Preconcentration Process Research Articles

Modelling of Multi-Step Microfiltration Process for Solvent Exchange

Industrial-scale microfiltration (MF) separation is applied to process a dispersed ternary system containing an organic solvent, water and fine particles. The objective of the separation is to exchange the organic solvent with water and concentrate the water-particle dispersion. The MF separation is carried out in a multi-step batch operation including pre-concentration, dilution mode, and post-concentration process steps. In this study, we present a practical computational algorithm which can be used as a basis for process simulations of both concentration and dilution modes. The numerical method is based on mass balance processing and on empirical relations of the rejection and the permeate flux to the feed composition. These empirical relations are obtained from the experimental data of a single test-run with the process liquid. We discuss the input data of the code and the respective experimental design with the necessary sampling. Finally, we provide optimum-search techniques considering economical aspects and technological demands.

Ultrasensitive Flow Injection Chemiluminescence Detection of DNA Hybridization Using Signal DNA Probe Modified with Au and CuS Nanoparticles

A novel and sensitive flow injection chemiluminescence assay for sequence-specific DNA detection based on signal amplification with nanoparticles (NPs) is reported in the present work. The "sandwich-type" DNA biosensor was fabricated with the thiol-functionalized capture DNA first immobilized on an Au electrode and hybridized with one end of target DNA, the other end of which was recognized with a signal DNA probe labeled with CuS NPs and Au NPs on the 3'- and 5'-terminus, respectively. The hybridization events were monitored by the CL intensity of luminol-H2O2-Cu(2+) after the cupric ions were dissolved from the hybrids. We demonstrated that the incorporation of Au NPs in this sensor design significantly enhanced the sensitivity and the selectivity because a single Au NP can be loaded with hundreds of signal DNA probe strands, which were modified with CuS NPs. The ratios of Au NPs, signal DNA probes, and CuS NPs modified on the gold electrode were approximately 1/101/103. A preconcentration process of cupric ions performed by anodic stripping voltammetry technology further increased the sensor performance. As a result of these two combined effects, this DNA sensor could detect as low as femtomolar target DNA and exhibited excellent selectivity against two-base mismatched DNA. Under the optimum conditions, the CL intensity was increased with the increase of the concentration of target DNA in the range of 2.0 x 10(-14)-2.0 x 10(-12) M. A detection limit of 4.8 x 10(-15) M target DNA was achieved.

Applications of silver nanoparticles capped with different functional groups as the matrix and affinity probes in surface‐assisted laser desorption/ionization time‐of‐flight and atmospheric pressure matrix‐assisted laser desorption/ionization ion trap mass spectrometry for rapid analysis of sulfur drugs and biothiols in human urine

A strategy is presented for the analysis of sulfur drugs and biothiols using silver nanoparticles (AgNPs) capped with different functional groups as the matrix and affinity probes in surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS) and atmospheric pressure-matrix assisted laser desorption/ionization ion trap mass spectrometry (AP-MALDI-ITMS). Biothiols adsorbed on the surface of AgNPs through covalent bonding were subjected to ultraviolet (UV) radiation that enabled desorption and ionization due to the excellent photochemical property of NPs. The proposed method has been successfully applied for the determination of cysteine and homocysteine in human urine samples using an internal standard. The limit of detection (LOD) and limit of quantification (LOQ) for cysteine and homocysteine in urine sample are 7 and 22 nM, respectively, with a relative standard deviation (RSD) of <10%. The advantages of the present method compared with the methods reported in the literature for biothiol analysis are simplicity, rapidity and sensitivity without the need for time-consuming separation and tedious preconcentration processes. Additionally, we also found that the bare AgNPs can be directly used as the matrix in MALDI-TOF MS for the analysis of sulfur drugs without the addition of an extra proton source.

