Flow injection determination of ethanol in whole blood using immobilized enzymes

Enzymatic methods for the determination of ethanol in whole blood are proposed. They use different types of detection and flow injection analysis (FIA) modes: fluorometric detection (use of normal FIA and stopped-flow/FIA); amperometric detection by monitoring of NADH (use of normal amperometric and pulse mode) and with the aid of a coupled enzymatic reaction (2,6-dichlorophenolindophenol/diaphorase). Determination ranges between 0.1 and 30.0 μg/ml are obtained (which in all cases comprise the legal range of ethanol in blood), with good precision and sampling frequency. The sensitivity of the methods can be manipulated by changing the injected sample volume or the pH.     

Flow injection,amperometric determination of ethanol in wines after solid-phase extraction

Ethanol in wines was determined by flow injection analysis with an amperometric detector using an oxidized nickel wire. Solid-phase extraction with a strong anion exchanger was used to remove interferences such as organic acids from the matrix, and the residue of the extraction was injected directly into the FIA system. The recoveries of ethanol from wines spiked with standards ranged from 101% to 103%. The response of the nickel electrode to ethanol is dependent on the applied potential and the pH of the carrier. The optimal conditions for the detection of ethanol were an applied potential of +0.60 V (vs. Ag/AgCl) in a carrier of 100 mM sodium hydroxide solution. The electrode exhibited a linear response from 10⁻⁵ to 10⁻³ M, with a detection limit of 1 × 10⁻⁶ M. The method was demonstrated by the determination of ethanol in wines.     

Determination of ethanol in liquor by near-infrared spectrophotometry with flow injection

A simple procedure for the determination of ethanol in a liquor by near-infrared (NIR) spectrophotometry with flow injection (FI) is proposed. A liquor sample is equilibrated off-line with dried chloroform to extract ethanol into the organic phase. The extract is injected into a carrier stream of dried chloroform passing through a home-made flow through cell (1 mm path length) sitting in a NIR spectrophotometer for continuous monitoring of absorbance at 2305 or 2636 nm. The ethanol content can be evaluated from a calibration established by a plot of change in absorbance versus concentration of ethanol standard solutions. Optimization of the system will be discussed. A calibration is linear in the range of 20–50% (v/v) ethanol. A throughput of 240 injections h⁻¹ can be obtained. The procedure is validated by comparing the results with an analysis using gas chromatography.     

Flow injection colorimetric method using acidic ceric nitrate as reagent for determination of ethanol

Ceric ammonium nitrate has been used for qualitative analysis of ethanol. It forms an intensely colored unstable complex with alcohol. In this work, a simple flow injection (FI) colorimetric method was developed for the determination of ethanol, based on the reaction of ethanol with ceric ion in acidic medium to produce a red colored product having maximum absorption at 415 nm. Absorbance of this complex could be precisely measured in the FI system. A standard or sample solution was injected into a deionized water donor stream and flowed to a gas diffusion unit, where the ethanol diffused through a gas permeable membrane made of plumbing PTFE tape into an acceptor stream to react with ceric ammonium nitrate in nitric acid. Color intensity of the reddish product was monitored by a laboratory made LED based colorimeter and the signal was recorded on a computer as a peak. Peak height obtained was linearly proportional to the concentration of ethanol originally presented in the injected solution in the range of 0.1-10.0% (v/v) (r² = 0.9993), with detection limit of 0.03% (v/v). With the use of gas diffusion membrane, most of the interferences could be eliminated. The proposed method was successfully applied for determination of ethanol in some alcoholic beverages, validating by gas chromatographic method.     

Spectrophotometric flow injection determination of chloride in ethanol

A flow injection procedure is described for the spectrophotometric determination of chloride in ethanol, based on the mercury(II) thiocyanate—iron(III) reaction. Effects of reagent composition and ethanol content of the sample are investigated in detail. The proposed system can analyse 120 samples of ethanol (94–100% v/v) per hour, with a relative standard deviation lower than 1%, when the chloride content ranges from 0.1–6.0 ppm. Recoveries of ca. 96% are found.     

流动注射化学发光法测定阿莫西林

在碱性介质中,铁氰化钾能够氧化阿莫西林产生微弱的化学发光,Na2SO3对该体系有较强的增敏作用,据此,结合流动注射技术,建立了测定阿莫西林的新方法.阿莫西林在5.0×10-8～2.0×10-5 g/mL范围内与化学发光强度呈良好的线性关系,检出限为3×10-8 g/mL,对2.0×10-6 g/mL的阿莫西林进行11次平行测定,相对标准偏差为1.5%.本法已用于胶囊中阿莫西林的测定,并初步探讨了该化学发光反应的机理.     

