Usefulness of the evaporative light scattering detector for direct screening of biological fluids

This paper reports a fast, simple procedure for the direct screening of bio logical fluids by using a flow configuration coupled on-line to an evaporat ive light scattering detector with no chromatographic separation. The poten tial of this coupling was exemplified for paracetamol. The configuration ad opted permits selective retention of paracetamol and its metabolites from d ilute urine or serum samples on a LiChrolut((R))EN sorbent column located i n the loop of a high pressure injection valve. Retained paracetamol is elut ed with acetonitrile and driven directly to the evaporative light scatterin g detector. Some analytical features are: detection limit 0.3 mug ml(-1), q uantitation interval 1-100 mug ml(-1), repeatability, as RSD, 1.0%. The rel iability of the method was studied at three concentration levels of paracet amol spiked to urine or serum blanks (1, 2 and 4 times the detection limit) yielding 0% of false positives and negatives, thanks to the high precision of the method. Finally a comprehensive study of 50 real urine samples (par acetamol free) obtained from different individuals (healthy, drug addicts a nd patients from a hospital) provided 4% of false positives and 0% false ne gatives for the threshold limit established. (C) 2001 Elsevier Science B.V. All rights reserved.