Determination Of Chlorine Research Articles

An improved N, N′-diethyl- p-phenylenediamine (DPD) method for the determination of free chlorine based on multiple wavelength detection

The N, N′-diethyl- p-phenylenediamine (DPD) standard method for the determination of free chlorine by spectroscopic detection at 515 nm has a limited analytical range, 0.7–56 μmol l −1. It is shown that detection performed at 324 nm enhances the method sensitivity by a factor of 2. For analyte concentrations above 100 μmol l −1, a decrease in the absorbance is observed at 515 nm, making the method ambiguous, while the absorbance still increases at 324 nm. By applying partial least squares (PLS) regression based on multiple absorbance values in the interval 200–600 nm, the useful analytical range can be extended further, up to 200 μmol l −1. This improvement is achieved whilst maintaining root mean square errors of cross-validation (RMSECV) of the same order as for the univariate standard method. The multivariate approach also enables identification of samples containing interfering metals, here as Fe 3+, which form light absorbing chelates with EDTA.

Elemental analysis of landfill gas by ICP emission spectrometry—new approach for monitoring organochlorine compounds

A new method for the determination of atomic chlorine in landfill gas samples based on direct gaseous injection and ICP emission spectrometry is described. Samples were collected from landfill gas sites using stainless-steel Gresham tubes and then transferred to a gas syringe linked to a gas sampling manifold. Based on monitoring the atomic chlorine line at 134.74 nm, linear calibration was established for standard gas mixtures (CH4/CO2 containing organochlorine compounds) over the concentration range 0–980 mg m−3 (atomic Cl basis) and the limit of detection (3s) was 0.98 mg m−3. Relative to GC-MS analysis, the main analytical advantages were rapid analysis time (3 min versus 20 min per sample) and simplicity of data evaluation.

Rapid determination of free active chlorine in water by diffuse reflectance spectroscopy after reaction with polyurethane foams

A simple and sensitive method for the determination of free active chlorine in waters has been proposed. It is based on the reaction of surface toluidine groups of polyurethane foams (PUF) with chlorine under acid conditions. A yellow-colored product of the reaction is determined immediately in the PUF using diffuse reflectance spectroscopy. The calibration curve is linear over 0.2–6 μg/ml or 5–150 μg in 25 ml of final aqueous solution. Interference from various foreign substances has been examined and the method has been successfully applied to the determination of free residual chlorine in water.

Determination of the fission averaged cross sections of some threshold reactions induced on chlorine, potassium, and calcium, and their role in the development of self-validated methods of neutron activation analysis

The feasibility of validating data obtained in the determination of chlorine, potassium, and calcium by neutron capture activation analysis, through their determination using threshold reactions has been studied. To this purpose the authors experimentally determined the following fission neutron spectrum averaged cross sections (in mb):37Cl(n,p)37S, 0.234±0.015;41K(n,α)38Cl, 0.740±0.044;42Ca(n,p)42K, 3.09±0.22;43Ca(n,p)43K, 2.27±0.12;44Ca(n,p)44K, 0.074±0.013. The application of these values to the analysis of some reference materials are presented. Also, the problem of mutual interferences has been addressed for the following pairs:36S(n,Γ)37S and37Cl(n,p)37S;37Cl(n,Γ)38Cl and41K(n,α)38Cl;41K(n,ψ)42K and42Ca(n,p)42K.

The miniaturisation of the standard method based on the N, N′-diethyl- p-phenylenediamine (DPD) reagent for the determination of free or combined chlorine

A miniaturised continuous flow method for the determination of free or combined chlorine in purification plant water has been developed. The method is based on the standard batch procedure which uses a phosphate buffer for pH adjustment and N, N′-diethyl- p-phenylenediamine (DPD) as a colorimetric reagent. The sample, the reagent and the buffer solutions are continuously pumped into a miniaturised flow system. The mixing, the thermostating and the chemical reaction take place in a manifold with an engraved zigzag flow channel. A flow through detector is positioned at the flow channel outlet. The flow channel volume is about 25 μl and the detector volume is 0.25 μl. An experimental design was performed revealing that the significant variables were the total flow rate and the length of the mixing channel. Based on the results from this experimental design a total flow rate of 90 μl/min and a channel length of 60 mm were selected. The total consumption of sample and reagent is less than 3.9 l per month when the system is operated continuously. The response time is less than 2 min. When combined chlorine, in essence chloramine, is determined, potassium iodide is added to the buffer solution. The limit of detection is 3.2 μM for free chlorine and 1.9 μM for monochloramine.

