Hand-Portable Gradient Capillary Liquid Chromatography Pumping

Sep 17, 2015 - *E-mail: [email protected]. ... The gradient pumping system consisted of two nanoflow pumps controlled by micro stepper motors, a mixe...
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Hand-portable Gradient Capillary Liquid Chromatography Pumping System Sonika Sharma, Alex Plistil, Hal E Barnett, H. Dennis Tolley, Paul B Farnsworth, Stanley D Stearns, and Milton L. Lee Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.analchem.5b02583 • Publication Date (Web): 17 Sep 2015 Downloaded from http://pubs.acs.org on September 19, 2015

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Analytical Chemistry

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Hand-portable Gradient Capillary Liquid Chromatography Pumping System

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Sonika Sharma†, Alex Plistil‡, Hal E. Barnett‡, H. Dennis Tolley‼, Paul B. Farnsworth†, Stanley

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D. Stearns‡, Milton L. Lee†*

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United States

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Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602,



VICI Valco Instruments, Houston, Texas 77055, United States

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Department of Statistics, Brigham Young University, Provo, Utah 84602, United States

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Corresponding Author E-mail: [email protected]

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ABSTRACT: In this work, a novel splitless nano-flow gradient generator integrated with a stop-

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flow injector was developed and evaluated using an on-column UV-absorption detector. The

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gradient pumping system consisted of two nano-flow pumps controlled by micro stepper motors,

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a mixer connected to a serpentine tube, and a high-pressure valve. The gradient system weighed

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only 4 kg (9 lbs) and could generate up to 55 MPa (8000 psi) pressure. The system could operate

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using a 24 V DC battery and required 1.2 A for operation. The total volume capacity of the pump

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was 74 µL, and a sample volume of 60 nL could be injected. The system provided accurate

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nanoflow rates as low as 10 nL/min without employing a splitter, making it ideal for capillary

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column use. The gradient dwell volume was calculated to be 1.3 µL, which created a delay of

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approximately 4 min with a typical flow rate of 350 nL/min. Gradient performance was

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evaluated for gradient step accuracy, and excellent reproducibility was obtained in day-to-day

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experiments (RSD < 1.2%, n = 4). Linear gradient reproducibility was tested by separating a

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three-component pesticide mixture on a poly(ethylene glycol) diacrylate (PEGDA) monolithic

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column. The retention time reproducibility was very good in run-to-run experiments (RSD