1973 Volume 22 Issue 7 Pages 819-823
The ring oven technique had been applied to the separation, concentration and determination of nickel in atmospheric particulates. The atmospheric particulates were collected at a rate of 20 to 30 l/min with membrane filter(Toyo TM-80). The analytical apparatus used was a portable glass ring oven, the bath liquid used was 100 ml of water, and the analytical procedure was carried out at 90°C. Preliminary experiments were made in order to determine the suitable considitions for the experiments. The No. 51A filter paper was found to be the best one. Nickel could be developed in a ring form with 0.01 to 0.2N hydrochloric acid. The operation is carried out by using 15 μl of this acid and then once again with 20 μl. No difference in the color intensity of nickel-dimethylglyoxime was recognized if the dimethylglyoxime concentration was in the range of 0.02 to 0.1 M in ethyl alcohol; Thus a concentration of 0.1 M of the reagent was employed throughout the experiments. When this reagent solution was added 4% ammonia water, the process, exposure of the paper to ammonia vapor, could be avoided. The detection limit was 0.03 μg and the determination range was 0.03 to 3.0 μg. Membrane filter was cut in a small disk form (Fig. 1), and a cutting this small disk was contacted in the middle of a piece of filter paper(No. 5lA, 55 mm φ) by directing the sample-bearing surface down and fixed with a drop of aceton. After sulfide is formed on original small disk by passing hydrogen sulfide, the filter paper is setted upon the ring oven placing upside-down. Nickel is eluted out to the ring zone on the filter paper with 0.05 N hydrochloric acid. After iron is masked by treating with 5% citric acid, 0.1 M ethyl alcohol solution of dimethylglyoxime(in 4% ammonia water) was sprayed in order to color nickel and then the paper was dried with a hair drayer. Fifty standard rings have been made by using a nickel standard solution and the amount of nickel in the sample was determined by promptly comparing the intensity of the color with the standard rings. The nickel standard solution used in this experiment contained iron(III) 100 times of nickel. Another analysis technique employed was as follows: The membrane filter is immersed in isopropyl alcohol and burned in an electric furnace at 150 °C. The ash is dissolved in 0.500 ml of 1 N hydrochloric acid and then nickel, is determined by using a semicircular glass ring oven. An amount of nickel, 0.5 to 1.0 μg in the sample could be determined by this technique. When the sample is collected in a residencial area, or when it is humid, a large amount of air should be passed through the paper or otherwise it was necessary to add 0.03 μg of nickel. It was found that to cut the sample filter paper as a disk is more suitable than to cut it as a triangle plate.
This technique can be carried out within a short time; it took about ten minutes and the limit of error is 5% when it is applied to the determination of nickel in atmospheric particulates. The technique may be also use for polluting substances in atmospheric particulates and in working environment.
