scholarly journals Microcin E492 Is an Unmodified Peptide Related in Structure to Colicin V

2002 ◽  
Vol 46 (1) ◽  
pp. 229-230 ◽  
Author(s):  
Anne-Marie Pons ◽  
Nathalie Zorn ◽  
David Vignon ◽  
François Delalande ◽  
Alain Van Dorsselaer ◽  
...  
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Solid Phase Extraction ◽  
Molecular Mass ◽  
Solid Phase ◽  
Reversed Phase ◽  
Phase Extraction ◽  
Colicin V

ABSTRACT The pore-forming microcin E492 was purified by solid-phase extraction and reversed-phase high-pressure liquid chromatography. Its molecular mass was 7,886 Da. The entire 84-amino-acid sequence was determined. There is no postranslational modification in the secreted microcin, and the sequence has homologies with the sequence of the microcin colicin V.

scholarly journals Determination of Antiviral Drugs and Their Metabolites Using Micro-Solid Phase Extraction and UHPLC-MS/MS in Reversed-Phase and Hydrophilic Interaction Chromatography Modes

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2123
Author(s):  
Luboš Fical ◽  
Maria Khalikova ◽  
Hana Kočová Vlčková ◽  
Ivona Lhotská ◽  
Zuzana Hadysová ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Solid Phase Extraction ◽  
Solid Phase ◽  
Gradient Elution ◽  
Reversed Phase ◽  
Tandem Mass ◽  
Phase Extraction ◽  
Hydrophilic Interaction

Two new ultra-high performance liquid chromatography (UHPLC) methods for analyzing 21 selected antivirals and their metabolites were optimized, including sample preparation step, LC separation conditions, and tandem mass spectrometry detection. Micro-solid phase extraction in pipette tips was used to extract antivirals from the biological material of Hanks balanced salt medium of pH 7.4 and 6.5. These media were used in experiments to evaluate the membrane transport of antiviral drugs. Challenging diversity of physicochemical properties was overcome using combined sorbent composed of C18 and ion exchange moiety, which finally allowed to cover the whole range of tested antivirals. For separation, reversed-phase (RP) chromatography and hydrophilic interaction liquid chromatography (HILIC), were optimized using extensive screening of stationary and mobile phase combinations. Optimized RP-UHPLC separation was carried out using BEH Shield RP18 stationary phase and gradient elution with 25 mmol/L formic acid in acetonitrile and in water. HILIC separation was accomplished with a Cortecs HILIC column and gradient elution with 25 mmol/L ammonium formate pH 3 and acetonitrile. Tandem mass spectrometry (MS/MS) conditions were optimized in both chromatographic modes, but obtained results revealed only a little difference in parameters of capillary voltage and cone voltage. While RP-UHPLC-MS/MS exhibited superior separation selectivity, HILIC-UHPLC-MS/MS has shown substantially higher sensitivity of two orders of magnitude for many compounds. Method validation results indicated that HILIC mode was more suitable for multianalyte methods. Despite better separation selectivity achieved in RP-UHPLC-MS/MS, the matrix effects were noticed while using both chromatographic modes leading to signal enhancement in RP and signal suppression in HILIC.

scholarly journals Development of a Solid-Phase Extraction Method for Determination of Pheophorbide a and Pyropheophorbide a in Health Foods by Liquid Chromatography

2004 ◽  
Vol 87 (4) ◽  
pp. 937-942 ◽  
Author(s):  
Harumi Oshima ◽  
Eiji Ueno ◽  
Isao Saito ◽  
Hiroshi Matsumoto
Keyword(s):  
Liquid Chromatography ◽  
Solid Phase Extraction ◽  
Solid Phase ◽  
Reversed Phase ◽  
Official Method ◽  
Phase Extraction ◽  
Pheophorbide A ◽  
Significant Difference ◽  
Spe Method

Abstract A simple solid-phase extraction (SPE) method was developed for the liquid chromatography (LC) determination of pheophorbide (Phor) a and pyropheophorbide (Pyro) a in health foods such as chlorella, spirulina, etc. The food sample was extracted with 85% (v/v) acetone. The extract was acidified with hydrochloric acid and loaded on a C18 cartridge. After washing with water, Phor a and Pyro a were eluted with the LC mobile phase. Phor a and Pyro a were separated by isocratic reversed-phase LC and quantitated by fluorescence detection. The recoveries for spiked samples of chlorella and the extract were 87.1–102.0%. Commercial health foods (chlorella, spirulina, aloe, kale, Jews mallow, and green tea leaves) were analyzed using the SPE method. The values found for Phor a and Pyro a ranged from 2 to 788 μg/g and from <1 to 24 μg/g, respectively. There was no significant difference between the SPE method and the official method in Japan (spectrophotometry after liquid–liquid extraction). The advantages of the SPE method are the short extraction times, lack of emulsions, and reduced consumption of organic solvents compared with the official method in Japan. The SPE method is considered to be useful for the screening of Phor a and Pyro a in health foods.

Extraction optimization of sixteen cephalosporins in milk by filtered solid phase extraction and ultra high pressure liquid chromatography coupled to tandem mass spectrometry

2017 ◽  
Vol 9 (8) ◽  
pp. 1282-1289 ◽  
Author(s):  
Jianfeng Wang ◽  
Xiaojing Fan ◽  
Yan Liu ◽  
Zhenxia Du ◽  
Yuechao Feng ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Pressure ◽  
Liquid Chromatography ◽  
Solid Phase Extraction ◽  
Solid Phase ◽  
Tandem Mass ◽  
Phase Extraction ◽  
Milk Samples ◽  
Ultra High Pressure ◽  
Hydrophilic Lipophilic Balance

A method employing a type of filtered solid phase extraction based on the PRiME hydrophilic lipophilic balance (HLB) was developed for extracting cephalosporin compounds from milk samples.

Spherical Clay Conglomerates:  A Novel Stationary Phase for Solid-Phase Extraction and “Reversed-Phase” Liquid Chromatography

1999 ◽  
Vol 71 (11) ◽  
pp. 2171-2178 ◽  
Author(s):  
Thomas D. Bucheli ◽  
Stephan R. Müller ◽  
Patrick Reichmuth ◽  
Stefan B. Haderlein ◽  
René P. Schwarzenbach
Keyword(s):  
Liquid Chromatography ◽  
Solid Phase Extraction ◽  
Stationary Phase ◽  
Solid Phase ◽  
Reversed Phase ◽  
Phase Extraction ◽  
Reversed Phase Liquid Chromatography ◽  
Phase Liquid
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