Górecki Tadeusz, Lynen Frederic, Szucs Roman, Sandra Pat
Pfizer Analytical Research Centre, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent, Belgium.
Anal Chem. 2006 May 1;78(9):3186-92. doi: 10.1021/ac060078j.
A new, empirical approach is introduced to correct for the varying response of aerosol-based detectors with the varying composition of the mobile phase during gradient elution in HPLC. A Corona charged aerosol detector was used in the experiments. The detector is characterized by a nearly universal response at a given, constant mobile-phase composition for sufficiently nonvolatile analytes. A second pump was used to deliver an exactly inverse gradient compared to the analytical HPLC system, and both flows were mixed in a tee piece before introduction to the Corona detector. The approach proposed made it possible to extend the universal response from isocratic to gradient elution conditions in HPLC, vastly improving the usefulness of this detection technique. The constant response of the detector obtained in this way was first demonstrated in flow injection analysis. Very similar calibration curves were obtained for six sulfonamide drugs after mobile-phase compensation. The approach was also applied to gradient elution with excellent results. The data were characterized by good precision ranging from 4% RSD at 10 mg/L to 1.6% RSD at 780 mg/L. The average limit of detection with a 2-microL injection was 0.5 mg/L, corresponding to 1 ng injected on the column. The approach proposed allows quantification of unknown compounds, e.g., in pharmaceutical mixtures. Measurement of analytes at a relative concentration of 0.05% versus the main component is demonstrated.
引入了一种新的经验方法，用于校正高效液相色谱（HPLC）梯度洗脱过程中基于气溶胶的检测器对流动相组成变化的不同响应。实验中使用了电晕充电气溶胶检测器。对于足够非挥发性的分析物，该检测器在给定的恒定流动相组成下具有近乎通用的响应特性。使用第二个泵输送与分析型HPLC系统完全相反的梯度，并且两种流动在三通管中混合后再引入电晕检测器。所提出的方法使得将通用响应从等度洗脱条件扩展到HPLC的梯度洗脱条件成为可能，极大地提高了这种检测技术的实用性。通过这种方式获得的检测器的恒定响应首先在流动注射分析中得到证明。对六种磺胺类药物进行流动相补偿后，获得了非常相似的校准曲线。该方法也应用于梯度洗脱，结果良好。数据的精密度良好，相对标准偏差（RSD）在10 mg/L时为4%，在780 mg/L时为1.6%。进样量为2 μL时的平均检测限为0.5 mg/L，相当于在柱上注入1 ng。所提出的方法能够对未知化合物进行定量，例如在药物混合物中。展示了相对于主要成分以0.05%的相对浓度测量分析物的情况。