Micelle-mediated extraction and cloud-point preconcentration of osthole and imperatorin from Cnidium monnieri with analysis by high performance liquid chromatography

A new method based on micelle-mediated extraction and cloud-point preconcentration was developed for the separation and determination of hydrophobic compounds osthole and imperatorin from Cnidium monnieri by high performance liquid chromatography with photodiode array detection. The non-ionic surfactant C 13E 8 (Genapol X-080) was chosen as the extract solvent. Various experimental conditions were investigated to evaluate and optimize the extraction and preconcentration process. The chromatographic separation was accomplished on a Zorbax SB-C 18 analytical column (150 mm × 4.6 mm i.d., 5 μm particle diameter) maintained at 30 °C and detected by UV absorption at 320 nm. The gradient elution was achieved with a mobile phase composed of 0.1% phosphoric acid and acetonitrile at a flow rate of 1.0 mL min −1. Under the optimum conditions, the calibration curve for both analytes was linear in the range of 0.52–33.5 μg mL −1 with the correlation coefficients greater than 0.9996. The intra-day and inter-day precision (RSD) is below 5.3% and the limits of detection (LOD) for the analytes are 93 and 124 ng mL −1 (S/N = 3). The proposed technique is a low cost, simple and sensitive method with high clean-up effect. Finally, the method was successfully applied to separate and determine osthole and imperatorin from C. monnieri, respectively.

Magnetic ovalbumin and egg white aggregates as affinity adsorbents for lectins separation

Simple and low-cost preparation of new magnetic adsorbents from ovalbumin and egg white, based on methanol precipitation and subsequent glutaraldehyde cross-linking has been developed. These adsorbents were used for preconcentration of two plant lectins from potato ( Solanum tuberosum) tubers and from wheat ( Triticum spp.) germs extracts. The adsorbed lectins were eluted with diluted hydrochloric acid. The specific activities of both lectins increased approximately 30–40 times during the preconcentration process.

Mixed hemimicelles solid-phase extraction based on cetyltrimethylammonium bromide-coated nano-magnets Fe 3O 4 for the determination of chlorophenols in environmental water samples coupled with liquid chromatography/spectrophotometry detection

Mixed hemimicelles solid-phase extraction (SPE) based on cetyltrimethylammonium bromide (CTAB)-coated nano-magnets Fe 3O 4 was investigated for the preconcentration of four chlorophenols (CPs) in environmental water samples prior to HPLC–spectrophotometry determination in this paper. By the rapid isolating (about 5 min) of Fe 3O 4 nanoparticles (NPs) through placing a Nd–Fe–B strong magnet on the bottom of beaker, the time-consuming preconcentration process of loading large volume sample in conversional SPE method with a column can be avoided. The unique properties of Fe 3O 4 NPs such as high surface area and strong magnetism were utilized adequately in the SPE process. This novel separation method produced a high preconcentration rate and factor. A comprehensive study of the adsorption conditions such as the Fe 3O 4 NPs zeta-potential, CTAB added amounts, pH value, standing time and maximal extraction volume was also presented. Under optimized conditions, four analytes of 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) were quantitatively extracted. The method was then used to determine four CPs in five real environmental water samples. High concentration factors (700) were achieved for each of the analytes, with observed detection limits ranging between 0.11 and 0.15 μg L −1. The accuracy of method was evaluated by recovery measurements on spiked samples. Good recovery results (83–98%) with satisfactory relative standard deviation (RSD) were achieved. It is important to note that satisfactory preconcentration factors and extraction recoveries for the four CPs were obtained with only a little amount of Fe 3O 4 NPs (0.1 g) and CTAB (60 mg). To the best of our knowledge, this was the first time a mixed hemimicelles SPE method based on Fe 3O 4 NPs magnetic separation had been used for the pretreatment of environmental water samples.

Ultrasensitive flow injection chemiluminescence detection of DNA hybridization using nanoCuS tags

A novel and sensitive biosensor for the determination of short sequence of DNA based on flow injection (FI)-chemiluminescence (CL) system of luminol–H 2O 2–Cu 2+ was developed in the present work. The DNA probe labeled with copper sulfide nanoparticles (CuS NPs) could hybridize with target DNA immobilized on glass–carbon electrode (GCE). The hybridization events were monitored by the CL intensity of luminol–H 2O 2–Cu 2+ after the cupric ions was dissolved from the hybrids. A preconcentration process of cupric ions was performed by anodic stripping voltammetry (ASV) technology to improve the sensitivity of the biosensor. Under the optimum conditions, the CL intensity was proportional to the concentration of target DNA in the range of 2.0 × 10 −12–1 .0 × 10 −10 M. A detection limit of 5.5 × 10 −13 M of target DNA was achieved. The CL intensity of two-base mismatched sequences and noncomplementary sequences were also detected. The experiments indicated that two-base mismatched sequences showed weaker CL intensity and noncomplementary sequences gave no response at all.

