Electrospray ionisation mass spectrometr

Taylor, M.R. and Teale, P., Gradient capillary electrochromatography of drug mixtures with UV and electrospray ionisation mass spectrometric detection, /. Chromatogr. A, 768, 89, 1997. 

J. Wollgast, L. Pallaroni, M.-E. Agazzi and E. Anklam, Analysis of procyanidins in chocolate by reversed-phase high-performance liquid chromatography with electrospray ionisation mass spectrometric and tandem mass spectrometric detection. J. Chromatogr.A 926 (2001) 211-220. 

Ryan, D. et al.. Liquid chromatography with electrospray ionisation mass spectrometric detection of phenolic compounds from Olea europaea, J. Chromatogr. A, 855, 529, 1999. 

Kotrebai, M., Birringgr, M., Tyson, J.F., Block, E. and Uden, P.C. (1999) Identification of the principal selenium compounds in selenium-enriched natural sample extracts by ion-pair liquid chromatography with inductively coupled plasma - and electrospray ionisation-mass spectrometric detection. Anal. Comm., 36, 249-252. 

McClean S, O Kane EJ, Smyth WF (2000) Electrospray ionisation-mass spectrometric characterisation of selected anti-psychotic drugs and their detection and determination in human hair samples by liquid chromatography-tandem mass spectrometry. J Chromatogr B Biomed Sci Appl 740(2) 141—157... 

M. Kotrebai, J. F. Tyson, E. Block, P. C. Uden, High performance liquid chromatography of selenium compounds utilising perfluorinated carboxylic acid ion pairing agents and inductively coupled plasma and electrospray ionisation mass spectrometric detection, J. Chromatogr. A, 866 (2000), 51-63. 

The electrospray ionisation mass spectrometric analyses were performed using a Finnigan LCQ ion trap mass spectrometer. The samples were dissolved in methanol or chloroform methanol system (10 1 v/v) and such solutions were introduced to the ESI source by continuous infosion by means of the instrument syringe pmnp with the rate of 3 iL/min. The ESI source was operated at 4.25 kV and the capillary heater was set to 200°C. For ESI-MS" experiments mass selected mono-isotopic parent ions were isolated in the trap and collisionally activated with 33% ejection RF-amplitude at standard He pressure. The experiments were performed in the positive and negative-ion mode. 

Sweetman, G. Trinei, M., Modha, J. et al. (1996) Electrospray ionisation mass spectrometric analysis of phospholipids of Escherichia coli. Mol. Microbiol., 20(1), 233-4. 

Justesen U, Arrigoni E. Electrospray ionisation mass spectrometric study of degradation products of quercetin, quercetin-3-glucoside and quercetin-3-rhamno-... 

For off-bead analysis, coupling between chromatographic separation and mass spectrometric detection has proven especially powerful. The combination between high performance liquid chromatography (HPLC) and electrospray ionisation mass spectrometry has the advantage that purity of product mixtures can be coupled on-line with the product identification. 

Rosenberg, E. The potential of organic (electrospray- and atmospheric pressure chemical ionisation) mass spectrometric techniques coupled to liquid-phase separation for speciation analysis. J Chromatogr A 2003, 1000, 841-889. 

Although introduction of FAB was a milestone in the development of mass-spectrometric ionisation techniques solving many biochemical-related problems, and was and still is a popular technique to use, it appears to be declining since the advent of electrospray. 

Owing to the anionic character of LAS, an electrospray ionisation (ESI) interface operated in negative ion mode is particularly attractive for the mass spectrometric detection of this surfactant type. Consequently, a great part of the atmospheric pressure ionisation-mass spectrometry (API-MS) work on LAS is devoted to the application of (— )-ESI-MS. 

Zambodin CG, Losito II, Palmisano E (2000) Liquid chromatography/electrospray ionisation sequential mass spectrometric identification of the main chlortoluron by-products during water disinfection using chlorine. Rapid Commun Mass Spectrom 14 824-828... 

Undoubtedly, mass spectrometric detection has a substantial role to play in condensed-phase chromatographic analyses of toxic impurities. As in GC/MS, it can be highly sensitive, although this is probably more analyte-specific than in GC/MS. Selectivity can be gained by SIM on single quadrupoles or, if necessary, SRM on MS/MS instruments. What must be considered is the appropriate ionisation mode to be used in LC/MS. Most modern instruments use atmospheric pressure ionisation sources, including electrospray ionisation (ESI), atmospheric pressure chemical ionisation (APCI) and more recently atmospheric pressure photoionisation (APPI). 

Cooper, J.J. and Marshall, A.G., Electrospray ionisation Fourier transform mass spectrometric analysis of wine. J. Agric. Food Chem. 49, 5710, 2001. 

The only mass spectrometric methods available during the era of the first cascade synthesis in 1978 [30] were electron impact (El) and field desorption (FD) mass spectrometry [31]. Fast atom bombardment (FAB) mass spectrometry is limited to fairly low mass ranges and not very suitable for compounds of low polarity. It was not until the development of new and gentle ionisation methods such as MALDI (matrix-assisted laser desorption ionization) [32] and ESI (electrospray ionization) [33] that the conditions were fulfilled for the start of intense research in the field of dendrimer chemistry. The following section will present the special features of these mass-spectrometric methods and their importance in dendrimer analysis. 

Electrospray ionisation (ESI) Electrospray ionisation is a method in which the analyte is sprayed at atmospheric pressure into an interface to the vacuum of the mass spectrometric ion source [28]. The sample solution is sprayed across a high potential difference (1 4 kV) from a needle tip into an orifice of the mass spectrometer. 

The introduction of liquid samples into the mass spectrometer has proved especially difficult. However, the advent of electrospray ionisation (ESI) and atmospheric pressure chemical ionisation (APCI) have overcome this problem and revolutionized the interfacing of HPLC with mass spectrometry. This success has pointed the way toward a major change in the mass spectrometric analysis of vitamin D, its analogs, and their metabolites. A disadvantage at the present time is that ionization using ESI and APCI is less efficient than the EI(+) used in GC-MS, but the immediate advantage is that it obviates the need for derivatiza-tion. 

In matrix assisted laser desorption/ionisation (MALDI) the material to be analysed (the analyte) is mixed with an analysis aid (the matrix) which is easily volatilised by the appropriate laser light [206-208]. In electrospray ioniation [209-211] the analyte is sprayed from a small orifice in a high electric field. Both techniques have been developed to introduce non-volatile materials into a mass spectrometer. These revolutionary techniques have effectively opened polymers to mass spectrometric characterisation. 

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