Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, Universitätsstrasse 31a, 93040 Regensburg, Germany.
Anal Bioanal Chem. 2011 Sep;401(5):1669-76. doi: 10.1007/s00216-011-5233-7. Epub 2011 Jul 15.
Two tubular capacitively coupled contactless conductivity detection (C(4)D) cells with different geometric dimensions were evaluated with regard to their main analytical characteristics under non-separation and separation conditions in conjunction with liquid chromatography. A comparison of the performance of the tubular cells to a previously tested thin-layer detection cell was drawn. Additionally, using a theoretical model the experimental results were compared with sets of calculated values and partially enabled to model the complex behavior of C(4)D detection in combination with high-performance liquid chromatography (HPLC). While cell 1 is characterized by a geometric cell volume of 0.6 μL, a wall thickness of 675 μm, and an inner diameter of 125 μm, the respective values for cell 2 are 2.3 μL, 200 μm, and 250 μm. The main analytical parameters were evaluated using a potassium chloride (KCl) solution. The limits of detection were 0.4 μM KCl (5.7 × 10(-6) S m(-1)) for cell 1 and 0.2 μM KCl (3.2 × 10(-6) S m(-1)) for cell 2, which compares well to the previously found 0.2 μM for the thin-layer cell. A pair of linear ranges was found for both cells in a concentration interval ranging from 1 × 10(-6) to 1 × 10(-4) M (corresponding to 1.5 × 10(-5) to 1.5 × 10(-3) S m(-1)) KCl, respectively. Furthermore, the detector cells were applied to the HPLC separation of a model compound system consisting of benzoic acid, lactic acid, octanesulphonic acid, and sodium capronate. Separation of the compounds was achieved with a Biospher PSI 100 C18 column using 60% aqueous acetonitrile mobile phase. Calibration curves for the examined model system were well correlated (r² > 0.997), and it was found that under separation conditions the arrangement with the lower cell volume (cell 1) yields higher sensitivity and respectively lower limits of detection for all model compounds. Compared with the thin-layer cell, the tubular cells show better overall performance in regard to the determined analytical characteristics.
两种管状电容耦合非接触电导检测（C(4)D）池具有不同的几何尺寸，在非分离和分离条件下与液相色谱联用，对其主要分析特性进行了评价。将管状池的性能与之前测试过的薄层检测池进行了比较。此外，使用理论模型将实验结果与一系列计算值进行了比较，并部分实现了结合高效液相色谱（HPLC）对 C(4)D 检测的复杂行为进行建模。池 1 的几何池体积为 0.6 μL，壁厚为 675 μm，内径为 125 μm，而池 2 的相应值分别为 2.3 μL、200 μm 和 250 μm。使用氯化钾（KCl）溶液评估主要分析参数。池 1 的检测限为 0.4 μM KCl（5.7 × 10(-6) S m(-1))，池 2 的检测限为 0.2 μM KCl（3.2 × 10(-6) S m(-1))，与之前发现的薄层池的 0.2 μM 相比，这一结果相当不错。两种池都在 1 × 10(-6) 到 1 × 10(-4) M（分别对应于 1.5 × 10(-5) 到 1.5 × 10(-3) S m(-1)) KCl 的浓度范围内找到了一对线性范围。此外，该检测池还应用于由苯甲酸、乳酸、辛烷磺酸和己酸钠组成的模型化合物体系的 HPLC 分离。使用 Biospher PSI 100 C18 柱，在 60%水乙腈流动相中实现了化合物的分离。所研究的模型体系的校准曲线相关性良好（r² > 0.997），并且发现，在分离条件下，具有较低池体积（池 1）的布置可提高所有模型化合物的灵敏度，并分别降低检测限。与薄层池相比，管状池在确定的分析特性方面具有更好的整体性能。
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