An evaluation of UPLC technology for the simultaneous analysis of actives in a multi-active drug
- Authors: Bawjee, Janita
- Date: 2011
- Subjects: High performance liquid chromatography
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10384 , http://hdl.handle.net/10948/d1008407 , High performance liquid chromatography
- Description: The evaluation of the potential to use Ultra Performance Liquid Chromatography (UPLC) for the simultaneous quantification of all the actives in a multi-active tablet is described in this work. Part of the evaluation was to ensure that the necessary regulatory requirements were adhered to by ascertaining that an analytical method is suitable for a specific purpose through analytical method validation for the specific multi-active tablet. The UPLC method was also tested for the analysis of similar products, namely tablet formulations that contain similar active ingredients in the same proportions but with an additional active ingredient. A method for the simultaneous determination of paracetamol, caffeine and codeine phosphate was developed using UPLC technology. The UPLC developed method was more efficient than the existing in-house HPLC method. The UPLC method was then validated in accordance to ICH and USP guidelines. The application of this UPLC method for the analysis of similar products containing paracetamol, caffeine, codeine phosphate and one extra active ingredient was very challenging. The low concentration of the additional component, differences in sample matrix and differences in formulations added to the challenges. The direct application for the analysis of products Y and Z was not successful; however the method could be used as a platform for further research. A cost comparison between the UPLC and HPLC methods showed the UPLC method to be more cost effective. Thus, while maintenance costs are higher for the UPLC instrument, column costs are comparable to HPLC columns, but solvent and waste disposal charges decrease considerably due to lower solvent use. The reduction in instrument time dramatically improves the cost effectiveness of UPLC over HPLC due to a concurrent reduction in analyst time requirement. The results of this study show that the analytical costs associated with the analysis of multi-active drugs using HPLC procedures can be reduced substantially by the CONFIDENTIAL INTELLECTUAL PROPERTY OF ASPEN PHARMACARE implementation of UPLC technology. The hypothesis that the enhanced chromatographic power of UPLC can be leveraged to provide faster analysis times hence increased product throughput rates, and lower operating costs for the analysis of multi-active drugs was accepted. These advantages were achieved whilst meeting all regulatory requirements for analytical methods as required by regulatory bodies.
- Full Text:
- Date Issued: 2011
Hydrogen economy : MEA manufacturing for PEM electrolysers
- Authors: Gojela, Ntombekaya
- Date: 2011
- Subjects: Water -- Electrolysis , Hydrogen
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10380 , http://hdl.handle.net/10948/1483 , Water -- Electrolysis , Hydrogen
- Description: The electrolysis of water was evaluated as a potentially efficient, as a low cost means of hydrogen production. The theoretical energy, voltage, current, and energy efficiencies of water electrolysis were considered by using various catalyst materials used in the fabrication of membrane electrode assemblies used in low temperature water electrolysis systems. Traditionally, iridium based catalysts have shown to be the most suitable material for its use on electrocatalysis of water to form hydrogen. This study showed that a combination of various elements as a binary and or ternary mixture in the base catalyst that was applied to the anode and cathode by using the Adam’s method had shown to give comparatively good results to that of using iridium oxide on its own. These catalysts were characterized by cyclic voltammetry, at different temperatures (30oC-80oC) with a range of catalyst loading of 0.2-0.5 mg.cm-2 noble metals. The study showed that the Ir40Co40 mixture as an anode catalyst was found to show highest hydrogen efficiency of 73 percent with a relatively low over potential of 0.925V at higher temperature of 80oC. The mixture also showed to give the best electrocatalytic activity with a low Tafel slope of 30.1mV.dec-1. Whereas the Ir50Pt50 showed a comparatively lower hydrogen efficiency of 65 percent with a lower over potential of 0.6V at 50oC. Ternary mixed oxide of Ir20Ru40Co40 showed an even lower over potential of 0.5- 0.6V over a large range of temperatures with a low hydrogen efficiency of 44 percent but gave good electrocatalytic activity in terms of the Tafel slope analysis. On the other hand, mixtures with relatively cheaper material such as Nickel in binary mixture systems such as Pt50Ni50 as cathode catalyst was found to show promising performance of a relatively low over potential that was less than 1.4 V with a low hydrogen efficiency of 62.1 percent Ternary cathode catalyst materials such as Pt33Ni33Co33 exhibited good performance with higher hydrogen efficiency of 65.2 percent at lower over potential of 1.2 V and a higher Tafel slope of 133.9 mV.dec-1 at 80 0C.
