Determination of Benzo(a)pyrene in Water by Synchronous Fluorimetry Following Preconcentration on Sephadex Gels

Abstract

Benzo(a)pyrene (BaP) which presents native fluorescence in solution has been determined in waters by synchronous solid-phase spectrofluorimetry. The relative fluorescence intensity of BaP fixed in Sephadex G-25 gel is measured after being packed in an 1-mm silica cell. Spectral characteristics of BaP-gel system are described. The applicable concentration range was 0.52–3.45 μg.L^?1 with a relative standard deviation of 1.2% and detection limit of 0.07 μg.L^?1. The method was applied to the analysis of waters with different provenances.     

Modification of Soxhlet Extractor for Rapid and Effective Recovery of Phenolic Pollutants Adsorbed on XAD-4 Resin

A newly modified extractor facilitated rapid extraction (10.0 mL, 1 h) of eleven phenols from XAD-4 resin for comparable recoveries to those with conventional Soxhlet extractor (80.0 mL, 3 h). Combined with analysis by gas chromatography and gas chromatography-mass spectrometry in selected ion monitoring mode as tert-butyldimethylsilyl derivatives, the overall method was linear (≥ 0.9991) with satisfactory precision (≤ 9.2% RSD), accuracy (≤ 7.7% RE), detection limit (≤ 0.02 μg L^?1), and recovery rates (≥ 75.0%) in 0.05 to 1.0 μg L^?1. Six phenolic pollutants were quantitatively screened along with bisphenol A (0.028 μg L^?1) from river water.     

Determination and speciation of selenium in water samples collected from Muğla (Turkey) province by hydride generation atomic absorption spectrometry

In this work, determination of selenium in various water samples was done by using hydride generation atomic absorption spectrometry. The most appropriate values of HCl concentration, NaBH₄ concentration, NaOH concentration, flow rate of argon and flow rate of waste solution were determined. The optimum concentration of the HCl, NaBH₄ and NaOH solutions were found to be 7.0 mol L^?1, 1.0% and 0.75%, respectively. The optimum flow rate of Ar gas and waste solution were also found to be 100.9 mL min^?1 and 4.0 mL min^?1, respectively. Values of LOD and LOQ were calculated separately for total Se and Se(IV). LOD and LOQ values were calculated 0.56 μg L^?1, 1.87 μg L^?1 for total Se and 0.72 μg L^?1, 2.40 μg L^?1 for Se(IV), respectively. The precision was evaluated by relative standard deviation (RSD%) was found to be 3.5% for total Se and 3.1% for Se(IV) (n = 11). A standard reference material (NIST 1643e) was used in order to check the accuracy of the proposed method. There was a good agreement between certified and found values for standard reference material. The method was applied to the analysis of total Se and Se(IV) concentrations in tap water samples collected from the various regions of Mu?la. Proposed method showed spike recovery ranges from 92% to 116% in water samples.     

Determination of Ethylenethiourea (ETU) at Trace Levels in Water Samples by Cathodic Stripping Voltammetry

A stripping voltammetric method for the determination of ethylenethiourea in water samples is described based on its adsorptive deposition at the hanging mercury drop electrode (HMDE). In a borate buffer (pH 9.0) as supporting electrolyte, ETU is deposited at +100 mV (vs. Ag/AgCl) and stripped during the cathodic scan. The linear range for the measurements was from 2.0 to 100 μg L^?1, with a detection limit calculated as 1.4 μg L^?1 after a deposition time of 300 s and a RSD of 1.9% (n=5) for 50 μg L^?1 of ETU measured. The interferences of some organic compounds and metallic ions were tested. Recoveries between 93 and 110% were obtained using the standard addition method for spiked samples of natural and drinking waters. The method is rapid and applicable in the monitoring of ETU residues in water samples.     