Online preconcentration using monoliths in electrochromatography capillary format and microchips

Online preconcentration and separation of analytes using an in situ photopolymerized hexyl acrylate-based monolith stationary phase was evaluated using electrochromatography in capillary format and microchip. The band broadening occurring during the preconcentration process by frontal electrochromatography and during the desorption process by elution electrochromatography was studied. The hexyl acrylate-based monolith provides high retention for neutral analytes allowing the handling of large sample volumes and its structure allows rapid mass transfer, thus reducing the band broadening. For moderately polar analytes such as mono-chlorophenols that are slightly retained in water, it was shown that enrichment factors up to 3500 can be obtained by a hydrodynamic injection of several bed volumes for 120 min under 0.8 MPa with a decrease in efficiency of 50% and a decrease of 30% for the resolution between 2- and 3-chlorophenol. An 8 min preconcentration time allows enrichment factors above 100 for polyaromatic hydrocarbons. The interest of these monoliths when synthesized in microchip is also demonstrated. A 200-fold enrichment was easily obtained for PAHs with only 1 min as preconcentration time, without decrease in efficiency.

Preconcentration technique for manganese by adsorption onto a tantalum wire for tungsten tube atomizer electrothermal atomization atomic absorption spectrometry

A preconcentration technique for manganese in water samples by adsorption on a tantalum wire was investigated for tungsten tube atomizer electrothermal atomization atomic absorption spectrometry. After preconcentration, the tantalum wire was directly inserted into the tungsten tube atomizer. In the preconcentration (adsorption) process for manganese, the optimal immersion time was 60 sec and the best pH was 9. Under the optimal conditions, the detection limit for manganese by the tantalum wire preconcentration method was 6.3 pg mL−1 (3S/N) and the relative standard deviation was 7.6%. The influences of concomitants on the preconcentration of manganese were evaluated. Even though 103 to 104-fold excess of matrix elements existed in aqueous solution, the manganese absorption signal was not significantly affected by the matrix elements. The method with preconcentration on a tantalum wire was applied to the determination of manganese in river waters and proved to be sensitive, simple, and convenient. Because this preconcentration method can be utilized in the in-situ treatment of trace manganese in environmental water samples, it was unnecessary to carry the water samples to the analytical work place. The technique was shown to be useful for the determination of manganese in environmental water samples at 0.1–1 g L−1 levels.

Study of tungstate–protein interaction in human serum by LC–ICP-MS and MALDI-TOF

Oral administration of sodium tungstate is an effective treatment for type 1 and 2 diabetes in animal models; it does not incur significant side effects, and it may constitute an alternative to insulin. However, the mechanism by which tungstate exerts its observed metabolic effects in vivo is still not completely understood. In this work, serum-containing proteins which bind tungstate have been characterized. Size exclusion chromatography (SEC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) with a Phenomenex Bio-Sep-S 2000 column and 20 mM HEPES and 150 mM NaCl at pH 7.4 as the mobile phase was chosen as the most appropriate methodology to screen for tungsten-protein complexes. When human serum was incubated with tungstate, three analytical peaks were observed, one related to tungstate-albumin binding, one to free tungstate, and one to an unknown protein binding (MW higher than 300 kDa). Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometric analysis of the tungsten-containing fractions collected from SEC-ICP-MS chromatograms, after desalting and preconcentration processes, confirmed the association of tungstate with albumin and the other unknown protein. [figure: see text]

Development and Application of C60-Fullerene Bound Silica for Solid-Phase Extraction of Biomolecules

Sample pretreatment is the most important procedure to remove the matrix for interfacing with mass spectrometry (MS). Additionally, for the samples with low concentration, the process of preconcentration is required before MS analysis. We have newly developed a solid-phase extraction stationary phase based on C60-fullerene covalently bound to silica for purification of biomolecules of different characteristics. Silica particles of different porosity are modified with aminopropyl linker and then covalently bound to C60-fullerenoacetic acid or C60-epoxyfullerenes. The developed materials have been successfully applied as an alternative to commercially available reversed-phase materials for solid-phase extraction. C60-fullerene silica is able to retain small and hydrophilic molecules like phosphopeptides, which can be easily lost by reversed-phase sorbents. The novel materials are applied for desalting and preconcentration of proteins and peptides, especially phosphopeptides. In addition, the C60-fullerene silica is applied for the solid-phase extraction of selected flavonoids with recoveries of approximately 99%. The recoveries are compared with the commercially available solid-phase extraction materials.

