Katsuhiko Kawabata

Determination of arsenic compounds using inductively coupled plasma mass spectrometry with ion chromatography

A combined system of inductively coupled plasma mass spectrometry (ICP-MS) with ion chromatography (IC) has been used for the determination of arsenic compounds. Arsenous acid (AsIII), monomethylarsonic acid (MMAs), dimethylarsinic acid (DMAs), trimethylarsine oxide (TMAsO) and arsenobetaine were separated by anion-exchange chromatography. Subsequently eluates were directly introduced into ICP-MS and detected at m/z 75. Separation parameters were optimized for the arsenic compounds as follows: column, two Excelpak ICS-A35 columns (150 mm × 4.6 mm I.D. each) packed with polymer-based hydrophilic anion-exchange resin (ion-exchange capacity: 0.15 mequiv. /g dry); mobile phase, 10 · 10−3M tartaric acid; flow-rate, 1.0 ml/min; column temperature, 50°C; injection volume, 20 μl. The detection limits for the five arsenic compounds were from 0.22 to 0.44 μ/l as an As element. The repeatability was better than 5% (relative standard deviation) for all arsenic compounds. The IC-ICP-MS system was applied to the determination of arsenic compounds in the urine of DMAs-exposed rats. AsIII, MMAs, DMAs and TMAsO were detected in the urine.

Speciation of organotin compounds using inductively coupled plasma mass spectrometry with micellar liquid chromatography

Chlorides of dimethyltin, trimethyltin, dibutyltin, tributyltin, diphenyltin and triphenyltin were completely separated within 20 min by micellar liquid chromatography using tris (hydroxymethyl) aminomethane dodecylsulfate as a mobile phase and butyl group bonded silica gel as a stationary phase. The eluates were directly introduced into the inductively coupled plasma mass spectrometer and detected at m/z= 120. Detection limits for the six organotin compounds were 24 to 51 pg as Sn. The linear dynamic range was 1 × 10–3 to 10 mg l–1. Relative standard deviation (n= 5) was less than 3% for all the organotin compounds.