Comparative efficiency of immobilized non-transition metal phthalocyanine photosensitizers for the visible light transformation of chlorophenols
- Agboola, Bolade, Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Agboola, Bolade , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286043 , vital:56233 , xlink:href="https://doi.org/10.1016/j.molcata.2005.12.009"
- Description: Photolysis of aqueous solutions of chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol) in the presence of immobilized non-transition metal phthalocyanine photosensitizers onto Amberlite® is presented. The photosensitizers studied are: Al (AlOCPc) and Zn (ZnOCPc) octacarboxyphthalocyanines; Al (AlPcS4) and Zn (ZnPcS4) tetrasulfophthalocyanines; sulfonated phthalocyanine complexes (containing mixtures of differently substituted derivatives) of Al (AlPcSmix), Zn (ZnPcSmix), Ge (GePcSmix), Si (SiPcSmix) and Sn (SnPcSmix). Photolysis of the chlorophenols resulted mainly in the formation of chlorobenzoquinone derivatives. The complexes showed order of activity towards the transformation of pentachlorophenol as follows: ZnOCPc > SiPcSmix > SnPcSmix > ZnPcSmix > GePcSmix > ZnPcS4 > AlPcSmix > AlOCPc > AlPcS4. The generation of singlet oxygen (1O2) by these immobilized MPc photosensitizers was found to play a major role in their photoactivities towards the transformation of these chlorophenols. Langmuir–Hinshelwood (L–H) kinetic model studies showed that the ZnOCPc, GePcSmix and ZnPcSmix photocatalysis occurred on the catalysts surface. © 2005 Elsevier B.V. All rights reserved.
- Full Text:
- Date Issued: 2006
- Authors: Agboola, Bolade , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286043 , vital:56233 , xlink:href="https://doi.org/10.1016/j.molcata.2005.12.009"
- Description: Photolysis of aqueous solutions of chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol) in the presence of immobilized non-transition metal phthalocyanine photosensitizers onto Amberlite® is presented. The photosensitizers studied are: Al (AlOCPc) and Zn (ZnOCPc) octacarboxyphthalocyanines; Al (AlPcS4) and Zn (ZnPcS4) tetrasulfophthalocyanines; sulfonated phthalocyanine complexes (containing mixtures of differently substituted derivatives) of Al (AlPcSmix), Zn (ZnPcSmix), Ge (GePcSmix), Si (SiPcSmix) and Sn (SnPcSmix). Photolysis of the chlorophenols resulted mainly in the formation of chlorobenzoquinone derivatives. The complexes showed order of activity towards the transformation of pentachlorophenol as follows: ZnOCPc > SiPcSmix > SnPcSmix > ZnPcSmix > GePcSmix > ZnPcS4 > AlPcSmix > AlOCPc > AlPcS4. The generation of singlet oxygen (1O2) by these immobilized MPc photosensitizers was found to play a major role in their photoactivities towards the transformation of these chlorophenols. Langmuir–Hinshelwood (L–H) kinetic model studies showed that the ZnOCPc, GePcSmix and ZnPcSmix photocatalysis occurred on the catalysts surface. © 2005 Elsevier B.V. All rights reserved.
- Full Text:
- Date Issued: 2006
Electropolymerizable iron (III) and cobalt (II) dicyanophenoxy tetraphenylporphyrin complexes
- Ozoemena, Kenneth I, Zhao, Zhixin, Nyokong, Tebello
- Authors: Ozoemena, Kenneth I , Zhao, Zhixin , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286080 , vital:56236 , xlink:href="https://doi.org/10.1016/j.inoche.2005.11.024"
- Description: Solution and solid phase electrochemical features of 5-[4-(3,4-dicyanophenoxy)phenyl],10,15,20-triphenylporphyrin complexes of iron(III) (FeCNOTPP(Cl)) and cobalt(II) (CoCNOTPP) have been described. These novel asymmetric dicyanophenoxy-derivatised cobalt and iron porphyrin complexes were electropolymerised onto glassy carbon electrodes, which in aqueous solutions, gave surface concentrations (ca. 10−10 mol cm−2) typical of monolayer coverages. The films also exhibited excellent stability and electrocatalysis towards the direct detection of important analytes as nitrite, nitric oxide, and hydrogen peroxide in aqueous solutions.