流动注射化学发光分析法测定卡马西平

基于酸性条件下溴化钠对NaIO4-H2O2-卡马西平化学发光反应体系具有明显的增敏作用,结合流动注射技术建立了一种测定卡马西平的新方法.在优化的实验条件下,方法的线性范围为1.0×10-9～8.0×10-6g/mL,检出限为3.6×10-10g/mL,相对标准偏差为2.5％(c=2.0×10-7g/mL,n=11),回收率在98.4％～100.6％间.     

流动注射化学发光法测定阿莫西林

在碱性介质中 ,阿莫西林抗生素对鲁米诺 KMnO4化学发光反应有增敏作用 ,据此建立了微量快速测定阿莫西林的流动注射化学发光分析法。该法线性范围为 1 .0× 1 0 -7～ 5 .0× 1 0 -5g mL ,检出限为 3.0× 1 0 -8g mL ;对 1 .0× 1 0 -6g mL阿莫西林 1 1次平行测定 ,其相对标准偏差为 1 .7%。此法已用于阿莫西林胶囊中阿莫西林的测定。     

Flow injection fluorimetric determination of thiourea

A flow injection configuration for the fluorimetric determination of thiourea is proposed. The procedure is based on the rapid oxidation of thiourea by thallium(III) with concomitant formation of fluorescent thallium(I). Linear calibration graphs were obtained between 5 x 10(-7) and 1 x 10(-5)M, with a sampling rate of 90 samples/hr. The usefulness of the method was tested in the determination of thiourea in fruit juices and fruit peels.     

流动注射化学发光分析法测定利福平

在酸性条件下,KMnO4能氧化利福平产生弱化学发光,并且,利福平能极大的增敏Na2SO3-KMnO4体系的化学发光信号。基于此,结合流动注射技术,建立了测定利福平的新方法。在优化的条件下,利福平在5.0×10-8g/mL~1.0×10-5g/mL范围内与化学发光强度呈良好的线性关系,检出限为3×10-8g/mL。对2.0×10-6g/mL的利福平进行11次平行测定,相对标准偏差为2.6%。该法用于胶囊和滴眼液中利福平的测定,并初步探讨了该化学发光反应机理。     

流动注射化学发光法测定己烯雌酚

基于己烯雌酚对鲁米诺与高碘酸钾在碱性介质中反应产生的化学发光信号有较强的增敏作用,建立了测定己烯雌酚的流动注射化学发光分析法。己烯雌酚质量浓度在13．4—1340μg／L范围内与化学发光强度呈良好的线性关系,检出限（3d）为4μg／L;对26．8μg／L己烯雌酚进行11次平行测定,相对标准偏差（RSD）为1．4％。该法已用于药物制剂中己烯雌酚的测定。     

流动注射化学发光法测定吗丁啉

在碱性条件下 ,H2 O2 氧化鲁米诺产生化学发光 ,吗丁啉对该体系的化学发光具有显著的增敏作用。基于此 ,建立了一种直接测定吗丁啉的流动注射化学发光分析法。该方法的线性范围在 1 .0× 1 0 -6～ 3.0× 1 0 -8g mL ,检出限 ( 3σ)为 5 .0× 1 0 -9g mL ,相对标准偏差为 2 .9% (n =1 1 ) ,已用于吗丁啉片剂及血清中吗丁啉的分析。     

高锰酸钾-亚硫酸钠-氨基比林化学发光体系的研究

采用流动注射技术,研究了高锰酸钾-亚硫酸钠-氨基比林体系的化学发光行为,对影响化学发光强度的诸因素进行了实验和探讨,建立了化学发光法测定氨基比林的新方法.方法的检出限为3×10-8 g/mL,线性范围为1.0 ×10-7～8.0×10-5 g/mL.对4.0×10-6 g/mL的氨基比林进行11次平行测定,得方法的相对标准偏差为1.7%.方法用于药剂中氨基比林含量的测定,结果与分光光度法测得值一致.     

流动注射化学发光法测定呋塞米

在酸性条件下呋塞米对Ce(Ⅳ)-Na_2SO_3弱化学发光体系具有很强的增敏作用,据此建立了流动注射化学发光法测定呋塞米的新方法.该法测定呋塞米的线性范围为0.01～1.0 mg/L,检出限为4×10~(-3)mg/L(3σ),RSD为2.2%(n=11,ρ=0.2mg/L),回收率为95%～105%.该法已应用于片剂和针剂中呋塞米含量的测定.     

