Chlorine Interference Research Articles

Study on element detection and its correction in iron ore concentrate based on a prompt gamma-neutron activation analysis system

A prompt gamma-neutron activation analysis (PGNAA) system was developed to detect the iron content of iron ore concentrate. Because of the self-absorption effect of gamma-rays and neutrons, and the interference of chlorine in the neutron field, the linear relationship between the iron analytical coefficient and total iron content was poor, increasing the error in the quantitative analysis. To solve this problem, gamma-ray self-absorption compensation and a neutron field correction algorithm were proposed, and the experimental results have been corrected using this algorithm. The results show that the linear relationship between the iron analytical coefficient and total iron content was considerably improved after the correction. The linear correlation coefficients reached 0.99 or more.

Exploration of an urban lake management model to simulate chlorine interference based on the ecological relationships among aquatic species

In eutrophic lakes, algae are known to be sensitive to chlorine, but the impact of chlorine on the wider ecosystem has not been investigated. To quantitatively investigate the effects of chlorine on the urban lake ecosystem and analyze the changes in the aquatic ecosystem structure, a dynamic response model of aquatic species to chlorine was constructed based on the biomass density dynamics of aquatic species of submerged macrophytes, phytoplankton, zooplankton, periphyton, and benthos. The parameters were calibrated using data from the literature and two simulative experiments. The model was then validated using field data from an urban lake with a surface area of approximately 8000 m2 located in the downtown area of Guangzhou, South China. The correlation coefficient (R), root mean square error-observations standard deviation ratio (RSR) and index of agreement (IOA) were used to evaluate the accuracy and reliability of the model and the results were consistent with the observations (0.446 R < 0.985, RSR < 0.7, IOA > 0.6). Comparisons between the simulated and observed trends confirmed the feasibility of using this model to investigate the dynamics of aquatic species under chlorine interference. The model can help managers apply a modest amount of chlorine to control eutrophication and provides scientific support for the management of urban lakes.

A System Dynamic Model for Shallow Urban Lake Coupling With the Interference of Chlorine

Ecological models play an important role in lake eutrophication research and management. Many integrated system models have been developed since the 1970s. However, their fixed structure limits flexibility and applicability in urban landscape lakes. An ecosystem dynamic model was constructed to simulate ecological restoration of an urban shallow lake under the interference of chlorine. The model was validated using the monitoring data of an urban lake in Guangzhou. The correlation coefficient (R), root mean squareerror-observations standard deviation ratio (RSR) and index of agreement (IOA) were calculated to evaluate accuracy and reliability of the model and their values for all of the compared variables were significant, less than 0.7, and larger than 0.6, respectively, which reflected good agreement of the model. The results give important insight into understanding eutrophic dynamic process in urban shallow lake. Furthermore, the exhibit model has great applicability in management of urban shallow lakes.

Rapid and sensitive detection of Pseudomonas aeruginosa in chlorinated water and aerosols targeting gyrB gene using real-time PCR.

For the rapid detection of Pseudomonas aeruginosa from chlorinated water and aerosols, gyrB gene-based real-time PCR assay was developed and investigated. Two novel primer sets (pa722F/746MGB/899R and pa722F/746MGB/788R) were designed using the most updated 611 Pseudomonas and 748 other bacterial gyrB genes for achieving high specificity. Their specificity showed 100% accuracy when tested with various strains including clinical isolates from cystic fibrosis patients. The assay was tested with Ps. aeruginosa-containing chlorinated water and aerosols to simulate the waterborne and airborne transmission routes (detection limit 3·3 × 10² CFU per PCR-2·3 × 10³ CFU per PCR). No chlorine interference in real-time PCR was observed at drinking water level (c. 1 mg l⁻¹), but high level of chorine (12 mg l⁻¹) interfered the assay, and thus neutralization was needed. Pseudomonas aeruginosa in aerosol was successfully detected after capturing with gelatin filters with minimum 2 min of sampling time when the initial concentration of 10⁴ CFU ml⁻¹ bacteria existed in the nebulizer. A highly specific and rapid assay (2-3 h) was developed by targeting gyrB gene for the detection of Ps. aeruginosa in chlorinated water and aerosols, combined with optimized sample collection methods and sample processing, so the direct DNA extraction from either water or aerosol was possible while achieving the desired sensitivity of the method. The new assay can provide timely and accurate risk assessment to prevent Ps. aeruginosa exposure from water and aerosol, resulting in reduced disease burden, especially among immune-compromised and susceptible individuals. This approach can be easily utilized as a platform technology for the detection of other types of micro-organisms, especially for those that are transmitted via water and aerosol routes, such as Legionella pneumophila.

The Influence of Chlorine on the Determination of Combined Water: An Investigation of a Correction Procedure

Differential thermal analysis, pH determination and ion chromatography were used to investigate the interference of chlorine in the determination of combined water (H2O+) by the Penfield tube gravimetric method. The magnitude of the chlorine interference was quantified and a correction method was proposed to obtain accurate results for H2O+. The method was applied to the determination of H2O+ in deep sea sediments containing chlorine and certified reference materials of oceanic polymetallic nodules.

