光谱-质谱联用技术测定第四纪沉积物中的铀、钍和钾  

DETERMINATION OF U,TH AND K FOR QUATERNARY SEDIMENTS BY INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION SPECTROMETRY-MASS SPECTROMETRY

作　　者：罗居德 文雯 杜金花 孟茹 LUO Jude;WEN Wen;DU Jinhua;MENG Ru(School of Earth Science and Resources,Chang'an University,Xi'an 710054,Shaanxi;Zhuhai Institute of Urban Planning and Design,Zhuhai 519000,Guangdong)

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]珠海市规划设计研究院,广东珠海519000

出　　处：《第四纪研究》2022年第5期1420-1429,共10页Quaternary Sciences

基　　金：国家自然科学基金青年基金项目(批准号:41602179);中央高校基金项目“黄河流域生态地质环境”专项重点(批准号:300102272901);新疆昌吉地区K45E001012等6幅1︰5万区域地质调查项目(批准号:DD20190065)共同资助。

摘　　要：电感耦合等离子体质谱法和原子发射光谱法(ICP-MS和ICP-OES)是释光或ESR测年中测定放射性元素含量的常见方法,其样品的预处理是保证测量结果准确的重要环节。本研究通过对8个国家标准沉积物样品(GSS-1a~8a)不同灰化温度后加氢氟酸和硝酸进行预处理,以Re作为ICP-MS测定时的内标元素,测定U和Th元素,ICP-OES测定K元素。结果表明,相对于350℃和450℃的灰化温度,550℃灰化温度对沉积物中有机质的去除更为彻底,且测定结果的精密度(RSD<1.3%)和稳定性更好。将干灰化法(550℃)-氢氟酸-硝酸消解体系与常见4种不同湿法消解体系(双氧水-氢氟酸-硝酸、盐酸-氢氟酸-硝酸、王水-逆王水-氢氟酸-硝酸和双氧水-盐酸-氢氟酸-硝酸)对标准沉积物消解后,ICP-MS测定U、 Th和ICP-OES测定K元素,干灰化法-氢氟酸-硝酸、盐酸-氢氟酸-硝酸和双氧水-盐酸-氢氟酸-硝酸消解体系下,U、 Th和K元素的结果在误差范围内基本一致。进一步将3种消解方式应用于大九湖的15个沉积物样品,结果表明,对于烧失量大于10%的样品,盐酸-氢氟酸-硝酸和双氧水-盐酸-氢氟酸-硝酸消解体系下,由于无法完全消解沉积物中全部有机质,导致测定的U、 Th和K元素有所偏低。但是沉积物经过干灰化法(550℃)处理后,样品极易溶解,消解液透亮无杂质,且加酸量少,对沉积物中U、 Th和K元素的测定结果更为稳定。这一结果揭示干灰化法-氢氟酸-硝酸消解体系适宜于对大批量第四纪沉积物样品U、 Th和K元素的光谱-质谱联用技术检测。The inductively coupled plasma mass spectrometry( ICP-MS) and optical emission spectrometry( ICP-OES) are common methods for determining potassium,uranium and thorium contents of sediments in luminescence or ESR dating. The quality of the analysis results depend partically on the pretreatment processes of samples. In this paper,eight national standard sediment samples( GSS-1a ~ 8 a) from Yichun of Heilongjiang, Baiyunebo of Inner Mongolia,Laizhou of Shandong,Yizhou of Guangxi,Liuyang of Hunan,Yangchun of Guangdong,Xuwen of Guangdong and Luochuan of Shaanxi were pretreated with hydrofluoric acid and nitric acid at different ashing temperatures,andRe was used as the internal standard element in ICP-MS to determine U and Th elements,and ICP-OES to determine K elements. The results showed that the calcination temperatures of 350 ℃,450 ℃ and550 ℃ did not affect the values of U,Th and K for the samples with a loss of less than 10%. However,for the samples with a loss of more than 10%,especially GSS-1 a and GSS-7 a,the ratios of the measured values of U,Th and K to the standard values after pretreatment at 450 ℃ were less than 0. 95,while the ratios at 350 ℃ were less than 0. 90. However,the measured results of the digestion solution after ashing at 550 ℃ were consistent with the standard values within the error range. Moreover,the precision( RSD < 1. 3%) and stability of the determination results are better.After the above-mentioned sediments were further digested by dry ashing( 550 ℃)-hydrofluoric acid-nitric acid digestion system,and compared with four common wet digestion systems( hydrogen peroxide-hydrofluoric acidnitric acid,hydrochloric acid-hydrofluoric acid-nitric acid,aqua regia-reverse aqua-hydrofluoric acid-nitric acid and hydrogen peroxide-hydrochloric acid-hydrofluoric acid-nitric acid). The results showed that the test results of U,Th and K elements of GSS-1a,GSS-6a and GSS-7a in the hydrogen peroxide-hydrofluoric acid-nitric acid and aqua regia-reverse aqua-hydrofluoric acid-nitric acid sys

关 键 词：第四纪沉积物 ICP-MS ICP-OES U、Th和K元素 

分 类 号：P597.3[天文地球—地球化学] P534.63[天文地球—地质学]