Fresenius J Anal Chem (1996) 356: 80-83 © Springer-Verlag 1996 ORIGINAL PAPER Jacek Czerwinski • Bogdan Zygmunt Jacek Namiesnik Head-space solid phase microextraction for the GC-MS analysis of terpenoids in herb based formulations Received: 27 February 1995/Revised: 25 October 1995/Accepted: 3 November 1995 Abstract Head-Space Solid Phase Microextraction (HS-SPME) has been employed for sampling of volatile components and their volatile decomposition products occurring in herbal medicines and herb extracts with subsequent injection into a gas chromatographic column. The identification and quantification was performed by coupled gas chromatography — mass spectrometry (GC-MS) with classical splitless injection, electron impact ionization and a quadrupole mass ana- lyzer. As fast and inexpensive technique for the isola- tion of organic analytes HS-SPME with GC-MS can be successfully employed for the quality control of herbal medicines and other formulations containing herb extracts. Analytical results with satisfying accu- racy and precision are given. i Introduction To determine selected analytes at lower and lower levels in a variety of samples (gases, liquids, solids) of increasingly complex matrices [1], techniques, like: Liquid—Liquid Extraction (LLE), Solid Phase Extrac- tion (SPE), Gas Extraction (Static Head Space — HS, Purge & Trap — P&T, Closed Loop Stripping Analysis — CLSA, Thin Layer Head Space — TLHS) and Super- critical Fluid Extraction (SFE) have been employed widely. The advantages and limitations of these tech- niques are dealt with in detail in reviews [2, 3]. The necessity to use solvents (extraction medium in LLE, elution medium in SPE) is a self-evident disadvantage of some of the above techniques. The fact that solvents and gases used for purging and for thermal desorption must be of very high purity is an additional drawback. J. Czerwinski • B. Zygmunt - J. Namiesnik (® ) Department of Analytical Chemistry, Faculty of Chemistry, Technical University of Gdansk (TUG), 11/12 Narutowicza St, 80-952 Gdansk, Poland A new interesting and promising approach, named, Solid-Phase Microextraction, was developed by Pawliszyn. Although quite new, it has already experi- enced a number of applications reviewed in 1994 [4]. They include determinations of various classes of analytes in solid, liquid and gaseous samples of differ- ent composition and matrix complexity (Table 1). In the case of liquid samples, the technique can be used in two different ways : by plunging the extraction fiber directly into a sample, or by placing it in the head-space being at equilibrium with a sample. Profound mathematical description of both ap- proaches has already been given by Pawliszyn et al. in a number of papers [5, 9, 11, 12, 13]. The former approach is experimentally simpler and is applicable to a wider range of analytes while the latter (Head-Space Solid Phase Microextraction) is lim- ited to volatile compounds but in a wide variety of sample matrices. The sensitivities of both techniques are similar for typical analytes of medium volatility. However, HS-SPME has a number of advantages over direct SPME. In general, matrices such as herbal medicines and other herb based formulations are rather complex what makes their analysis very difficult. Due to its character- istics, HS-SPME should prove very useful for the deter- mination of volatile organic compounds in such samples. A procedure to determine R- pinene, (3-myr- cene, limonene and menthol in herbal medicines was developed using HS-SPME for sampling and injection and GC-MS for identification and quantification. 2 Experimental 2.1 Materials and standard solutions. Common herb pharmaceutical formulations subjected to the analysis are as follows: — stomach drops (Herbapol, Krakow, Poland) containing T -ra V al- erianae, T-ra Amara, T-ra Menthae and T-ra Hyperici