超高效液相色谱/串联质谱法分析水中的微囊藻毒素

建立了超高效液相色谱/质谱快速、准确、高灵敏度地测定水体中痕量微囊藻毒素（MCYST）的分析方法,并用于实 际样品的分析。采用固相萃取法富集净化样品。该法在5 min内即可完成4种MCYST（LR、RR、LW、LF）的分离及检测;LR 、RR、LW、LF的定量检测限、回收率分别为1.3～6.0 ng/L、91.1%～111%;工作曲线的线性相关系数大于0.99,线性范 围达3个数量级。实际样品分析表明,在所测定的水库水样中均检出了LR和RR,其质量浓度分别为0.0447～2.73 μg/L和0.0208～1.36 μg/L;而在所有的检测样品中均未检出LW和LF。     

Study of uranium contamination of ground water in Punjab state in India using X-ray fluorescence technique

The elemental concentration of uranium in the samples collected from the ground water and the canal water in the Bathinda district of Punjab state, India, have been investigated using X-ray fluorescence technique. The residues obtained after drying the water samples were analysed using the energy dispersive X-ray fluorescence spectrometer consisting of Mo-anode X-ray tube equipped with selective absorbers as an excitation source and an Si(Li) detector. The uranium concentration values in significant fraction of the shallow ground water samples from the hand pumps is found to be above the permissible level of 15?ppb recommended by World Health Organisation for the drinking water, and its values in the canal water samples are below 5?ppb. To investigate the flyash from the coal-fired thermal power plants as a possible source of ground water contamination, the water samples collected from the surroundings of the power plants and the flyash samples were also analyzed. The results rule out flyash as a source of uranium contamination. Agrochemical processes occurring in the calcareous soils in the region are the favoured potential source of uranium contamination of the ground water.     

Development of an on-column affinity smart polymer gel glucose sensor

An on-column affinity smart polymer gel glucose sensor was developed as a non-enzymatic glucose sensor. A copolymer of 3-acrylamidophenylboronic acid and acrylamide, the so called "smart polymer", was synthesized in situ in a 5 cm long capillary tube with a detection window to provide the on-column detection. The optical density of this semitransparent affinity smart polymer gel, coated inside the tube, decreased with increasing glucose concentration and was detected using a UV-vis detector at 500 nm. The capillary tube was incorporated into a flow injection system. Under optimum conditions, a linear dynamic range of 0.5-16.0mM with a limit of detection of 0.5mM (S/N ≥ 3) was obtained. A single coated affinity smart polymer gel had good stability for up to 250 consecutive injections with relative standard deviation of less than 5%. The analysis time for each injection was 6 min. Ten glucose samples prepared in distilled water were analyzed by the developed method and the results compared well with those obtained from the conventional dinitrosalicylic acid (DNS) method (P>0.05). Real urine samples with known glucose levels were analyzed and the developed sensor provided comparable results to those from the normal strip test technique. Acceptable percentage recoveries, ranging from 88 ± 2% to 103 ± 4% from the spiked urine sample, were obtained.     

Determination of zinc,cadmium, lead and copper in sea water by means of computerized potentiometric stripping analysis

Water samples from the Arctic Sea were analyzed by the potentiometric stripping technique. Lead(II) and cadmium(II) were determined after pre-electrolysis for 32 min at—1.1 V vs. Ag/AgCl, the detection limits being 0.06 and 0.04 nM, respectively. Zinc(II) was determined after the addition of gallium(III) by pre-electrolysis for 16 min at —1.4 V vs. Ag/AgCl, the detection limit being 0.25 nM. Problems in the determination of copper(II) at the very low concentrations found in oceanic waters are outlined. The average zinc(II), cadmium(II) and lead(II) concentrations in eight different samples were 2.5, 0.16 and 0.10 nM as determined by potentiometric stripping analysis and 1.9, 0.16 and 0.09 nM as determined by solvent extraction/atomic absorption spectrometry. The advantages of this computerized technique for the analysis of sea water are discussed.     

