De Zan M M, Gil García M D, Culzoni M J, Siano R G, Goicoechea H C, Martínez Galera M
Laboratorio de Desarrollo Analítico y Quimiometría, Cátedra de Química Analítica I, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, C.C. 242, S3000ZAA Santa Fe, Argentina.
J Chromatogr A. 2008 Feb 1;1179(2):106-14. doi: 10.1016/j.chroma.2007.11.091. Epub 2007 Dec 4.
The effect of piecewise direct standardization (PDS) and baseline correction approaches was evaluated in the performance of multivariate curve resolution (MCR-ALS) algorithm for the resolution of three-way data sets from liquid chromatography with diode-array detection (LC-DAD). First, eight tetracyclines (tetracycline, oxytetracycline, chlorotetracycline, demeclocycline, methacycline, doxycycline, meclocycline and minocycline) were isolated from 250 mL effluent wastewater samples by solid-phase extraction (SPE) with Oasis MAX 500 mg/6 mL cartridges and then separated on an Aquasil C18 150 mm x 4.6mm (5 microm particle size) column by LC and detected by DAD. Previous experiments, carried out with Milli-Q water samples, showed a considerable loss of the most polar analytes (minocycline, oxitetracycline and tetracycline) due to breakthrough. PDS was applied to overcome this important drawback. Conversion of chromatograms obtained from standards prepared in solvent was performed obtaining a high correlation with those corresponding to the real situation (r2 = 0.98). Although the enrichment and clean-up steps were carefully optimized, the sample matrix caused a large baseline drift, and also additive interferences were present at the retention times of the analytes. These problems were solved with the baseline correction method proposed by Eilers. MCR-ALS was applied to the corrected and uncorrected three-way data sets to obtain spectral and chromatographic profiles of each tetracycline, as well as those corresponding to the co-eluting interferences. The complexity of the calibration model built from uncorrected data sets was higher, as expected, and the quality of the spectral and chromatographic profiles was worse.
在采用二极管阵列检测的液相色谱法（LC-DAD）对三元数据集进行分辨的多元曲线分辨（MCR-ALS）算法性能方面，评估了分段直接标准化（PDS）和基线校正方法的效果。首先，使用Oasis MAX 500 mg/6 mL柱通过固相萃取（SPE）从250 mL废水样品中分离出8种四环素（四环素、土霉素、金霉素、地美环素、甲烯土霉素、强力霉素、美他环素和米诺环素），然后在Aquasil C18 150 mm×4.6mm（5微米粒径）柱上通过LC进行分离，并通过DAD进行检测。先前使用超纯水样品进行的实验表明，由于穿透，最具极性的分析物（米诺环素、土霉素和四环素）有相当大的损失。应用PDS来克服这一重要缺点。对从溶剂中制备的标准品获得的色谱图进行转换，与实际情况对应的色谱图具有高度相关性（r2 = 0.98）。尽管仔细优化了富集和净化步骤，但样品基质仍导致较大的基线漂移，并且在分析物的保留时间处还存在加性干扰。通过Eilers提出的基线校正方法解决了这些问题。将MCR-ALS应用于校正和未校正的三元数据集，以获得每种四环素的光谱和色谱图，以及与共洗脱干扰物对应的图谱。正如预期的那样，从未校正数据集构建的校准模型的复杂性更高，光谱和色谱图的质量更差。
