建立了纤维素滤膜采样、超声波提取、二苯碳酰二肼分光光度法测定环境空气PM2.5中六价铬的方法.采样前滤膜用硝酸溶液净化以去除空白,碳酸氢钠溶液浸渍以降低六价铬的转化.稳定性试验表明常温下样品保存期不超过2天,冷冻条件下可保存10天.样品用碳酸氢钠溶液和超声波提取优于热水提取.浓度低于1 mg/L的铁、镁、钼和钒不干扰六价铬分析.方法简单灵敏,检出限0.1ng/m3,实际样品平行测量相对偏差为5.9%～18%,加标回收率为76%～92%,可应用于环境空气中六价铬的测定.%A simple and sensitive method for determining hexavalent chromium in PM2.5 was established by cellulose filter collection, ultrasonic wave extraction and 1,5-diphenylcarbazide spectrophotometry.It was concluded that the filters should be acid washed before coated with sodium bicarbonate for blank removal and Cr(VI)fixation.Stability studies showed that Cr(VI)could be preserved on filters within 2 d in room temperature and 10 d after frozen.Ultrasonic wave extraction with sodium bicarbonate was superior to hot water extraction.Iron, magnesium, molybdenum and vanadium, below 1 mg/L in concentration, did not interfere Cr(VI)analysis.The detection limit was 0.1ng/m3, the relative deviation of duplicate samples were 5.9%～18%and the recoveries were 76%～92%.This method cold be applied for hexavalent chromium determination in ambient air.
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