Q. When writing about experiments it’s common to name things like samples as “sample A.” Should “sample” be capitalized, as “Sample A” is referring to a specific sample, or is “sample” acting as a descriptive title and “A” is the proper noun?
A. In Chicago style, most generic nouns remain lowercase when paired with a letter or number: page 14, section 1.3, chapter 5, table 2, figure A.1, appendix B, apartment 2D, suite B, stage II, type 1, grade 3 (see CMOS 9.8 for additional examples). Exceptions are reserved for course titles and other official names and designations—as in Economics 101 (the title of an introductory course on economics; see 8.87), Category 5 (the highest level on the Saffir–Simpson wind scale), or Title IX (the civil rights law). Our preference, then, would be to write “sample A” (with a small s).
Some guides, especially in the sciences, specify initial caps for certain parts of a document (as in Table 2 and Figure A.1); see The CSE Manual: Scientific Style and Format for Authors, Editors, and Publishers, 9th ed., sec. 9.3.3, and the AMA Manual of Style, 11th ed., sec. 10.4. But a sample isn’t in this category, so we’d recommend lowercase even in scientific usage (as in this 2024 article on polygenic embryo screening in vol. 7, issue 5, of JAMA Network Open, which has “sample 1” but “Figure 1A”).
For the en dash in “Saffir–Simpson,” see CMOS 6.85.