- Full Text:
- Date Issued: 2006
- Authors: Ozoemena, Kenneth I , Zhao, Zhixin , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286080 , vital:56236 , xlink:href="https://doi.org/10.1016/j.inoche.2005.11.024"
- Description: Solution and solid phase electrochemical features of 5-[4-(3,4-dicyanophenoxy)phenyl],10,15,20-triphenylporphyrin complexes of iron(III) (FeCNOTPP(Cl)) and cobalt(II) (CoCNOTPP) have been described. These novel asymmetric dicyanophenoxy-derivatised cobalt and iron porphyrin complexes were electropolymerised onto glassy carbon electrodes, which in aqueous solutions, gave surface concentrations (ca. 10−10 mol cm−2) typical of monolayer coverages. The films also exhibited excellent stability and electrocatalysis towards the direct detection of important analytes as nitrite, nitric oxide, and hydrogen peroxide in aqueous solutions.
- Full Text:
- Date Issued: 2006
Comparative electrochemistry and electrocatalytic activities of cobalt, iron and manganese phthalocyanine complexes axially co-ordinated to mercaptopyridine self-assembled monolayer at gold electrodes
- Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286054 , vital:56234 , xlink:href="https://doi.org/10.1016/j.electacta.2005.08.007"
- Description: Comparative surface electrochemistry and electrocatalytic properties of solid ultrathin monolayer films of metallophthalocyanine (MPc) complexes of cobalt (CoPc), iron (FePc) and manganese (MnPc) self-immobilised, via axial ligation reaction, onto preformed 4-mercaptopyridine self-assembled monolayers (SAMs) on gold electrodes have been described. Surface electrochemical parameters of the modified electrodes showed that these MPc-SAMs are densely packed with flat orientations. The electrochemical, electrocatalytic and stability properties of these MPc complexes follow this order: FePc > MnPc > CoPc. This finding is remarkable as it suggests that the success of using this method of self-assembling of MPc onto gold electrode is largely dependent on the bond distance between the pyridine linker and the central metal of the MPc; the shorter the distance, the faster the co-ordination and the better the electrocatalytic properties towards L-cysteine and thiocyanate. Thus, the superiority of FePc-based SAM over those of the MnPc and CoPc, has been proposed to be the result of the more favorable axial co-ordination properties of FePc with pyridine (i.e. shorter Fe–N(pyridine) bond length.
- Full Text:
- Date Issued: 2006
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286054 , vital:56234 , xlink:href="https://doi.org/10.1016/j.electacta.2005.08.007"
- Description: Comparative surface electrochemistry and electrocatalytic properties of solid ultrathin monolayer films of metallophthalocyanine (MPc) complexes of cobalt (CoPc), iron (FePc) and manganese (MnPc) self-immobilised, via axial ligation reaction, onto preformed 4-mercaptopyridine self-assembled monolayers (SAMs) on gold electrodes have been described. Surface electrochemical parameters of the modified electrodes showed that these MPc-SAMs are densely packed with flat orientations. The electrochemical, electrocatalytic and stability properties of these MPc complexes follow this order: FePc > MnPc > CoPc. This finding is remarkable as it suggests that the success of using this method of self-assembling of MPc onto gold electrode is largely dependent on the bond distance between the pyridine linker and the central metal of the MPc; the shorter the distance, the faster the co-ordination and the better the electrocatalytic properties towards L-cysteine and thiocyanate. Thus, the superiority of FePc-based SAM over those of the MnPc and CoPc, has been proposed to be the result of the more favorable axial co-ordination properties of FePc with pyridine (i.e. shorter Fe–N(pyridine) bond length.
