Analytical chemistry is the sub-discipline of chemistry that determines what constituents are in a sample (i.e., qualitative analysis) and how much of each (i.e., quantitative analysis). In somes cases, a sample is analyzed for an "attribute" related to its chemical content, such as pH, specific gravity, or ash content determination. Analytical chemistry also involves the development of chemical analysis methods instrumentation for routine (such as quality control) and non-routine analyses. There are a great many sub-disciplines, dividing on such criteria as: