Analysis of Plant Material and Biological Matrices

Current methods for tropane alkaloids analysis have been well covered in the literature. An excellent comprehensive review written by B. Drager [45] appeared in 2002, describing the analysis of tropane and related alkaloids in plant material. Sample preparation procedures were reviewed, as well as the analytical methods used for performing the separation and detection of tropane alkaloids, such as gas chromatography (GC), liquid chromatography (LC), and capillary electrophoresis (CE). Therefore, this chapter will not describe in detail these well-known analytical methods but discuss some recently developed applications for the analysis of tropane alkaloids in plant material and biological matrices. 

Analyses of tropane alkaloids are mainly carried out by GC and HPLC and to a lesser extent by CE. This review describes recent applications developed for the analysis of this class of compounds in plant materials and biological matrices. Of course, mass spectrometry is generally used as the detection technique because of its high sensitivity and selectivity, but other techniques such as UV, fluorescence, flame ionization detection, nuclear magnetic resonance, among others have also been investigated. Finally, desorption electrospray ionization mass spectrometry is reported as a new interesting detection technique for the rapid analysis of samples without any sample preparation. 

Ammoniacal nitrogen is usually determined by flow methods involving derivatization reactions for spectrophotometric determination. Berthelot (or indophenol blue) [99,115-119] and Nessler methods [120] are the two most important examples, both adopted for the quantification of ammonium ion in matrices as diverse as natural waters, wastewaters, atmospheric samples, food, soil extracts, plant material, and biological fluids. Measuring the fluorescence intensity produced by the reaction of the ammonium ion with OPA is another widespread method for the analysis of this ion [121-125]. 

Selected methods for the analysis of ethylbenzene in various matrices are given in Table 1. Ethylbenzene can be determined in biological material (blood, subcutaneous fat, plant foliage, fish samples) using head-space gas chromatography (GC), GC with mass spectrometry, and GC with flame ionization detection (WHO, 1996a). 

Matrix solid-phase dispersion (MSPD) is the extraction method of choice for the analysis of solid samples, such as plant material, foodstuffs or tissue samples [26]. This method has been developed especially for solid or viscous matrices. MSPD is preferable to other extraction techniques, because the solid or viscous sample can be directly mixed with the sorbent material of the stationary phase [27]. As the carotenoid stereoisomers stay bound in their biological matrix until the elution step, they are protected against isomerisation and oxidation [28]. The extraction scheme of MSPD is shown in Figure 5.2.1. 

Tropane alkaloids are an important class of natural products possessing different and interesting pharmacological activities. Hyoscyamine (atropine in the racemate form), scopolamine, and cocaine are the major representatives of this class. They are commonly found in plant materials, mainly in genera belonging to three families Solanaceae, Erythroxylaceae, and Convolvulaceae. The importance of these compounds requires that there are accurate analytical methods for their determination in plants and in biological matrices. This chapter describes the state-of-the-art of analytical procedures (extraction and analysis) for analyzing tropane alkaloids. 

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