Pub Date : 2019-01-01DOI: 10.17159/0379-4350/2019/V72A2
Wei Chang, Dandan Zheng, Chaosheng Zhao, Yixin Yang
Cu 2 O/Cu/C/Ag porous composite was synthesized by heat-treatment and wet-chemical method using a typical metal-organic framework (Cu-BTC) as precursor. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and ultraviolet-visible spectroscopy (UV-vis). The results showed that the original structure of Cu-BTC was retained by high temperature calcination in nitrogen atmosphere. Uniform doping of Cu, C and Ag provided a triple trapping of photogenerated electron hole pairs and the Cu 2 O/Cu/C/Ag exhibited an enhanced photocatalytic activity for degradation of Congo Red under visible light irradiation. Heat-treatment of the MOFs with high temperature is a facile and effective way for preparation of photocatalytic composite with desirable properties. Keywords : Photocatalyst, cuprous oxide, dye degradation, Cu-BTC.
{"title":"Photocatalytic Activity of MOF-derived Cu2O/Cu/C/Ag Porous Composites","authors":"Wei Chang, Dandan Zheng, Chaosheng Zhao, Yixin Yang","doi":"10.17159/0379-4350/2019/V72A2","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/V72A2","url":null,"abstract":"Cu 2 O/Cu/C/Ag porous composite was synthesized by heat-treatment and wet-chemical method using a typical metal-organic framework (Cu-BTC) as precursor. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and ultraviolet-visible spectroscopy (UV-vis). The results showed that the original structure of Cu-BTC was retained by high temperature calcination in nitrogen atmosphere. Uniform doping of Cu, C and Ag provided a triple trapping of photogenerated electron hole pairs and the Cu 2 O/Cu/C/Ag exhibited an enhanced photocatalytic activity for degradation of Congo Red under visible light irradiation. Heat-treatment of the MOFs with high temperature is a facile and effective way for preparation of photocatalytic composite with desirable properties. Keywords : Photocatalyst, cuprous oxide, dye degradation, Cu-BTC.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67462676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.17159/0379-4350/2019/v72a18
B. Davoren, E. Ferg, N. Rust
Inconel 600TM, an austenitic high nickel alloy, has relatively low corrosion properties and is used extensively for aerospace and nuclear engineering applications. Other applications include exposure of the material to caustic and acidic environments and possible use in prosthetic implants. Electrochemical techniques, which include potentiodynamic polarization and polarization resistance, provide a means to rapidly determine the corrosion rates and the suitability of the alloy in a specific corrosive environment. The results from these two techniques were used to determine the corrosion rates as well as other thermodynamic properties for the alloy exposed to various strong and weak acids, salt and Ringer’s solution. The results showed slight differences in the corrosion rates determined by the two electrochemical techniques, with those from the polarization resistance technique being on average larger. The corrosion activation energies determined for the alloy in different solutions were indicative of the corrosion rates with some anomalies in values for results observed in the 10 % acetic acid solution. The microstructural composition of the alloy was also investigated by SEM-EDS and showed peculiar inclusions that can contribute to an acceleration of the corrosion
{"title":"An Investigation into the Corrosion Rates of Inconel 600™ in Different Corrosive Solutions","authors":"B. Davoren, E. Ferg, N. Rust","doi":"10.17159/0379-4350/2019/v72a18","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a18","url":null,"abstract":"Inconel 600TM, an austenitic high nickel alloy, has relatively low corrosion properties and is used extensively for aerospace and nuclear engineering applications. Other applications include exposure of the material to caustic and acidic environments and possible use in prosthetic implants. Electrochemical techniques, which include potentiodynamic polarization and polarization resistance, provide a means to rapidly determine the corrosion rates and the suitability of the alloy in a specific corrosive environment. The results from these two techniques were used to determine the corrosion rates as well as other thermodynamic properties for the alloy exposed to various strong and weak acids, salt and Ringer’s solution. The results showed slight differences in the corrosion rates determined by the two electrochemical techniques, with those from the polarization resistance technique being on average larger. The corrosion activation energies determined for the alloy in different solutions were indicative of the corrosion rates with some anomalies in values for results observed in the 10 % acetic acid solution. The microstructural composition of the alloy was also investigated by SEM-EDS and showed peculiar inclusions that can contribute to an acceleration of the corrosion","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67462887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.17159/0379-4350/2019/v72a32
C. G. Naik, G. Malik, H. Parekh
The novel coumarin derivatives (2, 3, 4, 5, 6, 7) have been synthesized from the reaction of o-acetyloxy benzoic acid with thionyl chloride yielding 2-acetoxy benzoyl chloride, which on further treatment with ethylacetoacetate gave 4-hydroxycoumarin. Substituted pyrazolones and thiazoles reacted with 4-hydroxy coumarin to give pyrazolones and methyl thiazoles related coumarin derivatives. The newly synthesized products were characterized with IR, H and C NMR, mass spectroscopic techniques and elemental analysis. The synthesized compounds were screened for their antibacterial and antifungal activity. All the compounds were found to have significant activity against the tested microorganisms.
