各位大侠,我们最近在使用
ICP-MS中出现了内标异常的情况。寻求各位的帮助。情况交代如下:
实验室为药物研发类实验室,在对胞磷胆碱钠注射液和盐酸利多卡因注射液的元素杂质分析中出现Sc/Y/In浓度异常偏高,Bi元素相对稳定。异常偏高出现在进样品基质后。
样品基质均为液体注射液,规格为5ml/0.5g,上机溶液为原溶液用稀硝酸及加金标液稀释100倍,内标溶液浓度500ng/ml混标。
项目开发时,各方法学参数均正常,等上方法验证时,出现内标异常偏高,当时采用清洗两级椎体,浸泡矩管和雾化器的维护方法。维护后开机走标曲及空白溶液显示均正常。但一上样品基质,内标开始上涨。数据如下:
| 45 Sc ( ISTD ) [ He ] | 89 Y ( ISTD ) [ He ] | 115 In ( ISTD ) [ He ] | 209 Bi ( ISTD ) [ He ] |
Sample Name | ISTD Recovery % | CPS | ISTD Recovery % | CPS | ISTD Recovery % | CPS | ISTD Recovery % | CPS |
Blk wash | | 41192.14 | | 307826.7 | | 513574.5 | | 1697987 |
Blk wash | | 41108.48 | | 307124.7 | | 516443.1 | | 1693373 |
Blk wash | | 41566.22 | | 307867.6 | | 519287.8 | | 1704694 |
Blk wash | | 40662.85 | | 309038.2 | | 514030.1 | | 1687415 |
Cal-1 | 100 | 40351.99 | 100 | 309738 | 100 | 519149.2 | 100 | 1716766 |
Cal-2 | 102.3 | 41275.34 | 100.1 | 309978 | 99.1 | 514645.9 | 101.2 | 1737226 |
Cal-3 | 98.9 | 39926.64 | 96 | 297374.4 | 96.7 | 501786.6 | 99 | 1699120 |
Cal-4 | 95.7 | 38631.84 | 93.4 | 289229.4 | 92.7 | 481313.4 | 96.4 | 1655451 |
Cal-5 | 93 | 37531.07 | 91.9 | 284758.2 | 91.9 | 477332 | 96.3 | 1652720 |
Cal-6 | 97.7 | 39431.54 | 93.4 | 289200.9 | 94.6 | 491246 | 97.2 | 1668673 |
Blk wash | 89.4 | 36062.13 | 86.6 | 268082.7 | 85.9 | 446137.4 | 88.1 | 1512451 |
Blk wash | 94.5 | 38123.44 | 92.8 | 287335.4 | 91.9 | 476966.4 | 94.4 | 1620050 |
Blk wash | 98 | 39535.37 | 94.7 | 293453.2 | 93.7 | 486575.7 | 95.7 | 1643493 |
Blk wash | 97.7 | 39421.53 | 96 | 297426.6 | 94.3 | 489586.8 | 95.7 | 1642677 |
Blk wash | 99.4 | 40094.4 | 98.2 | 304289.1 | 96.8 | 502675.9 | 97.4 | 1672719 |
Blank | 105.7 | 42671.18 | 101.5 | 314334.9 | 99.9 | 518768.5 | 100.5 | 1725137 |
Blank | 103.2 | 41623.34 | 100.6 | 311511.1 | 99.9 | 518602.5 | 100 | 1716281 |
Blank | 103.3 | 41673.53 | 100.7 | 312029.7 | 100.1 | 519566.1 | 100 | 1716770 |
Blank | 105.9 | 42717.89 | 102.6 | 317754.3 | 102 | 529758.3 | 100.7 | 1728553 |
Blank | 93.2 | 37618.66 | 91.2 | 282346.5 | 91.1 | 472990.4 | 89.7 | 1540682 |
Blank | 106.4 | 42941.87 | 103.5 | 320496.1 | 102.7 | 533353.8 | 101.4 | 1741371 |
Blank | 107.1 | 43217.45 | 103.5 | 320692 | 101.7 | 527900 | 100.9 | 1732369 |
Blk wash | 96.3 | 38850.2 | 92.3 | 285886.3 | 92 | 477519.5 | 90.7 | 1556631 |
Blk wash | 107.5 | 43397.55 | 103.6 | 320962.5 | 102.4 | 531857.8 | 101.1 | 1734927 |
Sample | 150.1 | 60588.48 | 135.4 | 419334.9 | 127 | 659213.4 | 116.4 | 1998358 |
Sample | 162.5 | 65569.65 | 144 | 445913.1 | 133.8 | 694488.2 | 117.6 | 2019140 |
Sample | 167.2 | 67473.86 | 146.7 | 454503.4 | 135.8 | 704999.1 | 117.8 | 2022471 |
Blk wash | 174.5 | 70431.39 | 153.3 | 474972.8 | 143.5 | 744874.1 | 128.4 | 2203481 |
Blk wash | 170.6 | 68845.83 | 151.4 | 468973.6 | 142.2 | 738017.8 | 126.5 | 2172217 |
Blk wash | 167.6 | 67628.26 | 148.2 | 459080 | 138.5 | 719058.4 | 124.8 | 2142096 |
Blk wash | 153.5 | 61930.25 | 136.6 | 423009.7 | 127.1 | 660081.8 | 114.3 | 1962475 |
Blk wash | 172.6 | 69629.9 | 150.5 | 466288.3 | 139.9 | 726135.6 | 125.6 | 2156883 |
Blk wash | 175.1 | 70669.76 | 153.4 | 475255.6 | 141 | 732019.4 | 126 | 2162944 |
Blk wash | 179.4 | 72372.65 | 158.3 | 490308.8 | 145.8 | 756798.3 | 130.3 | 2236337 |
Blk wash | 184.1 | 74308.04 | 157 | 486186.2 | 145.1 | 753322.8 | 129.5 | 2222425 |
后面的洗针完全下不来。
盐酸利多卡因注射液也是类似,一旦上了sp就会出现内标的升高。奇怪的是如果熄火后再次开始分析批(比如中午吃饭),In 115以下,包括它自己,cps值又能回到初始状态。
我们尝试过降低基质浓度,10倍甚至100倍,但内标CPS值不会降低,拔掉内标管,能降低到几百,但一旦插上内标管,依然稳定在比较高的数值。
也问过仪器厂家(安捷伦)的应用,怀疑过碳增敏,使用异丙醇依然没什么改变。
也怀疑过样品本底含内标的同质量数,但即使有应该也会随着不进样而冲洗下来,并且所测的目标元素采集的就是内标质量数附近的,通过检测cps值,最高不超过1000,基本在500左右,甚至部分在100以下。这种本底即含有高含量内标的可能也极低。
实验室还做过一次能力验证,样品是茶叶,采用微波消解最终测试的结果也出现内标异常升高,采用0.25g消解后到25ml,稀释100倍方法。碳含量理论上应该不高。
目前还没解决这个问题,想找大家帮忙出出主意。谢谢