- Full Text:
- Date Issued: 2011
Oorsaaipraktyke en vestiging van eenjarige raaigras in lusernweiding
- Authors: Badenhorst, Daniël
- Date: 2011
- Subjects: Alfalfa Alfalfa -- Irrigation
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/11792 , vital:26969
- Description: Die Eden- en Overbergdistrik in die Suid-Kaap vorm die mees suidelike substreke van die winterreëngebied. Dit is geleë tussen 33° 45‟ en 34° 50‟ suiderbreedte en tussen 19° 0‟ en 23° 45‟ oosterlengte. Die westelike grens van die substreek word gevorm deur die Villiersdorp-Botrivier-gebied. Aan die noordekant word die substreek begrens deur die Sonderend-, Lange- en Outeniquabergreekse. Die oostelike grens word gevorm deur die Bloukransrivier. Die Indiese Oseaankuslyn vanaf Nature‟s Valley in die ooste tot by Kleinmond in die weste vorm die suidelike grens. In die Suidkusstreek word 54.5% van die Wes-Kaapse melkproduksie en 24% van Suid-Afrika se melkproduksie deur 1900 melkprodusente geproduseer (Dowrey 2005). Ses en dertig persent van die bruto jaarlikse veeproduk is afkomstig vanaf suiwelprodukte wat hoofsaaklik vanaf aangeplante weiding geproduseer word. Aangeplante weiding beslaan 37.7% van die totale oppervlakte van die vee- en saaigebiede van die Suidkusstreek (Botha 2003). Weens beperkte, skaars besproeiingswater in groot dele van die Suid-Kaap, word heelwat weiding slegs aanvullend besproei (Protopapas 2004). Voervloeiprogramme vir melkproduksie onder aanvullende besproeiing bestaan hoofsaaklik uit kikoejoe (Pennisetum clandestinum) en lusern (Medicago sativa) (Botha 2003). Die droëmateriaalproduksie en weikapasiteit van lusern volg, soos kikoejoe, „n baie sterk seisoenale tendens met „n piek in die somer / herfs en „n laagtepunt in die winter (Durand 1993; Botha 1998; Botha 2003). Voervloeiprogramme met lusern of kikoejoe as hoofkomponente het gewoonlik voertekorte gedurende die winter tot gevolg. Hoofsaaklik om dié rede het boere uit die lusernproduserende gebiede van Heidelberg, Riversdal, Herbertsdale en Mosselbaai, deur hul onderskeie boereverenigings, „n versoek aan Outeniqua Navorsingsplaas gerig om ondersoek in te stel na moontlike oorsaaipraktyke wat die droëmateriaalproduksie van lusernstelsels gedurende die winter kan verhoog. Kikoejoeweiding word reeds die afgelope aantal jare suksesvol met Westerworldsraaigrasse oorgesaai vir beter herfs-, winter- en lenteproduksie. Anders as by kikoejoeweidings bestaan daar huidiglik geen beproefde oorsaaipraktyke wat die produksiepotensiaal van lusern in die winter en vroeë lente kan verhoog nie (Anoniem 2002).
