DOC《原子荧光光谱测定化妆品中痕量铅》

原子荧光光谱测定化妆品中痕量铅 黄宗平 (厦门出入境检验检疫局 福建厦门 361012) 摘要:介绍氢化物发生―原子荧光光谱法对化妆品中铅含量的定量分析方法,并研究原子荧光光谱测定铅的分析条件.

方法检出限低、精密度高、准确性好,可用于测定化妆品中的痕量铅. 关键词:原子荧光光谱;

化妆品;

痕量铅 中图分类号:O657.31 文献标识码:A 文章编号: HG-AFS DETERMINATION OF TRACE AMOUNTS OF LEAD IN COSMETICS HUANG Zong-ping (Xiamen Entry-Exit Inspection and Quarantine Bureau of P. R. C., Xiamen Fujian, 361012) Abstract: The hydride generation-atomic fluorescence spectrometric method was used for the determination of trace amounts of lead in cosmetics. The sample was digested with HNO3 and H2O2. Lead(Ⅱ) ion in the sample solution was oxidized to Pb(Ⅵ) and reacted with KBH4 to generate PbH4, which was led into the atomizer, and the lead content was determined by AFS according to the optimized working conditions. A linear calibration curve with lead concentration in the range of 0.0~200.0ng・ml-1 was prepared, having a correlation coefficient of 0.9998. RSD's of less than 1% were found at concentration levels of 19μg・g-1 and 38μg・g-1 with

11 determinations. Recoveries in the range of 96.0% to 101.5% were obtained. The detection limit achieved a value of 0.5ng・g-1, which was much lower than the value of 4μg・g-1 by AAS method. Keywords: HG-AFS;

Traces of lead;

Cosmetics 铅是一种重金属,在化妆品原料和成品中都有存在的可能[1].长期接触含铅量高的化妆品易引起人体慢性铅中毒.因此铅含量作为化妆品中的一个重要卫生项目,有非常严格的限量要求[2].目前,常采用原子吸收分光光度法进行测定[3].本法所采用的原子荧光光谱法[4,5]检出限更低,精密度高,准确性好,方便快捷. 试验部分 1.1 主要仪器与试剂 AFS2201双道原子荧光光度计(北京海光仪器公司). 盐酸羟铵溶液:120g・L-1,取盐酸羟铵12.0g和氯化钠12.0g溶于100ml水中 盐酸:3mol・L-1,取浓盐酸25ml,加水至100ml. 硼氢化钾:20 g・L-1,称取KOH 1.00g溶于200ml水中,溶解后加入KBH4 4.0g继续溶解,滤纸过滤后使用. 铁氰化钾―草酸溶液:溶解铁氰化钾20g、草酸4g于120ml水中,稀释至200ml. 铅标准溶液:1000μg・ml-1,由国家钢铁材料测试中心提供. 1.2 仪器分析条件 灯电流30mA,负高压360V,炉温800℃,原子化器高度8.0mm,读数时间10.0s, 氩气流量:载气400ml・min-1,屏蔽气800 ml・min-1,测量方法:统计测量,读数方式:峰面积. 1.3 试验步骤 1.3.1 样品前处理[6](浸提法) 称取试样约1.00g于25ml比塞管中,同时作试剂空白.加硝酸(优级纯)2ml、过氧化氢(30%)5ml,混匀(如出现大量泡沫,可滴加数滴辛醇),于沸水中加热2h;

取出,加入盐酸羟铵溶液1.0ml,放置15~20min,冷却后,用去离子水定容至25ml. 1.3.2 标样系列的配制 按试验方法,用5.00μg・ml-1铅标准溶液分别加入3mol・L-1盐酸5ml,铁氰化钾―草酸溶液10ml,定容至50ml,配制成0,0.020,0.040,0.080,0.200μg・ml-1铅标样系列. 测定 以20 g・L-1硼氢化钾为还原剂,盐酸(1+9)为载流,根据仪器操作规程,并按仪器分析条件,测定标样系列、空白溶液及样品溶液,以荧光强度If(无单位)为纵坐标,浓度C(ng・ml-1)为横从标,绘制标准曲线.按下式计算结果 C(Pb)= (C样―C空)?V *1000 ms 式中: C(Pb)――样品铅含量,μg・g -1 C样――样品溶液铅浓度,ng・ml-1 C空――空白溶液铅浓度,ng・ml-1 V ――定容体积,ml ms ――样品质量,g 结果与讨论 2.1 标准曲线线性 测定标准样品系列,绘制标准曲线,在0.0~200.0ng・ml-1 浓度范围内线性良好,曲线的相关系数为0.9998. 2.2 方法对照与检出限试验试验 本法与原子吸收光谱法测定结果对照见表1. 表1:测定结果比较(ρ/μg・g -1) Tab.1 Comparison of analytical results with those by atomic absorption spectrometry 样品 /Sample 眼影1# 眼影2# 腮红3# 色素4# 标准物质5# 1) 本方法 /This method AAS法/by AAS 18.8 17.8 30.2 28.9 27.6 26.5 31.5 31.2 38.2 37.5 注:1)标准值为37.9μg・g -1. Note:1)Certified value is 37.9μg・g -1. 对0#标样进行11次实验,荧光强度平均值Average= -1.2;