Selectivity analysis liquid chromatography mass

AmMa J, Yang H, Basile MJ and Kennelly EJ. 2004. Analysis of polyphenolic antioxidants from the fruits of three Pouteria species by selected ion monitoring liquid chromatography/mass spectrometry. J Agric... 

Figure F2.4.1 Liquid chromatography/mass spectrometry (LC/MS) analysis of isomeric carotenes in a hexane extract from 0.5 ml human serum. Positive ion electrospray ionization MS was used on a quadrupole mass spectrometer with selected ion monitoring to record the molecular ions of lycopene, p-carotene, and a-carotene at m/z (mass-to-charge ratio) 536. A C30 HPLC column was used for separation with a gradient from methanol to methyl-ferf-butyl ether. The a -trans isomer of lycopene was detected at a retention time of 38.1 min and various c/ s isomers of lycopene eluted between 27 and 39 min. The all-frans isomers of a-carotene and P-carotene were detected at 17.3 and 19.3 min, respectively.

Figure A.3A.2 Selection of chromatography-mass spectrometry system for the analysis of a sample. Abbreviations APCI, atmospheric pressure chemical ionization CF, continuous flow Cl, chemical ionization El, electron impact FAB, fast atom bombardment GC/MS, gas chromatogra-phy/mass spectrometry LC/MS, liquid chromatography/mass spectrometry.

DR Voyksner, JT Bursey, ED Pellizzari. Analysis of selected pesticides by high-performance liquid chromatography-mass spectrometry. J Chromatogr 312 221-235, 1984. 

A. Cohen, H. Schagerlof, C. Nilsson, C. Melander, F. Tjemeld, and L. Gorton, Liquid chromatography-mass spectrometry analysis of enzyme-hydrolysed carboxymethylcellulose for investigation of enzyme selectivity and substituent pattern, J. Chromatogr. A, 1029 (2004) 87-95. 

Liquid chromatography/mass spectrometry (LC/MS)-based techniques provide unique capabilities for pharmaceutical analysis. LC/MS methods are applicable to a wide range of compounds of pharmaceutical interest, and they feature powerful analytical figures of merit (sensitivity, selectivity, speed of analysis, and cost-effectiveness). These analytical features have continually improved, resulting in easier-to-use and more reliable instruments. These developments coincided with the pharmaceutical industry s focus on describing the collective properties of novel compounds in a rapid, precise, and quantitative way. As a result, the predominant pharmaceutical sample type shifted from nontrace/pure samples to trace mixtures (i.e., protein digests, natural products, automated synthesis, bile, plasma, urine). The results of these developments have been sig-... 

Mass spectrometry (MS) is based on the production of ions, that are subsequently separated or filtered according to their mass-to-charge m/z) ratio and detected. The resulting mass spectmm is a plot of the (relative) abundance of the generated ions as a function of the m/z. Excellent selectivity can be obtained, which is of utmost importance in quantitative trace analysis. This chapter is not a brief introdnction in MS, but rather highhghts important aspects for the discussions on liquid chromatography-mass spectrometry (LC-MS) to come. General discussion and tntorials in MS can be foimd elsewhere [1-2]. 

Chemical Analysis. Gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) techniques were used to analyze 4-chlorophenol and its oxidation intermediates. For GC-MS analysis, the samples were acetylated in pyridine. The samples were first evaporated to dryness. Then 200 xL of pyridine and 200 (xL of acetic anhydride were added to the dry residue. The samples were heated at 65 °C for 2-3 h to ensure the complete acetylation reaction, and then gently evaporated to dryness in a nitrogen stream. Finally, the residue was redissolved in 0.1 mL of hexane for GC analysis. A GC (HP model 5890) equipped with mass selective detector (HP model 5971) and SPB-5 capillary column (Supelco Co., PA., 25- X 0.2-mm i.d. X 0.33-p.m film thickness) was used. To separate different intermediate products, various oven-temperature programs were performed. The GC-MS interface line was maintained at 300 °C. The mass-... 

