PARENT SESSION

1A - Environmental Analytical Methods
Hall 8
8:30 AM - 12:30 PM, Monday, 28 April 2003
Chair: Schäffer, A.¹, ¹
Co-chair: Bester, K.², ²

(MO8/1) Derivatisation in LC-MSⁿ and GC-MSⁿ: A necessary approach to meet the low detection limits in environmental analysis.

Poelmans, Sofie¹, De Wasch, Katia¹, Noppe, Herlinde¹, Verslycke, Tim², Ghekiere, An², Van Hoof, Nathalie¹, De Brabander, Hubert¹, Janssen, Colin², ¹ Laboratory of Chemical Analysis - Ghent University, B-9820 Merelbeke, Belgium² Laboratory of Environmental Toxicology and Aquatic Ecology - Ghent University, B-9000 Ghent, Belgium

ABSTRACT- The chromatographic techniques, liquid chromatography (LC) and gas chromatography (GC) combined with a multiple stage mass spectrometer (MSⁿ) as detector, nowadays, are the techniques of choice for the analysis of compounds in the low concentration range. One of the great advantages of LC-MSⁿ is that there is no need for derivatisation to detect a whole variety of compounds. Although, even lower detection limits can be obtained after derivatisation for some compounds. On the contrary, detection with GC-MSⁿ invariably requires volatisation of compounds using a derivatisation. This derivatisation is often a time-consuming step, but can be essential if low detection limits are required. Both the steroid and ecdysteroid metabolism of the estuarine invertebrate Neomysis integer (Crustacea, Mysidacea) are being studied by our research groups. Alterations in these endocrine-regulated processes may be used as a biomarker for the effects of endocrine disruptors in invertebrates (De Wasch et al., Anal. Chim. Acta 473, pp. 59-69; Verslycke et al., Gen. Comp. Endocrinol. 126, pp. 190-199). In this perspective, analysis of endocrine disruptors in different environmental matrices (water, sediment, suspended solids, biological matrices,...), coupled with the detection of quantitative effects on (ecdy)steroid metabolism, requires very low detection limits. Since ionisation in LC-MSⁿ is often suppressed by a variety of matrix interferences and TMS-derivatives in GC-MSⁿ provide limited sensitivity depending on the matrix, different derivatisations for both detection methods were tested for a number of hormones and ecdysteroids. Pentafluoropropionic anhydride (PFPA), heptafluorobutyric anhydride (HFBA) and pentafluorobenzylbromide (PFBB) are some of the derivatisation reagents that were tested. Electron impact and chemical ionisation, in positive and negative ionisation mode, for GC-MSⁿ, electrospray and atmospheric pressure chemical ionisation for LC-MSⁿ, will be compared for the different derivatisation methods.

Key words: environmental analysis, derivatisation, endocrine disruption, GC-MSⁿ and LC-MSⁿ