Development and Evaluation of Multidimensional Gas Chromatographic and Mass Spectrometric Techniques for the Analysis of Highly Complex Chemical Mixtures

For the analysis of highly complex chemical mixtures, new interpretation methods and new techniques were introduced. The data interpretation methods introduced incorporates the unique chemical and physical interactions of compound classes with the stationary phase of a two-dimensional gas chromatographic system and the unique fragmentation pattern observed for different compound classes. Photo ionisation mass spectrometry, which produces mostly molecular ions, were successfully used in new two- and three-dimensional separation techniques

The optimisation of GC x GC and the analysis of diesel petrochemical samples

Comprehensive two-dimensional gas chromatography (GC x GC) is a new technique with a promising future in analytical chemistry. Researchers have already shown the advantages of this technique to unravel complex samples consisting of hundreds of compounds. The predominant advantage of GC x GC above conventional one-dimensional gas chromatography is the greatly enhanced peak capacity. To fully utilise this enhanced peak capacity the instrumentation needs to be run at optimum conditions. The optimisation of one-dimensional gas chromatography (GC) is done on a routine basis in analytical laboratories and handbooks are available to cover these optimisation strategies. This study was aimed at providing similar guidelines for GC x GC. Since the underlying theory of GC and GC x GC are essentially the same, conventional GC optimisation strategies were the point of departure for this research. The different operational parameters in GC x GC were identified and emphasis was then placed on a method to simultaneously optimise the flow rate in both columns, taking into consideration the common practice of series-coupling of columns of different internal diameters. The influence of second-dimension stationary phase, temperature program and modulator operation on the distribution and shape of chromatographic peaks in the two dimensions is also investigated. The results obtained from this study provide a useful new approach to optimise a GC x GC system where two gas chromatographic columns of various dimensions are connected in series. The use of diesel samples in this optimisation process presented some useful applications for future research in the petrochemical industry. Examples of potential applications such as “fingerprinting techniques” and compositional analysis are also discussed.Dissertation (MSc (Chemistry))--University of Pretoria, 2007.Chemistryunrestricte

Factors determining clinical outcomes in intussusception in the developing world: Experience from Johannesburg, South Africa

Background. Rates of open reduction of intussusception were noted to be unacceptably high during an institutional internal audit.Objectives. To determine the impact of revised protocols to better select patients for pneumatic reduction (PR), and document associated morbidity and mortality, and the factors that affect the above.Methods. Medical records of patients between 3 months and 3 years of age presenting to the Department of Paediatric Surgery at Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa, from 2007 to 2010 were reviewed. Determining factors, including duration of symptoms, admission C reactive protein (CRP) level and weight, were analysed against clinical outcomes, notably PR, bowel resection, relook laparotomy and death.Results. A total of 97 cases were suitable for inclusion. In 62 of these (63.9%), PR was attempted; this was successful in 32 cases (51.6%), giving an overall successful PR rate of 33.0%. In 7 of the 62 patients, a pneumoperitoneum was documented during the reduction attempt. Of the 65 patients who underwent surgery, 53 required intestinal resection and 12 had spontaneous or manual reduction. Ileostomy was necessary in 9 patients, and 7 required relook laparotomy. The overall mortality rate was 9.1%. Averages of ‘determining factors’ assessed against clinical outcome were as follows: mean weight (standard deviation (SD)) 7.4 (4.3) kg, mean duration of symptoms (DOS) 3.0 (SD 2.2) days, and admission CRP level 50.9 mg/L (range 1 - 249.3). Prolonged DOS and a raised CRP level predicted a poor outcome.Conclusions. Despite marked improvements in management and PR outcomes, intussusception remains associated with significant morbidity and mortality. Prolonged DOS and an elevated CRP predict worse outcomes. The use of these markers in association with clinical factors may assist management decisions, specifically with regard to operative or non-operative management. Awareness and education are key to prompt presentation and early diagnosis. Well-defined protocols introduced at all points of contact ensure early recognition and resuscitation as well as prompt referral for definitive management

