Thermoelectric-based temperature-controlling system for in-tube solid-phase microextraction

A temperature-controlling device for in-tube solid-phase microextraction was developed based on thermoelectric cooling and heating. This device can control the temperature of the capillary column from 0 to 100°C by applying a voltage to a Peltier cooler or stainless steel tube. The extraction temperatures for angiotensin I, propranolol, and ranitidine were optimized. In all cases, setting the temperature to 10°C for extraction achieved the best extraction efficiency. Desorption showed minimum peak broadening at 70°C, contributing to better chromatographic performance. Propranolol was selected as a model compound to compare the performance of temperature-controlled in-tube solid-phase microextraction at optimized conditions. Calibration curves exhibited good linearity (R(2) > 0.999) over the studied range, and the limit of detection and limit of quantification were about three times lower than those obtained at standard conditions (30°C extraction and desorption).