On-line determination of residual aluminium in potable and treated waters by flow-injection analysis

A portable, automated, flow-injection-based solid-state spectrophotometric field monitor for the determination of residual dissolved aluminium in potable and treated waters is described. Aluminium is determined by complexation with pyrocatechol violet to form a colloidal lake with a maximum absorbance at 580 nm. Interference from iron(III) is masked by reduction to iron(II) and complexation with 1,10-phenanthroline. The monitor operates on a 30-min analytical cycle, i.e., with 48 results per day, and each cycle includes an autocalibration step. Over the course of a 3-month field trial the reliability was greater than 90%. The performance conforms to industry specifications for both overall accuracy (bias < ± 10%) and repeatability (relative standard deviation < ± 10%), the linear range is 0–1000 μg l^?1 and the practical limit of detection is 45 μg l^?1.     

Preconcentration and Spectrophotometric Determination of Chromium (VI) and Total Chromium in Drinking Water by the Sorption of Chromium Diphenylcarbazone with Surfactant Coated Alumina

Abstract

A simple and inexpensive method for determining chromium (VI) in drinking water by spectrophotometry after preconcentration with sodium dodecyl sulphate (SDS) coated alumina column is described. Chromium(VI) is reacted with diphenylcarbazide (DPC) and the Cr-DPC complex is quantitatively adsorbed onto a SDS coated alumina column from 800 ml of sample solution. The complex is then eluted with a 8 ml mixture of methanol, acetone and hydrochloric acid and determined by spectrophotometry. Total chromium can be determined after oxidation of chromium (III) to chromium (VI) by KMnO₄. The relative standard deviation (10 replicate analyses) at the 10 μg l^?1 of chromium (VI) and 10 μg l^?1 of total chromium were 3.5% and 3.4% and corresponding limits of detection (based on 3 σ) were 0.040 μg l^?1 and 0.033 μg l^?1, respectively.     

Determination of cyanides in electroplating solutions as Ni(CN)42– and analysis by capillary electrophoresis

A CE method was developed for the determination of total (free and weakly bound) cyanide in electroplating solutions based on the use of a cationic surfactant (TTAB) and complexation with Ni(II)-NH₃ solutions to Ni(CN)₄ ^2–. Both direct complexation and cyanide distillation combined with complexation were tested. Under optimized conditions, this method is time-saving compared to standard methods. Total cyanide determined by CE had detection limits (with respect to the initial sample concentration) of 0.5 μg/mL for direct complexation and 50 ng/mL for distillation combined with complexation. Total cyanide and cyanide not amenable by chlorination (CNAC) were determined in real samples from spent electroplating baths.     

Differential-pulse polarographic determination of selenium species in contaminated waters

Selenium(IV), in the concentration range 2–100 μg l^?1 in contaminated waters, is determined by using the sensitive adsorption-controlled peak obtained by differential pulse polarography in dilute acid solution. Interfering heavy metals are removed on Chelex-100 resin. Selenium(VI) is not electroactive but can be determined after photolytic reduction in the absence of oxygen. Anion-exchange preconcentration is necessary if the total selenium is below the detection limit of 2 μg l^?1.     

Trace Detection of Mercury(II) Using Gold Ultra‐Microelectrode Arrays

The electroanalytical detection of trace mercury(II) at gold ultra‐microelectrode arrays is reported. The arrays consist of 256 gold microelectrodes of 5 μm in diameter in cubic arrangements which are separated from their nearest neighbor by 100 μm. The array was utilized in nitric acid using linear sweep voltammetry where a linear response from mercury additions over the range 10 μg L^?1?200 μg L^?1 (10^?8?10^?6 M) was observed with a sensitivity and detection limit of 0.11 nC/μg L^?1 and 3.2 μg L^?1 (16 nM) respectively from using a deposition time of 30 s at ?0.2 V (vs. SCE). This methodology was explored in 0.1 and 1 M chloride media over the mercury range 10 μg L^?1?200 μg L^?1 (5×10^?8?10^?6 M) where similar sensitivities of 0.087 nC/μg L^?1 and 0.078 nC/μg L^?1 were observed with an identical detection limit. The protocol is demonstrated to be useful for the determination of mercury for analysis of environmental water samples.     

