Riaz Asif, Kim Bojeong, Chung Doo Soo
School of Chemistry, Seoul National University, Seoul 151-747, Korea.
Electrophoresis. 2003 Aug;24(16):2788-95. doi: 10.1002/elps.200305537.
Trace metal ions in highly saline samples such as urine were determined with capillary electrophoresis (CE) without desalting or off-line preconcentration. By mixing with a dye, 4-(2-pyridylazo) resorcinol (PAR), the metal ions were converted into anionic complexes having strong absorbance near 500 nm. A large volume of the metal-PAR complex sample solution injected into a coated capillary was stacked isotachophoretically and separated under a reverse potential. The salt anion (chloride) and PAR in the sample matrix acted as the leading and terminating electrolytes, respectively. In a sample containing a 250 mM NaCl matrix, more than 400-fold enhancement in the absorbance detector response was realized compared to the normal CE injection mode. Combination of the dye complexation and isotachophoretic stacking provided excellent detection limits (S/N = 3) for three trace metal ions in the low ppb range (Fe(2+), 0.7 ppb, Ni(2+), 0.4 ppb; Zn(2+), 1.2 ppb) with absorbance detection. The migration time reproducibility was excellent (relative standard deviations: standard samples < 1%, urine samples approximately 1%). The proposed method is convenient and fast, and the sample analysis can be completed within 20 min.
采用毛细管电泳（CE）法，无需脱盐或离线预富集，即可测定高盐样品（如尿液）中的痕量金属离子。通过与染料4-(2-吡啶偶氮)间苯二酚（PAR）混合，金属离子转化为在500 nm附近具有强吸光度的阴离子络合物。将大量金属-PAR络合物样品溶液注入涂覆毛细管中，通过等速电泳堆积，并在反向电位下分离。样品基质中的盐阴离子（氯离子）和PAR分别作为前导电解质和终止电解质。在含有250 mM NaCl基质的样品中，与正常CE进样模式相比，吸光度检测器响应提高了400多倍。染料络合和等速电泳堆积相结合，采用吸光度检测法，对低ppb范围内的三种痕量金属离子（Fe(2+)，0.7 ppb；Ni(2+)，0.4 ppb；Zn(2+)，1.2 ppb）提供了出色的检测限（S/N = 3）。迁移时间重现性极佳（相对标准偏差：标准样品<1%，尿液样品约1%）。该方法简便快速，样品分析可在20分钟内完成。
