Determination of copper in industrial water by innovative flow injection flame atomic absorption spectrometry

An online flow injection procedure for the preconcentration of copper at µg L^?1 levels was developed using a novel chelating resin and flame atomic absorption spectrometry for the analysis of industrial water. Amberlite XAD-2 functionalized with dithizone resin was packed in a minicolumn for flow injection. The pH, sample and eluent flow rates, and eluent concentration were optimized to ensure maximum recovery of Cu(II). The effect of concomittant ions on Cu (II) sorption was also investigated. The limit of detection and enrichment factor for a 180 s preconcentration time were 76 and 0.6 µg L^?1, respectively. The resin offered precision of 1.0% for seven successive determinations of 100 µg L^?1 Cu(II). The resin was used for more than 300 sorption and desorption cycles without appreciable loss of efficiency. The accuracy of the preconcentration procedure was confirmed by fortified recovery studies in industrial water with NIST certified copper nitrate with recovery exceeding 96%. Validation was performed by the analysis of a standard reference material.     

DETERMINATION OF TRACE CADMIUM BY FLOW INJECTION ON-LINE MICROCOLUMN PRECONCENTRATION COUPLED WITH FLAME ATOMIC ABSORPTION SPECTROMETRY USING HUMAN HAIR AS A SORBENT

A novel method using a cone-shaped pipette tip packed with human hair as an adsorption material has been developed for the on-line flow injection preconcentration of trace Cd(II) ions based on its complex formation with the ammonium pyrrolidine dithiocarbamate (APDC) prior to flame atomic absorption spectrometric (FAAS) determination. Cd-PDC complex sorbed on the human hair was eluted by 4.0 mol L^?1 HNO₃. The enhancement factor is 19, and the detection limit (3σ) is 0.77 μg L^?1. The proposed method was successfully applied to the determination of trace cadmium in drinking water, beverage samples, and the certified reference materials.     

Determination of Cadmium and Lead in Water and Food by Organic Drop Microextraction and Flame Atomic Absorption Spectrometry

Single-solidified floating organic drop microextraction was used for the preconcentration and determination of Cd(II) and Pb(II). The procedure employed 1-(2-pyridylazo)-2-naphthol as a chelating agent, 1-undecanol as the extractant solvent, and methanol as the dispersive solvent. Factors influencing the recovery of Cd(II) and Pb(II) such as the pH, volume of extractant, volume of ligand, volume of dispersant, and stirring time were optimized by Plackett Burman design. In order to complete the optimization, a central 2³ +star orthogonal composite design was applied. The limits of detection for Cd(II) and Pb(II) were 0.15 and 0.52 μg L^?1. The validation of the procedure was evaluated by the analysis of TMDA 70 Fortified Water and NCSDC–73349 Bush Branches certified reference materials. The determined values were in good agreement with the certified values. The single-solidified floating organic drop microextraction method was employed for the determination of cadmium and lead in water, vegetables, and fruit.     

Column Solid Phase Extraction of Copper and Nickel on Triethylenetetramine Bonded Silica Gel for their Atomic Absorption Spectrometric Determination

Abstract

A procedure for the preconcentration of Cu(II) and Ni(II) is proposed using a minicolumn filled with silica gel modified by triethylenetetramine. The retained analytes on the modified silica gel were eluted with hydrochloric acid solution. The metal ions in the eluate were determined by flame atomic absorption spectrometry. The effect of various factors, such as pH of the sample solution, sample volume, flow rate of the sample solution, type of eluent, and matrix content of the sample solution, on preconcentration were examined to obtain optimum conditions. The recoveries for Cu(II) and Ni(II) ions under optimum preconcentration conditions were 98.3±1.3 and 99.2±1.4% at 95% confidence level, respectively. The analytical detection limits of Ni and Cu were found to be 0.22 and 0.36 µg L^?1, respectively. The proposed method was applied to the determination copper and nickel in river and synthetic sea water.     