- Full Text:
- Date Issued: 2011
The use of a Roving Creel Survey to monitor exploited coastal fish species in the Goukamma Marine Ptrotected Area, South Africa
- Authors: Van Zyl, Carika Sylvia
- Date: 2011
- Subjects: Fishing surveys , Fishery management -- South Africa , Fish populations -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10748 , http://hdl.handle.net/10948/1348 , Fishing surveys , Fishery management -- South Africa , Fish populations -- South Africa
- Description: A fishery-dependant monitoring method of the recreational shore-based fishery was undertaken in the Goukamma Marine Protected Area (MPA) on the south coast of South Africa for a period of 17 months. The method used was a roving creel survey (RCS), with dates, times and starting locations chosen by stratified random sampling. The MPA was divided into two sections, Buffalo Bay and Groenvlei, and all anglers encountered were interviewed. Catch and effort data were collected and catch per unit effort (CPUE) was calculated from this. The spatial distribution of anglers was also mapped. A generalized linear model (GLM) was fitted to the effort data to determine the effects of month and day type on the variability of effort in each section. Fitted values showed that effort was significantly higher on weekends than on week days, in both sections. A total average of 3662 anglers fishing 21 428 hours annually is estimated within the reserve with a mean trip length of 5.85 hours. Angler numbers were higher per unit coastline length in Buffalo Bay than Groenvlei, but fishing effort (angler hours) was higher in Groenvlei. Density distributions showed that anglers were clumped in easily accessible areas and that they favored rocky areas and mixed shores over sandy shores. Catch documented between October 2008 and December 2009 included a total of 361 fish, of 27 species from 12 families. Sparidae had the highest contribution (12 species). A Shannon-Weiner diversity index showed that diversity was higher in Buffalo Bay (0.81) than Groenvlei (0.57). Catch composition of retained fish (336 individuals) showed that the six numerically most important species were blacktail (Diplodus sargus capensis) (66 percent of catch), followed by galjoen (Dichistius capensis) at 11 percent, Cape stumpnose (Rhabdosargus holubi), belman (Umbrina robinsonii) and strepie at 3 percent, and elf (Pomatomus saltatrix) at 2 percent. Catch composition of an earlier study in Goukamma (Pradervand and Hiseman 2006) was compared with the present study, as well as data from the De Hoop MPA, which is closed to fishing. A multi-dimensional scaling plot of catch composition showed tight clustering of the De Hoop samples, and high variability among the Goukamma samples. A bray-curtis similarity index and dendrogram of similarity between study sites and study periods showed that there was an 83 percent similarity among De Hoop samples and a 75 percent similarity among Goukamma samples (ignoring the two outliers). The two sites are different with respect to species composition, but this is expected because they are different areas. Differences between time periods in Goukamma (i.e. the previous study versus the present study) were not significant. The most significant result from the catch composition analyses is the high variability among the Goukamma samples. This can be explained by the variable fishing methods used by anglers in Goukamma, compared with the standardized fishing methods used by researchers in De Hoop, and the fact that fish are more abundant and populations are more stable in De Hoop – giving higher sample sizes which reduce the variability in the statistics. Species-specific CPUE was calculated for the six numerically most important species. In both sections, CPUE was highest for blacktail, with an average of 0.133 fish per hour for Groenvlei, and 0.060 fish per hour for Buffalo Bay, over the 12 months. The second highest CPUE values per section were 0.030 for galjoen in Groenvlei and 0.039 for strepie in Buffalo Bay. Remaining CPUE values ranged from 0.014 (belman in Groenvlei) to the lowest value of 0.001 (strepie in Groenvlei). Total estimated CPUE for these six species in the MPA using the estimated effort and catch results amounted to 0.018 fish per hour. An annual estimated 3897 fish were landed in the reserve during 2009. Most fish (n=2481, 64 percent) were caught in the Groenvlei section. Numbers of blacktail were the highest of all species, within both sections (2353 fish). Strepie was the next most common (561 fish), but was caught almost entirely within the Buffalo Bay section (97 percent of individuals), followed by galjoen (548 fish) caught mostly within the Groenvlei section (92 percent of individuals). Size comparisons of the six species between the Goukamma and De Hoop MPAs showed that ranges in size are similar, but there are substantial differences in mean sizes between the two MPAs. Sample sizes of all species from the Goukamma MPA were too small to draw conclusions about stock status, except for blacktail. The Goukamma MPA is a popular fishing destination and angler effort is high. It can be considered a node of exploitation for surf zone fish, for which it provides no protection. Even though the MPA allows shore angling, sustainable fishing practices should be incorporated in management plans if the MPA is expected to protect and conserve its stocks. Of noteworthy concern is the occurrence of illegal night fishing (the public may not enter the reserve between sunrise and sunset) which leads to underestimates of catch and effort (night surveys were not conducted because of safety concerns). It is recommended that more communication should take place between the angling community and the reserve management. Sign boards giving information on species which are under pressure, and why they are under pressure, with a short explanation on their life cycles, is advised. The roving creel survey method was suitable for the study area and delivered statistically rigorous results. I thus recommend that it is continued in the future by management. I make some recommendations for reducing costs of future surveys, as well as for altering the survey design if funds are very limited.
- Full Text:
- Date Issued: 2011