The solvation parameter model is used to construct models for estimating the non-specific aquatic toxicity of organic compounds to the fathead minnow, guppy, golden orfe, water flea and the prokaryote Vibrio fischeri. Size is the characteristic solute property promoting toxicity and solute hydrogen-bond basicity in reducing it. Interspecies differences in toxicity result from differences in the above properties and also because of significant differences in the hydrogen-bond basicity and dipolarity/polarizability of biomembranes. In general, the octanol–water or dimyristoylphosphatidylcholine–water distribution systems are not good surrogate models for the aquatic toxicity for any of the species studied. The retention factor in correlation models for selected chromatographic systems is a suitable descriptor for estimating non-specific aquatic toxicity of organic compounds for some species, such as the tadpole and guppy.
{"title":"Models for estimating the non-specific aquatic toxicity of organic compounds","authors":"A. D. Gunatilleka, C. Poole","doi":"10.1039/A902875G","DOIUrl":"https://doi.org/10.1039/A902875G","url":null,"abstract":"The solvation parameter model is used to construct models for estimating the non-specific aquatic toxicity of organic compounds to the fathead minnow, guppy, golden orfe, water flea and the prokaryote Vibrio fischeri. Size is the characteristic solute property promoting toxicity and solute hydrogen-bond basicity in reducing it. Interspecies differences in toxicity result from differences in the above properties and also because of significant differences in the hydrogen-bond basicity and dipolarity/polarizability of biomembranes. In general, the octanol–water or dimyristoylphosphatidylcholine–water distribution systems are not good surrogate models for the aquatic toxicity for any of the species studied. The retention factor in correlation models for selected chromatographic systems is a suitable descriptor for estimating non-specific aquatic toxicity of organic compounds for some species, such as the tadpole and guppy.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"17 1","pages":"235-242"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74503005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a micromixer for the laminar flow regime based on the principle of flow lamination. The structure is made up from a glass/silicon/glass sandwich, has a total internal volume of ≡600 nL and measures 5 mm × 10 mm. Flow rates between 1–200 µL min–1 have successfully been used. Fluorescence quenching experiments were carried out for quantification and showed 95% mixing within 15 ms.
{"title":"Microstructure for efficient continuous flow mixing","authors":"F. G. Bessoth, A. deMello, A. Manz","doi":"10.1039/A902237F","DOIUrl":"https://doi.org/10.1039/A902237F","url":null,"abstract":"This paper presents a micromixer for the laminar flow regime based on the principle of flow lamination. The structure is made up from a glass/silicon/glass sandwich, has a total internal volume of ≡600 nL and measures 5 mm × 10 mm. Flow rates between 1–200 µL min–1 have successfully been used. Fluorescence quenching experiments were carried out for quantification and showed 95% mixing within 15 ms.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"17 1","pages":"213-215"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84316620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The electrochemical behaviour of sodium dithionite at a platinum electrode has been investigated in this paper. Two oxidation waves of sodium dithionite were observed with formation of sulfite as a stable intermediate species. It has been found that the oxidation of sodium dithionite to sulfite, according to the first wave, is controlled by the rate of mass transport, the oxidation of sulfite to sulfate, however, is not purely controlled by transport phenomena. Using the ratio of the limiting currents of both oxidation waves it was possible to determine the diffusion coefficient of sodium dithionite by extrapolation to the small rotation rate of the platinum electrode. From the obtained results it is also advisable to make use of the first oxidation reaction for analytical purposes.
