Fast atom bombardment quantitative

Several other interface designs were introduced over this period, including continuous flow fast atom bombardment (CFFAB)" and the particle beam interface (PBI)," but it was not until the introduction of the API source that LC/MS applications really came to the forefront for quantitative analysis. Early work by Muck and Henion proved the utility of an atmospheric pressure interface using a tandem quadrupole mass spectrometer. 

Whereas the use of conventional fast atom bombardment (FAB) in the analysis of polymer/additive extracts has been reported (see Section 6.2.4), the need for a glycerol (or other polar) matrix might render FAB-MS analysis of a dissolved polymer/additive system rather unattractive (high chemical background, high level of matrix-, solvent- and polymer-related ions, complicated spectra). Yet, in selected cases the method has proved quite successful. Lay and Miller [53] have developed an alternative method to the use of sample extraction, cleanup, followed by GC in the quantitative analysis of PVC/DEHP with plasticiser levels as typically found in consumer products (ca. 30 %). The method relied on addition of the internal standard didecylphthalate (DDP) to a THF solution of the PVC sample with FAB-MS quantitation based on the relative signal levels of the [MH]+ ions of DEHP and DDP obtained from full-scan spectra, and on the use of a calibration curve (intensity ratio m/z 391/447 vs. mg DEHP/mg DDP). No FAB-matrix was added. No ions associated with the bulk of the PVC polymer were observed. It was... 

Simms etal. [8] discuss the quantitative determination of cationic surface active agents at the sub-ppb level in sewage sludges using fast atom bombardment mass spectrometry. 

Gaskell SJ, Brownsey BG, Brooks PW, Green BN. 1983. Fast atom bombardment mass spectrometry of steroid sulphates qualitative and quantitative analyses. Biomed Mass Spectrom 10 215-219. 

It is evident from the spectra that absolute ion abundances cannot be used for quantitation. However, the ion abundance ratio of the two compounds remained constant over the selected concentration range. Therefore, internal standards must be used for quantitation by SIMS. This has been found to be true for fast-atom bombardment mass spectrometry (FABMS), also [124]. 

Fast atom bombardment mass spectrometry has been utilized for the quantitative determination of ionic species, in glycerol/water solutions, which are produced by chemical and enzymic reactions. It is shown that reaction constants can be determined in this manner and that they can be accurately related to those determined by other methods used in the analysis of aqueous solutions. The reactions studied include proton dissociation constants for organic acids, an enzyme equilibrium constant, and enzyme rate constants using natural substrates. 

Fast atom bombardment mass spectrometry (FABMS) has become an important addition to the ionization techniques available to the analytical chemist in recent years. It has been particularly useful in a number of diverse applications which include molecular weight determinations at high mass, peptide and oligosaccharide sequencing, structural analysis of organic compounds, determination of salts and metal complexes, and the analysis of ionic species in aqueous solutions. This paper will focus on some aspects of the quantitative measurement of ionic species in solution. The reader is referred to a more comprehensive review for more details of some of the examples given here as well as other applications (1). 

Kusmierz, X X Sumrada, R. Desiderio, D. M. 1990. Fast atom bombardment mass spectrometric quantitative analysis of methionine-enkephalin in human pituitary tissues. Anal Chem., 62,2395-2400. 

Clay, K. L., Sterre, D. O., and Murphy, R. C. (1984) Quantitative analysis of platelet activating factor (AGEPC) by fast atom bombardment mass spectrometry, Bio-med. Mass Spectrum 11, 47-49. 

Combined liquid chromatography/mass spectrometry (LC/MS)can play an important role in both qualitative and quantitative bioanalysis. LC/MS can be performed with a number of interfaces. Three interfaces are presently available in our laboratories i.e., the thermospray interface (TSP), the moving-belt interface (MBI), and continuous-flow fast atom bombardment (CF-FAB). These interfaces are supplementary with respect to their applicability and the type of information that can be obtained. 

Off-Line Reaction Monitoring For slow enzyme reactions and long-lived intermediates, off-line reaction monitoring is more convenient. In these methods, the known amounts of an enzyme and a substrate are mixed together and incubated at physiological conditions. Aliquots are withdrawn at predetermined intervals, and the reaction is quenched immediately. The time course of the reaction can be monitored with mass spectrometric analysis immediately or later, at a more convenient time, by using either fast atom bombardment (FAB) [7], continuous-flow (CF)-FAB [7], matrix-assisted laser desorption/ionization (MALDI) [8], or electrospray ionization (ESI) [9-11]. Established quantitation procedures can be employed to monitor the concentration of the reactant or product (usually, the latter) (see Chapter 14). As an example, an appropriate internal standard that has no affinity for the enzyme can be added to the reaction mixture to improve... 

