食品中铬的石墨炉原子吸收光谱测定法的改进

Improvement of determination of chromium in foods by graphite gurnace atomic absorption spectrometry

目的改进国标方法中石墨炉原子吸收光谱法测定食品中铬的检测方法。方法样品经炭化后,于马弗炉中经灰化完全后,冷却,用浓盐酸溶解样灰,用蒸馏水定容至25 ml,盐酸终浓度为3%,用石墨炉原子吸收仪测定。结果对玉米、花生、萝卜、白菜和鸡肉5种样品进行加标测定,回收率为95.0%～105.0%;有证标准物质测定结果相对标准偏差为1.8%～5.4%,且测定值均在证书给定的标准值范围内;该方法最低检出浓度为0.001 mg/kg(当称样量为2 g时)。结论用该方法对食品样品中铬进行测定,其背景干扰小,步骤简单,操作性强,具有良好的准确度和精密度,完全适合于食品样品中铬的测定。

[ Objective ] To improve the national standard method of measuring chromium in food by graphite furnace atomic absorp- tion spectrometry. [ Methods] After being carbonized, the samples were transferred into a muffle furnace to ash completely. The cooled ash samples were dissolved by concentrated hydrochloric acid, diluted to 25 mL with distilled water and final hydrochloric acid concentration of 3%. Finally, the chromium was detected by graphite furnace atomic absorption spectrophotometer. [ Results] The recovery rates of added standard with five different kinds of samples （ corn, peanut, radish, cabbage and chicken ） were 95%-105%. By measuring the chromium in certified reference materials, the relative standard deviations （RSD） were 1.8% -5.4% and the results were within the given standard value range. The detection limit of the method was 0. 001 mg/kg （ sample weight was 2 g ）. [ Conclusion ] This method has small background interference, simple steps, feasibility, and good accuracy and precision in determination of chromium in food samples. Therefore, it is very suitable for the determination of chromium in food samples.