Determination of picomole amounts of formaldehyde in air and bio-fluids based on its enhanced myoglobin-luminol chemiluminescence reaction

Abstract

The aim of this study was to assess the performance of selected destruction methods for the determination of heavy metals (Cd, Cu, Pb and Zn) in woodlouse (Oniscus asellus). A vigorous total analysis involving microwave destruction with HF, HCl and HNO₃ (method 1) was used as a reference method. Consistently low values for the dry ashing method may indicate incomplete dissolution of the elements and/or losses through volatilisation. Method 3 (concentrated HNO₃) that frequently is used in literature, produced erroneous values for Cd, Cu and Pb. Results were consistent with the microwave digestion, provided H₂O₂ was used during digestion (method 4, HNO₃/H₂O₂). Method 5 (HNO₃/HCIO₄, one destruction step) yielded low recoveries when only one destruction step was applied. Applying two destruction steps (method 6) resulted in values consistent with the microwave method, but was at the expense of reproducibility and rendered the method more lengthy and laborious. Because of the very good performance combined with speed and simplicity, destruction with HNO₃/H₂O₂ (method 4) emerged as the most convenient method.     

纳米银催化的鲁米诺化学发光体系测定呋喃硫胺的研究

基于纳米银能够增强鲁米诺-H2O2-呋喃硫胺体系化学发光的现象,建立了测定呋喃硫胺的流动注射化学发光新方法.对体系的化学发光机理进行了初步探讨,发现该体系的化学发光光谱的最大发射波长为425nm,该体系的发光体为激发态的3-氨基邻苯二甲酸根离子.该方法测定呋喃硫胺的线性范围为1.0×10-8～1.0×10-5g/mL,检出限4×10-9g/mL,对1.0×10-6g/mL呋喃硫胺连续9次测定的相对标准偏差(RSD)为1.9％.方法已用于药物呋喃硫胺片中呋喃硫胺的测定.     

Determination of fenfluramine based on potassium permanganate-calcein chemiluminescence system

Calcein was found to be able to use as chemiluminescence reagent and post-chemiluminescence was observed when fenfluramine was injected into the mixture after the CL reaction of calcein–potassium permanganate. Based on this phenomenon, a flow injection CL method was established for the determination of fenfluramine. The possible CL mechanism was proposed. The CL intensity was correlated linearly with the concentration of fenfluramine over the range of 1.0 × 10⁻⁷ to 6.0 × 10⁻⁶ g mL⁻¹ and the detection limit was 6 × 10⁻⁸ g mL⁻¹. The relative standard deviation was 2.2% for 5.0 × 10⁻⁷ g mL⁻¹ fenfluramine (n = 11). This method was applied to the determination of fenfluramine in weight-reducing tonic successfully.     

流动注射化学发光抑制法测定阿魏酸钠

提出了Fe2+-H2O2-亚甲基蓝化学发光新体系并用于阿魏酸钠的测定。实验发现,在酸性介质中,Fe2+-H2O2体系可与亚甲基蓝反应产生极强的化学发光,阿魏酸钠对此化学发光具有显著的抑制作用。据此,结合流动注射技术,建立了阿魏酸钠化学发光分析新方法。研究了影响化学发光强度的因素,化学发光信号的降低值(ΔI)与阿魏酸钠浓度在4.5×10-6～4.5×10-5mol/L范围内呈良好的线性关系,方法的检出限为7.0×10-7mol/L。对4.8×10-6mol/L的阿魏酸钠进行了11次平行测定,其RSD=0.8%,该法已用于片剂中阿魏酸钠含量的测定。     

Determination of bisphenol A in water via inhibition of silver nanoparticles-enhanced chemiluminescence