Hyphenated TLC techniques. TLC has been coupled with other instrumental techniques to aid in the detection, qualitative identification and, occasionally, quantitation of separated samples, and these include the coupling of TLC with high-pressure liquid chromatography (HPLC/TLC), with Fourier transform infra-red (TLC/FTIR), with mass spectrometry (TLC/ MS), with nuclear magnetic resonance (TLC/NMR) and with Raman spectroscopy (TLC/RS). These techniques have been extensively reviewed by Busch (1996) and by Somsen, Morden and Wilson (1995). The chemistry of oils and fats and their TLC separation has been so well established that they seldom necessitate the use of these coupling techniques for their identification, although these techniques have been used for phospholipid detection. Kushi and Handa (1985) have used TLC in combination with secondary ion mass spectrometry for the analysis of lipids. Fast atom bombardment (FAB) has been used to detect the molecular species of phosphatidylcholine on silica based on the molecular ion obtained by mass spectrometry (Busch et al, 1990). 

One of the major problems in analytical chemistry is the detection and identification of non-volatile compounds at low concentration levels. Mass spectrometry is widely used in the analysis of such compounds, providing an exact mass, and hence species identification. However, successful and unequivocal identification, and quantitative detection, relies on volatilization of the compound into the gas phase prior to injection into the analyser. This constimtes a major problem for thermally labile samples, as they rapidly decompose upon heating. In order to circumvent this difficulty, a wide range of techniques have been developed and applied to the analysis of nonvolatile species, including fast atom bombardment (FAB), field desorption (FD), laser desorption (LD), plasma desorption mass spectrometry (PDMS) and secondary-ion mass spectrometry (SIMS). Separating the steps of desorption and ionization can provide an important advantage, as it allows both processes to be... 

Grotjahn L, Taylor LCE. The use of signal averaging techniques for the quantitation and mass measurement of high molecular weight compounds using fast atom bombardment mass spectrometry. Org Mass Spectrom. 1985 20 146 52. 

Tetracycline antibiotics have been determined in bovine liver, kidney, and muscle, and in milk by solid-phase extraction followed by TLC7MS with FAB mass spectrometry (45,46). A reverse-phase C8 bonded phase silica TLC plate was used. Adjacent lanes of standards provided Rf values for the compounds of interest. This area of the chromatogram was cut into a trapezoidal shape, and additional solvent concentrated the sample in one end of the shape. That portion of the chromatogram was then placed on the FAB probe of a high-performance mass spectrometer. Then, the FAB support matrix (thioglycerol) was added to the plate. A detection limit of 0.1 microgram of sample per spot was reported for most of the tetracycline antibiotics. The trapezoidal slice from the TLC plate used to concentrate the sample for TLC/MS analysis was also used in an application of fast atom bombardment mass spectrometry to identify and quantitate the drug midazolam (a depressant and anaesthetic) in plasma extracts by Okamoto et al. (47). 

Sample preparation Condition a 3 mL 200 mg Bond Elut CIS SPE cartridge with two 3 mL portions of MeOH and two 3 mL portions of 5% acetic acid. Mix 500 p,L serum with 500 p.L 10% acetic acid, add to the SPE cartridge, wash with 3 mL water, elute with four 500 p,L portions of MeOHrwater 60 40. Evaporate the combined eluates to dr3mess under a stream of nitrogen, reconstitute the residue with 250 iL water, filter (0.22 p,m). Inject a 100 p,L aliquot onto column A and elute to waste with mobile phase A. After an unspecified time, backfiush the contents of column A onto column B using mobile phase B. Monitor the effluent from column B. (Sato,K. Kobayashi,K. Moore, C.M. Mizuno,Y. Katsumata,Y. Semi-quantitative analysis of cefaclor in human serum by capillary high performance liquid chromatography/fast atom bombardment mass spectrometry. Forensic Sci.Int. 1993, 59, 71-77.)... 

Beckner, C. F., and R. M. Caprioli Quantitative Aspects of Fast Atom Bombardment Mass Spectrometry. Biomed. Mass Spectrom. 11, 60 (1984). 

Gaskell, S. J., B. G. Brownsey, P. W. Brooks, and B. N. Green Fast Atom Bombardment Mass Spectrometry of Steroid Sulphates Qualitative and Quantitative Analyses. Biomed. Mass Spectrometry 10, 215 (1983). 

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