Determination of active chlorine in air by bonded phase sorbent collection and spectrophotometric analysis

The development and application of a collection method for total combined gas-phase active chlorine (i.e., Cl2, HOCl and chloramines) based on a sulfonamide-functionalized silica gel sorbent are presented. Preparation methods for the sorbent are described, as are procedures for chemical and physical characterization, such as chlorine capacity and chlorine collection efficiency. For determination of the collected chlorine, a modified version of the N,N′-diethyl-p-phenylenediamine (DPD) colorimetric method was employed, which yielded a detection limit of 0.1 µg of chlorine. At flow rates ranging from 31 to 294 ml min–1, the collection efficiency was >90% based on breakthrough analysis. Recovery of chlorine spikes from 0.05 g aliquots of the sorbent was not quantitative (≡60%) but was reproducible; the recovery is accounted for in samples by adding weighed amounts of sorbent to the standards. Analytical data for active chlorine concentrations (i.e., Cl2 + HOCl) above a swimming pool are presented.

Analysis of chlorine and other halogens by activation with photons and neutrons

The analysis of halogens in various matrices is described. Activation analysis with mainly high energy bremsstrahlung (PAA) and pile neutrons (NAA) was applied. In the case of chlorine, fast procedures were worked out requiring not more than 100 min for one determination. The particular problems of fluorine analysis are discussed. The described techniques were applied for the following cases: Determination of total chlorine resp. bromine in oil samples; determination of chlorine in wood, glasses and TiN powders; determination of iodine in ZnSe single crystals using instrumental photoactivation.The limits of detection are: (interference-free in μg/g) F: 0.03/–; Cl: 0.1/0.05; Br: 0.04/0.003 and I: 0.1/0.01 using PAA/NAA. Activation analysis, being independent upon the chemical status of the analyte and usually less affected by blank problems has been found to be a useful complement to conventional chemical analysis.

Determination of extractable organic bromine and chlorine in biological compartments of Atlantic cod (Gadus morhua) by neutron activation analysis

Tissues, eggs and bile of adult Atlantic cod raised in captivity and fed natural food with no additional halogenated compounds of any kind were analyzed by neutron activation. There was a large difference in the tissue distributions of extractable organic chlorine (EOCl) and bromine (EOBr). Liver lipid had the lowest levels of EOBr and EOCl, of all the components investigated, and eggs had the highest levels of EOCl. Heart contained the most EOBr and EOCl per unit lipid, of the tissues. The presence of a larger proportion of EOBr than EOCl in bile suggests a higher rate of excretion of EOBr. The EOCl concentratios found in cod egg lipids were about 5 times higher than the highest values previously reported for EOCl in lipid.

Analyte volatilization procedure for the determination of low concentrations of chlorine by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry

A simple method is described for the generation of a continuous flow of volatile chlorine by the oxidation of aqueous chloride for the determination of low concentrations of chlorine by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry (He MIP-AES). The chlorine atom emission line at 438.976 nm and ion emission lines at 479.454 and 481.006 nm were selected as the analytical lines of interest. Of the various oxidation reactions investigated, two analyte volatilization reactions with potassium permanganate and perbromate in combination with sulfuric acid were found to be the most appropriate for the generation of elemental chlorine. The gaseous chlorine is separated from the solution in a simple gas–liquid separator, dried with concentrated sulfuric acid and swept into the MIP with helium carrier gas for analysis. The best attainable detection limits (3 σ criterion) for chlorine at 438.976, 479.454 and 481.006 nm with the use of potassium permanganate as an oxidant were found to be 29.9, 6.8 and 12.3 ng ml −1, respectively. Typical calibration graphs obtained under the optimized experimental conditions are rectilinear over approximately three orders of magnitude of concentration. The present method has successfully been applied to the determination of chlorine as chloride in several water samples.

New test tools: Benzidine on cellulose and silica gel

Chromogenic reagents based on covalent and non-covalent immobilization of benzidine on cellulose and silica gels have been developed and investigated. New test tools and test methods have been elaborated for the determination of chlorine in the concentration range of 0.05–120 mg/L.

Stability and bactericidal activity of chlorine solutions.

