Effect of PDS, baseline correction and mean centering as signal pretreatments in the resolution of eight tetracyclines by application of MCR-ALS to HPLC-DAD data rrom effluent wastewater samples

GIL GARCÍA, MARÍA; CULZONI MARÍA JULIA; DE ZAN,; SANTIAGO VALVERDE, ROSARIO; GABRIEL SIANO; MARTINEZ GALERA, MARIA; GOICOECHEA, HÉCTOR C

Pollensa, España

Congreso; IX International Symposium on Analytical Methodology in The Environmental Field; 2007

The effect of Piecewise Direct Standardization (PDS), Baseline Correction and Mean Centering approaches was evaluated in the performance of Multivariate Curve Resolution (MCR-ALS) for the resolution of three-way data sets from liquid chromatography with diode-array detection (LC-DAD). Eight tetracyclines (tetracycline, oxytetracycline, chlorotetracycline, demeclocycline, methacycline, doxycycline, meclocycline and minocycline) were firstly 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 × 4.6 mm (5 mm particle size) column and detected by LC-DAD. Previous experiments, carried out with Milli-Q water samples, showed considerable losses of the most polar analytes (minocycline, oxitetracycline and tetracycline) due to breaktrough. PDS was applied to overcome this important drawback. Conversion of standard chromatograms obtained from standards prepared in solvent was performed obtaining a high correlation with those corresponding to real situation (r2 = 0.98). 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 and Mean Centering. The number of interferences obtained by MCR-ALS from uncorrected data sets was higher, as expected, and the quality of the spectral and chromatographic profiles was dramatically worse. The authors are grateful to the AECI (Project A/4932/06) for financial support