On‐Line Preconcentration System for Cobalt Determination in Bee Honey Using Flow Injection‐Flame AAS

Abstract

A methodology for the on‐line preconcentration and determination of cobalt by flame atomic absorption spectrometry (FAAS) coupled with flow injection (FI) in bee honey samples is proposed. For the retention of cobalt, 2‐(5‐bromo‐2‐pyridylazo)‐5‐diethylaminophenol (5‐Br‐PADAP) complexing reagent, and Amberlite XAD‐7 resin were used, at pH 9.5. The Co‐(5‐Br‐PADAP) complexes were completely removed from the column with ethanol. An enrichment factor (EF) of 50‐fold for a sample volume of 50 mL was obtained. The detection limit (DL) for the preconcentration of 50 mL of aqueous solution was 0.18 µg L^?1. The precision for 10 replicate determinations at the 10 µg L^?1 cobalt levels was 3.6% relative standard deviation (RSD), calculated with peak heights obtained. The calibration graph using the preconcentration system for cobalt was linear with a correlation coefficient of 0.9997 at levels near the DL, up to at least 300 µg L^?1. The method was successfully applied to determination of total cobalt in honey samples.     

Determination of Lead in Spiked Seawater Samples by Electrothermal Atomic Absorption Spectrometry using Chemical Modifiers

Abstract

The determination of lead in spiked sodium chloride solution with 3.4% salinity and natural sea‐water samples by electrothermal atomic absorption spectrometry (ETAAS) with Zeeman‐effect background correction was investigated using neodymium, samarium, and erbium salts as modifiers with the addition of citric acid (CA) as a reducing agent. In order to demonstrate the high potential of rare earth metals in combination with citric acid, optimum pyrolysis temperature, atomization temperature, and optimum masses of neodymium, samarium, and erbium were found for the determination of lead. These modifiers were used for the determination of lead in sodium chloride solution with 3.4% salinity and in natural sea water samples by means of the calibration graphs prepared with pure analyte solutions.

The detection limits for lead spiked sample matrices were calculated with the 2σ criterion between 2.0 to 2.1 ng mL^?1 for neodymium and citric acid, between 5.3 to 7.4 ng mL^?1 for samarium and citric acid, and between 1.7 to 2.1 ng mL^?1 for erbium and citric acid and for a sample volume of 10 µL. The recoveries for lead spiked sea water samples were 97–102%, with neodymium and citric acid modifier and erbium and citric acid modifier. They were only 66–68% without modifier.     

HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY DETERMINATION OF ANILINES WITH FLUORESCENT DETECTION AND PRE-COLUMN DERIVATIZATION

A simple, sensitive, and rapid reverse-phase high-performance liquid chromatography (RP-HPLC) method for the determination of anilines in water is proposed. The use of 2,7-diethylamino-2-oxo-2H-chromen-3-yl-benzothiazole-6-sulfonylchloride (coumarin 6-SO₂Cl) as a fluorigenic-labeling reagent was investigated. The label reacted with aniline within 30 min under mild conditions (ambient temperature, pH 9.0) to give sulfonamides that were separated by RP-HPLC employing fluorescence detection with an excitation wavelength of 470 nm and an emission wavelength of 520 nm. The optimum conditions for fluorescence, derivatization, and chromatographic separation were established. The calibration curves were linear for the range 0–800 ppb. The proposed method was applied for the determination of anilines in spiked drinking water samples and irrigation water samples with recoveries of 90.0–103.9% and relative standard deviations of 1.2–4.7%, respectively. This method showed good accuracy and repeatability that can be used for the quantification of aniline in real samples.     

DETERMINATION OF LEAD(II) BY FLOW-INJECTION ANALYSIS USING LUMINOL-POTASSIUM PERIODATE POST-CHEMILUMINESCENCE REACTION

The post-chemiluminescence (PCL) phenomenon arising from the potassium periodate–luminol reaction induced by lead(II) was investigated. A strong PCL signal was observed when lead(II) was injected into the mixture of potassium periodate and luminol in a flow-cell. The influencing factors on the PCL intensity of the system were investigated. Under the optimum experimental conditions, the present method allowed the determination of lead(II) in the concentration range of 1.0 × 10^?8 to 1.0 × 10^?5 mol/L and the detection limit for lead(II) was 2.3 × 10^?10 mol/L. The relative standard deviation was 3.2% for 11 replicate analyses of 1.0 × 10^?6 mol/L lead(II). Combined with cotton cellulose xanthate for separation, the proposed method was applied to the determination of lead(II) in real water samples with satisfactory results.     

