 相似文献
11.
Isabel Barbero Rodriguez Jesús Rodriguez Procopio Lucas Hernandez Hernandez 《Fresenius' Journal of Analytical Chemistry》1987,328(1-2):117-119
Summary Spectrophotometric and amperometric detectors were compared for the determination of clotiazepam by HPLC. Methanol-water (6040) containing 0.01 mol/l ammonium acetate and methanol-water (7030) containing 0.01 mol/l acetate buffer pH 4 were used as mobile phase in the spectrophotometric and amperometric detection, respectively. The minimum detectability for the spectrophotometric detection was 20 ng injected and the method was applied for the determination of clotiazepam in serum, whereas for the amperometric detection a limit of detection of 2.5 g injected was obtained, using this technique for clotizepam determination in tablets.
Bestimmung von Clotiazepam durch HPLC mit spektralphotometrischer und amperometrischer Detektion相似文献
12.
毛细管电泳安培法测定脂可平胶囊中的姜黄素 总被引:3,自引:3,他引:3
采用毛细管电泳柱端安培检测对脂可平胶囊中的姜黄素进行测定。着重研究了缓冲溶液浓度和酸碱度、检测电位、进样时间和高压对分离测定的影响。以微Pt电极为工作电极,电极电位为 1.0 V,以V(甲醇)∶V(乙醇)∶V(水)=5∶2∶3为非水介质,磷酸二氢钾和硼砂(pH 9.5)为缓冲体系,并用二阶样条小波进行滤波处理,姜黄素在1.0~120 mg/L范围内,峰高与其质量浓度呈良好的线性关系,线性回归方程:Y=20.2 146ρ,检出限为0.02 mg/L。 相似文献
13.
A flow-injection procedure for the determination of a commercially available fatty amine ethoxylate-based non-ionic surfactant in sea water over the range 0–50 mg l?1 is described. The procedure is based on measurement of the chemiluminescence emission resulting from oxidation of the tertiary amine group with sodium hypochlorite at pH 10.5 in the presence of Rhodamine B, which acts as a sensitizer. 相似文献
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A new approach for determining cyanide in microsamples is described. The method is based on capillary flow injection analysis (CFIA) with amperometric detection. The sensing electrode is a silver-plated microdisk electrode, where cyanide can react under formation of a dicyanoargentate complex. A remarkably low mass detection limit of 231 fmol cyanide is obtained for an injection volume of 60 nl. The sample throughput of the CFIA-arrangement is comparable with a conventional sized FIA-system. A practical application is given by analyzing the cyanide (amygdalin) concentration in apple kernels. 相似文献
16.
流动注射胶束化学发光法测定曲克芦丁 总被引:1,自引:0,他引:1
基于HCl介质中曲克芦丁与KIO4-MnSO4反应产生强的化学发光,且吐温-80的存在能使这一反应的化学发光强度大大增强。结合流动注射技术,建立了流动注射化学发光法测定曲克芦丁的新方法。在优化的实验条件下,曲克芦丁的质量浓度在2.0×10-7~8.0×10-5g/mL范围内与化学发光强度呈良好的线性关系,检出限为7×10-8g/mL。对1.0×10-6g/mL曲克芦丁进行11次平行测定,方法的相对标准偏差为1.8%。用于曲克芦丁片剂和针剂中曲克芦丁的测定。 相似文献
17.
A. Ya. Yashin 《Russian Journal of General Chemistry》2008,78(12):2566-2571
Amperometric detection in flow-injection systems intended for total determination of antioxidants (flavonoids, oxyaromatic acids, etc.) in various foodstuffs (berries, fruit, vegetables) and drinks (wine, tea, coffee, cognac, beer, etc.) was described and discussed. Advantages of this method were demonstrated. These measurements can underlie building of a bank of data on the content of antioxidants in foodstuffs and drinks. 相似文献
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Phytosiderophores of the mugineic acid family are separated by anion-exchange HPLC using NaOH gradient elution. Separation of mugineic acid (MA), 2'-deoxymugineic acid (DMA), 3-hydroxymugineic acid (HMA) and 3-epi-hydroxymugineic acid (epi-HMA) is obtained within 15 min. Detection of the underivatised phytosiderophores is performed using pulsed amperometric detection (PAD) at pH 13. The sensitivity of the detection increases in the order DMA < MA < HMA < epi-HMA and respective detection limits of 5 microM (DMA), 1 microM (MA) and < 0.5 microM (HMA, epi-HMA) are achieved. PAD is discussed in comparison with the well-established fluorimetric detection method after post-column derivatisation with ortho-phthaldialdehyde. The main advantage of PAD is the simplicity of the method (no derivatisation) and the high sensitivity for hydroxylated mugineic acids. The method is used for the determination of phytosiderophores in root washings of iron-deficient and non-deficient wheat and barley plants. 相似文献