1. Introduction
The SPME-fiber [1] in conjunction with both liquid and gas chromatography (GC) has been widely used in food analysis [2] and [3]. The SPME is mostly used as a headspace technique for concentrating the volatile compound from food, environmental or chemical samples and subsequent gas or high pressure chromatography. The advantages of the SPME method lie in its simplicity and ease of manipulation and the absence of organic solvent for the concentration process. The volatile substances are concentrated on an absorbing layer, transferred directly to the injection port and separated in the chromatographic process.
In a recent article, we have proposed a new concept for the global measurement of the volatile compound of food and other goods [4] and [5]. In our concept, the volatile substances are first adsorbed on a SPME-fiber and then measured by desorption in a gas chromatographic detector without the classical chromatographic separation of the components. The method allows for a rapid and quantitative determination of volatile compounds. In fact, for many industrial analyses, the need lies primarily in the monitoring of a production, in the monitoring of an environmental pollution or only in the documentation of a process rather than in the differentiation obtained by a chromatographic separation. The measurement of global properties, like the conductivity or the pH of water, the essential oil content in spices and herbs or the refractive index measurement of a liquid, is often used for quality control. The possibility of analyzing the volatile substances of a headspace in an easy way is the goal of the development of the electronic noses. The method we propose here goes in the same direction. It allows the global determination of volatile substances present in a headspace by a short process. An advantage of the method proposed here is that, if it becomes necessary to make further qualitative and quantitative investigations, the same concentration process used for the method described here can be applied for a chromatographic separation, so that the problems encountered on the production line can be analyzed by a more sophisticated laboratory.
This communication presents the apparatus we have developed for this purpose and discusses the signal obtained.