Sensitive detection of trace bisphenol A (BPA) in water samples has been accomplished via inhibition of luminol chemiluminescence (CL) by BPA on the silver nanoparticles (AgNPs)-enhanced luminol–KMnO₄ CL system for the first time. Under the optimized experimental conditions, the CL intensity was found to be proportional to the concentration of BPA ranging from 1.0 × 10⁻⁸ to 5.0 × 10⁻⁵ g L⁻¹. The detection limit (3σ) was estimated to be 1 × 10⁻⁹ g L⁻¹. Such a concentration level is approximately 1–4 orders of magnitude lower than those reported by other methods. The feasibility of the method for determination of BPA in real water samples has been demonstrated. Via examining CL and UV–vis spectra of the CL system, possible mechanism inherent in the AgNPs-enhanced CL assay and the follow-up inhibition of BPA on the above system was proposed. The method described herein is simple, selective and obviates the need of extensive sample pretreatment.     

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 asulam by fast stopped-flow chemiluminescence inhibition of luminol/peroxidase

An efficient, sensitive and fast stopped-flow method has been developed to determine asulam in water, based on its inhibition effect on the horseradish peroxidase-luminol-hydrogen peroxide chemiluminescence reaction, (HRP-luminol-H₂O₂). Ultra fast data acquisition (0.20 s) facilitates excellent selectivity because no interferences from concomitants in the matrix act in such short time scale. The precision as repeatability (expressed as relative standard deviation, n = 10) was 0.4% at a 40 pM level. The detection limit was 1.5 pM (0.35 ng/L) and 7.15 pM in pure and raw water, respectively. The calibration data over the range 5-60 pM present a correlation coefficient of r = 0.9993. The proposed method has been applied to determine asulam in water samples by using solid-phase extraction (SPE). Mean recovery value was 98.1 ± 2% at 50 pM level.     

流动注射化学发光抑制法测定维生素E

实验发现,H2SO4-KMnO4-甲醛在丙酮存在下发光信号大大增强,据此建立了H2SO4-KMnO4-甲醛-丙酮新体系。同时发现维生素E(VE)对H2SO4-KMnO4-甲醛-丙酮化学发光体系有强烈的抑制作用,建立了维生素E的流动注射化学发光抑制法的新体系。化学发光信号的降低值与VE的浓度在1.0×10-5~1.0×10-3mol/L的范围内呈良好的线性关系,方法的检出限为3.0×10-6mol/L。对1.0×10-4mol/L的VE进行11次平行测定,其相对标准偏差为1.5%。该法已用于VE片剂中VE的测定。     

Determination of nitrite by inhibition of the chemiluminescence of acriflavine in a flow-injection assembly

The indirect determination of nitrite was performed with a flow-injection assembly on the basis of the inhibition of the analytical output obtained in a luminometer by oxidation of acriflavine. The acriflavine solution merged with the nitrite and the resulting mixture was injected into a pure water stream. This solution merged with the oxidant solution (potassium permanganate in sulfuric acid medium) and the resulting chemiluminiscence was affected (inhibited) by the presence of nitrite after reaction with the aminoacridine. The method was applicable over the range 10-800 microg l(-1) of nitrite with a correlation coefficient of 0.9960. The relative standard deviation was 1.4% and the throughput was 76 samples h(-1). The influence of foreign substances was also tested. A solid-phase reactor, filled with Amberlite IRA-900, was inserted in the assembly for the on-line preconcentration of nitrite; the analytical output resulted in an increase of up to 11.5-fold. The method was applied to the determination of nitrites in residual waters, industrial formulations and soil samples.     