Attendee satisfaction in festival activity: Innibos National Arts Festival

Despite the growth in festival tourism in South Africa and the paucity and infrequent nature of festival research, very little research exists on addressing what classifies a festival as successful. Well organized, promoted and managed events have been linked to attendee satisfaction, resulting in a successful event. Similarly, there is a positive connection between customer satisfaction, loyalty and retention which underlines the importance for festivals to be successful and sustainable. This study employs an on-site survey of 500 visitors attending the Innibos National Arts Festival in Mbombela, South Africa. Eight constructs were investigated based on the SERVQUAL and Grönroos model to determine the overall satisfaction of the attendees. The statistical analysis was performed using the marginal distributions of variable and construct analysis based on the post data. This study aimed at determining the overall satisfaction levels of the between attendee’s at the festival

Mortality in paediatric burns victims: A retrospective review from 2009 to 2012 in a single centre

Background. Childhood mortality is high in low- and middle-income countries. Burns are one of the five leading causes of childhood injury mortality in South Africa (SA). While there is an abundance of literature on burns in the developed world, there are far fewer publications dealing with childhood mortality related to burns in Africa and SA.Objective. To describe the mortality of children admitted to a dedicated paediatric burns unit, and investigate factors contributing to reducing mortality.Methods. A retrospective review was performed of patients admitted to the Johnson & Johnson Paediatric Burns Unit, Chris Hani Baragwanath Academic Hospital, Johannesburg, SA, between May 2009 and April 2012.Results. During the study period, 1 372 patients aged ≤10 years were admitted to the unit. There were 1 089 admissions to the general ward and 283 admissions to the paediatric burns intensive care unit (PBICU). The overall mortality rate was 7.9% and the rate for children admitted to the PBICU 29.3%; 90.8% of deaths occurred in children aged ≤5 years. Of children admitted with an inhalational injury, 89.5% died. No child with a burn injury >60% of total body surface area (TBSA) survived.Conclusions. Our overall mortality rate was 7.9%, and the rate declined significantly over the 3-year study period from 11.7% to 5.1%. Age ≤5 years, the presence of inhalational injury, burn injury >30% of TBSA and admission to the PBICU were significant risk factors for mortality

Combined paediatric liver-kidney transplantation: Analysis of our experience and literature review

Background. Renal insufficiency is increasingly common in end-stage liver disease and allocation of livers to this category of patient has escalated. The frequency of combined liver-kidney transplantation (CLKT) has consequently increased. Indications for CLKT in children differ from those for adults and typically include rare congenital conditions; subsequently limited numbers of this procedure have been performed in paediatric patients worldwide. Scant literature exists on the subject. Methods. Subsequent to institutional approval, a retrospective chart analysis of all paediatric CLKTs performed at the Transplant Unit, Wits Donald Gordon Medical Centre, University of the Witwatersrand, Johannesburg, South Africa between January 2005 and July 2013 was conducted. Results. Defining children as younger than 18 years of age, 43 patients had received a liver transplant since 2005, of whom 8 received a CLKT. Indications included autosomal recessive polycystic kidney disease (n=3), primary hyperoxaluria type 1 (n=4) and heterozygous factor H deficiency with atypical haemolytic uraemic syndrome (n=1). Graft combinations included whole liver and one kidney (n=5), whole liver and two kidneys (n=1) and left lateral liver segment and one kidney (n=2), all from deceased donors. Patient age ranged from 4 to 17 years (median 9) and included 4 females and 4 males. Weight ranged from 13 to 42 kg (median 22.5). We describe one in-hospital mortality. The remaining 7 patients were long-term survivors with a survival range from 6 to 65 months. Conclusions. Although rarely indicated in children, CLKT is an effective treatment option, appropriately utilising a scarce resource and significantly improving quality of life in the recipient.