- Full Text:
- Date Issued: 2006
The effect of Ge, Si and Sn phthalocyanine photosensitizers on cell proliferation and viability of human oesophageal carcinoma cells
- Seotsanyana-Mokhosi, Itumeleng, Kresfelder, Tina, Abrahamse, Heidi, Nyokong, Tebello
- Authors: Seotsanyana-Mokhosi, Itumeleng , Kresfelder, Tina , Abrahamse, Heidi , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286115 , vital:56241 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2005.12.004"
- Description: The photodynamic activity of water soluble mixed sulfonated metallophthalocyanines complexes: GePcSmix, SnPcSmix and SiPcSmix on human oesophageal carcinoma (SNO) cells are reported, and compared with the activity of the unmetallated H2PcSmix and of the newly synthesized water soluble adjacently substituted binaphthalo phthalocyanine (complex 3). The alkaline phosphate (ALP) showed damage to the cell membrane in the presence of complex 3 without irradiation. The GePcSmix complex caused a relatively large increase in inflammation and a high intracellular ATP.
- Full Text:
- Date Issued: 2006
- Authors: Seotsanyana-Mokhosi, Itumeleng , Kresfelder, Tina , Abrahamse, Heidi , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286115 , vital:56241 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2005.12.004"
- Description: The photodynamic activity of water soluble mixed sulfonated metallophthalocyanines complexes: GePcSmix, SnPcSmix and SiPcSmix on human oesophageal carcinoma (SNO) cells are reported, and compared with the activity of the unmetallated H2PcSmix and of the newly synthesized water soluble adjacently substituted binaphthalo phthalocyanine (complex 3). The alkaline phosphate (ALP) showed damage to the cell membrane in the presence of complex 3 without irradiation. The GePcSmix complex caused a relatively large increase in inflammation and a high intracellular ATP.
- Full Text:
- Date Issued: 2006
Self-assembled monolayers (SAMs) of cobalt tetracarboxylic acidchloride phthalocyanine covalently attached onto a preformed mercaptoethanol SAM
- Mashazi, Philani N, Ozoemena, Kenneth I, Maree, David M, Nyokong, Tebello
- Authors: Mashazi, Philani N , Ozoemena, Kenneth I , Maree, David M , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283792 , vital:55989 , xlink:href="https://doi.org/10.1016/j.electacta.2005.10.004"
- Description: A feasible method of fabricating phthalocyanine sensor was developed by covalent attachment of cobalt tetracarboxylic acidchloride phthalocyanine (CoTCACIPc) onto a preformed 2-mercaptoethanol (2-ME) self-assembled monolayer (SAM) modified gold electrode (designated as CoTCACIPc-2-ME-SAM). The surface concentration of the CoTCACIPc was found to be 4.58 × 10−10 mol/cm2. The sensor gave a linear response to L-cysteine over the concentration range 0.28–20 μM with a detection limit of 5 × 10−7 M and best response time of 2 s.
- Full Text:
- Date Issued: 2006
- Authors: Mashazi, Philani N , Ozoemena, Kenneth I , Maree, David M , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283792 , vital:55989 , xlink:href="https://doi.org/10.1016/j.electacta.2005.10.004"
- Description: A feasible method of fabricating phthalocyanine sensor was developed by covalent attachment of cobalt tetracarboxylic acidchloride phthalocyanine (CoTCACIPc) onto a preformed 2-mercaptoethanol (2-ME) self-assembled monolayer (SAM) modified gold electrode (designated as CoTCACIPc-2-ME-SAM). The surface concentration of the CoTCACIPc was found to be 4.58 × 10−10 mol/cm2. The sensor gave a linear response to L-cysteine over the concentration range 0.28–20 μM with a detection limit of 5 × 10−7 M and best response time of 2 s.
- Full Text:
- Date Issued: 2006
Synthesis and electrochemical characterisation of α-and β-tetra-substituted oxo (phthalocyaninato) titanium (IV) complexes
- Tau, Prudence, Nyokong, Tebello
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283869 , vital:55998 , xlink:href="https://doi.org/10.1016/j.poly.2005.11.025"
- Description: The synthesis, spectroscopic and electrochemical characterisation of the following oxotitanium tetra-substituted phthalocyanines are reported: 1,(4)-(tetraphenoxyphthalocyaninato)titanium(IV) oxide (5a); 1,(4)-(tetra-tert-butylphenoxyphthalocyaninato)titanium(IV) oxide (5b); 2,(3)-(tetraphenoxyphthalocyaninato)titanium(IV) oxide (6a) and 2,(3)-(tetra-tert-butylphenoxyphthalocyaninato)titanium(IV) oxide (6b). Complexes 5a and 5b are substituted at the non-peripheral (α) positions, whereas complexes 6a and 6b are substituted at the peripheral (β) positions. Cyclic voltammograms of all four complexes are similar, with three reversible reduction couples and three quasi-reversible to irreversible oxidations. The first two reductions are two-electron processes, confirmed by spectroelectrochemistry to be due to TiIVPc−2/TiIIPc−3 and TiIIPc−2/TiIPc−3 redox processes. Spectroelectrochemistry showed that upon oxidation, the molecule decomposes. Oxidation is expected to occur at the ring. Chronocoulometry confirmed two electron transfer at the first and second reduction steps; and a one electron transfer at the third reduction.
