Analytical Sciences

Abstract − Analytical Sciences, 27(4), 381 (2011).

Comparison of Performance Parameters of Photothermal Procedures in Homogeneous and Heterogeneous Systems
Mikhail A. PROSKURNIN,*1 Elena S. RYNDINA,*1 Dmitrii S. TSAR’KOV,*2 Valerii M. SHKINEV,*3 Adelina SMIRNOVA,*4 and Akihide HIBARA*5
*1 M.V. Lomonosov Moscow State University, Vorob’evy gory, d. 1 str. 3, Moscow 119991, Russia
*2 Institute for Biomedical Problems of RAS, Khoroshevskoe shosse 76A, Moscow 123007, Russia
*3 Vernadsky Institute of Geochemistry and Analytical Chemistry of RAS, ul. Kosygina, d. 19, Moscow 119991, Russia
*4 Department of Mechanical Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
*5 Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan
The main types of analytical procedures used in thermal-lens spectroscopy and microscopy, which are based on photometric reactions in (i) aqueous solutions, (ii) organo-aqueous mixtures, (iii) polymer-containing (nonionic surfactants or polyethylene glycol) aqueous solutions, (iv) water-organic extraction systems, and (v) two-phase aqueous extraction systems, were compared from the viewpoint of both reproducibility and sensitivity. This comparison was made by examples of the determination of cobalt and iron for batch conditions, flow determination, and detection in HPLC, flow-injection analysis (FIA), and μFIA. It was revealed that for all five types, the real analytical efficiency (a decrease in the limit of detection (LOD) as compared to spectrophotometry) is primarily determined by the reaction conditions, provided that excitation of the thermal lens is the same. Aqueous solutions provide more efficient optimization of reaction conditions than do those in organo-aqueous solutions and solvent-extraction water-organic mixtures. The best results are achieved when shifting to polymer-containing aqueous solutions and two-phase aqueous extraction systems, which decreases in the LODs by a factor of 20 – 100%.