The foundations of Feigl's work on spot analysis were the works of Hugo Schiff (the earliest publication about "spot test" was Shiff's detection of uric acid in 1859[3]) and of Christian Friedrich Schonberg and Friedrich Goppelsröder on capillary analysis.
[2] On the occasion of Feigl's 70th birthday the Chemical Society of Midland sponsored a symposium in 1952, attended by 500 scientists from 24 countries, in which all plenary sessions were related to spot tests.
[2] The test uses the qualitative characteristics of colored compounds to account for performed chemical reactions.
Another application is high-throughput screening, whichoften uses spot assays to determine the growth of eg.
mated cells or to check for protein-protein interactions in a yeast two-hybrid test.