Development of a solid-phase microextraction/reflection-absorption infrared spectroscopic method for the detection of...

In this paper, the reflection-absorption infrared (IR) spectroscopic method combined with the principle of solid-phase micro-extraction (SPME) is proposed to detect chlorinated aromatic amines in aqueous solutions. This proposed method provides simplicity in both the optical system and equipment setup. Compared to the SPME/attenuated total reflection-IR method, this method reduces the cost for internal-reflection elements and optical systems. Meanwhile, it has no SPME/transmission IR method problems, which require high polymer film preparation techniques to obtain a standing film that has no physical/chemical property changes when immersed in an aqueous solution. The typical linear coefficients obtained using this method for chloroanilines in aqueous solutions are around 0.995 and the detection can be lower than 100 ppb. The thickness of the hydrophobic film is relatively important in the SPME/ATR-IR method, but the uncertainty caused by the film thickness can be partially eliminated in the proposed method. This is because the IR signals are proportional to the film thickness and can be corrected using hydrophobic film signals. The low detection limits have also indicated that this proposed method can compete with the currently existing IR methods, but allowing much simpler detection.