Author/Editor		Kožar-Logar, Jasmina; Franko, Mladen
Title		The effects of eluent's optothermal parameters on TLS detection in gradient HPLC
Type		članek
Source		Rev Sci Instrum
Vol. and No.		Letnik 74, št. 1
Publication year		2003
Volume		str. 300-2
Language		eng
Abstract		The effcts of changing solvent composition on the limits of detection (LOD) of thermal lens spectroscopy (TLS) detection in gradient elution HPLC have been studied from the perspective of solvent's thermooptical properties. The refractive index and the temperature dependence of refractive index were measured and are reported for the first time for the methanol-acetone and methanol-ammonium acetate solutions used in this work, and some other methanol based chromatographic eluents. The TLS signal noise during a gradient HPLC protocol is increasing and its value reaches the maximum with a considerable time delay (up to 3 min) compared to the end point of the gradient protocol. The length of the chromatographic column was found to be an important parameter in reduction of signal noise resulting from incomplete solvent mixing. For some carotenoids the LOD values on the order of 50-100 pg/mL can be obtained on a 25 cm column with solvents that yield an increase in TLS enhancement factor up to 1.6 times during the gradient HPLC analysis.
Descriptors		CHROMATOGRAPHY, HIGH PRESSURE LIQUID XANTHOPHYLL PHYTOPLANKTON CAROTENOIDS REFRACTOMETRY