{"title":"Novel Coumarin Derivatives: Synthesis, Characterization and Antimicrobial Activity","authors":"C. G. Naik, G. Malik, H. Parekh","doi":"10.17159/0379-4350/2019/v72a32","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a32","url":null,"abstract":"The novel coumarin derivatives (2, 3, 4, 5, 6, 7) have been synthesized from the reaction of o-acetyloxy benzoic acid with thionyl chloride yielding 2-acetoxy benzoyl chloride, which on further treatment with ethylacetoacetate gave 4-hydroxycoumarin. Substituted pyrazolones and thiazoles reacted with 4-hydroxy coumarin to give pyrazolones and methyl thiazoles related coumarin derivatives. The newly synthesized products were characterized with IR, H and C NMR, mass spectroscopic techniques and elemental analysis. The synthesized compounds were screened for their antibacterial and antifungal activity. All the compounds were found to have significant activity against the tested microorganisms.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67463420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.17159/0379-4350/2019/v72a17
E. Ngeno, Victor O. Shikuku, Francis Orata, Lilechi D. Baraza, S. Kimosop
In this study, clinoptilolite was used to sequester ciprofloxacin (CIP) and caffeine (CAF), two emergent contaminants, from aqueous solution using batch equilibration method and the effects of contact time, pH, initial contaminant concentration, temperature and adsorbent dosage investigated and herein reported. The adsorption kinetics was described by the pseudo-second-order model (PSO) and pore diffusion was not the sole operative rate-controlling step as depicted by the intraparticle diffusion model. The equilibrium data were modelled using three linear forms of Langmuir equation and Freundlich model and was best fitted by the Lineweaver-Burk linearization of Langmuir equation (type-1). Linearization is shown to induce errors that may lead to discrepancies in parameter values estimation. The derived thermodynamic functions revealed the adsorption processes are exothermic, spontaneous and physical in nature. The adsorption mechanism of CIP is strongly controlled by electrostatic interactions while CAF adsorption is weakly affected by changes in pH. The findings demonstrate that clinoptilolite in its unmodified form is a potential low-cost and eco-friendly adsorbent for removal of pharmaceutically active ingredients from water.
