Arsenic was analysed after volatilization as arsenic trichloride, facilitated by evaporative concentration of hydrochloric acid. The generated gas was enriched in a cold trap and then revolatilized into a flame-in-tube atomizer for atomic spectrometric determination. No interference was observed at the 50 and 250 g/l As levels when the potential interferents Ni, Co, Cu, and Fe were added at 5000 mg/l each, or as a mixture containing all ions at 1000 mg/l. Standardization against aqueous acidified As(III) solutions was therefore possible without the use of making agents. Analyses of five reference samples of various steel alloys showed good agreement with certified values. The detection limit for As was 3.9 g/l in the dissolved sample, or 0.39 g/g in the steel.