Determination of sulphur dioxide by flow injection analysis with amperometric detection

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.     

Determination of cyanide in microsamples by means of capillary flow injection analysis with amperometric detection

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.     

Determination of the pesticides fenthion and fenitrothion by flow injection with amperometric detection

The response of a glassy carbon amperometric detector in a flow system was studied. The values of the hydrodynamic variables were optimized. The detector functioned as a “thin-layer” cell. Methods are proposed for the determination of 1.6 × 10^?7?1.6 × 10^?5 Fenthion and 8 × 10^?6? 8× 10^?5 M Fenitrothion in a methanolic acetate-buffered carrier stream. The detection limits were 0.15 and 0.52 μM, respectively.     

Indirect determination of bromide by diffusion flow injection analysis with amperometric detection

Summary A rapid, indirect diffusion flow injection analysis (FIA) method with amperometric detection has been developed for the selective and sensitive determination of Br^–. The method is based on permanganate oxidation of Br^– to bromine. Bromine diffuses through a PTFE membrane and is quantified amperometrically at a platinum working electrode. Calibration graphs were linear up to the maximum concentration of Br^– investigated (10.0 mmol/l). The precision of the technique was better than a relative standard deviation of 0.7% at 10.0 mol/l, with a throughput of 30 samples per hour. The effects of temperature, acidity, working potential, composition of the reagent solution and interferents on the FIA signals were studied. The catalytic effect of Cl^– on the permanganate oxidation of the analyte was utilized to lower the detection limit to 1 mol/l (16 ng Br^–). Similar detection limits were achieved by combining the effects of higher acidity (4.0 mol/l H₂SO₄) and elevated temperatures (40°C). The method was successfully applied to the determination of Br^– in chloride and other reagents, as well as in natural waters.     

流动注射化学发光法测定盐酸美司坦

在碱性介质中,当把鲁米诺和KMnO4的混合溶液注入到盐酸美司坦溶液中时,会产生很强的化学发光现象。由此结合流动注射技术,建立了测定盐酸美司坦的流动注射化学发光新方法。该法的线性范围为2.0×10^-7-8.0×10^-6g/mL,检出限（3σ）为9×10^-8g/mL,对2.0×10^-6g/mL盐酸美司坦样品连续进行11次平行测定,其RSD为0.74%。已用于盐酸美司坦片剂中盐酸美司坦的测定。     

Determination of prazosin in pharmaceutical samples by flow injection analysis with multiple-pulse amperometric detection using boron-doped diamond electrode

This work describes the development of a simple, fast and low-cost method for determining prazosin (PRA) in pharmaceutical samples by flow injection analysis with multiple-pulse amperometric (FIA-MPA) detection using a boron-doped diamond film electrode. Electrochemical detection of PRA was optimized in phosphate buffer pH 4.0 by cyclic voltammetry, in which PRA presented two oxidation processes around at 0.97 and 1.40 V versus Ag/AgCl (3.0 mol L^?1 KCl). In these conditions, PRA also showed one reduction process at ?0.75 V that is dependent on the oxidation processes. Thus, the determination of PRA by FIA-MPA detection consisted on the application of a two-potential waveform, E ₁ (generator potential)?=?1.6 V/400 ms and E ₂ (collector potential)?=??1.0 V/30 ms, with sample loop of 150 μL and flow rate of 3.0 mL min^?1. The method showed good repeatability (RSD?<?3.0 %) and high analytical frequency (70 injections per h). The working linear range was obtained from 2 to 200 μmol L^?1 with a limit of detection of 0.5 μmol L^?1. The recovery tests in all samples were approximately 100 %, and the results were compared with chromatographic methods.     

Determination of sucrose by flow injection analysis with fourier transform infrared detection

A new methodology for the determination of sucrose in complex aqueous matrices by flow injection analysis with FTIR detection is presented. The methodology based on the enzymatic hydrolytic cleavage of sucrose by means of invertase to -D-glucose and -D-fructose. A special manifold consisting of two internally coupled injection valves being switched simultaneously is applied to facilitate recording FTIR spectra of the sample before and after the enzymatic reaction. The analytical readout is taken from the resulting difference spectrum obtained by subtracting the FTIR spectra of the sample before and after the reaction. The developed methodology uses a GC-IR software to continuously record the FTIR spectra of the effluent from the manifold. The proposed method gives linear results in the range of 10 to 100 mmol/l and has been successfully applied to the analysis of sucrose in synthetic mixtures as well as in real samples such as soft drinks.     

