LCGC North America-11-01-2016

LCGC North America

Reader’s Question: Early Eluted Peak

November 01, 2016

LC Troubleshooting

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What could be causing a peak to be eluted before the column dead time? In last month’s “LC Troubleshooting” (1) we looked at problems two readers had with ghost peaks in gradient runs. This month, we’ll continue looking at submitted questions and examine one submitted by another reader of this column.

Statistics for Analysts Who Hate Statistics, Part III: Principal Component Analysis

November 01, 2016

Special Feature

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Part III of this series takes a closer look at principal component analysis (PCA). PCA can be very useful for observing your data when the observations you wish to compare are described by many variables. It is a relatively easy way to obtain a simplified image of the data, while trying to maintain as much information as possible.

Workflow Development for the Analysis of Phenolic Compounds in Wine Using Liquid Chromatography Combined with Drift-Tube Ion Mobility–Mass Spectrometry

November 01, 2016

Peer-Reviewed Articles

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Here we propose an exemplary workflow for the analysis of phenolic extracts (i.e. wine) enabling confident differential analysis using high performance liquid chromatography in combination with low-field drift tube ion mobility quadrupole time-of-flight mass spectrometry (HPLC×IMS-QTOFMS). In this workflow, single-field collisional cross section values from low-field drift-tube IMS using nitrogen as drift gas (DTCCSN2) are readily extracted in addition to a retention time and a high resolution mass spectrum for each compound. “Alternating frames” experiments utilizing post-drift tube fragmentation also allow drift time-aligned MS/MS spectra to be obtained. Molecular feature extraction was highly repeatable with average precision values of 0.28% for retention time, 0.18% for drift time, and 1.5 ppm m/z determined for 233 molecular features found in all six technical replicates. The improved selectivity of this strategy increases confidence in intersample molecular feature alignment (i.e. compound identity confirmation), including the resolution of co-eluting isomeric compounds.

Supporting Bioanalysis with Dried Blood Spots

November 01, 2016

Sample Prep Perspectives

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Blood is perhaps the most widely used sample fluid in bioanalysis. Dried blood spots (DBS) have been used with clinical samples for over 50 years but are recently seeing a resurgence of interest. DBS hold several advantages associated with the use of small sample sizes obtained via finger pricks, reduction biohazard, and more. In the previous installment, we gave an overview of microsampling in bioanalysis. This month, we will dig deeper into bioanalysis using DBS.

Vol 34 No 11 LCGC North America November 2016 Regular Issue PDF

November 01, 2016

Issue PDF

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Click the title above to open the LCGC North America November 2016 regular issue, Vol 34 No 11, in an interactive PDF format.