Liquid chromatography-mass phase

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,... 

The need to understand the fate of pesticides in the environment has necessitated the development of analytical methods for the determination of residues in environmental media. Adoption of methods utilizing instrumentation such as gas chro-matography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), liquid chromatography/tandem mass spectrometry (LC/MS/MS), or enzyme-linked immunosorbent assay (ELISA) has allowed the detection of minute amounts of pesticides and their degradation products in environmental samples. Sample preparation techniques such as solid-phase extraction (SPE), accelerated solvent extraction (ASE), or solid-phase microextraction (SPME) have also been important in the development of more reliable and sensitive analytical 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. 

Apffel, A., Fischer, S., Goldberg, G., Goodley, P.C., Kuhlmann, F.E. (1995). Enhanced sensitivity for peptide mapping with electrospray liquid chromatography—mass spectrometry in the presence of signal suppression due to trifluoroacetic acid-containing mobile phases. J. Chromatogr. A 712, 177-190. 

Jandera, P., Holcapek, M., Theodoridis, G. (1998). Investigation of chromatographic behavior of alcohol ethoxylate surfactants in normal-phase and reversed-phase systems using high-performance liquid chromatography-mass spectrometry. J. Chromatogr. A 813(2), 299-311. 

High performance liquid chromatography-mass spectrometric methods Nitin et al. [75] developed and validated a sensitive and selective liquid chromatography-tandem mass spectrometric method (LC MS MS) for the simultaneous estimation of bulaquine and its metabolites primaquine in monkey plasma. The mobile phase consisted of acetonitrile ammonium acetate buffer (20 mM, pH 6) (50 50, v/v) at a flow rate of 1 mL/min. The chromatographic separations were achieved on two Spheri cyano columns (5 pm, 30 cm x 4.6 mm), connected in... 

Burkhard, L.P., Kuehl, D.W., Veith, G.D. (1985) Evaluation of reverse phase liquid chromatography/mass spectrometry for estimation of n-octanol/water partition coefficients for organic chemicals. Chemosphere 14(10), 1551-1560. 

Klejdus B, Vitamvasova D and Kuban V. 2001. Identification of isoflavone conjugates in red clover (Trifolium pratense) by liquid chromatography-mass spectrometry after two-dimensional solid-phase extraction. Anal Chim Acta 450 81-97. 

Reversed phase liquid chromatography-mass spectrometry was applied to extracts of Jamaica Bay (New York) water to determine 1-300 xg/l amounts of nonyl phenol ethoxylates and their metabolites [213]. 

Ferrer and Barcelo [131] used online solid-phase-liquid chromatography mass spectrometry for the simultanous determination of organotin antifouling herbicides in marine water. The solid-phase extraction was carried out on polymeric cartridges after percolation of 100 ml of the seawater sample, and... 

Van der Hoeven, R.A. et al. 1997. Liquid chromatography/mass spectrometry with on-line solid-phase extraction by a restricted-access C18 precolumn for direct plasma and urine injection. J. Chromatosr. A. 762 193-200. 

Ferrer I. and Barcelo, D., 1999. Simultaneous determination of antifouling herbicides in marina water samples by online solid-phase extraction followed by liquid chromatography-mass spectrometry. J Chromatogr A 854 197. 

Niederlander H.A.G. et al., 2006. High throughtput therapeutic drug monitoring of clozapine and metabolites in serum by online coupling of solid phase extraction with liquid chromatography-mass spectrometry. J Chromatogr B 834 98. 

Recent studies, including the use of Microtox and ToxAlert test kits [55,56], were carried out for the determination of the toxicity of some non-ionic surfactants and other compounds (aromatic hydrocarbons, endocrine disruptors) before implementation on raw and treated wastewater, followed by the identification and quantification of polar organic cytotoxic substances for samples with more than 20% inhibition. Furthermore, the study of their contribution to the total toxicity was obtained using sequential solid-phase extraction (SSPE) before liquid chromatography-mass spectrometry (LC-MS) detection. This combined procedure allows one to focus only on samples containing toxic substances. 

When the mobile phase is a gas, the technique is called gas chromatography-mass spectrometry (GC-MS). In this case, the mixture is in the gas phase as it moves through the column, and the individual separated mixture components emerge in the gas phase and mix with the gaseous mobile phase, which is usually helium. When the mobile phase is a liquid, or a mixture of liquids, the technique is called liquid chromatography-mass spectrometry (LC-MS). In this case, the mixture is in the liquid phase as it moves through the column and individual separated mixture components emerge dissolved in this liquid phase. 

While the alkyl chain distribution is determined on a non-polar RP8 and RP18, EO homologue distribution is determined using a polar phase. AEOs are not UV-absorbing species, so they cannot be directly determined by HPLC followed by standard optical detection systems (UV and FL), unless suitable derivatives are prepared [2], Because of this, methods based on liquid chromatography-mass spectrometry [77-79] are currently considered as the benchmark procedure that gives sufficiently high selectivity and sensitivity. 

H.Fr. Schroder, Determination of Fluorinated Surfactants and their Metabolites in Sewage Sludge Samples by Liquid Chromatography-Mass Spectrometry and -Tandem Mass Spectrometry after Pressurised Solvent Extraction and Separation on Fluorine Modified RP-Phases, J. Chromatogr. A, in press. 

Kang, W. et ah. Analysis of benidipine enantiomers in human plasma by liquid chromatography—mass spectrometry using a macrocyclic antibiotic (vancomycin) chiral stationary phase column, J. Chromatogr. B, 814, 75, 2005. 

Liquid Chromatography Mobile Phases Applicable to Mass Spectrometry. 161... 

Pulsed ultrafiltration MS (PUF-MS) represents an inline high throughput affinity screening method with a variety of potential uses in the discovery and development of pharmaceuticals [22]. The in-line combination of solution-phase equilibration, ultrafiltration, and electrospray liquid chromatography mass spectrometry (LC-ESI-MS) facilitates the identification of high affinity target-specific... 

Boyd JM, Hrudey SE, Li XF, Richardson SD (2011) Solid-phase extraction and high-performance liquid chromatography mass spectrometry analysis of nitrosamines in treated drinking water and wastewater. Trends Anal Chem 30(9) 1410-1421... 

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