{"title":"Electrochemical behaviour of sodium dithionite at a platinum electrode and determination of diffusion coefficient in alkaline solution","authors":"E. Gasana, P. Westbroek, E. Temmerman, H. Thun","doi":"10.1039/A907665D","DOIUrl":"https://doi.org/10.1039/A907665D","url":null,"abstract":"The electrochemical behaviour of sodium dithionite at a platinum electrode has been investigated in this paper. Two oxidation waves of sodium dithionite were observed with formation of sulfite as a stable intermediate species. It has been found that the oxidation of sodium dithionite to sulfite, according to the first wave, is controlled by the rate of mass transport, the oxidation of sulfite to sulfate, however, is not purely controlled by transport phenomena. Using the ratio of the limiting currents of both oxidation waves it was possible to determine the diffusion coefficient of sodium dithionite by extrapolation to the small rotation rate of the platinum electrode. From the obtained results it is also advisable to make use of the first oxidation reaction for analytical purposes.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"20 1","pages":"387-389"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85520499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper demonstrates the potential contribution to the environment from water soluble phosphorus contained in discarded tobacco products. Dry tobacco was soaked in water and the concentration of dissolved phosphorus was determined by absorptiometry and ion chromatography. The total phosphorus was also measured by absorptiometry following decomposition by a nitric–sulfuric acid decomposition method. As a result, it was found that ca. 1.2 mg of phosphorus (as total PO4-P) was dissolved from unit mass of dry tobacco. It is estimated that the amount of phosphorus that could pass into the Japanese environment through discarded cigarettes was 115–208 kg per day.
{"title":"Potential contribution of discarded cigarettes to anthropogenic eutrophication in an urban area","authors":"K. Fukushi, Nobuhiro Ishio, K. Hiiro","doi":"10.1039/A905554A","DOIUrl":"https://doi.org/10.1039/A905554A","url":null,"abstract":"This paper demonstrates the potential contribution to the environment from water soluble phosphorus contained in discarded tobacco products. Dry tobacco was soaked in water and the concentration of dissolved phosphorus was determined by absorptiometry and ion chromatography. The total phosphorus was also measured by absorptiometry following decomposition by a nitric–sulfuric acid decomposition method. As a result, it was found that ca. 1.2 mg of phosphorus (as total PO4-P) was dissolved from unit mass of dry tobacco. It is estimated that the amount of phosphorus that could pass into the Japanese environment through discarded cigarettes was 115–208 kg per day.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"13 1","pages":"345-347"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82462184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the present study, molecularly imprinted affinity sorbents against theophylline and 17β-estradiol are synthesised via precipitation polymerisation, a synthetic method that yields monodisperse, spherical polymer particles in the micron-scale range, quickly, cleanly and in good yield. The specific binding sites that are created during the imprinting process are analysed via radioligand binding analysis. The molecularly imprinted microspheres are highly specific and have higher load capacities compared to the ‘classical’ particles obtained by grinding the imprinted monolith. The successful imprinting against model compounds with very different hydrophobicities demonstrates the generality of the current simple approach.
{"title":"Molecularly imprinted monodisperse microspheres for competitive radioassay","authors":"L. Ye, P. Cormack, K. Mosbach","doi":"10.1039/A809014I","DOIUrl":"https://doi.org/10.1039/A809014I","url":null,"abstract":"In the present study, molecularly imprinted affinity sorbents against theophylline and 17β-estradiol are synthesised via precipitation polymerisation, a synthetic method that yields monodisperse, spherical polymer particles in the micron-scale range, quickly, cleanly and in good yield. The specific binding sites that are created during the imprinting process are analysed via radioligand binding analysis. The molecularly imprinted microspheres are highly specific and have higher load capacities compared to the ‘classical’ particles obtained by grinding the imprinted monolith. The successful imprinting against model compounds with very different hydrophobicities demonstrates the generality of the current simple approach.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"82 1","pages":"35-38"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82730846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Alberici, R. Sparrapan, M. Eberlin, D. Windmöller, R. Augusti
A polyetherimide (polyester)/silicone (PEI/S) sheet composite membrane with a 10 µm thick cross-linked silicone layer is found to display the required mechanical properties to work efficiently as the solution/high vacuum interface in membrane introduction mass spectrometry (MIMS) analysis of volatile organic compounds (VOC) in water. Owing to much shorter response and recovery times, the PEI/S membrane allows much faster analysis and calibration procedures as compared to the 250 µm silicone membrane usually used in MIMS. When using EI, owing to excessive water permeation, responses (signal intensity) for the PEI/S membrane are not always superior, being analyte-dependent. For the more polar VOCs, however, the PEI/S membrane shows 2–3 times greater responses, improving their relatively poor MIMS detection limits. When water–methane chemical ionization is applied, the problem of excessive water permeation is attenuated, and the PEI/S membrane displays greatly superior responses.