To determine the stability of sodium hypochlorite (diluted household bleach) when stored for 30 days in various types of containers and to determine the efficacy of low concentrations of free available chlorine to inactivate test bacteria. Laboratory-based study. Solutions of standard household bleach were prepared using tap water or sterile distilled water at dilutions of 1:100, 1:50, and 1:5. Chlorine concentrations were measured, and then the solutions were placed into five polyethylene containers and left at room temperature (20 degrees C) under various conditions (translucent containers with light exposure and with or without air; brown opaque container without light or air exposure). Samples for chlorine and pH determinations were taken at time 0 and on days 7, 14, 21, 30, and 40. Bactericidal activity of chlorine solutions was assessed using the Association of Official Analytical Chemists Use-Dilution Method. Test bacteria included Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella choleraesuis. Chlorine concentrations at 30 days varied from the 40% to 50% range for 1:50 or 1:100 dilutions stored in containers other than closed brown containers to 83% to 85% for the 1:5 dilution stored in closed but non-opaque containers to 97% to 100% for 1:50 or 1:5 solutions stored in closed brown containers. The lowest concentration of sodium hypochlorite solution that reliably inactivated all the test organisms was 100 ppm. These data suggest that chlorine solutions do not need to be prepared fresh daily, as is recommended currently, and the lowest concentration of chlorine that reliably inactivates S aureus, S choleraesuis, and P aeruginosa is 100 ppm.

Photoresist Stripping Composition

This paper describes the development of a process to clean photoresist and postetch residues from metal lines. The design rules for this 0.25 micron technology demand that not only should the device structure be clean but also that residual chlorine is reduced to minimise the possibilities of lateral erosion of the metal stack.Several analytical techniques are used in this evaluation, including FESEM for morphological examination, Wavelenght Dispersive X-Ray Fluorescence (WDXRF) and X-Ray Photoelectron Spectroscopy (XPS) for chlorine determination and finally electrical testing of the device to support our study.

A post metal etch cleaning process for 0.25 μm technology

This paper describes the development of a process to clean photoresist and postetch residues from metal lines. The design rules for this 0.25 micron technology demand that not only should the device structure be clean but also that residual chlorine is reduced to minimise the possibilities of lateral erosion of the metal stack. Several analytical techniques are used in this evaluation, including FESEM for morphological examination, Wavelenght Dispersive X-Ray Fluorescence (WDXRF) and X-Ray Photoelectron Spectroscopy (XPS) for chlorine determination and finally electrical testing of the device to support our study.

Determination of chlorine and pentachlorophenol in wood

Chlorine in wood was determined in connection with the development of a reference material (RM) of pentachlorophenol (PCP) in wood. The element was determined by photon activation analysis (PAA) using bremsstrahlung of 19 MeV electrons from an electron linear accelerator. The initial overall Cl content as well as the Cl remaining after extraction with methanol and subsequent extraction with water were determined. Moreover, the PCP fractions in the organic and in the aqueous extracts were analyzed by gas chromatography (GC). The results show that at least three quarters of the overall chlorine is bound in PCP and that PCP can be extracted to a high degree.

Solid-phase extraction and spectrophotometric determination of chlorine in air and residuals of free and combined chlorine in water utilizing azo dye formation

Oxidation of phenylhydrazine-4-sulfonic acid to the 4-diazobenzenesulfonic acid cation and its electrophilic coupling with N-(1-naphthyl)ethylenediamine dihydrochloride to give an azo dye is a new reaction scheme that is proposed for the spectrophotometric determination (545 nm) of chlorine in air and free and combined chlorine residuals in environmental waters. Masking of free chlorine with acetone permitted the determination of combined chlorine residuals in water. The maximum molar absorptivity was found to be 1.46 × 106 l mol–1 cm–1. A rectilinear calibration graph was obtained for 2.5–100 µg l–1 Cl. The azo dye could also be preconcentrated by solid-phase extraction on a C18 sorbent, leading to an enrichment factor of at least 40-fold. The limit of detection (without enrichment) was 0.2 µg l–1 Cl. Up to 50 µg l–1 bromate, 10 mg l–1 chlorate, 40 µg l–1 copper(II) and 100 µg l–1 iron(III) did not interfere. Chlorine dioxide was removed by bubbling the water sample with nitrogen. A comparison of the proposed method with the standard 4-N,N-diethylaminoaniline procedure was made and advantages of the present method are noted.

Simultaneous determination of chlorine and oxygen evolving at RuO2/Ti and RuO2-TiO2/Ti anodes by differential electrochemical mass spectroscopy

Chlorine and oxygen evolving at RuO2/Ti and RuO2–TiO2/Ti anodes have been simultaneously determined at electrode potentials from 1.0 to about 2V (vs Ag/AgCl) by differential electrochemical mass spectroscopy (DEMS). On the RuO2/Ti anodes, the threshold electrode potential for oxygen evolution increased with a decrease in RuO2 loading, while the chlorine evolution potential was unchanged. Low RuO2 loading anodes gave a high chlorine evolution ratio under various constant electrolysis potentials. On the RuO2–TiO2/Ti anodes, the threshold electrode potential for oxygen evolution increased with an increase in the TiO2 content more remarkably than that for chlorine evolution. High TiO2 content anodes gave a high chlorine evolution ratio at various constant electrolysis potentials. The combination of RuO2 and TiO2 exhibits a remarkable effect with respect to the enhancement of chlorine evolution selectivity.

