利用气相色谱顶空装置测定红磷储存过程中生成的磷化氢

Determination of Phosphine Liberated in the Storage of Amorphous Red Phosphorus by Headspace Gas Chromatography

采用气相色谱法测定了高温加速老化的红磷生成的磷化氢 ,用外标法定量。该方法的检测限达到 0 0 0 1μg/L,加标回收率大于 97% ,其相对标准偏差为 2 35 %～ 6 5 2 %。研究了微量水和铁离子等在红磷产生磷化氢过程中的作用 ,结果表明 :水是工业红磷产生磷化氢的必要条件 ,它为红磷生成磷化氢提供质子氢 ;随着红磷样品中水分的增加 ,它的氧化反应速度加快 ,磷化氢的生成量增加 ;但当水分含量达到一定数值时 ,磷化氢的增长幅度减缓 ;微量的铁盐影响红磷的氧化反应 ,不同酸的铁盐对反应的影响效果不同 ;亚铁氰化钾对抑制含铁盐红磷样品产生的磷化氢的释放有明显效果。

Formation and liberation of phosphine has been an important factor and concern in the safety of the storage of amorphous red phosphorous. A method was established for the analysis of phosphine, which was determined by gas chromatography with a flame photometric detector and a column of 3 mm i.d.×2 m glass tube packed with GDX-102 stationary phase. An aliquot of 0.2 mL of the gas was injected by headspace sampler for the determination of the target compound with external standard quantitation. The retention time of phosphine was 1.62 min at 50 ℃. The minimum detectable amount was 0.001 (μg/L), the recovery exceeded 97% and the relative standard deviations were from 2.35% to 6.52%. The accelerated ageing tests at (50 ℃) were used to study phosphine liberation from amorphous red phosphorus in presence of trace water and trace ferric cation. It was found that water was the most important agent in the generation of phosphine as it was the source of hydrogen for the reaction P→PH_3. With the increase of the moisture level in the red phosphorus sample, the reaction speeded up more quickly, and the generation amount of phosphine increased, but the phosphine liberation increased little when the level of moisture reached a certain limit.The reaction was affected by a trace amount of ferric salt. Different acidic ferric salts showed different results. Potassium ferrocyanide was found as an effective inhibitor to slow down phosphine liberation in the presence of trace ferric salt.