ON-LINE MINI-COLUMN SOLID-PHASE EXTRACTION COUPLED WITH SEQUENTIAL INJECTION FOR THE DETERMINATION OF CADMIUM IN ENVIRONMENTAL SAMPLES

□Trace cadmium(II) in environmental samples was separated and enriched in an automated fashion using a diphenylcarbazone-functionalized silica gel mini-column coupling with sequential injection. Cadmium was determined using a multicomponent system involving the analyte, potassium iodide, ethyl violet, and polyvinyl alcohol. Under the optimum conditions, the linear range for cadmium(II) was 0.015–0.50 µ g mL^?1, and the detection limit was 0.012 µ g mL^?1. The relative standard deviation of 11 determinations for 0.1 and 0.2 µ g mL^?1 standard solutions was smaller than 3.5%. This method was applied for the determination of cadmium(II) in water, plant, soil, and electroplating wastewater. No statistically significant differences in the results were observed between the reported method and those obtained by atomic absorption spectrometry. The analysis was performed within 13 min and a total reagent volume of only 0.14 mL (0.07 mL of eluent and 0.07 mL of reagents) was consumed in each determination of cadmium(II).     

重金属离子的场增强富集装置构建及应用研究

基于场增强效应,结合固相萃取技术设计一种新型富集装置富集水中微量重金属离子;并采用电感耦合等离子体原子发射光谱(ICP-AES)对富集的金属离子进行检测,实现微量金属离子的高倍富集。通过考察背景离子溶液浓度、富集时间、pH值、树脂用量等参数对富集的影响,优化富集装置设计与富集条件。采用此装置,水中Cu(Ⅱ)、Zn(Ⅱ)、Pb(Ⅱ)的富集倍数分别达到904倍,692倍,556倍,回收率在62.6%-84.2%之间,相对标准偏差为5.2%-9.4%。     

Inductively Coupled Plasma Optical Emission Spectrometric Determination of Gadolinium in Urine Using Flow Injection On‐Line Sorption Preconcentration in a Knotted Reactor

Abstract

An on‐line gadolinium preconcentration and determination system, implemented with ultrasonic nebulization coupled to inductively coupled plasma optical emission spectrometry (ICP‐OES), associated with flow injection (FI) was studied. Gadolinium was retained as Gd‐2‐(5‐bromo‐2‐pyridilazo)‐5‐diethylaminophenol complex (Gd‐5‐Br‐PADAP) at pH 9.0, on the inner walls of the knotted reactor (KR). The collected analyte complexes were quantitatively eluted from the 200 cm KR with 30% (v/v) nitric acid. An enhancement factor of 255‐fold was obtained (17 for KR and 15 for USN). The detection limit (DL) value for the preconcentration of 15 mL of sample was 4.0 ng L^?1. The relative standard deviation (RSD) was 3.5%, calculated from the peak heights obtained. The calibration graph using the preconcentration system for gadolinium was linear, with a correlation coefficient of 0.9996 at levels near the detection limit up to at least 200 µg L^?1. The method was successfully applied to the determination of gadolinium in urine samples.     

Simultaneous Determination of Six Trace Elements in Plant Medicines by Derivative Adsorption Waves in Conjunction with a Microwave Technique

Abstract

Complex adsorption waves of Cu(II), Pb(II), Cd(II), Ni(II), Co(II), and Zn(II) in substrate solution (pH=9.26) of diacetyldioxime‐ammonia‐ammonium chloride‐sodium citrate‐gelatin‐sodium sulfite were studied and a new method for determination of the six trace elements in aqueous solutions was developed. The results show that there are sensitive adsorption waves of Cu(II), Pb(II), Cd(II), Ni(II), Co(II), and Zn(II) complexes at about ?0.45, ?0.61,?0.78, ?1.07, ?1.23, and ?1.38 V, respectively. The method is easy to operate and is able to determine these trace elements in aqueous solutions rapidly and simultaneously. When the signal‐to‐noise ratio equals 3, the detection limits of copper, lead, cadmium, nickel, cobalt, and zinc are 3.2×10^?4, 4.8×10^?3, 1.9×10^?3, 1.7×10^?5, 2.1×10^?6, and 1.0×10^?3 µg/cm³. Good linear relationships exist between the concentrations and the current peaks when copper, lead, cadmium, nickel, cobalt, and zinc concentrations are within 6.5×10^?4～10⁰, 9.3×10^?3～10, 4.1×10^?3～10, 3.2×10^?5～10^?1, 4.0×10^?6～10^?2, and 2.1×10^?3～10 µg/cm³, respectively. In conjunction with a microwave assimilation technique, the method has been used in the rapid and simultaneous determination of these trace elements in some plant medicines with satisfactory results.     

