Objective: To investigate the aluminium content in unprocessed grains from different areas of China. Methods: From June 2013 to December 2014, nine provinces (Jilin, Shandong, Hubei, Hunan, Guangdong, Guangxi, Henan, Anhui and Jiangsu) were selected as sampling areas using stratified random sampling method. Three cities, counties or townships were randomly selected from each sampling area. Grain stations, grain depots, planting areas or farmers' markets located in non-aluminium mining areas or non-aluminium-involved industrial pollution areas were selected from each sampling area using a purposive sampling method. A total of 470 unprocessed grain samples (500 g per sample) including wheat, rice, corn, millet and soybean were collected from local grain stations, grain depots, planting areas and farmers' markets. The dried grains samples were analysed for aluminium content by inductively coupled plasma mass spectrometry. Bootstrap resampling method was applied to calculate the upper bound values of 95%CI of P(99) of aluminium contents for each kind of grain, which could be regarded as levels of concern for corresponding categories. Results: A total of 454 grain samples, including 109 wheat samples, 111 rice samples, 78 corn samples, 69 millet samples and 87 soybean samples, were used for analysis after excluding outlier values. There were 420 positive samples with detected aluminium and the overall detection rate was 92.5%. Among them, the aluminium contents were high in wheat and soybean with median values about 9.59 and 7.12 mg/kg, and maximum values about 31.55 and 28.80 mg/kg, respectively. The median and maximum values of aluminium contents in corn were about 4.65 and 26.79 mg/kg. Aluminium contents were low in rice and millet, with median values about 1.49 and 2.21 mg/kg, and maximum values about 7.56 and 8.07 mg/kg, respectively. Based on Bootstrap resampling method, the upper bound values of 95%CI of P(99) of aluminium contents in wheat, soybean, corn, rice and millet were 29.86, 28.80, 26.79, 7.56 and 8.07 mg/kg, respectively, which could be regarded as levels of concern for corresponding grains. Conclusion: Aluminium has been detected in most unprocessed grains. The accumulation of aluminium varies in different grains species.
目的： 调查中国未加工粮谷类食品的铝含量情况。 方法： 2013年6月至2014年12月，采用分层随机抽样选取吉林、山东、湖北、湖南、广东、广西、河南、安徽、江苏等9个省份作为采样地区，每个采样地区以单纯随机法选取3个市、县或乡作为采样点，通过立意抽样选择粮站、粮库、种植地或农贸市场采集本地自产的粮谷类食品，并要求采样点周围无铝矿区或含铝工业污染源。共采集粮谷类食品样品470份，每份样品500 g，以电感耦合等离子体质谱法检测干制粮谷类样品铝含量；基于Bootstrap再抽样方法计算各类食品铝含量P(99)的95%CI值，以上限值作为该类食品铝含量的关注水平。 结果： 剔除检测结果中异常值后，可用于统计分析的各类样品数分别为小麦109份、大米111份、玉米78份、小米69份、大豆87份，共计454份。检出铝的阳性样品420份（92.5%）。小麦和大豆的铝含量较高，M分别为9.59和7.12 mg/kg，最大值分别为31.55和28.80 mg/kg；其次为玉米，M为4.65 mg/kg，最大值为26.79 mg/kg；大米和小米的铝含量相对较低，M分别为1.49和2.21 mg/kg，最大值分别为7.56和8.07 mg/kg。基于Bootstrap再抽样法得到小麦、大豆、玉米、大米和小米铝含量P(99)的95%CI上限值分别为29.86、28.80、26.79、7.56和8.07 mg/kg，可以此作为相应粮谷类食品铝含量的关注水平。 结论： 铝在未加工的粮谷类中普遍存在，不同类别粮谷类对铝的富集能力不同。.
Keywords: Aluminum; Cereals; Food analysis; Mass spectrometry.