Sensitivity enhancement of indium determination by flame atomic absorption spectrometry (FAAS) was achieved: using a slotted quartz tube (SQT-FAAS) and slotted quartz tube atom trap (SQT-AT-FAAS). SQT was used as an atom trap (AT) where the analyte is accumulated in its inner wall prior to re-atomization. The signal is formed after re-atomization of analyte on the trap surface by introduction of 10 pi of isobutyl methyl ketone (IBMK). Sensitivity was improved 400 times using SQT-AT-FAAS system with respect to conventional FAAS and 279 times with respect to SQT-FAAS without any collection. Characteristic concentration (C(o)) and limit of detection values were found to be 3.63 ng mL(-1) and 2.60 ng mL(-1), respectively, using a sample flow rate of 7.0 mL min(-1) and a collection period of 5.0 min. In addition, interference effects of some elements on indium signal were studied. In order to characterize indium species trapped, X-ray Photoelectron Spectrometry (XPS) was utilized and it was found that indium was collected on the inner surface of SQT as In(2)O(3). The accuracy of the procedure was checked to determine indium in the standard reference material (Montana Soil, SRM 2710). Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.