- Full Text:
- Date Issued: 2006
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283869 , vital:55998 , xlink:href="https://doi.org/10.1016/j.poly.2005.11.025"
- Description: The synthesis, spectroscopic and electrochemical characterisation of the following oxotitanium tetra-substituted phthalocyanines are reported: 1,(4)-(tetraphenoxyphthalocyaninato)titanium(IV) oxide (5a); 1,(4)-(tetra-tert-butylphenoxyphthalocyaninato)titanium(IV) oxide (5b); 2,(3)-(tetraphenoxyphthalocyaninato)titanium(IV) oxide (6a) and 2,(3)-(tetra-tert-butylphenoxyphthalocyaninato)titanium(IV) oxide (6b). Complexes 5a and 5b are substituted at the non-peripheral (α) positions, whereas complexes 6a and 6b are substituted at the peripheral (β) positions. Cyclic voltammograms of all four complexes are similar, with three reversible reduction couples and three quasi-reversible to irreversible oxidations. The first two reductions are two-electron processes, confirmed by spectroelectrochemistry to be due to TiIVPc−2/TiIIPc−3 and TiIIPc−2/TiIPc−3 redox processes. Spectroelectrochemistry showed that upon oxidation, the molecule decomposes. Oxidation is expected to occur at the ring. Chronocoulometry confirmed two electron transfer at the first and second reduction steps; and a one electron transfer at the third reduction.
- Full Text:
- Date Issued: 2006
Electrocatalytic oxidation of thiocyanate, L-cysteine and 2-mercaptoethanol by self-assembled monolayer of cobalt tetraethoxy thiophene phthalocyanine
- Sehlotho, Nthapo, Nyokong, Tebello
- Authors: Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283814 , vital:55993 , xlink:href="https://doi.org/10.1016/j.electacta.2005.12.024"
- Description: Catalytic activity of a self-assembled monolayer (SAM) of cobalt tetra ethoxythiophene phthalocyanine (CoTEThPc-SAM) complex towards oxidation of thiocyanate (SCN−), L-cysteine (CYS) and 2-mercaptoethanol (2-ME) is reported. The oxidation of thiocyanate occurs via a two electron transfer, whereas L-cysteine and 2-ME require 1 electron. The oxidation of thiocyanate is catalysed by ring based processes, while L-cysteine is catalysed by both CoIII/CoII process and by ring based processes. 2-ME is catalysed by CoIII/CoII process. The oxidation of thiocyanate on CoTEThPc was performed in acid media instead of basic media commonly employed. The reaction order was found to be unity for all the analytes, showing that only one molecule of analyte interacts with one molecule of the catalyst during the rate determining step.
- Full Text:
- Date Issued: 2006
- Authors: Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283814 , vital:55993 , xlink:href="https://doi.org/10.1016/j.electacta.2005.12.024"
- Description: Catalytic activity of a self-assembled monolayer (SAM) of cobalt tetra ethoxythiophene phthalocyanine (CoTEThPc-SAM) complex towards oxidation of thiocyanate (SCN−), L-cysteine (CYS) and 2-mercaptoethanol (2-ME) is reported. The oxidation of thiocyanate occurs via a two electron transfer, whereas L-cysteine and 2-ME require 1 electron. The oxidation of thiocyanate is catalysed by ring based processes, while L-cysteine is catalysed by both CoIII/CoII process and by ring based processes. 2-ME is catalysed by CoIII/CoII process. The oxidation of thiocyanate on CoTEThPc was performed in acid media instead of basic media commonly employed. The reaction order was found to be unity for all the analytes, showing that only one molecule of analyte interacts with one molecule of the catalyst during the rate determining step.
