In the fall of 1805, Robiquet, then a young help working in the laboratory of Louis Nicolas Vauquelin, started analyses, with what rudimentary methods were then available, with asparagus juice.
Asparagine will turn out to be one of the 22 amino acids that build-up all living matter on earth, the first ever identified and understood as belonging to a new class of molecules.
Another type of natural red dye used from times immemorial was obtained from madder root in Central Asia and Egypt, where it was grown as early as 1500 BC.
Some 30 years later in April 1856, William Henry Perkin, then a mere youngster working as assistant at the Royal College of Chemistry in London within a team intent on research over the synthesis of quinine, a potent drug, discovered a process that obtained a purple dye (which he called mauveine) from aniline, which in turn could be easily obtained from coal tar; over the next ten years Perkin set up the first industrial model of molecules obtained through synthesis from coal tar and his success had prompted intense research from numerous teams all over Europe on coal tar by-products, while he himself pursued such a work on top of his industrial activity.
Thus it came that in 1868, in turn alizarin was proved to be obtainable from anthracene, in parallel by Perkin and by Carl Gräbe and Carl Theodore Liebermann, both working in Germany for the BASF company; unfortunately Perkin missed the patent priority by one single day, alizarin's extraordinary properties made it become the first really mass industry-produced dye and enabled the rise of BASF to first rank in the chemistry industry world.
Codeine is probably Robiquet's most important contribution, that prevails still today with a very strong presence and impact on daily life; in effect, until the beginning of the 19th century, raw opium was used in diverse preparations known as laudanum (see Thomas de Quincey's "Confessions of an English Opium-Eater"), paregoric elixirs (a number of them, very popular in England since the beginning of the 18th century), and health or even death hazards to users from improper preparation or improper use were frequent.
[2] This particular study, that demonstrated, as early as in 1810, the possibility to separate, using "energetic" methods, a simple "principle" that was the actual effective fraction of a traditional natural compound obtained by "soft" methods has been exemplary for the burgeoning community of chemists in the early 19th century, and will prompt very rapidly a flurry of similar attempts that will yield within a few decades an incredible number of molecules from an ever growing number of research groups throughout Europe, and soon in the trail, in the US.
Over a period of some fifteen years, Pierre Robiquet will also conduct a series of investigations on bitter almonds oil, a complex substance obtained from Prunus dulcis.
In 1830, together with Antoine Boutron-Charlard, Robiquet obtains a new molecule which he calls amygdalin; this component presented strange properties and was the first glycoside to be evidenced.
This last step was achieved some few months later (1832) by Friedrich Wöhler and Justus Liebig, these two got all the credit for this breakthrough result that was opening an entirely new branch for the industry of chemicals with wide-ranging applications.