LCGC North America-03-01-2016

A summary of what these techniques can tell us from a qualitative and quantitative perspective

How suitable is the column plate number for system suitability testing?

The results obtained from a new survey on sample preparation techniques were compared with the results of previous surveys from 1991 to March 2013. The survey investigated trends in technologies currently being used, sample loads, sample sizes, automation, the use of solid-phase extraction (SPE) devices (cartridges, disks, plates, tips), SPE chemistries, selection criteria, and problems encountered. Respondents were also asked about sample preparation technologies on the horizon.

Adequate detection of trans-resveratrol in wine is complicated by two factors: relatively low levels and interferences from matrix components. Here, we present two useful approaches to overcoming these issues depending on the instrumentation available. For HPLC–UV analyses, matrix peaks can be removed by microextraction using packed sorbent while simultaneously concentrating the trans-resveratrol peak by a factor of two. For LC–MS, the extracted ion chromatogram for the [M + H]+ analyte ion can be used to obtain specificity without prior extraction procedures.

This study describes the need to recover compounds above the boiling point of naphthalene by optimizing the thermal desorption chemistry for the determination of VOCs from C3 to C26 in soil gas samples using Method TO-17. Figures of merit, such as breakthrough, precision, linearity and detection capability will be presented, in addition to evaluating its real-world capability at sites with moderate diesel and semi-volatile polynuclear aromatic hydrocarbon (up to pyrene) contamination, in the presence of high humidity.

Chromatographers often use the term carrier-gas flow and velocity interchangeably when discussing column parameters. In LC, the two terms scale together, but in GC they do not: Doubling the flow does not double the velocity. This month's “GC Connections” investigates the reasons for this non-intuitive behavior and how it affects best practices for gas chromatographers.

Click the title above to open the LCGC North America March 2016 regular issue, Vol 34 No 3, in an interactive PDF format.