General Comments on Detectors for Chromatography

This book is concerned with the unique benefits of mass spectrometry for trace level quantitative analysis, so no detailed discussion of other chromatographic detectors is included except for occasional comparisons. However, some general aspects applicable to all detectors are discussed here, with special emphasis on how these generalizations apply to mass spectrometry (see also Section 6.2.3). 

The detection limit (LOD) of a detector for a specified analyte is the smallest amount or concentration of that analyte that produces a signal that is clearly 

The lower limit of quantitation (LLOQ, Section 8.4.2) is strictly a figure of merit for an integrated analytical method. It refers to the lowest concentration of analyte in a particular complex matrix that can be analyzed quantitatively by the analytical method with specified levels of accuracy and precision. Sometimes, if not critical for the end purpose of the analysis, the LLOQ can be estimated as the lowest concentration that provides a S/B ratio of 10 1 (Section 8.4.2). 

The linear dynamic range (sometimes referred to as the range of reliable response, or simply the calibration range) is the range of concentration or amount of analyte between the LLOQ and the higher point at which the calibration curve used to determine sensitivity (see above) deviates from linearity. This quantity can refer to either 

The dead volume refers to any void volume in the detector (or anywhere else in the chromatographic system) in which mixing can occur, thus causing deterioration of chromatographic resolution and selectivity (Section 3.5.12). 

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