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加熱白金表面でのアルカリ金属のイオン化に基づく熱陽イオン放射現象を利用した気体ハロゲン化物検出器の陽極特性を明らかにするために,Kを微量添加したフィラメントの陽極を用い,空気中における通常の電圧印加のほか印加中断時の温度特性と種々の気体ハロゲン化物や酸素暴露の影響などを調べた.有機ハロゲン化物は熱分解されてはじめて検出されること,陽極内部からのKの拡散供給が律速段階で,ハロゲン化物の暴露はこれを促進することが明らかにされた.又,イオン電流の増加率と試料ガスの種類及び濃度の関係も求められた.

環境水,水道水,排水などに微量含まれる低沸点有機ハロゲン化合物濃度を連続的にモニタリングするための簡便なシステムを確立した.測定はバブラーにより試料水中から有機ハロゲン化合物をパージし,ハロゲンに選択性のある熱陽イオン放射型検出器に間欠的に導入,イオン電流の増加分を水温と共に記録することによって行った.気液接触条件及び温度,共存物質の影響などを検討した.トリクロロエチレンに対する相対感度は1,1,1-トリクロロエタン:1.2;テトラクロロエチレン:0.98;クロロホルム:1.3;ブロモホルム:0.27であり,トリクロロエチレンの定量限界は3μg/l (S/N=5),相対標準偏差は5.7% (30μg/l)であった.

A method was investigated to evaluate the conversion efficiency of carbonyl halide into sym-diphenyl urea (DPU) without the measurement of recovery. The combustion gas of vinyl chloride monomer from a diffusion burner was used as a sample gas, and the gas was divided into two flows with almost the same flow rates of 0.4 l/min. These two flows were passed in parallel through two bubblers containing 20ml of aniline absorbing solution for 8 min at different sampling conditions, and DPU formed in the absorbing solution was determined by high performance liquid chromatography. When a condition in which carbonyl halide could be quantitatively converted into DPU would be adopted for one of the gas flows (A), the conversion efficiency in the condition for the other (B) could be evaluated from the ratio of analytical value of DPU of B to that of A. No difference could be detected between the conversion efficiencies with induction tube length of 20 and 40 cm. The efficiency and recovery was at a plateau(9497%) in the aniline concentration range of not less than 0.8 %. The residual gas after explosion of a mixed-gas containing trifluorobromomethane was also used as a sample, and similar results were obtained.

Nondispersive infrared method (NDIR) is one of the most reliable and accurate methods for the measurement of cffrbon monoxide (CO) concentration in urban air. Detector tube method is widely used for the same purpose as a field method because of its simplicity. Four types of detector tube (A, B, C and G) are available in the market and, in this paper, the obtained CO values by the four detector tubes were compared with NDIR results as the reference. Type B and C of the tube gave slightly larger values and type G gave values agreeing with NDIR. The type A tube gave remarkably higher results, which were due to, probably, the influence of hydrocarbons in the sample air.