COMPARISON OF NEW SOLID-PHASE EXTRACTION METHODS FOR CHROMATOGRAPHIC IDENTIFICATION OF DRUGS IN CLINICAL TOXICOLOGICAL ANALYSIS

Objectives: Newly presented solid-phase extraction methods (Solid Phas e Disc Extraction, SPEC(R)-Plus, Multi-Modal, and Solid Phase Micro Ex traction, SPME(R) have been checked with respect to their applicabilit y to clinical toxicological analysis. In comparison with conventional liquid/liquid-extraction and a common mixed-phase column technology, t heir use in general screening and selective extraction methodology is discussed. Design and Methods: Recovery studies were performed with ur ine-based samples including model substances, as well as drugs and met abolites from native urine samples. Chromatographic performance of the resulting extracts is presented in some examples. Results: Liquid/liq uid extraction, common mixed-phase column technique and the new SPEC(R )-Plus, Multi-Modal disc extraction method gave the best recoveries wi th respect to broad-spectrum general screening. The purity of the conc entrates was somewhat different, however. Solid-phase C18 and Solid-Ph ase Micro Extraction methodologies are better suited for selective dru g extraction. In SPEC(R) Disc or SME(R) extraction, the use of solvent s is greatly reduced or omitted. Recovery of some volatile substances is enhanced. SPEC(R) discs can be inserted directly into TLG chromatog raphic plates, SPME(R)(R) fibers into GC injection ports. Conclusions: The new solid-phase extraction technologies offer advantages in diffe rent respects: The mixed-phase disc extraction SPEC(R)1 Plus(TM) AR/MP 3 Multi-Modal delivers promising results with respect to broad-spectru m general screening. Solvent consumption is low, throughput times are short, the extracts are clean, and recovery rates are good, comparable , or even higher than with common mixed-phase column techniques. The n ew SPME(R) extraction method shows benefits in dedicated, selective ex traction procedures (e.g., analysis of volatile substances such as amp hetamines). Sampling is solvent-free, the handling is easy, and the yi elds of extraction are good, but only for selected substances. Broad-s pectrum general screening still remains problematic with this techniqu e. Further examinations have to be carried out including a larger numb er of drugs of toxicological relevance. Headspace sampling by SPME(R) offers a good alternative to conventional mechanized sampling in the a nalysis of volatile substances in biological samples, omitting the nee d for expensive instrumentation.