ADVANCES IN SEPARATION SCIENCE continued


and vacuum can be applied to accelerate liquid movement. A typical protocol involves linking subroutines for conditioning, sample loading, washing, elution, fraction collection, derivatization and plate loading for LC/MS. Optional modules enable liquid/liquid extraction, shakers and temperature-control stations on a 15-position deck.


Horizon Technology’s (Salem, N.H.) new SmartPrep Extractor uses posi- tive-pressure sample and solvent flow for high recovery and precision. The automated process facilitates recovery of up to four fractions from each SPE tube. Compatible tube sizes range from 1 to 6 mL; sample sizes are from 1 to 1000 mL.


Horizon’s SPE-DEX 4790 extracts semi- and nonvolatile analytes from drinking water. The control module can manage between one and eight extraction modules.


Hamilton Co. (Reno, Nev.) introduced a positive-pressure extraction and evaporation module that sits on the deck of the VANTAGE, STAR and NIMBUS liquid-handling platforms. The Hamilton MPE2


automated extrac-


tion and evaporation module can be used to dry the liquid sample that is eluted from an SPE process. Once the elution liquid is removed, the sample may be taken up in an organic solvent that is more compatible with the intended assay technology. The drying gas can be either compressed nitrogen or air. Heating the gas is an option.


Biotage (Charlotte, N.C.) presented a poster on interwell contamination during the loading and drying of plates. This led to the development of the Biotage ACT Plate Adapter (patent pending), which sits atop a multiple-well plate. It significantly reduces cross-contamination, even with volatile analytes.


QuEChERS methods and products In addition to conventional QuEChERS, UCT (Bristol, Penn.) has developed protocols called AOAC QuEChERs (AOAC 2007.01) and Buffered QuEChERS (EN 15662). Carbon black is replaced with a proprietary polymeric sorbent called Chlorofiltr to remove chlorophyll without significant loss of planar analytes. UCT QuEChers products show very low background compared to packed tubes prepared in the lab.


Dried-blood-spot processors GERSTEL’s DBSA (dried-blood-spot analyzer) automates sample process- ing, from card to injector. Evaluation of the analyzer with samples of dried bovine and rat blood spiked with ketamine and amitriptyline and other drugs using an LC/MS/MS analyzer showed that the blood spots produced signals that were about 110% of target for bovine blood, with RSDs of 4–6%.


The CAMAG (Wilmington, N.C.) DBS-MS 500 dried-blood-spot sample- prep workstation supplies liquid samples for assay by LC/MS. Its spacious XY platform provides ample room for 2000 DBS cards. Cards are identified and tracked with inputs from a barcode reader. The spot is punched and added to the vial, and the card is then returned to its tray. Internal standard is added just before extraction. Appropriate wash solvents dissolve the analytes, which are separated from the card matrix by centrifugation. Supernatant is recovered and prepared for injection into the LC/MS. Percent coefficient of variation for peak area ratios is better than 3%, and carryover is insignificant.


AMERICAN LABORATORY 22


Sample extraction system The Waters Oasis PRiME HLB uses a new, patented polymer to reduce the steps in SPE workflow. Conditioning of the sorbent bed and washing are eliminated, leading to two- or three-step protocols.


LC columns


Chemists at MilliporeSigma looked for a surface chemistry that provided slightly different selectivity than conventional alkanes, particularly when screening for a pain panel. They found that the added aromaticity of a biphenyl phase provided a separation of eight target analytes in 2.2 minutes—hence Ascentis Express Biphenyl U/HPLC columns. Biphenyl is bonded to porous silica on a 2.7-μm-diameter Fused-Core silica. This format provides UHPLC column efficiency with pressure drop compatible with legacy HPLC instruments.


COSMOCORE core-shell particles (Nacalai Tesque, Kyoto, Japan) are 2.6 μm in diameter with a 0.5-μm silica shell. Bonded surface chemistries include C18, cholester and pentabromophenyl (PBr).


Akzo Nobel (Pasadena, Calif.) added phenylhexyl surface chemistry to the Kromasil line of columns. This phase seems to be particularly well-suited for separation of histamines under reversed-phase liquid chromatogra- phy (RPLC) conditions. It is available on either 1.8-μm or 2.5-μm Kromasil particles as Eternity XT 1.8 or Eternity XT 2.5. The UHPLC version provides very short run times.


GPC LF Series columns from Shodex (Tokyo, Japan) are packed with a 6-μm-diameter packing with a maximum pore size of 3000 Å, which has an exclusion limit of 2,000,000 for polystyrene. The columns offer a wide operating range. For more resolution, two columns are connected in series. This provides a more uniform and convenient way to construct a linear calibration plot than having to tune the column chain by connect- ing a series of narrow-range-porosity columns.


In the name of Shodex Asahipak NH2P-50 series columns, the “P” desig- nates polyvinyl alcohol polymer bead, which permits ligand attachment via ether linkages, which are more durable, especially at high pH.


Four new SEC columns in the KW400 series from Shodex have protein exclusion limits of 150, 500, 600 and 20,000 kD. The stationary phase is porous silica with a hydrophilic polymer coating. Specifications include Pmax


: 1450 psi, Fmax


: 0.35 mL/min, temperature range: 5–45 °C, pH range:


3–7.5, particle size: 3 μm for the 150- and 600-kD phases and 5 μm for the larger pore sizes.


Shodex narrow-pore ODP2 HP series columns have reversed-phase selectivity for small molecules, but the pores of the 5-μm-diameter poly(hydroxymethacrylate) particles are narrow enough to exclude large proteins. The columns show strong retention of highly polar metabo- lites. High salt concentration is not required to get good peak shapes. Recommended range is 1–50 mM. The columns are thus well-suited for chromatography of drugs and metabolites in biological fluids with MS detection using conventional RPLC mobile phases, even with basic pH.


Building on the success of HILICpac VG-50 columns, Shodex introduced the HILICpac VT-50 for more polar analytes such as phosphorylated sac- charides and organic acids. OHpak LB-800 columns, for aqueous SEC


MAY 2016


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