{"title":"Caffeine and Ciprofloxacin Adsorption from Water onto Clinoptilolite: Linear Isotherms, Kinetics, Thermodynamic and Mechanistic Studies","authors":"E. Ngeno, Victor O. Shikuku, Francis Orata, Lilechi D. Baraza, S. Kimosop","doi":"10.17159/0379-4350/2019/v72a17","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a17","url":null,"abstract":"In this study, clinoptilolite was used to sequester ciprofloxacin (CIP) and caffeine (CAF), two emergent contaminants, from aqueous solution using batch equilibration method and the effects of contact time, pH, initial contaminant concentration, temperature and adsorbent dosage investigated and herein reported. The adsorption kinetics was described by the pseudo-second-order model (PSO) and pore diffusion was not the sole operative rate-controlling step as depicted by the intraparticle diffusion model. The equilibrium data were modelled using three linear forms of Langmuir equation and Freundlich model and was best fitted by the Lineweaver-Burk linearization of Langmuir equation (type-1). Linearization is shown to induce errors that may lead to discrepancies in parameter values estimation. The derived thermodynamic functions revealed the adsorption processes are exothermic, spontaneous and physical in nature. The adsorption mechanism of CIP is strongly controlled by electrostatic interactions while CAF adsorption is weakly affected by changes in pH. The findings demonstrate that clinoptilolite in its unmodified form is a potential low-cost and eco-friendly adsorbent for removal of pharmaceutically active ingredients from water.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67462764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.17159/0379-4350/2019/V72A11
C. I. Nkanga, X. Noundou, R. B. Walker, R. Krause
Despite the well-known anti-mycobacterial actions of isoniazid (INH) and rifampicin (RIF), the clinical success of tuberculosis (TB) therapy requires prolonged administration of multiple drugs in high doses, which often result in frequent adverse effects and low patient adherence. Although liposomes are promising candidates for controlled delivery of anti-TB drug, the high cost of synthetic and highly purified natural lipids currently used in liposomal technology might preclude the universal application of therapeutic liposomes. This work aimed at evaluating the potential of a cost-effective lipid material, crude soybean lecithin (CL), to co-encapsulate RIF and INH for liposomal dual delivery. RIF was encapsulated in CL-liposomes with/without cholesterol using film hydration method, after which INH was incorporated using a freeze–thawing technique. Dynamic light scattering, differential scanning calorimetry, X-ray diffraction and dialysis were used for liposome characterization. Liposomes containing CL alone (CLL) exhibited 90 % encapsulation efficiency for RIF and 59 % for INH. The mean size and surface charge of CLL were 1114 nm and –63 mV, respectively. In addition, CLL showed a controlled release profile for the co-encapsulated drugs. CLL would be promising vehicles for macrophage-targeting drug delivery. The present findings demonstrate the feasibility of using CL for preparation of combination products for liposomal delivery.
{"title":"Co-encapsulation of Rifampicin and Isoniazid in Crude Soybean Lecithin Liposomes","authors":"C. I. Nkanga, X. Noundou, R. B. Walker, R. Krause","doi":"10.17159/0379-4350/2019/V72A11","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/V72A11","url":null,"abstract":"Despite the well-known anti-mycobacterial actions of isoniazid (INH) and rifampicin (RIF), the clinical success of tuberculosis (TB) therapy requires prolonged administration of multiple drugs in high doses, which often result in frequent adverse effects and low patient adherence. Although liposomes are promising candidates for controlled delivery of anti-TB drug, the high cost of synthetic and highly purified natural lipids currently used in liposomal technology might preclude the universal application of therapeutic liposomes. This work aimed at evaluating the potential of a cost-effective lipid material, crude soybean lecithin (CL), to co-encapsulate RIF and INH for liposomal dual delivery. RIF was encapsulated in CL-liposomes with/without cholesterol using film hydration method, after which INH was incorporated using a freeze–thawing technique. Dynamic light scattering, differential scanning calorimetry, X-ray diffraction and dialysis were used for liposome characterization. Liposomes containing CL alone (CLL) exhibited 90 % encapsulation efficiency for RIF and 59 % for INH. The mean size and surface charge of CLL were 1114 nm and –63 mV, respectively. In addition, CLL showed a controlled release profile for the co-encapsulated drugs. CLL would be promising vehicles for macrophage-targeting drug delivery. The present findings demonstrate the feasibility of using CL for preparation of combination products for liposomal delivery.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67462925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.17159/0379-4350/2019/v72a30
Sujay Mahata, Ishani Mitra, Subhajit Mukherjee, Reddy B. Venkata Pera, G. Ghosh, W. Linert, Sankar Ch. Moi
Different species of L-ascorbic acid and their corresponding complex formation ability with Cu(II) and Ni(II) metal ions in aqueous medium has been studied in the pH range from 2.0–12.5. The stability constants of different complexes of Cu(II) and Ni(II) with the bidentate ligand, L-ascorbic acid were determined theoretically using MINIQUARD software. Speciation of ligand and complex of Cu(II)/Ni(II) ascorbate were experimentally investigated by the titration method in solution within this pH range. Different Cu (II) and Ni(II)-L-ascorbic acid species percentages with variation of pH were calculated within the studied pH range with the help of another computer programs SIM and SPECIES. Different species distribution diagrams and the equilibria for the formation of the species were also investigated and at higher pH, ML2 species was found to be the major species in the case of both the metal complexes. All the theoretical possible structures of Cu(II) and Ni(II) complexes with L-ascorbic acid were optimized and square pyramidal and square planer geometry have been evaluated for Cu(II) and Ni(II) respectively by Gaussian09 software. Their corresponding HOMO-LUMO energy and reactivity parameters such as chemical hardness (ç), ionization potential (I), electron affinity (A), electro negativity (÷), chemical potential (ì), electrophilicity index (ù) have been calculated in order to provide a better understanding of the electronic structure of complexes with the experimental results.