Determination of some inorganic species in edible vegetable oils and fats by ion chromatography

A procedure has been developed for the ion chromatographic determination of total chlorine, phosphorus and sulphur and of iron, copper, nickel, zinc, cobalt, lead and cadmium in edible vegetable oils and fats. The organic matrix which strongly interferes in analytical procedures, is completely removed by saponification followed by oxidative UV photolysis. This method is simpler and requires less reagents compared with other sample pretreatment procedures. To oil and fats, ethanol and potassium hydroxide were added, and they were saponified for half an hour. Hydrogen peroxide was added and the sample was subjected to UV photolysis at 85±5°C. In less than 1 h organic constituents were completely degraded, while inorganic constituents, except nitrates, iodides and manganese, remained unaffected by UV radiation. Chlorine, phosphorus and sulphur, present in different organic compounds, can be quantified as total amounts only, without speciation. The clear sample solutions were directly injected on to an ion chromatograph equipped both with a conductivity detector, for the determination of total chloride, phosphate and sulphate ions using a carbonate–hydrogencarbonate eluent, and a post-column reactor and a variable-wavelength UV–Vis detection system, for the determination of lead and cadmium using an oxalate eluent and iron, copper, nickel, zinc and cobalt using a pyridine-2,6-dicarboxylic acid eluent. The method has been tested on spiked and unspiked samples of vegetable oils and fats and was found to be satisfactory for the determination of the previously cited elements. Ion chromatographic responses were compared to voltammetric ones and were found to be in good agreement (±3%).

Determination of halogen species of humic substances using HPLC/ICP-MS coupling

A mass spectrometric method for the determination of chlorine, bromine and iodine species of humic substances (HS) has been developed by coupling a HPLC system with ICP-MS. Using size exclusion chromatography, the method was applied to the characterization of natural water samples (ground water, seepage water from soil, brown water) and a sewage water sample. Quantification of iodine/HS species was carried out by the on-line isotope dilution technique, which was not possible for bromine and chlorine species because of mass spectroscopic interferences by using a quadrupole ICP-MS. Characteristic fingerprints of the halogen/HS species, correlated with the corresponding UV chromatogram, were obtained dependent on the different origin of HS. Biological influences were indicated when following changes of the iodine/HS species composition by aging. The formation of iodine/HS species from inorganic iodide was investigated by labelling experiments with an 129I– spike solution, resulting in the finding that specific HS fractions are preferably iodinated.

Sequential Determination of Chlorine and Carbon Isotopic Composition in Single Microliter Samples of Chlorinated Solvent

Chlorinated hydrocarbons, significant environmental pollutants, may be characterized by stable isotopic compositions of carbon and chlorine. Previously published analytical methods needed separate preparations for carbon and chlorine and were not ideal for environmental studies because of low sensitivity and precision. This method quantitatively extracts both carbon and chlorine from a single aliquot of chlorinated solvent of a size practically applicable to natural systems. Samples of 1−2 μL of chlorinated solvent are combusted in sealed tubes with cupric oxide at 620−820 °C. After separation of CO2 for isotopic analysis of carbon, the residue contains all the chloride in water-soluble form. It is then processed by conventional methods for chlorine isotopic analysis and gives a yield of 97 ± 27% (SD) on standard trichloroethylene (TCE) and 97 ± 4% on standard perchloroethylene (PCE) for the whole of the Cl preparation process. TCE and PCE laboratory standards show reproducibilities (SD) for both products...

Comparison of Methods and Kits for Colorimetric Determination of Residual Chlorine in Water

Abstract The use of 3,3',5,5'-tetramethylbenzidine (TMB) for residual chlorine determination in water offers 2 possibilities, one at pH 1-2 and absorbance measurement at 450 nm and another at pH 3.8-5.8 and measurement at 650 nm. The reaction of chlorine with TMB reaches its maximum sensitivity at pH 1-2. The detection limit is 2 ng/mL. A calibrated scale for colorimetric determination of residual chlorine in water with 3,3',5,5'-tetramethylbenzidine (TMB), prepared with tropaeolin O (C.I. 14270), is described. This scale is stable for several months and can be useful in replacing the conventional and much less stable scale prepared from standard solutions of oxochlorate (I). Kits for determination of residual chlorine in water by visual comparison, including a 3-dimensional scale or a color scale printed on paper or a plastic material, are described in this article. A comparative study of the analytical qualities and applications of the TMB methods against other reagents methods is performed.