ANALYSIS OF CAPSAICIN AND DIHYDROCAPSAICIN IN HOT PEPPERS BY ULTRASOUND ASSISTED EXTRACTION FOLLOWED BY GAS CHROMATOGRAPHY–MASS SPECTROMETRY

A simple method for the analysis of capsaicin and dihydrocapsaicin in peppers by ultrasound assisted extraction (USAE) followed by gas chromatography–mass spectrometry (GC-MS) has been developed. USAE conditions were optimized by experimental design in order to maximize analyte extraction. A full factorial design involving extraction variables such as solvent (ethanol and water), extraction time (5–25 min), extraction temperature (25–50 °C), sample amount (0.25–0.5 g), and ultrasound amplitude (40–80%) was applied. The most significant conditions for capsaicinoid extraction by USAE were solvent type, extraction time, and sample amount. The obtained results were compared with other extraction methods: the official Soxhlet method and a previously reported solid phase microextraction method. Results showed that the extraction efficiency with the application of USAE (98%) was as good as that obtained with Soxhlet and the precision of recovery was less than 5%; in addition, the extraction time was decreased from 5 h to 25 min. The GC-MS analytical method was linear in the range 10–100 μg/mL for capsaicin and dihydrocpsaicin with correlation coefficient r = 0.998 and peak area variability of ～1% for both capsaicinoids. The method was applied to the analysis of 11 varieties of hot peppers cultivated in México. A large concentration range for capsaicin (101–6800 μg/g) and dihydrocapsaicin (110–2736 μg/g) was found in these pepper samples.     

一种新的液液萃取模式-分散液液微萃取

分散液-液微萃取是2006年才问世的一种新型微萃取技术。它基于使用微量注射器将微升级萃取剂快速注入样液内,在分散剂-水相内形成萃取剂微珠,很大地扩展了有机萃取剂和水样之间相接触面,大大加快了萃取平衡的速度,使目标化合物迅速萃入萃取剂微珠内,提高了萃取效率和富集倍数。萃取富集操作与后续检测方法有很好的相容性,萃取相可直接进样气相色谱、高效液相色谱、薄层色谱、气相色谱-质谱、分光光度、火焰原子吸收光谱和电热原子吸收光谱,对目标化合物进行测定。它不仅适用于痕量有机物的分离富集,也适用于痕量无机金属离子的分离富集,已成功地应用于各种坏境水样(包括高含盐量水样)、多种饮料、生物样品、煤和矿物样品中痕量组分的分离富集,是一种有发展前途的环境友好的分离富集技术。     

1‐Pyrenemethanol,a Useful Fluorometric Reagent for the Detection and Determination of Carboxylic Acids in Atmospheric Samples

Abstract

A rapid fluorometric procedure for the selective and sensitive determination of carboxylic acids, based on pre‐column derivatization using 1‐pyrenemethanol, was optimized and applied to atmospheric sampling. The optimum conditions for derivatization were determined to be: reaction solvent–dichloromethane, temperature ?44°C, reaction time ?30 min, and reagent/total acid ratio ?15. Separation of the derivatives of acids up to twenty carbons by reversed‐phase (C₈) chromatography was achieved in 25 min using a water/acetonitrile gradient with a limit of detection for the derivatives of 20 pg for a 20 µL injection. A scanning detector with good spectral resolution allows qualitative identification of the components in complex samples. When used in atmospheric analysis, the recoveries of carboxylic acids from spiked samples were >80% with repeatabilities below 10% RSD. Low molecular weight acids were encountered predominantly in the vapor phase (0.20 to 92 ng/m³), whereas higher molecular weight acids were found mostly in particulate form (0.15–129 ng/m³).     

On‐Line Preconcentration and Analysis of Zinc in Water by Flow Injection‐Knotted Reactor: Application to Geological and Environmental Exploration

Abstract

A preconcentration on‐line system composed of flow injection (FI) and a knotted reactor (KR), associated with inductively coupled plasma atomic emission spectrometry (ICP‐AES) has been used to determine Zn concentrations in river water. The zinc was retained as Zn‐2(5‐bromo‐2‐pyridilazo)5‐diethylaminofenol precipitated complex on the knotted reactor (KR). The limit of detection (0.09 µg L^?1 of Zn) of this method makes it particularly suitable for hydrochemical exploration in geological and environmental projects. This application has been validated in the volcanogenic gold (copper, zinc, lead) deposit of La Carolina in the province of San Luis, Argentina. The Carolina Stream and the Grande River have been sampled for water downstream this deposit. The regional background in river water is 2 µg L^?1. Six times this concentration has been observed at more than 6.5 km from the source, La Carolina mine.     

