ADVANCES IN SEPARATION SCIENCE continued N2 supply. These gas purifiers operate silently to deliver 5 nines nitrogen


at 300 mL/min and 175 psi. The GT-HE removes the same impurities. A color LED allows operation to be monitored, even from across the room.


Air and zero-air GASTRAP models include the GT-ZAIR (zero-air) version, which uses a catalyst to reduce methane to less than 0.05 ppm. The GT-AR selectively removes oxygen, moisture and CO2 argon gas supply.


from an existing


VICI DBS Instruments (Vigonza, Italy), which recently joined VICI Instruments (Houston, Texas), introduced the FID Station Plus. It uses the latest polymer membrane technology to produce hydrogen at a purity of 6–7 nines hydrogen at a maximum flow of 600 cc/min. This is sufficient for using hydrogen as a carrier gas and FID detection. The zero A side produces 1.5 L of air with maximum hydrocarbon content lower than 0.5 ppm. An integrated microprocessor controls all functions of the gas station, including the LCD touchscreen. Leak detectors and water-level monitors provide continuous monitoring of production and leaks. The hydrogen gas volume is less than 50 mL.


Liquid chromatography


UHPLC systems The Vanquish Flex UHPLC system from Thermo Fisher Scientific offers full biocompatibility over a pH range of 2–12. Chloride compatibility is up to 1 M. The unit’s serial, dual-piston pump, with a Pmax


of 15,000 psi, has


automated compressibility compensation, which does not depend on the composition of the mobile phase. Dwell volume is 670 μL, with the mixer contributing 400 μL. The dual-stage mixer couples a proprietary capillary unit with a 50-μL volume mated to a 350-μL static mixer.


The ACQUITY UPLC, introduced by Waters (Milford, Mass.) in 2004, reduced column internal diameters to about 2 mm, and dwell volume became important. The rigid requirements associated with validated methods often conflicted with and sometimes precluded adoption of clearly superior separations technology, particularly when separations required gradient elution.


Even within the ACQUITY brand, the larger dwell volume of the ACQUITY H class, with its pre-pump quaternary gradient (400 μL dwell volume), did not exactly mimic the dual-pump gradient of the original ACQUITY (120 μL dwell volume), especially using gradient elution. Even larger differences were noted for conversion between instruments such as the Waters Alliance (<650 μL dwell volume) and chromatographs from differ- ent vendors.


This may not appear to be much of a problem, but it is a huge issue in comparing, troubleshooting and method transfer between different laboratories. The originating laboratory doing method development is often blessed with a research-grade instrument, while the QC or contract research organization (CRO) lab may have conventional HPLCs, often with large dwell volumes. Once a method is transferred, the results do not match. Such situations are addressed with the ACQUITY Arc from Waters and Nexera-i MT from Shimadzu (Columbia, Md.).


The Nexera-i MT (intelligent method transfer) has two flow paths on the same chassis, one for conventional HPLC and the other for UHPLC. Newly


AMERICAN LABORATORY 20


developed Analytical Conditions Transfer and Optimization software helps mitigate the effect of dwell volume on chromatograms obtained on different models. The ACQUITY Arc also has dual-flow paths supported by Empower software.


In addition to method transfer, chromatographers are finding it useful to have a modern and legacy instrument in the same bench space. The Nexera-i MT and ACQUITY Arc mimic other brands of HPLC, which im- proves scheduling flexibility.


Multiplexed LC/MS Shimadzu demonstrated a way to double throughput in LC/MS using staggered injection with two flow columns and flow paths feeding a high-speed mass spectrometer. Nexera MX Dual Stream Technology au- tomates the entire LC/MS process, from column wash and equilibration to data collection from the MS. Samples are managed and injected as fast as every 20 seconds from the SIL-30ACMP autosampler, which holds six 384-well plates for a total of 2304 samples. Carryover is an incredibly low 0.0004% without rinsing. Four protein biomarkers can be separated in the Cytochrome P450 family every 38 seconds versus every 82 seconds for a conventional, nonmultiplexed workflow.


Preparative liquid chromatograph With conventional preparative LC, fractions are isolated in a fraction collector. Then the mobile phase is evaporated. Most often, water is the least volatile liquid. Wet materials tend to form cakes with a surface of low permeability. Thus, mobile phase and mobile-phase additives (buffer and trifluoroacetic acid, etc.) are trapped in the residue. The mobile phase can eventually be removed, but the process takes hours.


Shimadzu scientists came up with a better idea—the Crude2Pure auto- mated purification/powderization system. The process has been extended to the Prominence UFPLC (ultrafast preparative and purification liquid chromatograph). In 90 minutes, nonexpert users can obtain up to five fractions of highly purified sample as a dried powder.


After the initial chromatographic separation on the Prominence, up to five fractions are collected on Shim-pack C2P-H trapping columns, which capture and retain the target analytes during the subsequent wash to remove mobile-phase contaminants. The trap column is washed with aqueous ammonia, which converts the salts to freebase that is collected in a volatile organic solvent. Dry-down time to powder is reduced by up to 90%. Prominence UFPLC integrates and automates the entire process in a single, simple-to-operate instrument. It also reduces bench space by 70% compared to the Crude2Pure system.


Dalian Elite Analytical Instruments Company (DEAIC, Dalian, PRC) has emerged as the largest vendor of HPLCs produced in China. For years, I’d wondered when DEAIC would seek to export its instruments. DEAIC had a booth at Pittcon 2016, looking to work with distributors and OEMs. The company also packs and markets HPLC columns. Sales are approaching 10,000 columns per year.


HPLC analyzers The BioEthanol analyzer from Shimadzu is a Prominence-i inte- grated HPLC equipped with a refractive index detector that measures


MAY 2016


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