A biocomposite material composed of sodium alginate (SA), Fe2O3 nanoparticles, and ionic liquid 1-decyl-3-methyl imidazolium bromide ([DMIM]Br) was fabricated and used for the immobilization of myoglobin (Mb) on the surface of a carbon ionic liquid electrode (CILE) The CILE was fabricated by mixing graphite powder with ionic liquid N-butylpyridinium hexafluorophosphate (BPPF6) together UV-Vis absorption and FTIR spectroscopic results indicated that Mb retained its native structure in the composite material A pair of well-defined redox peaks appeared on the cyclic voltammogram in pH 7.0 phosphate buffer solution (PBS) with the formal peak potential (E-0') at -0256 V (versus SCE), which was the typical electrochemical behavior of Mb heme Fe(III)/Fe(II) redox couples The Mb-modified electrode showed good electrocatalytic activity to the reduction of trichloroacetic acid (TCA) and NaNO2 with wide linear range, good sensitivity, and reproducibility The calibration range for TCA detection was between 0 6 and 12.0 mmol L-1 with the linear regression equation as lss (mu A) = 42 44C (mmol L-1) + 50 57 and a detection limit of 0.4 mmol L-1 (3 sigma) The Mb-modified electrode also applied to NaNO2 determination in the concentration range from 40 to 100 0 mmol L-1 with a detection limit of 1.3 mmol L-1 (3 sigma) So the proposed electrode has potential applications as third-generation biosensors. (C) 2010 Elsevier Inc All rights reserved