CHEM 7750

Slide 1: 

Franklin IfeanyichukwuUba CHEM 7750 - Separation science

LC detectors : 

LC detectors Refractive index Detector (RID) Electrolytic conductivity detector Evaporative light scattering detector (ELSD) Electrochemical detectors Fluorescence detector http://hplc.chem.shu.edu/HPLC/index.html UV-Detector

Slide 3: 

ELSD principle R.P.W.Scott, Chrom-Ed Book series, Book 5, 2003. Elution Droplet formation Solvent Evaporation Light scattering (Rayleigh) Detection at 45O Mass detector

Slide 4: 

http://upload.wikimedia.org/wikipedia/en/6/69/Rayleigh_sunlight_scattering.png Rayleigh scattering ɵ ɵ High energy photon Particle = Scattering angle Elastic collision KE conservation Particles smaller than wavelength of light

Slide 5: 

http://www.sielc.com/images/ELSD_Schematic.gif ELSD Instrumentation http://www.chem.agilent.com/

Cholesterol and COPs : 

Cholesterol and COPs http://www.scielo.cl/fbpe/img/bres/v36n3-4/fig01.gif

Previous methods : 

Previous methods Thin Layer Chromatography Qualitative Loading capacity restrictions Prone to contamination Gas Chromatography High temperatures (inlet/oven) Volatile derivatives (quantitative efficiency) High Pressure Liquid Chromatography No derivatives Faster Better accuracy than GC and TLC

Elution conditions : 

Elution conditions Normal phase column – 250 mm x 46 mm i.d. 16 % Alumina / 84% Silica ( 5μm ) Guard Column – 20 mm x 2 mm Gradient elution – 1.0 mL/min Dichloromethane (A) / Acetonitrile : Water (99.05:0.95) (B) 94:6 / A:B for 0 – 6 min 79:21/ A:B for 27 min Linear Gradient to 94:6 for 5 min ELSD detector : 75OC; N21.5 L/min

ELSD optimization : 

ELSD optimization

Results : 

Results

Slide 11: 

Normalized peak areas versus concentration (0.1 – 1.0 g) Area = k (conc.)m Linearity m = coefficient of curvature in conc./peak area curves ln(area) = lnK + mln(conc.)

Conclusions : 

Conclusions Fast analytical technique MDL of 75 ng/injection Stable and reproducible detector No baseline shift due to solvent changes

Acknowledgement : 

Acknowledgement Dr Gilman CHEM 7750 Classmates Hashim Jon Suzana Treyvon Akanksha Paul Danielle Nyote Sung Sudha Kumuditha