Liquid chromatography-mass ionization methods

Chong, B.E., Yan, F., Lubman, D.M., Miller, F.R. (2001). Chromatofocusing nonporous reversed-phase high-performance liquid chromatography/electrospray ionization time-of-flight mass spectrometry of proteins from human breast cancer whole cell lysates a novel two-dimensional liquid chromatography/mass spectrometry method. Rapid Com-mun. Mass Spectrom. 15, 291-296. 

D Hurtaud, B Delepine, P Sanders. Particle-beam liquid chromatography-mass spectrometry method with negative ion chemical ionization for the confirmation of oxacillin, cloxacillin and dicloxacillin residues in bovine muscle. Analyst 119 2731-2736, 1994. 

Salm P, Taylor PJ, Rooney F (2008) A high-performance liquid chromatography-mass spectrometry method using a novel atmospheric pressure chemical ionization approach for the rapid simultaneous measurement of tacrolimus and cyclosporin in whole blood. Ther Drug Monit 30 292-300... 

A liquid chromatography-mass spectrometry (LC-MS) method that can quantitatively analyze urinar y normal and modified nucleosides in less than 30 min with a good resolution and sufficient sensitivity has been developed. Nineteen kinds of normal and modified nucleosides were determined in urine samples from 10 healthy persons and 18 breast cancer patients. Compounds were separ ated on a reverse phase Kromasil C18 column (2.1 mm I.D.) by isocratic elution mode using 20 mg/1 ammonium acetate - acetonitrile (97 3 % v/v) at 200 p.l/min. A higher sensitivity was obtained in positive atmospheric pressure chemical ionization mode APCI(-i-). 

The method for chloroacetanilide soil metabolites in water determines concentrations of ethanesulfonic acid (ESA) and oxanilic acid (OXA) metabolites of alachlor, acetochlor, and metolachlor in surface water and groundwater samples by direct aqueous injection LC/MS/MS. After injection, compounds are separated by reversed-phase HPLC and introduced into the mass spectrometer with a TurboIonSpray atmospheric pressure ionization (API) interface. Using direct aqueous injection without prior SPE and/or concentration minimizes losses and greatly simplifies the analytical procedure. Standard addition experiments can be used to check for matrix effects. With multiple-reaction monitoring in the negative electrospray ionization mode, LC/MS/MS provides superior specificity and sensitivity compared with conventional liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/ultraviolet detection (LC/UV), and the need for a confirmatory method is eliminated. In summary,... 

More recently, liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) have been evaluated as possible alternative methods for carfentrazone-ethyl compounds in crop matrices. The LC/MS methods allow the chemical derivatization step for the acid metabolites to be avoided, reducing the analysis time. These new methods provide excellent sensitivity and method recovery for carfentrazone-ethyl. However, the final sample extracts, after being cleaned up extensively using three SPE cartridges, still exhibited ionization suppression due to the matrix background for the acid metabolites. Acceptable method recoveries (70-120%) of carfentrazone-ethyl metabolites have not yet been obtained. 

BARNES, K.A., SMITH, R.A., WILLIAMS, K., DAMANT, A.P., SHEPHERD, MJ.A., Microbore high performance liquid chromatography/electrospray ionization mass spectrometry method for the determination of the phytoestrogens genistein and daidzein in comminuted baby foods and soya flour, Rapid Comm. Mass Spectrom., 1998,12,130-138. 

D. R. Robb, T. R. Covey, and A. P. Bruins. Atmospheric Pressure Photoionization An Ionization Method for Liquid Chromatography-Mass Spectrometry. Anal. Chem., 72(2000) 3653-3659. 

Nowadays, ESI is the leading member of the group of atmospheric pressure ionization (API) methods and the method of choice for liquid chromatography-mass spectrometry coupling (LC-MS, Chap. 12). [10-13] Currently, ESI and MALDI (Chap. 10) are the most commonly employed ionization methods and they opened doors to the widespread biological and biomedical application of mass spectrometry. [5,10,11,13-17] Moreover, ESI serves well for the analysis of ionic metal complexes [18,19] and other inorganic analytes. [20-22]... 

The year 2002 was an extraordinary year for liquid chromatography-mass spectrometry (LC/MS) practitioners. On October 9, 2002, the Royal Swedish Academy of Sciences annonnced their decision to award the Nobel Prize in Chemistry to John B. Fenn, Koichi Tanaka, and Kurt Wiithrich for their development of analytical methods for the identification and structnral analysis of biological macromolecnles. Fenn and Tanaka shared the prize for developing electrospray and soft-laser desorption, respectively. These soft-ionization techniqnes allow macromolecules to be ionized withont fragmentation. 

Robb, D. B., Covey, T. R., and Bruins, A. P. (2000). Atmospheric pressure photoionization an ionization method for liquid chromatography-mass spectrometry. Anal. Chem. 72, 3653 — 3659. 

Muller, C., Schafer, P., Stortzel, M., Vogt, S., and Weinmann, W. (2002). Ion suppression effects in liquid chromatography-electrospray-ionization transport-region collision induced dissociation mass spectrometry with different serum extraction methods for systematic toxicological analysis with mass spectra libraries. /. Chromatogr. B 773, 47— 52. 