Determination of Total Selenium in Human Urine and Serum by Graphite-Furnace Atomic-Absorption Spectrophotometry with Palladium-Nickel-Ammonium Nitrates as a Matrix Modifier

After human urine or serum was diluted (1 + 9) with HNO₃ (0.2%, v/v) and standard additions of Se solution (100 μ L^?1), the diluted sample (10 μL) was introduced into the graphite cuvette. The matrix modifier [10μL, containing Pd (0.6 μg) + Ni (25 μg) + NH₄NO₃ (80 μg) in HNO₃ (0.2%, v/v) for urine, or Pd (0.3 μg) + Ni (30 μg) + NH₄NO₃ (80 μg) + Triton X-100 (0.04%) in HNO₃ (0.2%, v/v) for serum, respectively] was added and the mixture was heated according to a temperature program. The matrix modifier containing NH₄NO₃ in a suitable amount and a small amount of Pd enhanced the sensitivity for Se. The method detection limits (3σ) after dilution were about 4.9 ± 0.8 and 2.36 ± 0.18 μg L^?1 for urine and serum, respectively. The accuracy of this method was tested with SRM #2670 human urine Se and Seronorm Trace Elements #116 human serum Se, respectively, and the results of 97.6 – 101% and 100 – 104% were obtained with precision ± 0.3% and ± 2%, respectively. This method can be applied easily and accurately to the determination of concentration of total Se in human urine and serum.     

Rubidium Determination In Mineral and Thermal Waters By Atomic-Absorption Spectrometry

Abstract

A new procedure for rubidium determination in mineral and thermal waters using flame atomic-absorption spectrometry is described. to supress ionisation interference potassium solution was added. Rubidium can be determined in presence of Ca, Mg, Sr, Li, Cs, Fe, Al, CO² ₃, F^? and S^2? at higher levels that levels of these elements in waters. the precision and accuracy of the method were also investigated. In 163 mineral and thermal waters analysed, the rubidium concentration range is between 0.08 to 0.84 μg mL^?1.     

An ionic liquid-based sensor for diclofenac determination in water

This paper details a miniaturised, solid state ion-selective electrode selective for diclofenac. The sensor comprises a novel ionic liquid electroactive material – an imidazolium–diclofenac ion associate. The ion associate is present in a plasticised poly(vinyl chloride) (PVC) membrane on planar carbon electrodes, with an intermediate poly(3,4-ethylenedioxythiophene) layer. The sensitivity and selectivity of the sensor were determined using chronopotentiometric methods. In response to diclofenac, a slope of ?53.3 ± 3.6 mV/dec was observed. A limit of detection of 2.90 × 10^?3 g L^?1 is reported, with a linear range of 3.18 × 10^?3 g L^?1 to 3.18 g L^?1. The sensors show good selectivity towards diclofenac against pertinent interferent molecules, with a response time of <15 s.     

Redox Speciation of Inorganic Arsenic in Water and Saline Samples by Adsorptive Cathodic Stripping Voltammetry in the Presence of Sodium Diethyl Dithiocarbamate

