Analytical Chemistry, chromatography, separation, purification, detection, automation, integration, programming, data handling, data processing, database, SQL, instrumentation, HPLC, GC, CE, LC-MS, LC/MS, GC-MS, GC/MS, wet chemical analysis, fluorescence, ELSD, CLND, liquid drop, sampling, concentration, preconcentration, sensor, sensing, process analysis, environmental analysis, method development, microfabrication, microfluidics, high throughput, combinatorial chemistry, drug discovery  

Hanghui Liu's Home Page

Who am I

Analytical Chemistry Webbed

The Barnett Institute 

Dept. of Chem. & Biochem. at

Texas Tech University

An Integrated LC/MS/UV/ELSD/CLND System for Combinatorial Chemistry

Plastic Devices for Multiple Channel Electrospray Mass Spectrometry 


How to achieve high throughput, small sample requirement, low cost, lack of cross contamination? Multiple channel plastic devices which are interfaced to a mass spectrometer could be one of the feasible approaches. 

We developed an automated high throughput (720 samples/hr) ESI-MS system based on a microfabricated platic 96-well plate to which 96 channels and 96 ESI tips are incorporated. The feasibility of the system has been demonstrated through the high throughput analysis of peptides and proteins as well as IC50 determination in HIV-1 enzyme inhibition assays. 

Other type of microfabricated plastic devices have also been tested.

A Falling Drop for Sample Injection in Capillary Zone Electrophoresis 


Falling Drop for Sample Injection 
The inlet of a capillary is joined to an open stream of buffer formed on an inclined narrow surface and a constant voltage is applied to the capillary. A drop of sample falls directly to the capillary inlet and then is washed away quickly. Thus, a short sample plug with limited dilution by the stream of buffer is injected in electrokinetic mode. No moving parts are involved and no adjustment of voltage is necessary in the injection process. The method is simple, reproducible, easy to automate and should prove to be a valuable complement to the present injection techniques for capillary zone electrophoresis.

Analytical Chemistry in a Drop: Extraction 


Extraction in a Drop 
A micro (~0.0013 mL) organic drop is suspended inside a flowing aqueous drop from which the analyte is extracted. The aqueous phase is continuously delivered to the outer drop and is aspirated away from the bottom meniscus of the drop. After the sampling/extraction period, a wash solution replaces the sample/reagent in the aqueous layer, resulting in a clear outer aqueous drop housing a colored organic drop containing the extracted material. This also results in an automatic backwash. The color intensity of the organic drop, related to the analyte concentration, is monitored by a light emitting diode (LED) based absorbance detector. After the analytical cycle, the organic drop is removed and replaced by a new one. This unique micro extraction system is simple, flexible, permits automated backwashing, consumes only micro quantities of organic solvents and is capable of being coupled with other analytical systems. This concept should prove valuable for preconcentration and matrix isolation on a micro scale.

Like to see more drops? Please go to 

Novel Analytical Chemistry Systems Using Liquid Drops 

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