Oven/iew Waters, Sediments, and Soils. Ion-Selective Electrodes Water Applications. Isotope Dilution Analysis. Liquid Chromatography Size-Exclusion Liquid Chromatography-Mass Spectrometry Mass Spectrometry Peptides and Proteins. Voltammetry Overview. 

Liquid chromatography-mass spectrometry The initial attempts to couple LC with MS lacked important attributes for trace analysis sensitivity, robustness, and reliable quantitation. Moreover, the cost of the early LC-MS instruments was prohibitive for most laboratories. The revolutionary introduction of atmospheric pressure ionization (API) techniques, mainly electrospray (ESI) and atmospheric pressure chemical ionization (APCI), resulted in greater applicability of LC-MS and manufacture of more reliable, affordable, and user-friendly instruments. Thus, LC-MS is now becoming an indispensable part of the analytical strategy in many routine laboratories, enabling direct, selective, and sensitive multiclass, multiresidue analysis of more polar, low volatile, and/or thermolabile pesticides, such as carbamates, phenylureas, sulfonylureas, imidazoles, triazoles, imidazolinones, chlorophenoxy acids, and many others. 

The most commonly used analytical technique for sugars is HPLC with a refractive index detector (RID). Although the HPLC-RID method is simple, the RID lacks sensitivity and selectivity. Therefore, UV and fluorescence detection is frequently used, coupled with pre- or postcolumn derivatization, for analysis with higher sensitivity. Liquid chromatography-mass spectrometry (LC-MS) using electrospray ionization also requires pre- or postcolumn derivatization. LC-MS using atmospheric pressure chemical ionization does... 

See a/so Clinical Analysis Sample Handling. Gas Chromatography Mass Spectrometry. Liquid Chromatography Liquid Chromatography-Mass Spectrometry. Mass Spectrometry Ionization Methods Ovenriew Atmospheric Pressure Ionization Techniques Time-of-Flight Selected Ion Monitoring Stable Isotope Ratio. Peptides. Proteins Traditional Methods of quence Determination. Quality Assurance Internal Standards. 

See also Capillary Electrophoresis Overview. Chir-optical Analysis. Liquid Chromatography Column Technology Mobile Phase Selection Reversed Phase Instrumentation Amino Acids. Mass Spectrometry Peptides and Proteins. Nuclear Magnetic Resonance Spectroscopy Techniques Nuclear Overhauser Effect. Proteins Traditional Methods of Sequence Determination Foods. 

Figure 9.4 High-pressure liquid chromatography separation of 50 pg of a natural phosphatidylcholine mixture from egg yolk. The reconstructed ion chromatograms of diglyceride ions were selected from data acquired by full mass scanning from 120 amu to 820 amu. The relative intensity is shown based on the peak height. Column 3 pm Ultrasphere-ODS (4.6 mm x 7.5 cm). Mobile phase MeOH/hexane/0.1 m NH4OAC (71 5 7), 1 mlmin . Reprinted with permission from Kim, H. Y. and Salem, N. Jr, Phospholipid molecular species analysis by thermospray liquid chromatography/mass spectrometry. Anal. Chem., 58 (1), 9-14, 1986.

Today, MS is one of the most powerful analytical techniques particularly in pharmaceutical analysis where good selectivity and high sensitivity are often needed. Liquid chromatography-mass spectrometry (LC-MS) has become a highly developed tool for the determination of dmgs in... 

Due to its high sensitivity and selectivity, liquid chromatography-mass spectrometry (LC-MS) is a powerful technique. It is used for various applications, often involving the detection and identification of chemicals in a complex mixture. Ultra Performance Liquid Chromatography Mass Spectrometry Evaluation and Applications in Food Analysis presents a unique collection of up-to-date UPLC-MS/MS methods for the separation and quantitative determination of components, contaminants, vitamins, and aroma and flavor compounds in a wide variety of foods and food products. 

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