HIGH-SENSITIVE DETERMINATION OF ARSENIC I N THERMALLY CRACKED GASOLINE BY OXY-COMBUSTION HYDRIDE GENERATION ATOMIC-ABSORPTION SPECTROMETRY

Organic and inorganic arsenic compounds in thermally cracked gasoline are known as catalyst poisons in the aromatization process. It is, the refore, important to determine trace arsenic in cracked gasoline. An o xy-combustion method was investigated to decompose the gasoline. Durin g the decomposition, organic arsenic compounds were converted complete ly to inorganic arsenic species. After absorbing the inorganic arsenic in hydrochloric acid-iodate-iodide solution, arsenic was reduced to a rsine with sodium tetrahydrogenborate and then the arsine was introduc ed into a quartz cell heated by an air-acetylene flame. The peak heigh t of the arsenic atomic absorption signal was measured. Several condit ions; acidity in the reduction process, amount of sodium tetrahydrobor ate, and reaction time for arsine generation were optimized. The detec tion limit of the proposed method was 5 ng g-1. This method was applie d to the determination of arsenic content in individual fractions from a fractionater in the aromatic hydrocarbon process.