This paper describes a new voltammetric procedure for the inorganic speciation of As(III) and As(V) in water samples. The procedure is based on the chemical reduction of arsenate [As(V)] to arsenite [As(III)] followed by the voltammetric determination of total arsenic as As(III) at the hanging mercury drop electrode (HMDE) by adsorptive cathodic stripping voltammetry (AdCSV) in the presence of sodium diethyl dithiocarbamate (SDDC). The reduction step involved the reaction with a mixture of Na₂S₂O₅ and Na₂S₂O₃ in the concentrations 2.5 and 0.5 mg mL^?1, respectively, and the sample heating at 80 °C for 45 min. The linear range for the determination of total arsenic as As(III) in the presence of SDDC was between 5 and 150 μg L^?1 for a deposition time of 60 s (r=0.992). A detection limit of 1.05 μg L^?1 for total As was calculated for the method in water samples using a deposition time of 60 s. The detection limits of 4.2 μg L^?1 and 15.0 μg L^?1 for total As in seawater and dialysis concentrates, respectively, were calculated using a deposition time of 60 s. The relative standard deviations calculated were 2.5 and 4.0% for five measurements of 20 μg L^?1 As(V) as As(III) in water and dialysis concentrates, respectively, after chemical reduction under optimized conditions. The method was applied for the determination of As(III) and total As in samples of dialysis water, mineral water, seawater and dialysis concentrates. Recovery values between 86.0 and 104.0% for As(III) and As(V) added to the samples prove the satisfactory accuracy and applicability of the procedure for the arsenic monitoring.     

Spectrophotometric Determination of Gadolinium(III) With O-Hydroxyhydroqoinonephthalein in Mixed Micelles of N-Hexadecylpyridinilm Chloride and Brij 35

Abstract

A sensitive, simple and selective spectrophotometric method for the determination of gadolinium(III) is proposed using o-hydroxyhydroquinonephthalein(Qnph), by analogy with phenylfl-uorone(Phfl), in the presence of N-hexadecylpyridinium chlo-ride(HPC)-Brij 35 mixed surfactants. The calibration curve is rectilinear in the range of 0 – 16.0 μg per 10 ml at 590 nm with an apparent absorption coefficient(?) of 1.2 × 10⁵ 1 cm^?1 mol^?1 and Sandell sensitivity of 0.0013 μg/cm² gado-linium(III).     

Simultaneous Determination of Atrazine and Chlorpyrifos in Pesticide Formulations,in Soils and Waters by Derivative Spectrophotometry and Ratio Spectra Derivative

Abstract

A new method is described to analyse a binary mixture of atrazine and chlorpyrifos, using first-derivative spectrophotometry for atrazine and first derivative of the ratio spectra for chlorpyrifos. The procedure does not require any separation step. Calibration graphs were linear up to 15 μg.mL^?1 of atrazine and to 10 μg.mL^?1 of chlorpyrifos. The method has been applied to determine both compounds in pesticide formulations, in soils and waters.     

Ultra‐sensitive Voltammetric Aluminum Determination on a Solid Bismuth Electrode for Water Filter Verification

This work presents a new ultra‐sensitive method of Al(III) as Al‐cupferron complex voltammetric determination, in 0.04 M ammonium sulfate of pH=6.1 and 0.003 M cupferron by environmentally friendly and durable Bismuth Bulk Annular Band Electrode (BiABE). The optimal measuring parameters include: potential window from ?700 to ?1250 mV versus Ag|AgCl, preconcentration time and potential of 120 s, ?700 mV, respectively. The electrode surface can be activated by fast in situ method: applying short conditioning by the potential of ?1300 mV. The best obtained analytical parameters are: range of linearity 0.2–1.2 μg L^?1 with high sensitivity of 1.333 μA/μg L^?1, limit of detection 0.04 μg L^?1 and repeatability below 2.3 %. The described procedure was verified using various CRMs, i. e. surface waters, waste waters and tea leaves. Satisfactory recovery values were obtained in the interval 99.2–103.5 %. Developed DPV procedure was used to determine Al in tap and natural waters in aspect of recovery of aluminum, which was added to the samples. For the first time, we tested also Al removal efficiency from water by the water filters mounted in the trip bottle.     