Determination of four aromatic amines in water samples using dispersive liquid-liquid microextraction combined with HPLC

A new method for the determination of four aromatic amines in water samples was developed by using dispersive liquid-liquid microextraction (DLLME) technique combined with HPLC-variable wavelength detection (HPLC-VWD). In this extraction method, 0.50 mL methanol (as dispersive solvent) containing 25.0 microL tetrachloroethane (as extraction solvent) was rapidly injected by a syringe into 5.00 mL water sample. Accordingly, a cloudy solution was formed. After centrifugation for 2 min at 4000 rpm, the fine droplets of the tetrachloroethane containing the analytes were sedimented in the bottom of the conical test tube (7+/-0.2 microL). Then, 5.0 microL of the settled phase was determined by HPLC-VWD. Parameters such as the kind and volume of extraction solvent and dispersive solvent, extraction time, and salt concentration were optimized. Under the optimum conditions, the enrichment factors ranged from 41.3 to 94.5. Linearity was observed in the range of 5-5000 ng/mL. The LODs based on S/N of 3 ranged from 0.8 to 1.8 ng/mL. The RSDs (for 400 ng/mL of p-toluidine and o-chloroaniline, 100 ng/mL of p-chloroaniline and p-bromoaniline) varied from 4.1 to 5.3% (n=6). The water samples collected from rivers and lakes were successfully analyzed by the proposed method and the relative recoveries were in the range of 85.4-111.7% and 90.2-101.3%, respectively.     

Reverse micelle-mediated dispersive liquid-liquid microextraction of 2,4-dichlorophenoxyacetic acid and 4-chloro-2-methylphenoxyacetic acid

A supramolecular solvent consisting of reverse micelles of decanoic acid, dispersed in a continuous phase of tetrahydrofuran:water, was proposed as an efficient microextraction technique for extraction of selected chlorophenoxy acid herbicides from water samples prior to high-performance liquid chromatography UV determination. The disperser solvent (1.0 mL tetrahydrofuran) containing 20 mg decanoic acid was rapidly injected into 10.0 mL of water sample. After centrifugation, the reverse micelle-rich phase (25 ± 0.5 μL) was floated at top of the home-designed centrifuge tube. The solvent was collected and 20 μL of it was injected into high-performance liquid chromatography for analysis. The results showed that the in situ solvent formation and extraction process can be completed in a few seconds. Under the optimal conditions, limits of detection of the method for 4-chloro-2-methylphenoxyacetic acid and 2,4-dichlorophenoxyacetic acid were in the range of 0.5-0.8 μg L(-1) and the repeatability of the proposed method, expressed as relative standard deviation, varied in the range of 2.5-3.2%. Linearity was found to be in the range of 1-200 μg L(-1) and the preconcentration factors were between 148 and 157. The mean percentage recoveries exceeded 92.0% for all the spiking levels in real water samples.     

Determination of lithium in human serum by electrothermal atomic absorption spectrometry

An efficient method was developed for the determination of nanogram levels of lithium in biological samples. Serum samples from human subjects from southeastern Spain, treated or not treated with lithium carbonate, were analyzed by electrothermal atomic absorption spectrometry. The samples were previously treated with a matrix modifier consisting of 0.1% Triton X-100 and injected through a graphite tube with L'vov platform. The Li concentrations measured by the procedure described for the 3 certified reference samples used were not significantly different (p > 0.05) than certified levels. Sample recoveries and variability during several days, with coefficients of variation from 4.00 to 14.8%, demonstrated the reliability and accuracy of this technique. Mean Li concentration determined in the serum of individuals with psychiatric disorders treated with Li (n = 117, 5.077 +/- 1.795 microg Li/mL) was significantly higher (p < 0.001) than that in individuals not treated with Li (n = 24, 1.902 +/- 2.054 ng Li/mL).     

Carbon nanotubes functionalized mesoporous silica for in‐tube solid‐phase microextraction of polycyclic aromatic hydrocarbons

A mesoporous silica was functionalized by carbon nanotubes to enhance the extraction performance. The mesoporous material was coated on stainless steel wires, and three wires were inserted inside of a polyetheretherketone tube for in‐tube solid‐phase microextraction. The tube was coupled to high‐performance liquid chromatography with diode array detection to obtain online analytical system, then its extraction performance was evaluated using eight polycyclic aromatic hydrocarbons as the targets. In order to good sensitivity and accuracy, four conditions were optimized such as sampling volume, sampling rate, methanol content in the sample, and desorption time. Under the optimum conditions, an online analytical method was established and exhibited low limits of detection from 0.005 to 0.050 µg/L, wide linear range of 0.016‐20.00 µg/L with acceptable correlation coefficients in 0.9921‐0.9999, as well as large enrichment factors in the range of 311‐2412. The method was successfully applied to determine trace polycyclic aromatic hydrocarbons in some real water samples including, two kinds of bottled water, tap water, and river water, a few polycyclic aromatic hydrocarbons were detected but none quantified in these samples.     

