تسجيل الدخول

تسجيل

Toxicological screening , HPLC screening using the systematic toxicological identification procedure

المؤلف:  Sue Jickells , Adam Negrusz (Editors)

المصدر:  Clarkes Analytical Forensic Toxicology

الجزء والصفحة:  229-230

2026-10-15

283

Toxicological screening

HPLC screening using the systematic toxicological identification procedure

The systematic toxicological identification procedure (STIP) system is based on a rapid and simple extraction method followed by isocratic reversed-phase HPLC with diode-array detection. A library of retention times and ultraviolet (UV) spectra is available for about 400 common drugs. A disadvantage of the system is that a large number of drugs elute between 1 and 3 min and this problem is exacerbated with substances devoid of a characteristic UV spectrum (e.g. maximum 210 nm). In such cases a second chromatographic analysis may be required. The technique is also less sensitive than GC screening methods. In this century liquid chromatography with triple quadrupole mass spectrometric detection (LC-MS/MS) has become increasingly introduced into the clinical laboratory. The quality, robust ness, applicability and sensitivity are increasing enormously, but instrument price is decreasing as a result of strong competition between growing numbers of companies.

The great sensitivity of LC-MS/MS makes it possible to precipitate proteins and extract the relevant drugs and their metabolites just by diluting the serum or plasma eight times with an acetonitrile/methanol mixture containing an internal standard. Run times are about 5–7 minutes on average. This method is still lacking a generally available MS library of toxic compounds. Nevertheless, is it quite easy to select a number of relevant drugs on the basis of their masses and collision masses. For instance, if tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs), cardiac drugs, anticonvulsants or anti-HIV drugs are suspected, the masses of the relevant drugs in one of these pharmacological groups are selected and within 10 minutes such a series of drugs can be excluded or determined. LC with single MS does not have this possibility owing to lack of sensitivity and selectivity. Although the price of one LC-MS/MS setup equals that of two LC-MS set ups, one LC-MS/MS has more to offer in TDM and clinical and forensic toxicology than three LC-MS set-ups. Over the next decade an increasing number of laboratories will exchange their HPLC equipment with DAD, ECD and fluorescence detectors for one or two LC-MS/ MS instruments.