Atmospheric pressure chemical ionization characterized

A number of analytical techniques such as FTIR spectroscopy,65-66 13C NMR,67,68 solid-state 13 C NMR,69 GPC or size exclusion chromatography (SEC),67-72 HPLC,73 mass spectrometric analysis,74 differential scanning calorimetry (DSC),67 75 76 and dynamic mechanical analysis (DMA)77 78 have been utilized to characterize resole syntheses and crosslinking reactions. Packed-column supercritical fluid chromatography with a negative-ion atmospheric pressure chemical ionization mass spectrometric detector has also been used to separate and characterize resoles resins.79 This section provides some examples of how these techniques are used in practical applications. 

W.E. Neff, W.C. Byrdwell, Characterization of model triacylglycerol (triolein, trilinolein and trilinolenin) autoxidation products via high performance liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry, Journal of Chromatography A, 818, 169 186 (1998). 

Negative atmospheric pressure chemical ionization (APC) low-energy collision activation mss spectrometry has also been employed for the characterization of flavonoids in extracts of fresh herbs. Besides the separation, quantitative determination and identification of flavonoids, the objective of the study was the comparison of the efficacy of the various detection systems in the analysis of flavonoids in herb extracts. Freeze-dried herbs (0.5g of chives, cress, dill, lovage, mint, oregano, parsley, rosemary, tarragon and thyme) were ground and extracted with 20 ml of 62.5 per cent aqueous methanol. After sedimentation the suspension was filtered and used for HPLC analyses. Separations were carried out in an... 

Maillard, M.-N., Giampaoli, P., and Cuvelier, M.-E., Atmospheric pressure chemical ionization (APCI) liquid chromatography-mass spectrometry characterization of natural antioxidants, Talanta, 43, 339, 1996. 

Justesen, U., Negative atmospheric pressure chemical ionization low-energy collision activation mass spectrometry for the characterization of flavonoids in extracts of fresh herbs, J. Chromatogr. A, 902, 369, 2000. 

Grayer, R.J. et al.. The application of atmospheric pressure chemical ionization liquid chromatography-mass spectrometry in the chemotaxonomic study of flavonoids characterization of flavonoids from Ocimum gratissimum var., Phytochem. Anal., 11, 257, 2000. 

A striking feature of the ILs is their low vapor pressure. This, on the other hand, is a factor hampering their investigation by MS. For example, a technique like electron impact (El) MS, based on thermal evaporation of the sample prior to ionization of the vaporized analyte by collision with an electron beam, has only rarely been applied for the analysis of this class of compounds. In contrast, nonthermal ionization methods, like fast atom bombardment (FAB), secondary ion mass spectrometry (SIMS), atmospheric pressure chemical ionization (APCI), ESI, and MALDI suit better for this purpose. Measurement on the atomic level after burning the sample in a hot plasma (up to 8000°C), as realized in inductively coupled plasma (ICP) MS, has up to now only rarely been applied in the field of IE (characterization of gold particles dissolved in IE [1]). This method will potentially attract more interest in the future, especially, when the coupling of this method with chromatographic separations becomes a routine method. 

Li, W. ., C. L. Chan, and H. W. Lueng. 2000. Liquid chromatography atmospheric pressure chemical ionization mass spectrometry as a tool for the characterization of anthraquinone derivative from Chinese herbal medicine. J. Pharm. Pharmacol. 52 723-729. 

The development of mass spectrometric ionization methods at atmospheric pressures (API), such as the atmospheric pressure chemical ionization (APCI)99 and the electrospray ionization mass spectrometry (ESI-MS)100 has made it possible to study liquid-phase solutions by mass spectrometry. Electrospray ionization mass spectrometry coupled to a micro-reactor was used to investigate radical cation chain reaction is solution101. The tris (p-bromophenyl)aminium hexachloro antimonate mediated [2 + 2] cycloaddition of trans-anethole to give l,2-bis(4-methoxyphenyl)-3,4-dimethylcyclobutane was investigated and the transient intermediates 9 + and 10 + were detected and characterized directly in the reacting solution. However, steady state conditions are necessary for the detection of reactive intermediates and therefore it is crucial that the reaction must not be complete at the moment of electrospray ionization to be able to detect the intermediates. 

Holcapek, M., Jandera, P., Zderadicka, P., and Hruba, L. 2003. Characterization of triacylglycerol and diacylglycerol composition of plant oils using high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. J. Chromatogr. 1010, 195-215. 