Application of Graphene as a Sorbent for Simultaneous Preconcentration and Determination of Trace Amounts of Cobalt and Nickel in Environmental Water and Vegetable Samples

A new method using a column packed with graphene as adsorbent was developed for the preconcentration of trace amounts of cobalt (Co) and nickel (Ni) prior to their determinations by flame atomic absorption spectrometry. Several factors influencing the extraction efficiency of Co and Ni and their subsequent determinations, such as pH, amounts of the chelating agent, flow rates of sample and eluent solution, eluent type and its volume, breakthrough volume, and adsorption capacity were established. Under the optimum conditions, the calibration graphs were linear in the range of 4.0‐200.0 μg L^?1 and 5.0‐200.0 μg L^?1 with detection limits of 0.36 μg L^?1 and 0.51 μg L^?1 for Co and Ni, respectively. Good relative standard deviations for ten determinations of 100.0 μg L^?1 of Co and Ni were 3.2 and 3.6%, respectively. The results for determination of Co and Ni in tap water, river water, sea water, vegetable and spiked samples have demonstrated the accuracy and applicability of the proposed method. To validate the proposed method, three certified reference materials of environment water (GSBZ 50030‐94 and GSB 07‐1186‐2000) and tomato leaf (GSBZ 51001‐94) were analyzed, and the determined values were in good agreement with the certified values.     

Development of an Enzyme Immunoassay for the Determination of the Herbicide Metsulfuron-Methyl Based on Chicken Egg Yolk Antibodies

Abstract

The development of an indirect competitive enzyme immunoassay for the sulfonylurea herbicide metsulfuron-methyl (MSM) is described. In contrast to traditional antibody generation in mammals, this extremely sensitive method is based on chicken egg yolk antibodies (IgY). They were raised in laying hens using an MSM-derivative-BSA hapten as immunogen. With a 1:10000 dilution of the antibody solution and a coating antigen (MSM-derivative-KLH) concentration of 10 μg L^?1 the IC₅₀ value achieved for the target analyte was 0.4 μg L^?1. The least detectable dose was established at 13 ng L^?1. Cross-reactivity was tested with 5 structurally related compounds, where only sulfometuron showed a significant binding. The ELISA was tested with spiked tap and surface water samples. This paper, for the first time, demonstrates the production of high-affinity IgY antibodies for a herbicide compound.     

238U and 222Rn activity concentrations and total radioactivity levels in lake waters

The concentrations and distributions of natural radioactivity, uranium and radon in lake waters from around Van, Turkey were investigated with an aim of evaluating the environmental radioactivity. Fourteen lake waters were collected from different six lakes around Van (Turkey) to determine ²³⁸U, ²²²Rn and total alpha and total beta distributions in 2009. The total α and total β activities were counted by using α/β counter of the multi-detector low background system (PIC-MPC-9604) and the ²³⁸U concentrations were determined by inductively coupled plasma-mass spectrometry (Thermo Scientific Element 2) and radon concentrations were measured with the solid state nuclear track detector technique. The activity concentrations ranging from ND to 0.039 Bq L^?1 and from 0.026 to 3.728 Bq L^?1 for total alpha and beta, respectively, and uranium concentrations ranging from 0.083 to 3.078 μg L^?1, and radon concentrations varying between 47.80 and 354.86 Bq m^?3 were observed in the lake waters.     

Automated determination of total arsenic in sea water by flow constant-current stripping analysis with gold fibre electrodes

Total arsenic in sea water is determined in a fully automated flow system, by means of potentiostatic deposition for 4 min at a 25-μm gold fibre electrode and subsequent constant-current stripping in 5 M hydrochloric acid. Previously the sample is acidified with hydrochloric and arsenic(V) is reduced to arsenic(III) with iodide. During stripping, the potential vs. time transient is recorded with a real-time measurement rate of 26.5 kHz and a potential resolution of 1 mV. Cleaning and regeneration of the gold electrode are fully automated. The total arsenic concentrations in two reference sea waters (NASS-1 and CASS-1) were evaluated by single-point standard addition and found to be 1.58 and 1.14 μg l^?1 with standard deviations of 0.39 and 0.28 μg l^?1, respectively; certified values are 1.65 ± 0.19 and 1.04 ± 0.07 μg l^?1. The arsenic(III) content in these samples was below the detection limit (0.15 μg l^?1).