The increasing demand for the analysis of trace organic chemicals in blood and urine by the solvent extraction technique described previously (1) has led to an investigation of methods to facilitate sample handling and improve efficiency (2). In order to extend the method to the smaller laboratory animals it was found necessary to reduce the sample volume from 5 ml to 1 or 2 ml. In addition, it was desirable to take serial samples from an animal or human subject during the course of a chemical exposure so that changes of its concentration in the blood could be measured. This, too, necessitated smaller samples so that the total volume of blood lost would be minimized. The cell described below has a length of 10 mm and requires only 0.5 ml of solution. This gives a sensitivity of 1 - 10 ppm (minimum amount detectable) for many organic chemicals in a 1 ml sample of blood or urine.
D. S. Erley, "Long Path Infrared Microcell," Appl. Spectrosc. 15, 80-81 (1961)