An agroindustry water discharge sample was taken to the laboratory to analyse alkanes and polyaromatic hydrocarbons (PAH
Posted: Fri Jul 15, 2022 4:45 pm
An agroindustry water discharge sample was taken to thelaboratory to analyse alkanes and polyaromatic hydrocarbons (PAHs)with a wide range of polarity. The compounds can be analysed usingthree separation methods: gas chromatography (GC), high performanceliquid chromatography (HPLC) and supercritical fluid chromatography(SFC).
i) Explain why the faster analysis was achieved using SFC withsupercritical fluid CO2 as a mobile phase compared to HPLC withmethanol:water as a mobile phase. (3 marks)
ii) The affinity of the analytes towards the mobile phase inSFC, is said to be a function of density. Explain the meaning ofthis statement. (2 marks)
iii) Write an order of B term (molecular diffusion) and C term(mass transfer) on band broadening (H) for SFC, HPLC and GCsystems. (2 marks)
iv) Separation by SFC resulted in all alkanes being eluted inless than 2 minutes. However, PAHs were eluted in the range of 5-7minutes. Discuss a way to reduce the analysis time of thisseparation. (4 marks)
v) SFC using carbon dioxide (CO2) as the mobile phase and silicaas the stationary phase is generally equated to a normal phasepartition High Performance Liquid Chromatography (HPLC). Explainthis statement.
i) Explain why the faster analysis was achieved using SFC withsupercritical fluid CO2 as a mobile phase compared to HPLC withmethanol:water as a mobile phase. (3 marks)
ii) The affinity of the analytes towards the mobile phase inSFC, is said to be a function of density. Explain the meaning ofthis statement. (2 marks)
iii) Write an order of B term (molecular diffusion) and C term(mass transfer) on band broadening (H) for SFC, HPLC and GCsystems. (2 marks)
iv) Separation by SFC resulted in all alkanes being eluted inless than 2 minutes. However, PAHs were eluted in the range of 5-7minutes. Discuss a way to reduce the analysis time of thisseparation. (4 marks)
v) SFC using carbon dioxide (CO2) as the mobile phase and silicaas the stationary phase is generally equated to a normal phasepartition High Performance Liquid Chromatography (HPLC). Explainthis statement.