Simple and selective method for determination of iodide in pharmaceutical products by flow injection analysis using the iodine-starch reaction.
This work exploited the well-known iodine-starch reaction for development of a simple flow-injection (FI) method for determination of iodide in pharmaceutical samples. Iodide in an injected zone was oxidized to iodine. A gas diffusion unit enables selective permeation of iodine through a hydrophobic membrane. Detection was made very selective for elemental iodine by employing formation of the I(3)(-)-starch complex. The detection limit (3 S/ N) of the system was 1 mg I L(-1). For a liquid patent medicine used for asthma treatment we suggested modification of the system. Direct injection of this sample, which contains a particularly high concentration level of iodide (ca. 9000 mg I L(-1)), can be achieved by coupling a dialysis unit to the FI system. This has increased the working range to 6000-10,000 mg I L(-1) without employing complicated nanoliter injection.
Nacapricha
D
D
Department of Chemistry, Faculty of Science, Mahidol University, Rama 6 Road, 10400 Bangkok, Thailand. scdnc@mahidol.ac.th
Uraisin
K
K
Ratanawimarnwong
N
N
Grudpan
K
K
D017022:Flow Injection Analysis / Q000379:methods*; D007455:Iodine / Q000737:chemistry*; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D011199:Potentiometry; D013213:Starch / Q000737:chemistry*; D013464:Sulfuric Acids / Q000737:chemistry
D004364:Pharmaceutical Preparations; D013464:Sulfuric Acids; D013213:Starch; D007455:Iodine; C033158:sulfuric acid