流动注射-化学发光法测定非洛地平

基于非洛地平在碱性条件下对鲁米诺-K3Fe(CN)6化学发光体系具有很强的增敏作用,结合流动注射技术,建立了直接测定非洛地平的流动注射-化学发光新方法.方法的线性范围为6.0×10(-9)～3.0×10(-6)g/mL,检出限为2.1×10(-9)g/mL,对浓度为1.0×10(-7)g/mL非洛地平平行测定11次,其...     

Determination of ascorbyl 6-palmitate in food matrices by amperometric flow injection analysis

In this paper a rapid method based on a FIA (flow injection analysis) system with amperometric detection for the evaluation of ascorbyl 6-palmitate in foods is described. The selectivity of the proposed method is related to the low anodic potential applied to the working glassy carbon electrode (+0.1 V vs. Ag/AgCl) that leaves out interferences from ascorbic acid and phenolic compounds. By flow injection analysis, under optimised conditions, the calibration curve was linear in the range 0-20 mg l(-1) and the detection limit was 0.2 mg l(-1).     

流动注射-化学发光法测定富马酸依美斯汀

在酸性条件下,KMnO4与甲醛能够产生微弱的化学发光,而富马酸依美斯汀的存在能够大大增强该化学发光强度;结合流动注射技术,建立了测定富马酸依美斯汀的流动注射-化学发光新方法。该方法的线性范围分别为3.0×10-8～2.0×10-7g/mL,2.0×10-7～1.0×10-6g/mL和1.0×10-6～8.0×10-6g/mL。检出限为1.0×10-8g/mL,对2.0×10-6g/mL富马酸依美斯汀滴眼液平行测定11次,其相对标准偏差为1.3%。该方法已成功应用于滴眼液中富马酸依美斯汀的含量测定。     

精氨酸的流动注射化学发光法测定

在碱性介质中,精氨酸对硫氰化钾 鲁米诺化学发光体系有增敏作用,建立了用硫氰化钾 鲁米诺 精氨酸体系测定精氨酸的新方法。用该方法测定精氨酸的线性范围为0.01～2.0μg/mL,检出限0.01μg/mL,采样频率为190次/h,对3μg/mL的精氨酸连续平行测量10次,RSD为1.2%。用该方法对皮革屑中酶法提取的精氨酸进行了测定,并与氨基酸测定仪测定的结果进行了比较。     

Determination of carbaryl by flow injection with luminol chemiluminescence inhibition detection

A flow-injection procedure is described for the determination of carbaryl based on its inhibition effect on luminol-cobalt(II) chemiluminescence reaction in alkaline medium in the presence of hydrogen peroxide. The calibration data over the range 5.0?×?10^?7 to 20?×?10^?6?M give a correlation coefficient (r ²) of 0.9972 with relative standard deviations (RSD; n?=?4) in the range of 1.0–2.1% with a limit of detection (3?×?blank noise) of 2.37?×?10^?7?M for carbaryl. The sample throughput was 120?h^?1. The effects of some carbamates, anions, and cations were studied on luminol CL system for carbaryl determination. The proposed method has been applied to determine carbaryl in natural waters.     

Determination of phenylephrine hydrochloride by flow injection analysis with chemiluminescence detection

A new method is proposed for the determination of phenylephrine hydrochloride by flow injection analysis with direct chemiluminescence detection. The method is based on the oxidation of the drug by potassium permanganate in sulfuric acid medium at 80 degrees C. The calibration graph is linear over the range 0.03-8 ppm phenylephrine hydrochloride, with a relative standard deviation (n = 51, 0.5 ppm) of 1.1% and sample throughput of 134/h. The influence of 38 different foreign compounds was tested, and the method was applied to the determination of phenylephrine hydrochloride in 8 different pharmaceutical formulations.     