{"title":"Polyetherimide–silicone: a 10 µm ultrathin composite membrane for faster and more sensitive membrane introduction mass spectrometry analysis","authors":"R. Alberici, R. Sparrapan, M. Eberlin, D. Windmöller, R. Augusti","doi":"10.1039/A902185J","DOIUrl":"https://doi.org/10.1039/A902185J","url":null,"abstract":"A polyetherimide (polyester)/silicone (PEI/S) sheet composite membrane with a 10 µm thick cross-linked silicone layer is found to display the required mechanical properties to work efficiently as the solution/high vacuum interface in membrane introduction mass spectrometry (MIMS) analysis of volatile organic compounds (VOC) in water. Owing to much shorter response and recovery times, the PEI/S membrane allows much faster analysis and calibration procedures as compared to the 250 µm silicone membrane usually used in MIMS. When using EI, owing to excessive water permeation, responses (signal intensity) for the PEI/S membrane are not always superior, being analyte-dependent. For the more polar VOCs, however, the PEI/S membrane shows 2–3 times greater responses, improving their relatively poor MIMS detection limits. When water–methane chemical ionization is applied, the problem of excessive water permeation is attenuated, and the PEI/S membrane displays greatly superior responses.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"2 1","pages":"221-223"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91381972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An optical oxygen sensor based on the photoluminescent quenching of palladium tetrakis(4-carboxyphenyl)porphyrin (PdTCPP) self-assembled membrane on an alumina plate has been developed. The luminescence intensity of PdTCPP membrane decreased with increase of oxygen concentration, indicating that this membrane is a highly sensitive device for oxygen concentration. The signal changes of this membrane are large enough to allow quantification of oxygen with good sensitivity (I0/I100 > 3). The response times of the sensor are 36 s on going from argon to oxygen and 148 s from oxygen to argon. This is a photostable sensing membrane that exhibits minimal decrease (ca 5%) in initial intensity after continuous irradiation for 24 h.
{"title":"Photoluminescent oxygen sensing using palladium tetrakis(4-carboxyphenyl)porphyrin self-assembled membrane on alumina","authors":"Y. Amao, K. Asai, I. Okura","doi":"10.1039/A900721K","DOIUrl":"https://doi.org/10.1039/A900721K","url":null,"abstract":"An optical oxygen sensor based on the photoluminescent quenching of palladium tetrakis(4-carboxyphenyl)porphyrin (PdTCPP) self-assembled membrane on an alumina plate has been developed. The luminescence intensity of PdTCPP membrane decreased with increase of oxygen concentration, indicating that this membrane is a highly sensitive device for oxygen concentration. The signal changes of this membrane are large enough to allow quantification of oxygen with good sensitivity (I0/I100 > 3). The response times of the sensor are 36 s on going from argon to oxygen and 148 s from oxygen to argon. This is a photostable sensing membrane that exhibits minimal decrease (ca 5%) in initial intensity after continuous irradiation for 24 h.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"1 1","pages":"179-180"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87636610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Amy Smith, J. R. Kirchhoff, R. A. Hudson, L. Tillekeratne
A capillary electrophoresis method with reductive electrochemical detection was developed for the separation of the novel enzyme cofactor pyrroloquinoline quinone (PQQ) and three isomeric analogues. Tuning the reduction potential of the o-quinone moiety to a value more positive than the reduction potential for oxygen was accomplished by adjusting the capillary buffer to pH 2, thus eliminating the need for deoxygenation. To counter the suppression of the electroosmotic flow (EOF) at pH 2, a negative separation voltage of –22.5 V was applied to a 25 µm id capillary resulting in migration of the anionic isomers toward the electrochemical detector. Fast and efficient separation was achieved in 0.15 mM phosphate buffer at pH 2. A mass detection limit for PQQ of 2 fmol was obtained with end-column detection. This approach may find utility for the separation and sensitive detection of a wide range of reducible quinones.