研究了不同种类的l -抗坏血酸在pH为2.0 ~ 12.5的水溶液中与Cu(II)和Ni(II)金属离子形成络合物的能力。用MINIQUARD软件对Cu(II)和Ni(II)与双齿配体l -抗坏血酸配合物的稳定性常数进行了理论测定。在此pH范围内，用滴定法研究了Cu(II)/Ni(II)抗坏血酸盐配体和配合物的形态。在研究的pH范围内，利用另一个计算机程序SIM和species计算不同Cu (II)和Ni(II)- l -抗坏血酸的种类百分比随pH的变化。结果表明，在较高的pH条件下，两种金属配合物均以ML2物种为主。对Cu(II)和Ni(II)与l -抗坏血酸配合物的所有可能的理论结构进行了优化，并利用Gaussian09软件分别对Cu(II)和Ni(II)进行了方锥体和方平面几何的评价。计算了它们对应的HOMO-LUMO能量和反应性参数，如化学硬度(ç)、电离势(I)、电子亲和力(A)、电负性(÷)、化学势(ì)、亲电性指数(ù)，以便与实验结果更好地理解配合物的电子结构。
{"title":"Speciation Study of L-ascorbic Acid and its Chelated Cu(II) & Ni(II) Complexes: an Experimental and Theoretical Model of Complex Formation","authors":"Sujay Mahata, Ishani Mitra, Subhajit Mukherjee, Reddy B. Venkata Pera, G. Ghosh, W. Linert, Sankar Ch. Moi","doi":"10.17159/0379-4350/2019/v72a30","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a30","url":null,"abstract":"Different species of L-ascorbic acid and their corresponding complex formation ability with Cu(II) and Ni(II) metal ions in aqueous medium has been studied in the pH range from 2.0–12.5. The stability constants of different complexes of Cu(II) and Ni(II) with the bidentate ligand, L-ascorbic acid were determined theoretically using MINIQUARD software. Speciation of ligand and complex of Cu(II)/Ni(II) ascorbate were experimentally investigated by the titration method in solution within this pH range. Different Cu (II) and Ni(II)-L-ascorbic acid species percentages with variation of pH were calculated within the studied pH range with the help of another computer programs SIM and SPECIES. Different species distribution diagrams and the equilibria for the formation of the species were also investigated and at higher pH, ML2 species was found to be the major species in the case of both the metal complexes. All the theoretical possible structures of Cu(II) and Ni(II) complexes with L-ascorbic acid were optimized and square pyramidal and square planer geometry have been evaluated for Cu(II) and Ni(II) respectively by Gaussian09 software. Their corresponding HOMO-LUMO energy and reactivity parameters such as chemical hardness (ç), ionization potential (I), electron affinity (A), electro negativity (÷), chemical potential (ì), electrophilicity index (ù) have been calculated in order to provide a better understanding of the electronic structure of complexes with the experimental results.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67463184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.17159/0379-4350/2019/v72a25
Behzad Khalil, Aref Atashrazm, Mona Rasoulian
N-sulfonated cyclohexylhydantoin (NSCH), a new N-sulfonic acid compound, was prepared and characterized using FT-IR, H NMR, C NMR, UV-Vis and TGA analysis. The potential catalyst efficiency was examined, using synthesis of chromene, xanthene and hydroquinoline derivatives under solvent-free conditions. All of the examined model reactions gave excellent yields, and required short reaction times. Simple catalyst preparation and work-up under mild reaction condition, with low cost and the ability to recover the catalyst for reuse without significant loss of activity are some of the notable advantages of the introduced catalyst.
