Nitrogen at a constant pressure of 11.258 psi was used as a carrier gas. The injection temperature was maintained at 2600C, and all injections were made in split mode with a split ratio of 10:1. The injection volume was 1 mL. The GC oven temperature was held at 500C for 3 minutes, raised to 220 0C at 300C/minute, then programmed to 2500Cat300C/minute and held for 5 minutes. The ECD detector temperature wasmaintained at 3000C. The makeup gas was nitrogen at a makeup flow of 29 mL/minute. The GC chromatograms for iodine standard solution and seaweed samples are shown inFig. 1 . Seaweeds are known to contain both bromine andiodine, which can also react with 3-pentanone. The peak at 12.08 minutes was identified as 2-iodo-3-pentanone by comparison of the GC chromatogram of the KI standard so-lution through the sample pretreatment step. The peak at 9.90 minutes was identified as 2-bromo-3-pentanone by compari-son of the GC chromatogram using the KBr solution as a reference standard.