A semicircular glass ring oven

Rapid qualitative and quantitative analysis of inorganic microsubstance by a glass ring oven technique. III

Abstract

Circular filter paper is used in the conventional ring oven technique. In order to increase the sensitivity and to reduce the volume of sample solution a new ring oven of hard glass which makes use of fan-shaped sheets of filter paper is proposed.
Figure 1 illustrates the semicircular glass ring oven. The ring oven body is a semicircular hollow vessel. The external diameter is 65 mm, internal diameter is 25 mm, and width is 25 mm. The interior side has a groove, whose width is 5 mm and depth is 5 mm. Two semicircular glass plates whose external diameter is 30 mm, internal diameter is 25 mm and thickness is 2 mm are set in this groove. A fan-shaped sheet of filter paper(center angle: 180°, 90°, 72°, 60°, 36°) is placed between the two glass plates, and the whole is set in the groove. Twenty five mililiters of bath-liquid was placed in a 50-ml round-bottom flask, and the liquid was heated by an alcohol lamp. When water was used as bath-liquid, the surface temperature of oven reached 90°C after about ten minutes, and the temperature was constant for more than ten hours. Different surface temperature may be realized by using appropriate organic solvents. The analysis was carried out according to the conventional ring oven technique. By using a fan-shaped filter paper (center angle 36°) the sensitivity as high as ten times that of the conventional technique was obtained, rendering it possible to reduce the volume of sample solution to one tenth. The appropriate volume of sample solution, less than 1.0 μl, was determined according to the center angle of the filter paper used (Table I). The standard rings were prepared on filter paper of the same dimension. The determination was carried out by comparing the ring of the sample to the standard rings. Alternatively, the standard rings may be prepared on circular filter papers.
In this technique, fourteen ions could be separated into two or three groups. The efficiency of separation was less than the conventional technique using circular filter paper, but it was expected that the efficiency would be increased by the use of appropriate masking and developing reagents and color reagents. The results obtained by the use of the fan-shaped filter paper agreed with those obtained by the use of circular filter paper within 1%.
The determination could be performed within about five minutes. The present technique is suitable for the detection and determination of a dilute component in simple mixtures.