The study focused on comparison of on-line sample concentration techniques, i.e. sample stacking modes, applied in capillary electrophoresis in order to improve the detection of components of stamp pad inks so that destruction of analysed document could be minimized. In particular, such techniques were taken into consideration as: normal stacking mode/field amplified sample stacking (NSM/FASS), high-salt concentration, sweeping, electrokinetic injection + FASS, and field enhanced sample injection (FESI). At first, two mixtures of 4 red dyes and 4 violet/blue dyes were examined. As a result, in case of red dyes two environments: ACN/1 mg mL⁻¹ aqueous NaCl (95:5, v/v) and 10-fold water dilution of BGE preceded by water plug (6 s, 0.7 psi) injection, were chosen as the most promising for further examination. Regarding the blue/violet dyes, the 100-fold water dilution of BGE was selected as giving the best increase of height of peaks. Ultimately, nine stamp pad inks in three colours (red, blue and violet) produced by different manufacturers were examined under the optimal conditions. Only 5 dots cut-out from inked paper were sampled. Almost all examined samples were possible to be differentiated basing on the obtained electrophoretic profiles. In conclusion, the developed sample stacking mode of MECC–based method was found as a useful tool in the differentiation of stamp pad inks for the purposes of forensic questioned document analysis.

该研究的重点是比较毛细管电泳中使用的在线样品浓缩技术（即样品堆积模式），以改善对印台油墨成分的检测，从而最大程度地减少对分析文档的破坏。特别地，将此类技术考虑为：正常堆叠模式/场放大样品堆叠（NSM / FASS），高盐浓度，吹扫，电动进样+ FASS和场增强样品进样（FESI）。首先，检查了4种红色染料和4种紫色/蓝色染料的两种混合物。结果，在红色染料的情况下，两种环境：ACN / 1 mg mL ^-1选择NaCl水溶液（95：5，v / v）和BGE的10倍水稀释，再注入水塞（6 s，0.7 psi）作为最有希望的进一步检查方法。对于蓝色/紫色染料，选择BGE的100倍水稀释液可以最大程度地增加峰高。最终，在最佳条件下检查了由不同制造商生产的三种颜色（红色，蓝色和紫色）​​的九种印台油墨。仅从墨纸上切下的5个点被采样。几乎所有被检查的样品都可以根据获得的电泳图谱进行区分。总之，已发现基于MECC的方法的已开发样品堆叠模式可作为区分法印章油墨的有用工具，用于法证可疑文件分析。