Nicholas H. Snow is the Founding Endowed Professor in the Department of Chemistry and Biochemistry at Seton Hall University, and an Adjuncy Professor of Medical Science. During his 30 years as a chromatographer, he has published more than 70 refereed articles and book chapters and has given more than 200 presentations and short courses. He is interested in the fundamentals and applications of separation science, especially gas chromatography, sampling, and sample preparation for chemical analysis. His research group is very active, with ongoing projects using GC, GC-MS, two-dimensional GC, and extraction methods including headspace, liquid-liquid extraction, and solid-phase microextraction. Direct correspondence to: LCGCedit@mmhgroup.com
Is Golay’s Famous Equation for HETP Still Relevant in Capillary GC? Part 1: A Common View of HETP
January 1st 2022In this instalment we take a close look at Golay’s famous equation that most people see as relating HETP (height equivalent to a theoretical plate) to the carrier gas flow rate or average linear gas velocity in a capillary column.
Remembering Harold McNair: Three Fundamental Areas of Understanding in Gas Chromatography
September 1st 2021Professor Harold Monroe McNair, among the original icons of chromatography, passed away on 27 June 2021 at the age of 88. In this tribute to the remarkable man and using his works as a guide, we explore three fundamental areas of understanding in GC, seeing ideas about problems that still challenge gas chromatographers today.
Capillary Gas Chromatography: Getting the Best Separation Without Turning (Too Many) Wrenches
August 9th 2021This column will examine simple steps that can be taken to optimize a separation without changing the column. Adjusting temperature, flow, and sampling with an eye towards the classical method optimization goals of high resolution, high speed, high sample capacity, and ease of use will be discussed.
Going Low: Understanding Limit of Detection in Gas Chromatography
May 17th 2021A review of the history and fundamentals for determining and reporting limit of detection (LOD) for analytical instruments and methods. Includes a discussion of the International Union of Pure and Applied Chemistry (IUPAC) and propagation of errors methods used for calculating LOD, and explains the limitations of the IUPAC method in modern chromatography.
Going Low: Understanding Limit of Detection in Gas Chromatography (GC)
May 1st 2021The limit of detection (LOD) of an analytical method may be defined as the smallest concentration of analyte that has a signal significantly greater than that of a blank sample signal. We explore the sources of experimental uncertainty and variability in LOD determinations.
Columns - Control or Chaos: How Can We Run a Gas Chromatograph from Anywhere?
March 5th 2021A look at how the data system controls the functions of the instrument. The same fundamental electronic principles used to manually control gas chromatographs in the 1970s are still at the center of today’s modern electronically controlled systems.
Let’s Get Small: Powerful Gas Chromatography in Small Packages
March 1st 2021Capillary GC has been miniaturized, while maintaining some performance aspects of full-size laboratory systems. The benefits and challenges involved with considering these newer, smaller gas chromatographs for typical analytical problems are discussed.
Flying High with Sensitivity and Selectivity:- GC–MS to GC–MS/MS
February 1st 2021Mass spectrometry (MS) is the most powerful detector available for gas chromatography (GC). This article reviews the fundamentals of MS/MS and how they relate to MS as a detector for GC, then examines scenarios where use of GC–MS/MS can solve complex problems.
What Chromatograms Can Tell Us About Our Analytes
January 1st 2021Many chromatographic methods are automatically performed by today’s data systems, yet trace their origins to early, simpler techniques. This piece discusses how our data systems both assist and hinder in obtaining maximum information from chromatograms.
What Chromatograms Can Teach Us About Our Analytes
January 1st 2021For GC, how do data systems both assist and hinder us in obtaining maximum information from chromatograms? We explain how a chromatogram can provide a wealth of information about an individual analyte in a sample, about the sample itself, and about how well a GC instrument is performing.
Control or Chaos: How Can We Run a Gas Chromatograph from Anywhere?
November 1st 2020This instalment explores how the data system controls the functions of the GC instrument. Drawing on classical electronics and instrument designs, the article describes the evolution of instrument controls from knobs and gauges on the front panel of the instrument to computer control and current web-based systems.