面粉样品用水分散,含油脂高的样品需另加石油醚,用超声提取和离心分离.分取一定量的上层清液流经On-Guard Ⅱ RP柱除去部分有机杂质,所得流出液用于离子色谱-电感耦合等离子体质谱法(IC-ICP-MS)测定其溴酸盐含量.为尽可能提高ICP-MS检测的灵敏度,选用了仪器高功率工作参数,质谱干扰主要是多原子干扰,选用同位素79Br作为测量同位素.由于经过了色谱柱分离,消除了多原子干扰,在离子色谱分析中采用硝酸及氨水作为流动相,溴酸盐工作曲线的线性范围为100 μg·L-1以内,方法的检出限(3σ/b)为0.6 μg·L-1.应用此方法分析了两种样品,测得平均回收率为97%,测定值的相对标准偏差(n=8)在3.3%~8.3%之间.

Sample of flour or its products was dispersed with water (for fatty sample petroleum ether was added together with the water) and extracted ultrasonically.The mixture was centrifuged and a definite aliquot was taken for purification by passing through the On-Guard Ⅱ column to remove part of organic impuritres.Eluate from the column was used for IC-ICP-MS analysis to determined content of bromate.To achieve to the best sensitivity of the MS detection,high power parameters were adopted.The isotope 79Br was selected as the analytical isotope and the main MS interference of multi-atom was eliminated by separation on the chromatographic column.Nitric acid and aqueous ammonia were used as the mobile phase.Linearity range of the working curve was in the range within 100 μg·L-1 of BrO-3 ion.Detection limit (3σ/b) of the method found was 0.6 μg·L-1.The proposed method was used to analyze 2 kinds of samples for their bromate contents,giving value of average recovery of 97% and values of RSD′s (n=8) in the range of 3.3%-8.3%.