NIST Publishes Guide to Units
The National Institute of Standards and Technology (NIST, Gaithersburg, Maryland) has published a reference guide to the modern metric system that covers the correct U.S. usage of metric units.
The National Institute of Standards and Technology (NIST, Gaithersburg, Maryland) has published a reference guide to the modern metric system that covers the correct U.S. usage of metric units. "The International System of Units (SI)" describes recent changes in the system since 1998. The publication includes accepted spellings of various units as well as a chapter on units for quantities that describe biological effects and symbols for expressing values for enzyme catalytic activity. The U.S. Omnibus Trade and Competitiveness Act of 1988 designated the metric system as the preferred weights and measures system for U.S. trade and commerce, and U.S. Public Law 110-69 in 2007 replaced the old definition of the metric system with the SI definition.
Modern HPLC Strategies: Improving Retention and Peak Shape for Basic Analytes
August 16th 2024In high-performance liquid chromatography (HPLC), it is common for bases and unreacted ionized silanols on silica-based columns to cause irreproducible retention, broad peaks, and peak tailing when working with basic analytes. David S. Bell, Lead Consultant at ASKkPrime LLC offers innovative HPLC strategies that can help mitigate such issues.
Reliable Separation and Efficient Group-type Quantitation of Total Petroleum Hydrocarbons (TPHs)
September 11th 2024Petroleum contamination from leaking underground storage tanks, for example, is a significant concern for both the environment and human health. Thorough characterization of the contamination is required to form appropriate risk assessments and remediation strategies, but until now, the determination of total petroleum hydrocarbons (TPHs) in soil has typically involved a convoluted and labour-intensive process. In this article, the analysis of TPH in environmental media is simplified using flow-modulated GC×GC–FID with quantitation based on pre-defined compound groupings. This approach overcomes the drawbacks of conventional solvent fractionation approaches, by eliminating the need for sample fractionation and automating data processing workflows.
The Reality Behind Column Insertion Distance
September 10th 2024Column insertion distance is critical to good chromatography. What happens if the column is installed too low in the injection port? Is insertion distance more important when performing split injection or splitless injection? Does the position of the column in the injection port impact reproducibility?
