Fast atom bombardment quantification

While fast atom bombardment (FAB) [66] and TSI [25] built up the basis for a substance-specific analysis of the low-volatile surfactants within the late 1980s and early 1990s, these techniques nowadays have been replaced successfully by the API methods [22], ESI and APCI, and matrix assisted laser desorption ionisation (MALDI). In the analyses of anionic surfactants, the negative ionisation mode can be applied in FIA-MS and LC-MS providing a more selective determination for these types of compounds than other analytical approaches. Application of positive ionisation to anionics of ethoxylate type compounds led to the abstraction of the anionic moiety in the molecule while the alkyl or alkylaryl ethoxylate moiety is ionised in the form of AE or APEO ions. Identification of most anionic surfactants by MS-MS was observed to be more complicated than the identification of non-ionic surfactants. Product ion spectra often suffer from a reduced number of negative product ions and, in addition, product ions that are observed are less characteristic than positively generated product ions of non-ionics. The most important obstacle in the identification and quantification of surfactants and their metabolites, however, is the lack of commercially available standards. The problems with identification will be aggravated by an absence of universally applicable product ion libraries. 

HPLC with column switching and mass spectrometry was applied to the online determination and resolution of the enantiomers of donepezil HC1 in plasma [38]. This system employs two avidin columns and fast atom bombardment-mass spectrometry (FAB-MS). A plasma sample was injected directly into an avidin trapping column (10 mm x 4.0 mm i.d.). The plasma protein was washed out from the trapping column immediately while donepezil HC1 was retained. After the column-switching procedure, donepezil HC1 was separated enantioselectivity in an avidin analytical column. The separated donepezil HC1 enantiomers were specifically detected by FAB-MS without interference from metabolites of donepezil HC1 and plasma constituents. The limit of quantification for each enantiomer of donepezil HC1 in plasma was 1.0 ng/ml and the intra-and inter-assay RSDs for the method were less than 5.2%. The assay was validated for enantioselective pharmacokinetic studies in the dog. 

The closely allied topics of secondary neutral mass spectrometry (SNMS), fast atom bombardment (FAB), and laser ablation SIMS are important, but are beyond the scope of this chapter. SNMS is a technique in which neutral atoms or molecules, sputtered by an ion beam, are ionized in an effort to improve sensitivity and to decouple ion formation from matrix chemical properties, making quantification easier. This ionization is commonly effected by electron beams or lasers. FAB uses a neutral atom beam to create ions on the surface. It is often useful for insulator analysis. Laser ablation creates ions in either resonant or nonresonant modes and can be quite sensitive and complex. 

Manz I, Dietrich I, Przybylski M, et al. 1985. Identification and quantification of metabolite conjugates of activated cyclophosphamide and ifosfamide with MESNA in urine by ion-pair extraction and fast atom bombardment mass spectrometry. Biomed Mass Spectrom 12 545-553. 

Selected ion monitoring (SIM) and fast atom bombardment (FAB) techniques of mass spectrometry have been used for detection and quantification of different crystalline forms of triamterene. The use of electron impact mass spectrometry in the analysis of diuretic agents has been described. 

Buyn, J., Henderson, J.P., and Heinecke, J.W. (2003) Identification and quantification of mutagenic halogenated cytosines by gas chromatography, fast atom bombardment, and electrospray ionization tandem mass spectrometry. Anal. Biochem., 317, 201-209. 

A. A. Staempfli, I. Blank, R. Fumeaux, and L. B. Fay, Study on the decomposition of the Amadori compound iV-(l-deoxy-D-fiuctos-l-yl)-glycine in model systems Quantification by fast atom bombardment tandem mass spectrometry,... 

Lehmann, W.D., Kessler, M., and Konig, W.A., Investigations on Basic Aspects of Fast Atom Bombardment Mass Spectrometry Matrix Effects, Sample Effects, Sensitivity and Quantification, Biomed. Mass Spectrom., 11, 217, 1984. 

Several methods have been developed specifically for naphthenic acids, a class which includes the surface active carboxylate surfactants. Naphthenic acids are present as a complex mixture of a number of homologues with only a small range in molar mass (166-450 mol/g), little change in solubility character, and have been difficult to assay using conventional analytical methods. Methods such as negative ion-mode mass spectrometry using fast atom bombardment (FABMS), have been successfully applied to the analysis of naphthenic acid mixtures [93, 94], Other promising techniques include fluoride ion chemical ionization mass spectrometry (FI-MS) [95], and electrospray ionization mass spectrometry (ESIMS), which may allow for the quantification of the various naphthenic acid fractions [96]. 

Fast atom bombardment (FAB) mass spectrometry has been widely used for the analysis of high-MW and/or thermally labile compounds [204]. As with all ionisation techniques that use a direct insertion probe, accurate and precise quantification is difficult to achieve here. With FAB and FIB/LSIMS the sample signal often dies away when the matrix, rather than the sample, is consumed therefore, one cannot be sure that the ion signal obtained represents the entire sample. Quantification in FD or FAB-MS has been described as technically difficult, but possible when internal standards are used [205]. Lat-timer et al. [206] compared FAB and FD as ionisation techniques for mass spectrometric analysis of... 

Fast atom bombardment. FAB has been demonstrated as a means of determining LAS and ABS in environmental samples. Good abundance of the molecular anions is seen. Calibration with a single internal standard yields inaccurate results for determination of homolog distribution of LAS because of dilferences in surface activity, and hence FAB ionization, between homologs. Three internal standards of various alkyl chain lengths are required for accurate quantification (12). When subjected to CAD, the molecular ions produce the characteristic daughter ions mentioned above, at mh 183 for LAS and 197 for ABS (10,13). 

---