Determination of methimazole and carbimazole by flow-injection with chemiluminescence detection based on the inhibition of the Cu(II)-catalysed luminol-hydrogen peroxide reaction

This paper reports an indirect flow-injection (FI) method for the determination of the anti-hyperthyroid drugs methimazole and carbimazole in pharmaceuticals. The method was based on the inhibition that these thioimidazole drugs caused on the Cu(II)-catalysed chemiluminescence (CL) reaction between luminol and H₂O₂. The CL reaction was induced on-line and injection of the sample produced negative peaks as a result of the Cu(II) complexation by the analytes. The height of the FI peaks was proportional to the drug concentration in the sample. The linear range was 2-100 and 3-120 mg l⁻¹ for methimazole and carbimazole, respectively. The relative standard deviation was 1.9% for methimazole and 2.1% for carbimazole at the 50 mg l⁻¹ level (n=10). Common excipients present in pharmaceutical tablets were found not to interfere with the analysis. The method was applied to the determination of methimazole and carbimazole in pharmaceutical formulations with recoveries in the range 100±4%.     

Determination of folic acid by chemiluminescence based on peroxomonosulfate-cobalt(II) system

Based on the chemiluminescence (CL) phenomena of folic acid in peroxomonosulfate-cobalt(II) system, a rapid and sensitive CL method was developed for determination of folic acid in pharmaceutical preparations and its urinary metabolism processes. Under the optimum conditions, the relative CL intensity was linear over the concentration ranging from 10⁻⁹ to 8 × 10⁻⁷ mol L⁻¹ (R² = 0.9991) with a detection limit as low as 6 × 10⁻¹⁰ mol L⁻¹ (S/N = 3) and relative standard deviation was 2.63% for 2 × 10⁻⁸ mol L⁻¹ folic acid (n = 11). This method has been successfully applied to the determination of folic acid in tablets and human urine. The blank CL emission was yielded owing to the formation of singlet oxygen molecular pair from the quenching experiment of 1,4-diazabicyclo[2.2.2]octane, and pterine-6-carboxylic acid might be the degradation intermediate in this system and it also acts an energy acceptor and sensitizes the chemiluminescence based on the studies of the CL and fluorescence spectra.     

纳米金催化鲁米诺-硝酸银化学发光新体系测定头孢哌酮钠

在碱性条件下,以金纳米粒子为催化剂的鲁米诺-硝酸银发光体系,可产生很强的化学发光,头孢哌酮钠对该体系有抑制作用,基于此建立了一种测定头孢哌酮钠的新方法.在最佳实验条件下,用该法测定头孢哌酮钠的线性范围为5.0×10~(-7)~9.0×10~(-4) g/mL,检出限为1.0×10~(-7) g/mL,相对标准偏差为1.6%(ρ=3.0×10~(-6)g/mL,n=11).该法简便、快速、且线性范围宽,将其用于药物制剂中头孢哌酮钠含量的测定,测得平均回收率为101.2%,结果令人满意.     

Determination of bisphenol A based on chemiluminescence from gold(III)-peroxymonocarbonate

Peroxymonocarbonate (HCO₄⁻) was produced by the online reaction of bicarbonate with hydrogen peroxide. A strong chemiluminescence (CL) was observed when HCO₄⁻ reacted with AuCl₄⁻ without any special CL reagent. When bisphenol A (BPA) was added to AuCl₄⁻-HCO₄⁻ CL system, the CL emission was inhibited significantly. This new CL system was developed as a flow-injection method for the determination of BPA. Under the optimum experimental conditions, the inhibited CL intensity was linearly related to the concentration of BPA from 0.3 to 80 μM (R = 0.9958). The detection limit of BPA was 0.08 μM. The relative standard deviation for 12 repeated measurements of 1.0 μM BPA was 2.9%. The interferences of some cationic ions can be removed by an online cation-exchange column. The applicability of the present CL system was demonstrated for the sensitive and selective determination of BPA in real samples (mineral water bottle, baby bottle, beverage bottle and polycarbonate container). Based on the CL spectrum, UV-visible adsorption spectra, and the quenching effect of reactive oxygen species scavengers, a possible CL mechanism was proposed.     