A comparative analysis of uranium in potable waters using laser fluorimetry and ICPMS techniques

The main objective of this work is the accurate measurement of uranium in the potable water sources of Muktsar district of Punjab, India. In the present work, a laser fluorimetry technique was used for the analysis of uranium. Inductively coupled plasma mass spectrometry (ICPMS) technique was also applied to verify and compare the uranium content analyzed using laser technique. About 16 samples from waterworks, bore wells, and hand pumps that supply the drinking water to local population were collected for this purpose. An indigenous laser fluorimeter supplied by RRCAT, Indore was employed for the analysis. Uranium concentrations obtained were in the range from 0 to 10???g?L^?1 in ten samples, 11?C30???g?L^?1 in three samples, and more than 100???g?L^?1 in three samples namely Channu ground water, Warning Khera pump, and Killanwale village hand pump. The USEPA guideline value for uranium in safe drinking water is 30???g?L^?1. Also, a data comparison with similar studies carried out in other countries is presented.     

Elemental content in deionized water by total-reflection X-ray fluorescence spectrometry

This study aimed to evaluate minor and trace elements in the water during different water purification steps of a deionized water production plant, located at CENA, by total-reflection X-ray fluorescence (TXRF) technique, using Ga as internal standard for elemental quantification. This approach was capable of determining Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, As, Se, Br, Rb at concentrations higher than 40–100 μg L⁻¹, and for K, Ca, Sc, Ti, V and Sr at concentrations higher than sub mg L⁻¹ in the water samples. TXRF spectrometer encompasses an X-ray tube with a Mo target with a Zr filter. The elemental characteristic X-rays were recorded by a Si(Li) semiconductor detector and the X-ray spectra deconvoluted by AXIL software.     

Dispersive liquid–liquid microextraction with little solvent consumption combined with gas chromatography–mass spectrometry for the pretreatment of organochlorine pesticides in aqueous samples

Dispersive liquid–liquid microextraction with little solvent consumption (DLLME-LSC), a novel dispersive liquid–liquid microextraction (DLLME) technique with few solvent requirements (13 μL of a binary mixture of disperser solvent and extraction solvent in the ratio of 6:4) and short extraction time (90 s), has been developed for extraction of organochlorine pesticides (OCPs) from water samples prior to gas chromatography/mass spectrometry analysis. In DLLME-LSC, much less volume of organic solvent is used as compared to DLLME. The new technique is less harmful to environment and yields a higher enrichment factor (1885–2648-fold in this study). Fine organic droplets were formed in the sample solution by manually shaking the test tube containing the mixture of sample solution and extraction solvent. The large surface area of the organic solvent droplets increases the rate of mass transfer from the water sample to the extractant and produces efficient extraction in a short period of time. DLLME-LSC shows good repeatability (RSD: 4.1–9.7% for reservoir water; 5.6–8.9% for river water) and high sensitivity (limits of detection: 0.8–2.5 ng/L for reservoir water; 0.4–1.3 ng/L for river water). The method can be used on various water samples (river water, tap water, sea water and reservoir water). It can be used for routine work for the investigation of OCPs.     

Application of dispersive liquid-liquid microextraction combined with high-performance liquid chromatography for the determination of methomyl in natural waters

A new method was developed for determination of methomyl in water samples by combining a dispersive liquid-liquid microextraction (DLLME) technique with HPLC-variable wavelength detection (VWD). In this extraction method, 0.50 mL of methanol (as dispersive solvent) containing 20.0 microL of tetrachloroethane (as extraction solvent) was rapidly injected by syringe into a 5.00-mL water sample containing the analyte, thereby forming a cloudy solution. After phase separation by centrifugation for 2 min at 4000 rpm, the enriched analyte in the settled phase (8 +/- 0.2 microL) was at the bottom of the conical test tube. A 5.0-microL volume of the settled phase was analyzed by HPLC-VWD. Parameters such as the nature and volume of the extraction solvent and the dispersive solvent, extraction time, and the salt concentration were optimized. Under the optimum conditions, the enrichment factor could reach 70.7 for a 5.00-mL water sample and the linear range, detection limit (S/N = 3), and precision (RSD, n = 6) were 3-5000 ng/mL, 1.0 ng/mL, and 2.6%, respectively. River and lake water samples were successfully analyzed by the proposed method. Comparison of this method with solid-phase extraction, solid-phase microextraction, and single-drop microextraction, indicates that DLLME combined with HPLC-VWD is a simple, fast, and low-cost method for the determination of methomyl, and thus has tremendous potential in trace analysis of methomyl in natural waters.     