- Full Text:
- Date Issued: 2006
Household wealth status and natural resource use in the Kat River valley, South Africa
- Shackleton, Charlie M, Shackleton, Sheona E
- Authors: Shackleton, Charlie M , Shackleton, Sheona E
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181301 , vital:43717 , xlink:href="https://doi.org/10.1016/j.ecolecon.2005.04.011"
- Description: Much work has demonstrated the significant role and value of non-timber forest products (NTFPs) in the livelihoods of rural people in southern Africa and elsewhere. The findings provide a mean or composite picture, averaged across the sample households within each community. Yet, within any given community, there is significant socio-economic differentiation. It is important to acknowledge such differentiation when considering policy and management interventions to support rural livelihoods and promote sustainable resource use. This paper reports on a study in South Africa, the objective of which was to explore wealth-related differences and similarities in the use and value of NTFPs. Data on NTFP consumption, purchase, and sale were collected from households in three rural villages. Households were divided into three wealth classes and patterns of NTFPs use between the classes examined. There was no difference in the proportions of households in each wealth class using NTFPs, nor the total number of NTFPs used per household. Yet, there was some supporting evidence that poorer households derive greater benefits from NTFPs than do wealthy or intermediate households. One clear difference was that, with increasing wealth, households purchased significantly more NTFPs, and a greater proportion of wealthy households did so. Conversely, a greater proportion of poor households were involved in the sale of one or more NTFPs, and they sold a greater number per household, compared to wealthy and intermediate households. Detailed examination of use and value of four NTFPs (fuelwood, wild fruits, edible herbs, and grass hand brushes) revealed that in all instances, the poorest households used more of the resource per capita than the other wealth classes. This was not the case for comparisons based on the total household as the unit of analysis. Gross annual direct-use value did not differ between the wealth classes for any of the four NTFPs examined, at the household level. But on a per capita basis, a significantly higher gross annual direct-use value was evident within poorer households for fuelwood and edible herbs. The significance of these differences is discussed.
- Full Text:
- Date Issued: 2006
- Authors: Shackleton, Charlie M , Shackleton, Sheona E
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181301 , vital:43717 , xlink:href="https://doi.org/10.1016/j.ecolecon.2005.04.011"
- Description: Much work has demonstrated the significant role and value of non-timber forest products (NTFPs) in the livelihoods of rural people in southern Africa and elsewhere. The findings provide a mean or composite picture, averaged across the sample households within each community. Yet, within any given community, there is significant socio-economic differentiation. It is important to acknowledge such differentiation when considering policy and management interventions to support rural livelihoods and promote sustainable resource use. This paper reports on a study in South Africa, the objective of which was to explore wealth-related differences and similarities in the use and value of NTFPs. Data on NTFP consumption, purchase, and sale were collected from households in three rural villages. Households were divided into three wealth classes and patterns of NTFPs use between the classes examined. There was no difference in the proportions of households in each wealth class using NTFPs, nor the total number of NTFPs used per household. Yet, there was some supporting evidence that poorer households derive greater benefits from NTFPs than do wealthy or intermediate households. One clear difference was that, with increasing wealth, households purchased significantly more NTFPs, and a greater proportion of wealthy households did so. Conversely, a greater proportion of poor households were involved in the sale of one or more NTFPs, and they sold a greater number per household, compared to wealthy and intermediate households. Detailed examination of use and value of four NTFPs (fuelwood, wild fruits, edible herbs, and grass hand brushes) revealed that in all instances, the poorest households used more of the resource per capita than the other wealth classes. This was not the case for comparisons based on the total household as the unit of analysis. Gross annual direct-use value did not differ between the wealth classes for any of the four NTFPs examined, at the household level. But on a per capita basis, a significantly higher gross annual direct-use value was evident within poorer households for fuelwood and edible herbs. The significance of these differences is discussed.