Flow injection analysis of doxycycline or chlortetracycline in pharmaceutical formulations with pulsed amperometric detection

A flow injection with pulsed amperometric detection for determination of doxycycline or chlortetracycline in pharmaceutical formulations is described. Doxycycline or chlortetracycline were studied at a gold rotating disk electrode with cyclic voltammetry as a function of pH of supporting electrolyte solution. The optimized PAD waveform parameters were obtained with a flow injection system. The optimized pulsed conditions of doxycycline were 1150 mV (versus Ag/AgCl reference electrode) detection potential (E_det) for 220 ms (150 ms delay time and 70 ms integration time), 1500 mV (versus Ag/AgCl reference electrode) oxidation potential (E_oxd) for 70 ms oxidation time (t_oxd) and 250 mV (versus Ag/AgCl reference electrode) reduction potentail (E_red) for 400 ms reactivation time (t_red). The optimized pulsed conditions of chlortetracycline were 1050 mV (versus Ag/AgCl reference electrode) detection potential (E_det) for 300 ms (200 ms delay time and 100 ms integration time), 1300 mV (versus Ag/AgCl reference electrode) oxidation potential (E_oxd) for 70 ms oxidation time (t_oxd) and 250 mV (versus Ag/AgCl reference electrode) reduction potentail (E_red) for 400 ms reactivation time (t_red). The optimized PAD waveform was applied to the determination of doxycycline hydrochloride and chlortetracycline hydrochloride standard solution and in pharmaceutical formulations. The linear dynamic ranges of doxycycline hydrochloride and chlortetracycline hydrochloride were 1 μM–0.1 mM. The sensitivity of this method was found to be 23 μA/mM for doxycycline hydrochloride and 33.76 μA/mM for chlortetracycline hydrochloride. The detection limit for both compounds is 1 μM. The doxycycline hydrochloride and chlortetracycline hydrochloride content in commercially available tablet dosage forms by the proposed method was comparable to those specified by the manufacturer.     

Determination of trace amounts of chromium (VI) by flow injection analysis with chemiluminescence detection

A new sensitive chemiluminescence (CL) method combined with continuous flow injection analysis is described for the determination of Cr(VI). Strong CL signals were generated by Cr(VI)-catalysed oxidation of gallic acid in the presence of potassium permanganate and hydrogen peroxide. Effects of reagent concentrations, temperature, pH, flow rates, mixing coil length and mixing flow sequences on the chemiluminescence intensity were studied. Under the optimised experimental conditions, the relationship between the logarithm of concentration (log?C) of Cr(VI) and the logarithm of intensity (log?I) is linear over the range of 2?×?10^?11 – 5?×?10^?4?mol?L^?1, with the detection limit (3σ) of 4?×?10^?12?mol?L^?1. Relative standard deviation of ten measurements of 1?×?10^?9?mol?L^?1 Cr(VI) is 1.7%. This flow injection analysis (FIA) system proved to be able to analyse up to 40 samples h^?1. Effects of various interferences possibly present in the water samples were investigated. Most cations and anions, as well as organic compounds, did not interfere with the determination of Cr(VI) in water samples. The experimental results obtained for chromium in reference materials were also in good agreement with the certified values.     

Application of amperometric sol-gel biosensor to flow injection determination of glucose

A glucose biosensor with enzyme immobilised by sol–gel technology was constructed and evaluated. The glucose biosensor reported is based on encapsulated GOX within a sol–gel glass, prepared with 3-aminopropyltriethoxy silane, 2-(3,4-epoxycyclohexyl)-ethyltrimetoxy silane and HCl. A flow system incorporating the amperometric biosensor constructed was developed for the determination of glucose in the 1×10⁻⁴–5×10⁻³ mol l⁻¹ range with a precision of 1.5%. The results obtained for the analysis of electrolytic solution for iv administration and human serum samples showed good agreement between the proposed method and the reference procedure, with relative error <5%.     

流动注射化学发光法测定青霉素G钾

在甲醛的存在下,酸性KMnO4与青霉素G钾能够产生很强的化学发光,从而建立了KMnO4-甲醛-青霉素G钾化学发光体系来测定青霉素G钾.青霉素G钾的测定线性范围为2.0×10-7～1.0×10-5 g/mL,方法的检出限为1.4×10-7 g/mL,对4.0×10-7 g/mL的青霉素G钾进行11次平行测定,相对标准偏差为1.0%,用此法测定青霉素G钾取得了较好的结果.