If you want to pursue this even further, to get VERY detailed information that is free on the web, there are a number of patent databases that will go into detail on these analysis techniques and devices. By far the biggest one, with more than 70 million records representing over 30 million full text patents from 72 nations, is the European Patent Office's Espacenet. In its advanced search, the title/abstract words: cocaine analysis get 9 hits. Number 8 is a German patent: DE4037686 from 1991-05-16, English title: "Quantitative determn. of cocaine and its main metabolites - by thin layer chromatography followed by conversion to a fluorescing prod. by heating" The "Patent Family" and "Legal Status" tabs don't link to English language equivalent patents. But if you copy/paste the Classification numbers into the advanced search page, and limit to "publication no." us, you can limit to US patents.
For example, the European (ECLA) class C07D451/12 and number us gets 56 hits. ECLA number G01N30/90 gets 86 US patents, which seem a bit closer to this topic. Espacenet uses pdf files, and it's much easier to display and print full text from it than from our own US database, which requires a special TIFF viewer such as AlternaTIFF, to see any drawings or ANY pre-1976 scanned full text. But there's an important tradeoff that may induce you to install that viewer: USPTO searches the entire text of all 1976 and later patents, not just abstracts and titles; and this is word-processed text - not pdf searching as in Google Patents. USPTO gets 2742 hits for: cocaine and analysis; 15 hits even when you limit that search to the "Claims" - aclm/cocaine and aclm/analysis. "Claims" are the legal statements that spell out precisely what the inventor is claiming protection for.