Cloud Point Extraction of Polycyclic Aromatic Hydrocarbons in Aqueous Solution with Silicone Surfactants

Abstract Cloud point extraction (CPE) processes with two silicone surfactants, Dow Corning DC-190 and DC-193, were studied as preconcentration and treatment for the water polluted by three trace polycyclic aromatic hydrocarbons (PAHs): anthracene, phenanthrene and pyrene. For all cases, the volumes of surfactant-rich phase obtained by two silicone surfactants were very small, i.e. a lower water content in the surfactant-rich phase was obtained. For example, less than 3% of the initial solution was obtained in a 1% (by mass) surfactant solution, which was much smaller than that of TX-114 in the same surfactant concentration. And TX-114 is known as a high compact surfactant-rich phase among most nonionic surfactants, thus the comparison showed that an excellent enrichment was ensured in the analysis application by the CPE process with the silicone surfactants, and the lower water content obtained in the surfactant-rich phase is also important in the large scale water treatment. The influences of additives and phase separation methodology on the recovery of PAHs were discussed. Comparing with DC-193. DC-190 has a lower cloud point and a higher recovery (near 100%) of all the three PAHs in same surfactant concentration, which was required for application as a preconcentration process prior to HPLC system. However the DC-190 solution is hard to be phase separated only by heating, whereas DC-193 has a relative higher phase separating speed by heating, but a high cloud point (around 360K) limits its application. Due to the phase separation by heating is the only method of CPE suitable to the large scale water treatment, the mixtures of two silicone surfactants solutions were investigated in this study. A solution containing 1% of mixed DC-190 and DC-193 (in the ratio of 90:10) removed anthracene, phenanthrene and pyrene near 100% with a relative low cloud point and quick phase separating speed.

Direct fluorometric detection of paramagnetic and heavy metal ions at sub‐amol level using an aromatic polyaminocarboxylate by CZE: Combination of pre‐ and on‐capillary complexation technique

The low sensitivity of simple CZE for detecting metal ions is a long-standing problem even when an LIF detection system is employed. We have successfully achieved an ultrasensitive CE-LIF using a simple CZE mode (typical detection limit: 10(-11)-10(-10) mol/dm(3)). Both the design of a newly synthesized ligand and the combination of a precapillary derivatizing technique with an on-capillary ternary complexing technique have enabled us to achieve this extremely low LOD and high resolution of large metal complexes. The direct fluorescent detection of the paramagnetic metal ions was achieved for the first time despite their intrinsic fluorescent quenching nature. The fluorescent ligand (L) consists of a polyaminocarboxylate chelating moiety, a strongly emissive fluorescein moiety and a spacer connecting the two portions. The migration behavior of various metal-L complexes was investigated. The resolution among the complexes was improved by the introduction of a ternary complex equilibrium of the kinetically stable mother complexes with OH(-) ion. The analytical potential of our simple system was examined, and it was proved that the system was one of the most sensitive methods without the need for any preconcentration process.

On‐line preconcentration of weak electrolytes by electrokinetic accumulation in CE: Experiment and simulation

A new on-line preconcentration technique was developed that makes possible to determine nanomolar concentrations of weak acidic analytes in CE. The method consists of long-running electrokinetic sample injection and stacking (electrokinetic immobilization) of the analytes at a boundary of two electrolytes with different pH values (pH 9.5 and 2.5) and consequent mobilization of the stacked uncharged analytes in a micellar system (containing SDS micelles). Several factors including buffer concentration, pH, applied voltage, time of preconcentration, and SDS concentration were tested to optimize the analysis method. An about 4600-fold increase of the sample concentration (in comparison with the standard CZE) can be achieved during the preconcentration step. Two preservatives applied in food industry -- benzoic acid and sorbic acid were used as model samples. The applicability of the proposed method in food analysis was demonstrated by determination of nanomolar concentrations of benzoic acid in sunflower oil. An extended version of the computer program Simul was used for modeling both the preconcentration and mobilization processes taking place in the capillary.