AN AMPEROMETRIC TYROSINASE INHIBITION-BASED BIOSENSOR FOR THE DETERMINATION OF SULFITE IN NATURAL WATERS

A tyrosinase-based amperometric biosensor for the determination of sulfite in natural waters is reported based on the inhibitory effect of the analyte on the biocatalytic activity of tyrosinase. Titanium dioxide sol modified with gold nanoparticles, multi-walled carbon nanotubes, and Nafion were used for entrapment of the enzyme. The analytical characteristics of the biosensor were evaluated with respect of sensitivity, limit of detection, repeatability, and reproducibility. The biosensor demonstrated a linear range up to 5.10 μM, a high sensitivity of 0.75 μA/μM, and a low limit of detection, 0.08 μM. Possible matrix effects were examined for ions usually found in water samples. The biosensor was successfully used for the determination of sulfite in spiked spring and surface water.     

Determination of Aldehydes in Environmental Water by Solid-Phase Microextraction and Gas Chromatography - Ion Trap Mass Spectrometry

Microwave-assisted extraction coupled to headspace solid-phase microextraction with on-fiber derivatization with gas chromatography ion trap mass spectrometry analysis is reported for the determination of aldehydes in environmental water. Hexanal, (E)-2-hexenal, heptanal, octanal, nonanal, E-2-decanal, and E, E-2,4-decadienal were employed to develop and validate this method. The effects of relevant parameters on the quantitative extraction of these analytes in this one-step procedure were systematically investigated. The aldehydes were extracted from environmental water by a poly(dimethylsiloxane)/divinylbenzene fiber using o-(2, 3, 4, 5, 6-pentafluoro)-benzylhydroxylamine as the derivatization reagent. Under microwave-assisted heating, the aldehydes were transferred from water by headspace solid phase microextraction. Thus, efficient extraction and derivatization were simultaneously achieved. The recovery values ranged from 72.2–96.9%, and the relative standard deviation was between 4.1–14% for the aldehydes. The detection limits were from 0.001–0.005 µg L^?1. The method was validated illustrating its potential for the analysis of environmental water while offering simplicity and rapid analysis.     

Modified nanoporous carbon as a novel sorbent before solvent-based de-emulsification dispersive liquid–liquid microextraction for ultra-trace detection of cadmium by flame atomic absorption spectrophotometry

Combination of different extraction methods is an interesting work in the field of sample pretreatment. In the current study, for the first time, solid phase extraction combined with solvent-based de-emulsification dispersive liquid–liquid microextraction (SPE-SD-DLLME) was developed for preconcentration and trace detection of cadmium in water samples using flame atomic absorption spectrophotometry (FAAS). The adsorbed cadmium ions on prepared SPE (75 mL of aqueous solution) were eluted by optimized elution solvent and introduced to the second microextraction step. The effective variables of SPE including the pH of sample, flow rates, type, concentration and volume of the eluent and the effect of potentially interfering ions of the separation of cadmium were evaluated and optimized. Also, several factors that influence the SD-DLLME step such as pH, neocuproine concentration (the cadmium binding ligand), type of dispersed/de-emulsifier solvent, volume of disperser/de-emulsifier solvent and type and volume of extraction solvents were investigated. SPE-SD-DLLME provides a preconcentration factor of 165 for cadmium ions. Calibration plot was linear in the range of 0.1–50 μg L⁻¹ with correlation of determination (r²) of 0.988. The precision and limit of detection of proposed method were 5.1% (RSD%, n = 8) and 0.03 μg L⁻¹, respectively.     

HPLC-MS联用法测定猪肉组织中5种磺胺类药物的残留

建立一种用高效液相色谱与质谱联用法测定猪肉组织中磺胺类药物残留的方法,该方法检测猪肉中的磺胺类药物快速、准确。样品经2%的醋酸水溶液提取后通过固相萃取柱净化,用甲醇洗脱,吹干,然后用流动相A溶解,用DAD及MS检测器检测。采用AgilentHC-C18(4.6×250mm,5μm)色谱柱,以0.3%甲酸和5%甲醇的水溶液-0.3%甲酸的甲醇溶液为流动相进行梯度洗脱。在添加水平为0.1mg/kg,0.2mg/kg,0.5mg/kg时,对于不同的药物,回收率范围为55.3%~102.8%,相对标准偏差在0.79%~10.4%之间,方法的最低检出限为0.1~0.5ppb。通过大量的实验结果表明,该方法适用于猪肉组织中磺胺类药物的残留测定。