Characterization of groundwater contaminants using dynamic thermal stripping and adsorption/thermal desorption-GC-MS

Summary Alternate methods to the time consuming solvent extraction technique used in the characterization of groundwater contaminants were sought to reduce the analysis time and allow for automation. By adsorbing (ADS) groundwater samples on a quartz tube filled with graphitized charcoal (Carbotrap, Carbotrap C) and thermally desorbing it in a Envirochem Unacon 810 unit directly interfaced with a GC-MSD, it was possible to detect the major groundwater contaminants originating from several types of industrial landfills. Compounds such as aniline, dioxane, and phenols were measured simultaneously with minimal sample preparation. The results were compared to those obtained by dynamic thermal stripping (DTS) followed by GC-MS. These methods are much more cost effective than solvent extraction since they require only a few minutes of the analyst's time for the introduction of the sample. ADS was superior to DTS and solvent extraction for the analysis of water soluble compounds which are poorly extracted into solvents. DTS provided cleaner chromatograms and allowed for lower detection limit than ADS. The two techniques are therefore complementary.     

Development of a new microelectrolysis system for in-situ electrodeposition of ultra-traces of gold prior to measurement by ETAAS

Electrodeposition is known to be suitable for separation and preconcentration of extremely low concentrations of analyte from bulk samples and is instrumentally is very simple. In this approach a new combined system was designed for in-situ electrodeposition of ultratrace levels of gold from micro samples on to a graphite furnace prior to determination by electrothermal atomic absorption spectrometry (ETAAS). Sediment samples were digested and traces of the gold content were extracted with boiling aqua regia. To prevent the highly corrosive effect of aqua regia media, the graphite tube surface was pre-coated by electrodeposition of ppm amounts of Pd prior to sample introduction. Separation of the analyte from the matrix was achieved by electrodeposition of the analyte in situ on the Pd/C surface of the furnace tube. Vanadium was also used as a modifier to stabilize the analyte from decomposition at charring temperatures. By using the proposed microelectrolysis preconcentration technique a considerable improvement in sensitivity and detection limit was achieved compared with conventional ETAAS. Characteristic masses for ED-ETAAS techniques in both nitric acid and aqua regia were reported to be m(o)=4.1 pg, with %RSD=2.9; the calculated LOD was 0.105 ppb, and typical calibration graphs for this element in nitric acid and aqua regia for both techniques were linear up to 70 microg L(-1) with about 99% recovery. Six reference sediments samples were tested by the proposed technique and by the Conv-ETAAS method. The results were in agreement with recommended values (reported by a reference laboratory using UV-visible spectrometry), demonstrating the efficiency of extraction and preconcentration of ultratrace levels of gold.     

Determination of total selenium content in sediments and natural water by graphite furnace-atomic absorption spectroscopy after collection as a selenium(IV) complex on activated carbon

A trace level of Se was collected on activated carbon (AC) as the Se(IV)-3-phenyl-5-mercapto-1,3,4-thiadiazole-2(3H)-thione (Bismuthiol II) complex. The AC was directly introduced as an AC-suspension into the graphite tube atomizer and the Se concentration was determined by atomic absorption spectroscopy (T. Okutani, T. Kubota, N. Sugiyama and Y. Turuta, Nippon Kagaku Kaishi, (1991) 375). The amount of Se in heavily contaminated samples including sediment, lake water and seawater was determined using this method. The sediments were digested with HNO(3)HClO(4)HF and the interference from AlF(3) was removed using H(3)BO(3)HClO(4). Lake water and seawater were acidified with H(2)SO(4) and digested with KMnO(4). The Se concentrations of these samples were determined by this method with satisfactory results. The above method is simple, rapid and applicable to heavily contaminated samples.     