In recent years the rapid development of high-sensitivity analytical techniques such as mass spectrometry (MS) and liquid chromatography (LC) supported the investigation of the endocannabinoids as part of a complex lipid network. The identification of lipid components of the endocannabinoid system can be achieved in a single analytical step by state-of-the-art platforms such as tandem mass spectrometry (MS/MS), which provides the detailed structural information necessary for characterization of lipids and increases specificity in complex biological matrices. Furthermore, the implementation of ionization techniques such as electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) allow the coupling of LC to MS, and permits the separation and analysis of endocannabinoids with greater speed and accuracy. 

Schweiggert, U., Kammerer, R.D., Carle, R. and Schieber, A. (2005) Characterization of carotenoids and carotenoid esters in red pepper pods (Capsicum annuum L.) by high performance liquid chromatog-raphy/atmospheric pressure chemical ionization mass spectrometry. Rapid Communications in Mass Spectrometry 1 9, 261 7-2628. 

Nunez, A., Ashby, R. D., Foglia, T. A., and Solaiman, D. K. Y. 2001. Analysis and characterization of sophorolipids by liquid chromatography with atmospheric pressure chemical ionization. Chromatographia, 53, 673-677. 

Mass spectrometry (MS) is playing an increasingly visible role in the molecular characterization of combinatorial libraries, natural products, drug metabolism and pharmacokinetics, toxicology and forensic investigations, and proteomics. Toward this end, electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photo-ionization (APPI) have proven valuable for both qualitative and quantitative screening of small molecules (e.g., pharmaceutical products) [9-14]. 

Atmospheric pressure chemical ionization, like electrospray ionization, is a mass spectrometer ionization source in which ionization occurs not in a vacuum but at atmospheric pressure. In contrast to electrospray ionization, in which the ionization process occurs in solution phase, atmospheric pressure chemical ionization is a gas-phase ionization process whereby gas-phase molecules are isolated from the carrier solvent before ionization [6]. Because the ionization mechanisms of APCI and electrospray are fundamentally different (gas-phase and liquid-phase ionization, respectively) the two methods have the potential to provide complimentary analyte characterization. To generalize, electrospray ionization is more... 

Atmospheric pressure ionization (API) techniques are the most commonly used techniques in DM studies. Since the ionization occurs at the atmospheric pressure, API can be characterized as a soft ionization technique. There are three commonly used API sources [59] that can directly couple LC with MS electrospray ionization (ESI) [60], atmosphere pressure chemical ionization (APCI) [61-63], and atmospheric pressure photoionization (APPI) [64,65], The properties of the compound, such as its structure, polarity, and molecular weight, lead to the selection of one of these ionization techniques for sample analysis. 

Dyszel S.M. (1985) Characterization of green coffee beans by combined thermogravimetric analysis/atmospheric pressure chemical ionization mass spectrometry. Thermochimica Acta 87, 89-98. 

Mottram, H.R., Crossman, Z.M., and Evershed, R.P., Regiospecific characterization of the triacylglycerols in animal fats using high performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry, Analyst, 126, 1018-1024, 2001. 

Homogenized garlic was extracted by SF-CO2 and the major thiosulfinates were characterized with liquid chromatography/ atmospheric pressure chemical ionization mass spectroscopy (LC/APCI/MS) [59]. In addition to the thiosulfinates, small quantities of ajoene were also found in the SF extracts of garlic homogenates. The identified thiosulfinates are listed in Table (1). 

A high-performance liquid chromatographic/atmospheric pressure chemical ionization-mass spectrometric (HPLC/APCI-MS) method has been developed for the determination of the pesticide clofentezine (3,6-bis(2-chlorophenyl)-l,2,4.5-tetrazine) in plum-, strawberry-, and blackcurrant-based fruit drinks <1995RCM1441>. The structural characterization and the mass spectrometric behavior of pyridazinofurocoumarins, prepared by the inverse electron demand Diels-Alder reaction between furocoumarinones and 3,6-bis(methoxycarbonyl)-l,2,4,5-tetrazine, were studied under electron ionization conditions via sequential product ion fragmentation experiments <2004RCM564>. 

FIGURE12.5 IMS of a 0.2- jL stock TATP at 80°C (A) with 4.7-ppmv ammonia and (B) with 8.1-ppmv ammonia. (From Ewing Waltman and Atkinson, Characterization of triacetone triperoxide by ion mobility spectrometry and mass spectrometry following atmospheric pressure chemical ionization. Anal. Chem. 2011, 83,4838-4844. With permission.)... 

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