Flow injection chemiluminescence determination of medazepam

A new flow injection chemiluminescence method for the assay of medazepam is explored. The method involves the use of permanganate in sulfuric acid for the oxidation of medazepam with the emission of chemiluminescence detected by a photomultiplier tube. A simplex procedure was employed for optimising the conditions for high sensitivity detection, which were found to be 1.03 × 10^–3 mol L^–1 permanganate, 0.153 mol L^–1 sulfuric acid and 3.43 mL min^–1 flow rate. The linear calibration range was 3.7 × 10^–5 to 1.7 × 10^–3 mol L^–1. The detection limit (3σ) and the sample throughput were 1.85 × 10^–5 mol L^–1 and 100 per hour, respectively. The relative standard deviation for 5 replicate determinations of 1.9 × 10^–4 mol L^–1 medazepam was 0.15%. Common excipients (starch, glucose, maltose, lactose) used in pharmaceutical preparations had no effect. Received: 2 February 1998 / Revised: 20 May 1998 / Accepted: 25 May 1998     

Flow injection chemiluminescence determination of paracetamol

A simple chemiluminometric method using flow injection has been developed for the determination of paracetamol (acetaminophen), based on the chemiluminescence produced by the reduction of tris(2,2′-bipyridyl)ruthenium(III). The latter is obtained by oxidation of tris(2,2′-bipyridyl)ruthenium(II) by potassium permanganate in dilute sulphuric acid in the presence of paracetamol. A standard or sample solution was injected into the ruthenium(II) stream (flow rate 1.5 ml min⁻¹) which was then merged with potassium permanganate in dilute sulphuric acid stream (flow rate 0.5 ml min⁻¹). The chemiluminescence intensity is enhanced by the presence of manganese(II) ions. Under the optimum conditions, a linear calibration graph was obtained over the range of 0.3-50.0 μg ml⁻¹ and the detection limit was 0.2 μg ml⁻¹ (s/n = 3). The relative standard deviation of the proposed method calculated from 20 replicate injections of 5.0 μg ml⁻¹ paracetamol was 1.1%. The sample throughput was 90 h⁻¹. The method was successfully applied to the determination of paracetamol in commercial pharmaceutical formulations.     

Flow injection spectrophotometric determination of nitrite

4-Nitroaniline, which gives intensely yellow solution on dissolution in dilute hydrochloric acid, has been found to react with nitrite almost instantaneously in acidic medium yielding a colourless product that has been identified as 4-nitrophenyl diazo cation. The measurement of decrease in colour intensity suggested a new, simple and one-step reaction procedure that has been used for the reversed flow injection determination of 5microg-5 mg/l. NO(2)-N. The limit of detection has been found to be 2 microg/l. NO(2)-N. A number of species such as copper(II) and lead(II), which interfere in other spectrophotometric procedures, do not affect the results. The method has been applied to determine nitrite in natural waters when the %RSD was in the range 1.8-3.5%.     

流动注射双安培法测定橙皮甙

基于橙皮甙的不可逆氧化和氧化铂的不可逆还原体系构成了双安培法直接检测橙皮甙的新方法。在外加电压为0.2 V时,通过偶合橙皮甙在一支电极上的氧化和氧化铂在另一支电极上的还原两个不可逆电极过程,构成流动注射双安培检测体系。在pH 8.95的B-R缓冲溶液中,测得橙皮甙的氧化电流与其浓度在6.0×10-6~8.0×10-4mol/L范围内呈良好的线性关系(r=0.9997,n=11),检出限为1.0×10-6mol/L。连续30次测定6.0×10-4mol/L橙皮甙,其峰电流相对标准偏差(RSD)为3.2%,常用药物赋形剂和无机离子均不干扰橙皮甙的测定。方法已用于江中健胃消食片中橙皮甙含量的测定。     

流动注射化学发光法测定盐酸普萘洛尔

在酸性条件下,KMnO4氧化盐酸普萘洛尔可产生化学发光,Fe2 的存在对于这一化学发光反应具有增敏作用,基于此建立了测定盐酸普萘洛尔的化学发光分析法。在选定的实验条件下,盐酸普萘洛尔的质量浓度在4.0×10-7～1.0×10-5g mL范围内与化学发光强度具有线性关系(相关系数为0.9992),检出限为1×10-7g mL盐酸普萘洛尔,相对标准偏差为2.9%(4.0×10-6g mL盐酸普萘洛尔,n=11)。该法已用于盐酸普萘洛尔片剂中盐酸普萘洛尔的测定,并与药典方法进行了对照。