Analyser injection systems based on the principle of flow-injection analysis depend on the technique used. They generally take the form of an injection loop valve; the injected sample volume is determined by the volume of the valve. Injection systems are seldom designed with a time factor to define this volume. The authors report on an original injection system, which enables the two techniques to be used. The paper describes the evaluation of this system using both injection techniques and the comparison between them. The results show good linearity (r = 0.999 to 1.000) and an average precision (CV = 1.04 to 1.51%) for the volume-based injection technique; (ii) good linearity (r = 1.000) and better precision (CV = 0.73 to 1.30%) for the time-based injection technique. The system can be used equally well by the loop and by the clock; however, the latter is preferable because of its practicability.
A versatile injection system for flow-injection analysis