Label‐Free Fluctuation Spectroscopy Based on Coherent Anti‐Stokes Raman Scattering from Bulk Water Molecules

Nanoparticles (NPs) and molecules can be analyzed by inverse fluorescence correlation spectroscopy (iFCS) as they pass through an open detection volume, displacing fractions of the fluorescence‐emitting solution in which they are dissolved. iFCS does not require the NPs or molecules to be labeled. However, fluorophores in μm –mm concentrations are needed for the solution signal. Here, we instead use coherent anti‐Stokes Raman scattering (CARS) from plain water molecules as the signal from the solution. By this fully label‐free approach, termed inverse CARS‐based correlation spectroscopy (iCARS‐CS), NPs that are a few tenths of nm in diameter and at pM concentrations can be analyzed, and their absolute volumes/concentrations can be determined. Likewise, lipid vesicles can be analyzed as they diffuse/flow through the detection volume by using CARS fluctuations from the surrounding water molecules. iCARS–CS could likely offer a broadly applicable, label‐free characterization technique of, for example, NPs, small lipid exosomes, or microparticles in biomolecular diagnostics and screening, and can also utilize CARS signals from biologically relevant media other than water.     

Determination of Organochlorine Pesticides in Sediments from Authie Bay Using Microwave Assisted Solvent Extraction

The aim of this study was to develop an analytical method to determine the organochlorine concentrations in sediments. Combination of Microwave assisted Solvent Extraction (MASE) and capillary gas chromatography with specific detection (electron capture detector) was a viable approach for the determination of pesticides in solid matrixes. In this study, MASE development was focused on the selection of a suitable extraction solvent for all the target analytes. MASE procedure was validated by comparison with conventional methods such as Soxhlet and sonication extraction. The proposed method was then applied to determine the organochlorine insecticides concentrations in samples from Authie Bay (France). Environmental water samples were analysed and five target analytes were detected in concentrations from 0.03 to 0.56 ng/g of dry sediment. These investigations showed the accumulation and the persistency of these products in sediments in spite of the fact they were banned a few decades ago.     

Determination of heavy metal complexes with humic substances by HPLC/ICP-MS coupling using on-line isotope dilution technique

An isotope dilution mass spectrometric (IDMS) method has been developed for the simultaneous determination of the complexes of 11 heavy metals (Ag, Cd, Cu, Mo, Ni, Pb, Tl, U, W, Zn and Zr) with humic substances (HS) by coupling HPLC with ICP-MS and applying the on-line isotope dilution technique. The HPLC separation was carried out with size exclusion chromatography. This HPLC/ICP-IDMS method was applied to samples from a brown water, ground water, sewage and seepage water as well as for a sample containing isolated fulvic acids. The total contents of heavy metals and of their complexes were analyzed in these samples with detection limits in the range of 5–110 ng/L. The analysis of heavy metal/HS complexes from the different waters resulted in characteristic fingerprints of the distribution pattern of heavy metals in the separated HS fractions. A comparison between the total heavy metal concentrations and their portions bound to humic substances showed distinct differences for the various metals. Simultaneous ¹²C detection was used for the characterization of HS complexes not identified by UV detection and for the determination of relative DOC concentrations of chromatographic peaks. Received: 21 February 1997 / Revised: 27 May 1997 / Accepted: 28 May 1997     

The determination of lead in water and sediment samples using a lead ion-selective electrode

Lead concentrations in water and sediment samples near a stationary metal emission source were determined using the lead ion-selective electrode. These results were then verified by use of atomic absorption spectrophotometric methods. Samples were collected at three strategic sites near a local lead company in Southeast Houston, Texas. Accumulated rain water and sediment (soil deep down core) were analyzed in order to estimate lead concentration as a function of depth. Data indicate that the level of lead concentrations in both surface water and water extracted from the sediments exceed the limits for drinking water as established by the Environmental Protection Agency. The lead concentrations of the soil samples were higher in most cases when compared with various soils in the United States. The highest concentrations of lead were found in surface water samples.     

Radon concentration in drinking water sources of the region adjacent to a tectonically active Karak Thrust,southern Kohat Plateau,Khyber Pakhtunkhwa,Pakistan

A total of 84 drinking water samples from tube wells, natural springs, hand pumps and open wells in the region adjacent to a tectonically active Karak Thrust, Pakistan, were analyzed for radon content determination. These samples have a mean, maximum and minimum radon values of 9.4 ± 0.4, 25.1 ± 0.9, and 1.1 ± 0.2 Bq l^?1, respectively. This study indicates that 24 % of samples from tube wells, 44 % from springs, and 50 % from hand pumps have radon levels in excess of the EPA recommended maximum contaminant level of 11.1 Bq l^?1. The mean annual effective doses of all the samples are lower than the reference level of 0.1 mSv a^?1. Drinking water from majority of the sources within the region is generally safe as far as radon related health hazards are concerned with exception of few isolated cases.