{"title":"2,4-Dioxo-1,3-diazaspiro[4,5]decane-3-sulfonic Acid as a Novel Solid Phase Halogen-free Acid Catalyst: Preparation, Characterization and Evaluation","authors":"Behzad Khalil, Aref Atashrazm, Mona Rasoulian","doi":"10.17159/0379-4350/2019/v72a25","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a25","url":null,"abstract":"N-sulfonated cyclohexylhydantoin (NSCH), a new N-sulfonic acid compound, was prepared and characterized using FT-IR, H NMR, C NMR, UV-Vis and TGA analysis. The potential catalyst efficiency was examined, using synthesis of chromene, xanthene and hydroquinoline derivatives under solvent-free conditions. All of the examined model reactions gave excellent yields, and required short reaction times. Simple catalyst preparation and work-up under mild reaction condition, with low cost and the ability to recover the catalyst for reuse without significant loss of activity are some of the notable advantages of the introduced catalyst.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67463496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.17159/0379-4350/2019/v72a27
Nokuthula Khanyile, R. Krause, Sibulelo L. Vilakazi, N. Torto
A dopamine (DA) colorimetric probe based on the growth and aggregation of un-functionalized gold nanoparticles (AuNPs) is reported. Upon addition of AuNPs to dopamine at various concentrations, the shape, size and colour change of the nanoparticles results in spectral shifts to higher wavelengths and hence colour change is the mode of detection. The colour change can be easily observed by the naked eye from as low as 5.0 nM DA, even under sub-optimal conditions. Under optimal pH conditions the calculated limit of detection was 2.5 nM (3ó). The probe was successfully applied to whole blood sample and showed good selectivity and sensitivity towards DA. The simple, sensitive and selective probe could be an excellent alternative for on-site and immediate detection of DA without the use of instrumentation and would thus be useful for rapid diagnostic applications.
{"title":"Un-functionalized Gold Nanoparticles as a Simple Colorimetric Probe for Sensitive and Selective Detection of Dopamine","authors":"Nokuthula Khanyile, R. Krause, Sibulelo L. Vilakazi, N. Torto","doi":"10.17159/0379-4350/2019/v72a27","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a27","url":null,"abstract":"A dopamine (DA) colorimetric probe based on the growth and aggregation of un-functionalized gold nanoparticles (AuNPs) is reported. Upon addition of AuNPs to dopamine at various concentrations, the shape, size and colour change of the nanoparticles results in spectral shifts to higher wavelengths and hence colour change is the mode of detection. The colour change can be easily observed by the naked eye from as low as 5.0 nM DA, even under sub-optimal conditions. Under optimal pH conditions the calculated limit of detection was 2.5 nM (3ó). The probe was successfully applied to whole blood sample and showed good selectivity and sensitivity towards DA. The simple, sensitive and selective probe could be an excellent alternative for on-site and immediate detection of DA without the use of instrumentation and would thus be useful for rapid diagnostic applications.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67463558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.17159/0379-4350/2019/v72a24
F. Siddiqui, Nawab Sher, Asia Naz, Najmul Hasan, S. N. Shah, Muhamad Shehzad
A simple and sensitive colorimetric spectrophotometric method based on application of chemical kinetics was produced and developed for the quantitative determination of 3-amino methyl hexanoic acid (pregabalin) in bulk and pharmaceutical preparations. Ninhydrin, a chromogenic agent was reacted with pregabalin at 70 °C and the absorbance was measured at 575 nm and kinetic correlation was evaluated between absorbance and time. The initial-rate, rate-constant and fixed-time (80 min) methods were employed for the estimation of pregabalin in the range of 10–30 μg mL which showed good correlation >0.9990 in all three cases with LOQ values ranging from 1.2–1.5 μg mLand LOD values ranging from 0.76–0.95 μg mL. Method validation was carried out using ICH recommendations and the variables were evaluated and optimized. The newly developed method has useful applications to determine pregabalin in pharmaceutical formulation with good recovery (98.38 to 102.12 %t) and precision (RSD < 1.4 %). Standard free energy changes and association constant were found to be 1.212 × 10 and –4.747, respectively, as determined by the Benesi–Hildebrand equation.
