The impact of column connection on band broadening in very high pressure liquid chromatography

A series of experiments was conducted to evaluate the degree of band broadening in very high pressure LC due to column connections. Different column manufacturers use slightly different designs for their column fittings. If the same column connections are repeatedly used to attach columns of different origins, different void volumes form between capillary tubes and column inlets. An Agilent Ultra Low Dispersion Kit (tubing id 75 μm) was installed on an Agilent Infinity 1290 ultra HPLC and used to connect successively an Agilent, a Phenomenex, and a Waters column. A series of uracil (unretained) samples were injected and eluted at a wide range of flow rates with a water/acetonitrile mixture as eluent. In order to determine the variance contribution from column connections as accurately as possible a nonretained probe compound was selected because the variance contribution from the column is the smallest for analytes, which have very low k values. Yet, this effect still has an impact on the resolution for moderately retained compounds (k > 2) for narrow-bore columns packed with fine particles, since variance contributions are additive for linear chromatographic systems. Each injection was replicated five times under the same experimental conditions. Then NanoViper column connections (tubing id 75 μm) were used and the same injections were made. This system was designed to minimize connection void volumes for any column. Band variances were calculated as the second central moment of elution peaks and used to assess the degree of band broadening due to the column connections. Band broadening may increase from 3.8 to 53.9% when conventional metal ferrules were used to join columns to connection sites. The results show that the variance contribution from improper connections can generate as much as 60.5% of the total variance observed. This demonstrates that column connections can play a larger role than the column packing with respect to band dispersion.

Developing a marine conservation program in temperate Australia: determining priorities for action

The temperate seascapes of southern Australia have, until recently, received less conservation attention than the country's tropical waters. Here, we describe the results of an expert elicitation aimed at identifying gaps and opportunities in marine conservation for temperate waters. The process highlighted the need for focusing conservation attention on temperate bays, estuaries and inlets. The subsequent development of the Great Southern Seascapes program by The Nature Conservancy is aimed at beginning to address this need. The program focuses on the following actions for temperate Australian bays, estuaries and inlets: (a) increased protection, (b) ‘in the water’ restoration, (c) initiatives to address sea-level rise, (d) improved management and increased stakeholder involvement, (e) science and monitoring, and (f) community, government, and corporate engagement and funding. Actions taken to date, including commencing Australia's first ever oyster reef restoration project, and future directions, are outlined.