Determination of Cadmium in Seawater by Vapor Generation Atomic Fluorescence Spectrometry After Online Preconcentration with a Novel Alkyl Phosphinic Acid Resin

Vapor generation atomic fluorescence spectrometry (VG‐AFS) coupled with online preconcentration on a short column (4.6 mm×50‐mm length) packed with a newly synthesized alkyl phosphinic acid resin (APAR) was developed for the determination of trace Cd in seawater. During the online preconcentration process, Cd in seawater was concentrated on the column while the matrix of seawater was separated flowing out of the column. Cd concentrated on the column was then eluted effectively from the column with 0.1 mol L−1 tartaric acid within 40 s. When the sample volume was 200 mL, an enrichment factor 189 was achieved. The detection limit of this proposed method for Cd is 2.67 ng L−1. The recovery of Cd is 96.6% obtained by spiking the correspondence standard, and the precision (RSD) is 4.34% (n=6). The established APAR/VG‐AFS was applied to the determination of soluble Cd in the seawater around Xiamen Island, China.

Factorial design for Fe, Cu, Zn, Se and Pb preconcentration optimization with APDC and analysis with a portable X-ray fluorescence system

Preconcentration of heavy metals in water with ammonium pyrrolydine dithiocarbamate (APDC) is a common practice in analytical chemistry. A literature review on this topic showed that several authors use this precipitation agent, but in different preconcentration conditions, conducting to divergent results. The objective of this work is to use factorial design to optimize the factors involved in the preconcentration process of heavy metals using APDC. Five factors were studied: sample volume, solution pH, APDC concentration, APDC volume and stirring time. The assays were performed by energy dispersive X-ray fluorescence (EDXRF). The values for detection limits within 95% confidence level, in μg L −1, were: Fe (6.0 ± 0.1), Cu (4.0 ± 0.1), Zn (2.0 ± 0.1), Se (4.0 ± 0.1) and Pb (5.0 ± 0.1). The value for quantification limit for the five elements was 20 μg L −1, with 3% deviation. Multi-element standard solutions were prepared. Precipitation procedure was applied in the spiked solutions and the samples were filtered in cellulose ester membrane for quantification measurements. The optimum values obtained were 300 mL of sample solution, pH 4, 1 mL of 2% APDC and 10 min of stirring time. The concentration results obtained for the validation measurements were satisfactory for in situ survey employing a portable instrument.

Can Breath Isoprene Be Measured by Ozone Chemiluminescence?

Isoprene, involved in the biosynthetic pathway to cholesterol, is the prevalent hydrocarbon in breath. Breath isoprene measurement is of great interest as a measure of basal cholesterol production rate. We investigated the merits and pitfalls of isoprene measurement via its chemiluminescence (CL) reaction with ozone. For many subjects, apparent concentrations measured are higher than those obtained by a gas chromatography (GC) reference method that can be traced to ozone-induced CL with simultaneously present lower olefins and sulfur compounds. A warm column preconcentration method eliminates the lower olefins and greatly improves sensitivity while a silver-form, ion-exchange resin can remove the sulfur gases. The breath sample is captured on a miniature synthetic carbon sorbent column maintained at 55 degrees C, under which conditions ethylene, propylene, and water vapor are not significantly captured while the preconcentration process greatly improves the limit of detection for isoprene to 0.6 ppbv (S/N=3). The captured isoprene is released by heating the column to 150 degrees C. Breath samples from different subjects were collected both before and after meals and analyzed in a double-blind fashion in two laboratories, with the second laboratory performing quantitation by cryofocusing GC-flame ionization detection with parallel measurement by mass spectrometry to provide identity confirmation. For all individuals studied, the CL and the GC results agreed when both warm column preconcentration and passage through Ag+-form cation-exchange resin, which removes divalent sulfur gases, were implemented prior to CL measurement. The intensity of CL from the reaction with ozone can be much higher for some sulfur gases than for isoprene. Even though present at lower concentrations than isoprene, unless removed prior to CL measurement, for some individuals sulfur gases can cause unacceptably large (up to 500%) errors, making the sulfur gas removal step critical.

