Friday, May 17, 2013
Sunday, May 12, 2013
Sunday, April 29, 2012
|Tema Malam Kimia Bagi Tahun 2012 Night In The Garden|
|Pendaftaran Jemputan dan Hadirin|
|Ketibaan Timbalan Dekan Jaringan Industri PPS Kimia|
|Ketibaan Timbalan Dekan Hal Ehwal Pelajar & Akademik |
|Ucapan oleh Timbalan Dekan Jaringan Industri & Masyarakat|
bagi mewakili Dekan PPS Kimia untuk majlis pembukaan
Malam Kimia 2012
Wednesday, November 2, 2011
Use of NMR inStructure Elucidation of Natural Products: A Novel Polyacetylene from CentellaasiaticaStructure elucidationis an important part of natural products chemistry. Very often chemists isolate a pure compoundfrom a natural source – e.g., crude extract from plants, marine organisms orbacterial broth, and it would be necessary to know the structure of thecompound. For the past 3-4 decades NMR(nuclear magnetic resonance) spectroscopy has become the primary tool toachieve this. In this presentation, Professor Govindan will illustrate theprocess through the example of determining the structure of a unique, highlyoxygenated polyacetylene isolated from the Malaysian medicinal herb, Centella asiatica. He will illustrate the use of various NMRspectra, such as proton and carbon NMR, COSY, TOCSY, HMQC and HMBC inestablishing the carbon connectivities and functional group placements. The role of IR (infrared) spectroscopy and MS(mass spectrometry) will also be illustrated.
BriefBiographical Sketch – Dr. Meledath GovindanMeledath Govindan iscurrently a Professor of Chemistry at
Dr. Govindan received his Ph.D. in chemistry from the
Tuesday, October 18, 2011
Fluorinated HPLC Phases — Looking Beyond C18 for Reversed-Phase
Professor Hassan Y. Aboul-Enein
Pharmaceutical and Medicinal Chemistry Department, National Research Centre, Dokki,E-mail: firstname.lastname@example.org and email@example.com
Cairo 12311, EGYPT
Reversed-phase high performance liquid chromatography (HPLC) is one of the most utilized forms of chromatography. The C8 and C18 stationary phases are the most widely used for reversed-phase HPLC. However, analysts occasionally encounter difficult separations for which selectivity, ruggedness or reproducibility are not obtained easily using traditional C8 and C18 phases. These separations might require the use of novel or selective phases that interact with analytes in a manner different than C8 or C18 phases .
¢ These types of stationary phases separate compounds based upon selective stationary phase interactions such as steric recognition charge transfer or π–π interactions. One class of selective or novel phases that have been used for a variety of separations are fluorinated phases
¢ Fluorinated phases can provide different elution orders, leading to enhanced selectivity for difficult-to-separate compounds
¢ Fluorinated phases also offer the possibility to use simpler mobile phases and avoid using extreme pH conditions and complex mobile-phase preparations.
¢ Fluorinated packings also exhibit excellent selectivity for compounds having hydroxyl, nitro and other polar groups in large ring systems.
This presentation will present several types of fluorinated stationary phases and show several examples of how this extra selectivity has been used to achieve chromatographic separation for a broad range of applications.