- Full Text:
- Date Issued: 2006
A stability-indicating high performance liquid chromatographic assay for the determination of orlistat in capsules
- Mohammadi, Ali, Haririan, I, Rezanour, Nasrin, Ghiasi, L, Walker, Roderick B
- Authors: Mohammadi, Ali , Haririan, I , Rezanour, Nasrin , Ghiasi, L , Walker, Roderick B
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184267 , vital:44195 , xlink:href="https://doi.org/10.1016/j.chroma.2006.03.038"
- Description: A stability-indicating HPLC method was developed and validated for the quantitative determination of orlistat in capsule dosage forms. An isocratic separation was achieved using a Perfectsil® target ODS-3, 250 mm × 4.6 mm i.d., 5 μm particle size column with a flow rate of 0.7 ml/min and using a UV detector to monitor the eluate at 210 nm. The mobile phase consisted of methanol:acetonitrile:trifluoroacetic acid (82.5:17.5:0.01, v/v/v). The drug was subjected oxidation, hydrolysis, photolysis and heat to apply stress conditions. Complete separation was achieved for the parent compound and all degradation products in an overall analytical run time of approximately 15 min with the parent compound orlistat eluting at approximately 9 min. The method was linear over the concentration range of 0.02–0.75 mg/ml (r = 0.9998) with a limit of detection and quantitation 0.006 and 0.02 mg/ml, respectively. The method has the requisite accuracy, selectivity, sensitivity and precision to assay orlistat in capsules. Degradation products resulting from the stress studies did not interfere with the detection of orlistat and the assay is thus stability-indicating.
- Full Text:
- Date Issued: 2006
- Authors: Mohammadi, Ali , Haririan, I , Rezanour, Nasrin , Ghiasi, L , Walker, Roderick B
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184267 , vital:44195 , xlink:href="https://doi.org/10.1016/j.chroma.2006.03.038"
- Description: A stability-indicating HPLC method was developed and validated for the quantitative determination of orlistat in capsule dosage forms. An isocratic separation was achieved using a Perfectsil® target ODS-3, 250 mm × 4.6 mm i.d., 5 μm particle size column with a flow rate of 0.7 ml/min and using a UV detector to monitor the eluate at 210 nm. The mobile phase consisted of methanol:acetonitrile:trifluoroacetic acid (82.5:17.5:0.01, v/v/v). The drug was subjected oxidation, hydrolysis, photolysis and heat to apply stress conditions. Complete separation was achieved for the parent compound and all degradation products in an overall analytical run time of approximately 15 min with the parent compound orlistat eluting at approximately 9 min. The method was linear over the concentration range of 0.02–0.75 mg/ml (r = 0.9998) with a limit of detection and quantitation 0.006 and 0.02 mg/ml, respectively. The method has the requisite accuracy, selectivity, sensitivity and precision to assay orlistat in capsules. Degradation products resulting from the stress studies did not interfere with the detection of orlistat and the assay is thus stability-indicating.
- Full Text:
- Date Issued: 2006
New and improved : Linda in Java
- Authors: Wells, George C
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6613 , http://hdl.handle.net/10962/d1011511 , http://www.sciencedirect.com/science/article/pii/S0167642305000869
- Description: This paper discusses the current resurgence of interest in the Linda coordination language for parallel and distributed programming. Particularly in the Java field, there have been a number of developments over the past few years. These developments are summarised together with the advantages of using Linda for programming concurrent systems. Some problems with the basic Linda approach are also discussed and a novel solution to these is presented. The power and flexibility of the proposed extensions to the Linda programming model are illustrated by considering a number of example applications, including a detailed case study of visual language parsing.
- Full Text:
- Date Issued: 2006
- Authors: Wells, George C
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6613 , http://hdl.handle.net/10962/d1011511 , http://www.sciencedirect.com/science/article/pii/S0167642305000869
- Description: This paper discusses the current resurgence of interest in the Linda coordination language for parallel and distributed programming. Particularly in the Java field, there have been a number of developments over the past few years. These developments are summarised together with the advantages of using Linda for programming concurrent systems. Some problems with the basic Linda approach are also discussed and a novel solution to these is presented. The power and flexibility of the proposed extensions to the Linda programming model are illustrated by considering a number of example applications, including a detailed case study of visual language parsing.
- Full Text:
- Date Issued: 2006
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