Method based on Chelex-100 ion-exchange resin for the removal of chlorine interference in the determination of chlorite ion

A simple, inexpensive method for the removal of chlorine interference in the determination of chlorite ions in potable water is described. The method is based on the ability of an ion-exchange resin (Chelex-100) to react with chlorine but not with chlorite ion when mixtures of the two species are passed down a column containing the resin. The method was found to be accurate for chlorite concentrations in the range 0.08–13.0 mg 1 −1 in the presence of at least a four-fold excess of chlorine (whether present as chlorine or chloramine) and the sample system used will remove chlorine concentrations of at least 6 mg 1 −1. Attempts to regenerate the used Chelex-100 by removal of the chlorine proved unsuccessful. The method was successfully applied in trials at a water treatment plant.

An investigation of gas chromatography with atomic emission detection for the determination of empirical formulas

AbstractThe atomic emission detector (AED) is a valuable tool for the identification of unknowns in complex mixtures. To the extent that elemental response factors are independent of compound structure, gas chromatographic results allow calculation of atomic ratios for unknown compounds. In favorable cases, empirical formulas can be found. An algorithm for automated calculation of empirical formulas for all the peaks in a chromatogram has been developed. When finite accuracy prevents an exact determination of empirical formulas, the algorithm gives a list of all formulas for each compound which are compatible with the user‐defined limits.Examples are given of calculations for fatty acid methyl esters, substituted phenols, and pesticides. Analyses of volatile pollutants and polychlorinated biphenyls reveal a nonlinearity for hydrogen response, and an interference of chlorine on hydrogen. A lubricating oil analysis is used to illustrate the identification of unknowns.

Determination of Residual Ozone or Chlorine Dioxide in Water with ACVK – an Updated Version

Abstract The determination of residual ozone or residual chlorine dioxide can be carried out with Acid Chrome Violet K (C.I. code no. 61710, formerly 6170), now available as dye for analytical use under the name of Alizarin Violet 3R (Aldrich 22, 783-8; MW 622.25). The discoloration of the dye in an NH3-NH4CI buffered solution of pH 8.1 to 8.5 is specific both for ozone and for chlorine dioxide without interference of chlorine, chloramines, chlorite or chlorate ions in concentrations possibly encountered in treated drinking water. Detection limit : 0.02 mg L−l: standard deviation : 0.01 mg L−l are obtained both for ozone and chlorine dioxide.

Elimination of major molecular chlorine interference in the iodimetric determination of sulphur in saline sediments

Free chlorine evolved during the high-frequency induction furnace combustion of saline sediments at >1500°C interfered very seriously in the iodimetric titration of liberated sulphur dioxide. Remedies based on absorption of chlorine on copper, antimony and other traps were only partly successful; copper was the most efficient but the loss of titratable sulphur was still very large. Sample desalination with refluxing anhydrous methanol in a Soxhlet extractor was the only method found to give satisfactory performance. This procedure was successful for a broad range of salinity values (reference sample mixed with sodium chloride in ratios of 0.09–1.6) without affecting the sulphur minerals present. The procedure showed excellent precision and good agreement with the “best” values available for the USGS MAG-1 Marine Mud (0.40% S) with a relative standard deviation of 1.29%. Iodimetric determination of sulphur in salt core samples (with the sediment in minor proportions) would also be possible.

Selective determination of chlorine dioxide using gas diffusion flow injection analysis

An automated absorbance technique for the determination of aqueous chlorine dioxide has been developed by utilizing gas diffusion flow injection analysis. A gas diffusion membrane is used to separate the donor (sampling) stream from the acceptor (detecting) stream. The absorbance of chlorine dioxide is monitored at 359 nm. The first method uses distilled water as the acceptor stream and gives a detection limit of 0.25 mg/L chlorine dioxide. This system is over 550 times more selective for chlorine dioxide than chlorine. To further minimize chlorine interference, oxalic acid is used in the acceptor stream. The detection limit for this system is 0.45 mg/L chlorine dioxide. This second system is over 5400 times more selective for chlorine dioxide than chlorine. Both methods show excellent selectivity for chlorine dioxide over iron and manganese compounds, as well as other oxychlorinated compounds such as chlorite and perchlorate ions. 18 references, 7 figures, 3 tables.

A sensitive method for measuring organic carbon in sediment

In order to determine organic carbon in sediments, a sensitive method was devised by the combination of an ordinary wet combustion and TOC analyzer for aqueous samples. The carbon dioxide evolved by wet combustion was absorbed into 0.2 N NaOH solution and determined with a TOC analyzer. The accuracy and the determination limit of the method were determined. Carbon ranges from 0.4 to 48 mg were determined accurately without interference of chlorine and sulfur. This method was applied to the study of the composition of river sediment on the basis of extractability by various solvents.