Extraction and speciation of arsenic in plants grown on arsenic contaminated soils

A sequential arsenic extraction method was developed that yielded extraction efficiencies (EE) that were approximately double those using current methods for terrestrial plants. The method was applied to plants from two arsenic contaminated sites and showed potential for risk assessment studies. In the method, plants were extracted first by 1:1 water–methanol followed by 0.1 M hydrochloric (HCl) acid. Total arsenic in plant and soil samples collected from contaminated sites was mineralized by acid digestion and detected by inductively coupled plasma-atomic emission spectrometry (ICP-AES) and hydride generation-atomic absorption spectrometry (HG-AAS). Arsenic speciation was done by high performance liquid chromatography coupled with HG-AAS (HPLC–HGAAS) and by HPLC coupled with ICP-mass spectrometry (HPLC–ICP-MS). Spike recovery experiments with arsenite (As(III)), arsenate (As(V)), methylarsonic acid (MA) and dimethylarsinic acid (DMA) showed stability of the species in the extraction processes. Speciation analysis by X-ray absorption near edge spectroscopy (XANES) demonstrated that no transformation of As(III) and As(V) occurred due to sample handling. Dilute HCl was efficient in extracting arsenic from plants; however, extraction and determination of organic species were difficult in this medium. Sequential extraction with 1:1 water–methanol followed by 0.1 M-HCl was most useful in extracting and speciating both organic and inorganic arsenic from plants. Trace amounts of MA and DMA in plants could be detected by HPLC–HGAAS aided by the process of separation and preconcentration of the sequential extraction method. Both organic and inorganic arsenic compounds could be detected simultaneously in synthetic gastric fluid extracts (GFE) but EEs by this method were lower than those of the sequential method. The developed sequential method was shown to be reliable and applicable to various terrestrial plants for arsenic extraction and speciation.

Immunochemical Potentiometric Method for HIgG and Anti‐HIgG Determination, Using a NH3 Probe and Immunoprecipitation as Preconcentration Procedure

With the aim of improving the LOD value of a previous method, able to determine HIgG using a classic immunosensor, a pretreatment involving immunoprecipitation of the urease enzyme marked immunocomplex was introduced. By new method we determined HIgG using anti‐HIgG conjugated with urease for immunocomplex formation, and then protein G‐agarose was added for the immunoprecipitation process, which was able to concentrate the immunocomplex (and thus also the HIgG) up to 10,000‐fold. In this way the marked immunocomplex was separated from the marked anti‐HIgG excess, subsequently detected after urea addition in solution, by a gas diffusion potentiometric electrode for NH3. The formation of the marked antigen–antibody complex was the first step of the assay, the immunoprecipitation of the complex; the second and third step consisted first in removal of the nonspecific binding protein and then in eluting the precipitated immunocomplex from the microcolumn. The last step was the enzymatic measurement as checked by NH3 sensor. In addition, using the same procedure, namely, using the same conjugated urease and the same sensor for the NH3, it was possible to determine also the anti‐HIgG, in any case preceding the process of preconcentration by immunoprecipitation by means of a classical competitive process in homogeneous solution.

Preconcentration of trace lead by adsorption onto a tantalum wire for electrothermal atomization atomic absorption spectrometry with a tungsten tube atomizer

A preconcentration method of lead in waters by adsorption on a tantalum wire was developed for electrothermal atomization atomic absorption spectrometry with a tungsten tube atomizer. After the preconcentration, the tantalum wire was directly inserted into the tungsten tube atomizer. In the preconcentration (adsorption) process for lead, the optimal immersing time was 90 s and the best pH was 4. Under the optimal conditions, the detection limit for lead by the tantalum wire preconcentration method was 6.0 pg mL − 1 (3S/N) and the relative standard deviation was 6.1%. The influences of large amounts of concomitants on the preconcentration of lead were evaluated. Even though 10 3 to 10 4-fold excess of matrix elements existed in aqueous solution, the lead absorption signal was not significantly affected by the matrix elements. The method with preconcentration on a tantalum wire was applied to the determination of lead in river waters and proved to be sensitive, simple, and convenient. Because this preconcentration method can be utilized in the in-situ treatment of trace lead in environmental water samples, it was unnecessary to carry the water samples to the analytical work place. The present technique was shown to be useful for the determination of lead in environmental water samples at 0.1−1 μg L − 1 .