The difference between qualitative and quantitative

Qualitative analysis is used to determine what substances are present in a sample, that is, to analyze “what is there””； For example, the retention time on the chromatogram is used to determine which specific component a particular peak represents. Quantitative analysis involves determining the amount or concentration of a certain substance in a sample, that is, analyzing \"how much\"” ； For example, the specific content of a substance is calculated based on the size of its peak area. Simply put, “qualitative” analysis is used to identify a substance, while “quantitative” analysis is used to determine the amount or concentration of that substance. .

For qualitative analysis, we also provide numerical values; for quantitative analysis as well, numerical values are given, but these two sets of values do not correspond to each other. Qualitative analysis can determine the qualitative components of a substance; how could there be numerical values, or rather empirical values?

This post was last edited by qqgd on 2025-6-28 at 16:20. In analysis and testing, qualitative analysis and quantitative analysis are the two main types of sample analysis. When analyzing a component in a sample, it is necessary to first know what this component is, and also to determine how much of it is present in the sample; this constitutes a complete qualitative and quantitative analysis. For chromatographic analysis, various methods can be employed for the qualitative identification of components. For conventional components that have been sufficiently studied, considerable research has been conducted by analytical chemists on their retention behavior on specific chromatography columns; generally, retention time is used for qualitative identification. For some components that cannot be identified based on retention time, qualitative analysis can be carried out by combining them with mass spectrometry or spectroscopy; generally, qualitative analysis using mass spectrometry is highly accurate and widely applicable. For quantitative analysis, an accurate quantitative assessment of a certain component is generally carried out on the basis of ensuring precise determination; for this purpose, the internal standard method, external standard method, and standard curve method can be employed. For many common organic compounds, quantitative analysis can be performed using response factors. Modern chromatographic analysis systems are typically equipped with sufficient data processors and databases, and for conventional or established analytical methods in various industries/fields, there are specialized data processing software tools available for qualitative and quantitative analysis. In chromatographic analysis, the configuration of the analytical instruments – including chromatography columns with appropriate separation capabilities, detectors suitable for detecting the analyte components, and even appropriate post-column derivatization systems – constitutes the necessary conditions for analyzing certain specific components. The experience and knowledge of analysts, on the other hand, are important capabilities for guiding and interpreting various phenomena in analysis. A mature chromatographic analysis method, combined with appropriate chromatographic analysis software, can carry out qualitative and quantitative analysis of specific samples, especially for routine analyses in the laboratory quality control departments of various enterprises.