2 1. Explain why a chromatograph is less suitable than other instruments for direct on-line process control. What aspects of the design of the measuring and control systems can make on-line control more readily achievable? Give explanations as necessary. 2. (a) Because of its high sensitivity, it is proposed to use an electron- capture detector with a chromatograph column. What special precautions would have to be taken? (b) Why might an ECD be preferred to a TCD as a detector? (c) Why is the FID so successful and widely used in the oil and petrochemical industries? What precautions must be taken? 3. (a) FIGURE 1 opposite is a diagram of an oxygen analyser based on the magnetic wind principle. The matched platinum coils wound round the bypass path have two functions. What are they?