{"title":"Separation of negatively charged isomeric quinones in acidic solution by capillary electrophoresis with reductive electrochemical detection","authors":"Amy Smith, J. R. Kirchhoff, R. A. Hudson, L. Tillekeratne","doi":"10.1039/A906790F","DOIUrl":"https://doi.org/10.1039/A906790F","url":null,"abstract":"A capillary electrophoresis method with reductive electrochemical detection was developed for the separation of the novel enzyme cofactor pyrroloquinoline quinone (PQQ) and three isomeric analogues. Tuning the reduction potential of the o-quinone moiety to a value more positive than the reduction potential for oxygen was accomplished by adjusting the capillary buffer to pH 2, thus eliminating the need for deoxygenation. To counter the suppression of the electroosmotic flow (EOF) at pH 2, a negative separation voltage of –22.5 V was applied to a 25 µm id capillary resulting in migration of the anionic isomers toward the electrochemical detector. Fast and efficient separation was achieved in 0.15 mM phosphate buffer at pH 2. A mass detection limit for PQQ of 2 fmol was obtained with end-column detection. This approach may find utility for the separation and sensitive detection of a wide range of reducible quinones.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"69 1","pages":"371-374"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87511724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A chemiluminescent (CL) H2O2 sensor based on horseradish peroxidase (HRP) immobilized by the sol–gel method has been proposed in this paper. A new process of fabricating a non-cracking HRP encapsulated sol–gel membrane has been suggested. Flow injection analysis (FIA) was used to give reproducible results. Under optimum conditions, the sensor showed a linear response toward hydrogen peroxide in the range 0.01–2 mM with a detection limit of 8 µM. The linear relative coefficient r = 0.998. The sensor showed rapid response, good reproducibility (relative standard deviation = 2.4%) and a long lifetime of at least two months. The proposed sensor was used to determine a 30% H2O2 solution that has been stored for a long time. The results were in good agreement with the standard volumetric method.
{"title":"Sol–gel horseradish peroxidase biosensor for the chemiluminescent flow determination of hydrogen peroxide","authors":"Jun Li, Kemin Wang, Xiaohai Yang, D. Xiao","doi":"10.1039/A901946D","DOIUrl":"https://doi.org/10.1039/A901946D","url":null,"abstract":"A chemiluminescent (CL) H2O2 sensor based on horseradish peroxidase (HRP) immobilized by the sol–gel method has been proposed in this paper. A new process of fabricating a non-cracking HRP encapsulated sol–gel membrane has been suggested. Flow injection analysis (FIA) was used to give reproducible results. Under optimum conditions, the sensor showed a linear response toward hydrogen peroxide in the range 0.01–2 mM with a detection limit of 8 µM. The linear relative coefficient r = 0.998. The sensor showed rapid response, good reproducibility (relative standard deviation = 2.4%) and a long lifetime of at least two months. The proposed sensor was used to determine a 30% H2O2 solution that has been stored for a long time. The results were in good agreement with the standard volumetric method.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"9 1","pages":"195-197"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88009954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An annealing evolutionary algorithm (AEA), which combines aspects of genetic algorithms and simulated annealing, is proposed to find the global minimum of a non-linear least square function for spectral fitting. By application of the algorithm to the fitting of structural parameters from experimental extended X-ray absorption fine structure (EXAFS) spectra of two Cu samples, it was found that reasonable results were obtained. Comparing with genetic algorithms and EXCURVE88, the AEA method is faster and more accurate in analysis of EXAFS spectra.
{"title":"Analysis of extended X-ray absorption fine structure spectra using annealing evolutionary algorithms","authors":"W. Cai, Liya Wang, Z. Pan, X. Shao","doi":"10.1039/A904553H","DOIUrl":"https://doi.org/10.1039/A904553H","url":null,"abstract":"An annealing evolutionary algorithm (AEA), which combines aspects of genetic algorithms and simulated annealing, is proposed to find the global minimum of a non-linear least square function for spectral fitting. By application of the algorithm to the fitting of structural parameters from experimental extended X-ray absorption fine structure (EXAFS) spectra of two Cu samples, it was found that reasonable results were obtained. Comparing with genetic algorithms and EXCURVE88, the AEA method is faster and more accurate in analysis of EXAFS spectra.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"33 1","pages":"313-315"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88531709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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