Tolonen, A. and Uusitalo, L, Fast screening method for the analysis of total flavonoid content in plants and foodstuffs by high-performance liquid chromatography/electrospray ionization time-of-flight mass spectrometry with polarity switching. Rapid Commun. Mass Spectrom., 18, 3113, 2004. 

Liquid chromatography-electrospray ionization mass spectrometry (LC-ESTMS) for analysis of sildenafil has also been developed and applied to 40 botanical products. About half of the analyzed samples proved to contain undeclared additives of the three drugs sildenafil, vardenafil, and tadalafil <2004JPBA525>. A similar electrokinetic capillary chromatography method to that proposed for the determination of sildenafil 82 has been reported for vardenafil 98 and tadalafile 99. Statistical evaluation of the electrophoretic results was achieved. The described method is thought to be rapid and sensitive <2004JCH231>. 

Tang, L., Fitch, W. L., Alexander, M. S., and Dolan, J. W. (2000). Expediting the method development and quality control of reversed-phase liquid chromatography electrospray ionization mass spectrometry for pharmaceutical analysis by using an LC/MS performance test mix. Anal. Chem. 72 5211-5218. 

Wu, S. T., Xia, Y. Q., and Jemal, M. (2007). High-field asymmetric waveform ion mobility spectrometry coupled with liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-FAIMS-MS/MS) multicomponent bioanalytical method development, performance evaluation and demonstration of the constancy of the compensation voltage with change of mobile phase composition or flow rate. Rapid Commun. Mass Spectrom. 21 3667-3676. 

To establish a sensitive and specific liquid chromatography-mass spectrometry (time-of-flight) [LC-MS (TOF)] method for the determination of donepezil in human plasma after an oral administration of 5 mg donepezil hydrochloride tablet [29]. Alkalized plasma was extracted with isopropa-nol-n-hexane (3 97) and loratadine was used as internal standard (IS). Solutes were separated on a Cis column with a mobile phase of metha-nokacetate buffer (pH 4.0) (80 20). Detection was performed on a TOF mass spectrometry equipped with an electrospray ionization interface and operated in positive-ionization mode. Donepezil quantitation was realized by computing the peak area ratio (donepezil-loratadine) (donepezil m/z 380 [M + H]+ and loratadine m/z 383[M + H]+) and comparing them with calibration curve (r = 0.9998). The linear calibration curve was obtained in the concentration range of 0.1-15 jUg/1. The detection limit of donepezil was 0.1 /zg/1. The average recovery was more than 90%. The intra- and inter-run precision was measured to be below 15% of RSD... 

Hancock, W. S. Apffel, A. Chakel, J. Souders, C. M Timkulu, T. Pungor, E. Guzzetta, A. W. 1996. Reversed-phase peptide mapping of glycoproteins using liquid chromatography/electrospray ionization-mass spectrometry. Methods Enzymol., 271,4QA-421. 

Little JL, Wempe MF, Buchanan CM (2006) Liquid chromatography-mass spectrometry/mass spectrometry method development for drug metabolism studies examining lipid matrix ionization effects in plasma. J Chromatogr B 833 219-230... 

Liu W, Cai HL, Li HD (2007) High performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-MS/ESI) method for simultaneous determination of venlafaxine and its three metabolites in human plasma. J Chromatogr B Anal Technol Biomed Life Sci 850 405-411... 

EPA EPA Chemical QC Guidelines EPA method 539 Determination of hormones in drinking water by solid phase extraction (SPE) and liquid chromatography electrospray ionization tandem mass spectrometry (LC-MS/MS) [77]... 

As an instrumental approach to conventional electrophoresis, capillary electrophoresis offers the capability of on-line detection, micropreparative operation and automation (6,8,45-47). In addition, the in tandem connection of capillary electrophoresis to other spectroscopy techniques, such as mass spectrometry, provides high information content on many components of the simple or complex peptide under study. For example, it has been possible to separate and characterize various dynorphins by capillary electrophoresis-mass spectrometry (33). Therefore, the combination of CE-mass spectrometry (CE-MS) provides a valuable analytical tool useful for the fast identification and structural characterization of peptides. Recently, it has been demonstrated that the use of atmospheric pressure ionization using Ion Spray Liquid Chromatography/ Mass Spectrometry is well suited for CE/MS (48). This approach to CE/MS provides a very effective and straightforward method which allow the feasibility of obtaining CE/MS data for peptides from actual biological extracts, i.e., analysis of neuropeptides from equine cerebral spinal fluid (33). 

There are two important methods in which ions or, less often, neutral compounds in solution (often containing formic acid) have their solvent molecules stripped by evaporation, with simultaneous ionization leaving behind the ions for mass analysis. Coupled with liquid chromatography instrumentation, these methods have become immensely popular. 

A sensitive liquid chromatography/ electrospray ionization tandem mass spec-trometrical (LC/ESI-MS/MS) method was developed for the identification and quantification of two polyisoprenylated benzophe-nones, xanthochymol and isoxanthochymol, in the extracts of the fruit rinds, stem bark, seed pericarps and leaves of G. indica and in... 

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