Gas chromatography was used to analyse for residues of toxic solvents, including benzene and 1,2-dichloroethane (DCE), in a pharmaceutical preparation. The following conditions were used: Column: 30 m long capillary with polysiloxane stationary phase Carrier gas: He at 35 cm s–1 constant flow Oven program: 40 °C at t = 0, increasing at 10 °C min–1 to 240 °C at t = 20 min. Detector: flame ionisation (FID) Benzene eluted with retention time = 11.5 min, peak width = 0.26 min 1,2-dichloroethane (DCE) eluted with retention time = 11.8 min, peak width = 0.28 min (i) What are the strengths and limitations of the flame ionisation detector in this application, compared with other possible methods of detection? (ii) What is the resolution, RS, for the separation of benzene and DCE on this column? (iii) Suggest two ways by which the resolution of benzene and DCE might be improved. Explain your choices.
Gas chromatography was used to analyse for residues of toxic solvents, including benzene and 1,2-dichloroethane (DCE), in a pharmaceutical preparation. The following conditions were used:
Column: 30 m long capillary with polysiloxane stationary phase
Carrier gas: He at 35 cm s–1 constant flow
Oven program: 40 °C at t = 0, increasing at 10 °C min–1 to 240 °C at t = 20 min. Detector: flame ionisation (FID)
Benzene eluted with retention time = 11.5 min, peak width = 0.26 min 1,2-dichloroethane (DCE) eluted with retention time = 11.8 min, peak width = 0.28 min
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(i) What are the strengths and limitations of the flame ionisation detector in this application, compared with other possible methods of detection?
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(ii) What is the resolution, RS, for the separation of benzene and DCE on this column?
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(iii) Suggest two ways by which the resolution of benzene and DCE might be improved. Explain your choices.
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