Determination of nitrite in tap waters based on fluorosurfactant-capped gold nanoparticles-enhanced chemiluminescence from carbonate and peroxynitrous acid

Fluorosurfactant (FSN)-capped gold nanoparticles (GNPs), which exhibit higher stability at a wider pH range and high ionic strength, were utilized for investigating the chemiluminescence (CL) effect on the reaction between high concentration carbonate (~0.3 M) and peroxynitrous acid. When the pH of the colloidal solution was 10.2 by dropwise addition of 0.05 M NaOH, FSN-capped GNPs offer an enhanced CL intensity. Based on the CL spectra, XPS spectra and the quenching effect of reactive oxygen species, a possible CL mechanism is proposed. The tolerance of FSN-capped GNPs towards salt concentrations (salt proofing effect) within a large pH range is an interesting feature, compared to the other previously reported work on nanoparticles CL systems. The CL intensity is proportional to the concentration of nitrite in the range from 0.1 to 100 μM. The detection limit (S/N = 3) is 0.036 μM and the relative standard deviation (RSD) for seven repeated measurements of 0.5 μM nitrite was 2.4%. This method has been successfully applied to determine nitrite in tap waters with recoveries of 97-106%.     

鲁米诺-焦性没食子酸体系抑制化学发光法测定5-磺基水杨酸

基于碱性介质中5-磺基水杨酸对鲁米诺-焦性没食子酸体系化学发光的抑制作用,建立了流动注射化学发光测定5-磺基水杨酸的新方法.在最佳实验条件下,测定5-磺基水杨酸的线性范围为1.0×10-7～1.0×10-5mol/L,相关系数为0.9996(n=5),检出限为6.8×10-8mol/,L(n=11),对1.0×10-6...     

Determination of nickel in water by chemiluminescence

The acetone chemiluminescence determination of nickel in water was investigated. Optimization data for the determination of Ni2+ and interference data for over 20 species are provided. The limit of detection for Ni2+ by this method is 2.5 ng ml-1, and the linear dynamic range is from 10 ng ml-1 to 1 microgram ml-1. The application of the method to the determination of Ni2+ in river and waste waters is discussed.     

鲁米诺-高锰酸钾体系化学发光法测定5-磺基水杨酸

基于碱性介质中5-磺基水杨酸对鲁米诺-KMnO4体系化学发光的增强作用,建立了流动注射化学发光法测定5-磺基水杨酸的新方法。最佳实验条件下,测定5-磺基水杨酸的线性范围为5.0×10-6~8.0×10-4mol/L,线性相关系数为0.9994(n=8),检出限为3.8×10-6mol/L(n=11),对5.0×10-5mol/L的5-磺基水杨酸进行测定,其相对标准偏差为1.4%(n=11)。方法应用于强力霉素废水中5-磺基水杨酸的测定。     

Determination of phenol by flow-injection with chemiluminescence detection based on the hemin-catalysed luminol-hydrogen peroxide reaction

This study established a novel flow injection (FI) methodology for the determination of phenol in aqueous samples based on luminol chemiluminescence (CL) detection. The method was based on the inhibition that phenol caused on the hemin-catalysed chemiluminescence reaction between luminol and hydrogen peroxide in alkaline solution. Optimum conditions and possible mechanisms have been investigated. The linear range was 2.0×10(-9) to 4.0×10(-7)gmL(-1) for phenol. The proposed method is sensitive with a detection limit of 4.0×10(-10)gmL(-1). The relative standard deviation for 11 measurements was 2.3% for 1.0×10(-7)gmL(-1) phenol. The method was applied for the determination of phenol in waste water samples. The results obtained compared well with those by an official method.     

Determination of phosphate based on inhibition of crystal growth of calcite

The growth of calcium carbonate seed crystals (calcite) is strongly inhibited by the presence of phosphate ions. The kinetics of crystal growth were followed potentiometrically using a calcium ion-selective electrode or through the use of a pH electrode. The study of different variables on such a process was carried out with the aim of developing kinetic methods to determine phosphate ions (50–400 ng ml^?1). The selectivity and sensitivity of these processes allow the application of crystallization reactions to the determination of phosphate in human urine.