{"title":"Kinetic Approach to Determine 3-Amino Methyl Hexanoic Acid in Pharmaceutical Formulations","authors":"F. Siddiqui, Nawab Sher, Asia Naz, Najmul Hasan, S. N. Shah, Muhamad Shehzad","doi":"10.17159/0379-4350/2019/v72a24","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a24","url":null,"abstract":"A simple and sensitive colorimetric spectrophotometric method based on application of chemical kinetics was produced and developed for the quantitative determination of 3-amino methyl hexanoic acid (pregabalin) in bulk and pharmaceutical preparations. Ninhydrin, a chromogenic agent was reacted with pregabalin at 70 °C and the absorbance was measured at 575 nm and kinetic correlation was evaluated between absorbance and time. The initial-rate, rate-constant and fixed-time (80 min) methods were employed for the estimation of pregabalin in the range of 10–30 μg mL which showed good correlation >0.9990 in all three cases with LOQ values ranging from 1.2–1.5 μg mLand LOD values ranging from 0.76–0.95 μg mL. Method validation was carried out using ICH recommendations and the variables were evaluated and optimized. The newly developed method has useful applications to determine pregabalin in pharmaceutical formulation with good recovery (98.38 to 102.12 %t) and precision (RSD < 1.4 %). Standard free energy changes and association constant were found to be 1.212 × 10 and –4.747, respectively, as determined by the Benesi–Hildebrand equation.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67463488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.17159/0379-4350/2019/v72a33
P. Pansuriya, G. E. Maguire, H. Friedrich
The anti-malarial lumefantrine was characterized in the solid as well as the solution state. The solid state analysis was carried out by single crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), DSC, TG-DTG and ATR-IR. The single crystal structure of lumefantrine has been solved. The structure is stabilized via interas well as intra-C–H...Cl interactions, intra hydrogen bonding O–H...N interactions and C–H...O weak interactions. The Hirshfeld surface intermolecular interactions have been studied using the crystal structure. Solution structure analyses have been done by NMR, COSY/NOESY, HSQC and mass spectrometry. The thermal properties were studied by solid-state differential scanning calorimetry and thermogravimetric analysis of the drug under nitrogen as well as in air.
{"title":"Structural Characterization and Thermal Properties of the Anti-malarial Drug: Lumefantrine","authors":"P. Pansuriya, G. E. Maguire, H. Friedrich","doi":"10.17159/0379-4350/2019/v72a33","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a33","url":null,"abstract":"The anti-malarial lumefantrine was characterized in the solid as well as the solution state. The solid state analysis was carried out by single crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), DSC, TG-DTG and ATR-IR. The single crystal structure of lumefantrine has been solved. The structure is stabilized via interas well as intra-C–H...Cl interactions, intra hydrogen bonding O–H...N interactions and C–H...O weak interactions. The Hirshfeld surface intermolecular interactions have been studied using the crystal structure. Solution structure analyses have been done by NMR, COSY/NOESY, HSQC and mass spectrometry. The thermal properties were studied by solid-state differential scanning calorimetry and thermogravimetric analysis of the drug under nitrogen as well as in air.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67463436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：