Detection tube method for trace level arsenic

• The detection tube method enabled visual determination of As(V), at 0.01 mg As L−1.
• The color development was conducted by a modified molybdenum blue method.
• As(III) was also detected at 0.01 mg As L−1 by this method after oxidation to As(V).

Arsenic pollution of surface and ground waters has been reported in many developing countries, and it is therefore an important task to detect arsenic rapidly using a simple and inexpensive tool. This work focused on the detection of arsenic at 0.01 mg As L−1 by visual determination. A small column packed with the poly(vinylchloride) particles coated with a quaternary ammonium salt was used as a detection tube. Molybdoarsenic heteropoly acid (molybdenum blue) was derived from arsenate under modified reaction conditions. The molybdenum blue solution (20 mL) was introduced into the detection tube by suction with a syringe to form color band. As(III) was measured after oxidation with sodium dichloroisocyanuric acid. The color band length in the detection tube was correlated linearly with the arsenic (As(III) + As(V)) concentration in the range of 0.01–0.1 mg As L−1, and the relative standard deviations in the concentration range were around 1%. Arsenic was successfully detected at 0.01 mg As L−1 using this detection tube.

The color band length was correlated almost linearly with the arsenic concentration in the range of 0.01–0.1 mg L−1.Figure optionsDownload as PowerPoint slide