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Points Interview with Mariana Reynoso and Gabriel Gonzalez-Bravo

Updated: Jul 24, 2023

The History of Elemental Analysis in Mexico

Today’s post features an interview with Mariana Reynoso, a Mexico-based pharmaceutical historian and Gabriel Gonzalez-Bravo, a Mexico-based chemistry researcher. These scholars focus on the history of chemistry and pharmaceutical sciences in Mexico.

Mariana and Gabriel recently authored ‘Johann Wilhelm Schaffner, Leopoldo Rio de la Loza, and elemental analysis in Mexico’ in the recently-published issue of the History of Pharmacy and Pharmaceuticals. Find out more about their backgrounds, article and future research plans in this interview.

Please tell readers a little bit about yourself.


I have a bachelor’s degree in Pharmaceutical Chemistry from the Universidad Nacional Autónoma de México (UNAM). My thesis was on the history of the first Mexican pharmacist academic dissertations in the Escuela Nacional de Medicina, and ever since I have kept my research along these lines, pairing this with a career in pharmaceutical technology affairs. I have a doctorate degree from the Universidad Complutense de Madrid, where I studied the history of pharmaceutical legislation in 19th Century Mexico. At the Universidad Autónoma del Estado de Mexico, I was responsible for the Laboratory of Pharmacy at the Faculty of Chemistry from July 2012 to February 2023. Currently I am Director for the Internationalization of Research and Advanced Studies and I seek out international collaborations for our students, teachers and programs. The history of pharmacy has been an activity of joy that fulfills my career.


I have a bachelor’s degree in Pharmaceutical Chemistry from La Salle University in Mexico, a Master’s in Chemistry from the Faculty of Chemistry UNAM and a Doctorate in Chemistry from the CINVESTAV. I have devoted my whole life to experimental chemistry. Currently I am a full researcher at the Institute of Chemistry, UNAM, where I conduct experimental and theoretical research on the nature of stereo-electronic effects and weak interactions to establish their importance in conformation, reactivity and molecular recognition.

The authors at the Institute of Chemistry

What got you interested in the history of alcohol, pharmacy, drugs, or pharmaceuticals?


As a bachelor student in pharmaceutical biological chemistry, I found myself locked out of the university due to a very long strike. One teacher offered me to work in a history of pharmacy thesis dissertation. I agreed just to be able to graduate and I admit that, at first, I thought the topic was pointless, but it served the purpose to get the diploma. When I visited the archive and worked with the very old texts, I heard the whisper of my 19th century classmates. They yelled: “rescue me from oblivion, vindicate my demands, help me,” and I believe that telling their story helped my generation to understand our identity and to be proud of who we are as pharmacists. See, in Mexico we have quite an identity crisis because our degree is different from the rest of the world’s pharmacy degrees. Knowing the origin of this confusion allowed me to make peace with it. My thesis became a book that was very well received by historians of science.


One day at the Institute of Chemistry, someone asked a question that I couldn’t answer because it had to do with the institute’s history, and I knew nothing about it. So, I began to do some research and found out that our history is very rich. Acknowledging it made me feel professionally self-esteemed. Since then, for the past few years, I have done collaborative work in the history of chemistry. I even found a lost book which is very important for Mexico: the first text book of chemistry written in this country. We recently published a facsimile edition of this book, to spread the work of the 19th century chemist, pharmacist and physician Leopoldo Rio de la Loza.

What motivated you to write this article specifically?

Mariana and Gabriel:

One day we found ourselves asking what the date of the first elemental analysis made in Mexico was. We knew Leopoldo Rio de la Loza had done this analysis, for the history of which we received an award from a London society, but we could not find the answer to our question. Leopoldo Rio de la Loza’s analysis was a known fact, so we dug in the available historical documents to found out that it was indeed the first elemental analysis made in Mexico (probably in the whole American continent). But we found something even more thrilling: it was the only elemental analysis made in the 19th century, and within a large part of the 20th century.

Explain your article in a way that your bartender won’t find boring.

Mariana and Gabriel:

Once upon a time there was a well-known chemist and pharmacist called Leopoldo Rio de la Loza, who was born in New Spain (present-day Mexico). His father had an industrial plant that produced chemical products, and he died in a terrible fire in the chemical company, so Leopoldo had to take over the plant. When Leopoldo was young, he witnessed a war of independence, and he became Mexican instead of Spanish. He was embedded in the enthusiasm of constructing a great new nation: Mexico. All he knew about was pharmacy and chemistry, so science was the trench from which he fought for the new independent nation. He followed the latest European findings regarding sciences and he was devoted to creating new institutions and teaching newer techniques to analyze Mexican medicinal plants in order to uncover the secret, curative properties hidden inside them.

One day, he met a German guy called Schaffner, who had studied with Liebig, one of the most prominent European chemists of the time. Schaffner taught Rio de la Loza a way of analyzing the components of a given substance. This so called “elemental analysis” technique happened through an innovative apparatus called a kaliapparat that made possible to trap carbon from molecules, and to quantify it. We believe Leopoldo used the kaliapparat to analyze pipitzahoic acid (today known as perezone), a substance found in a medicinal plant called pipitzahuac’s root. He published the proportions of the elements: oxygen, hydrogen, carbon, and nitrogen found in pipitzahoic acid (which were not accurate, but errors were common in those days). For this work, he obtained the first-class medal of the London Universal Society for the Protection of the Industrial Arts in 1856. After this great success, one would expect the elemental analysis technique to flourish in Mexico. Mysteriously, elemental analysis was not explored again in Mexico until the middle of the twentieth century (almost one century after Leopoldo’s analysis). The abandonment of the elemental analysis caused the country to lag way behind Europe in chemistry and pharmacy. This article describes why elemental analysis was forgotten. That reason may had come down to professional envy and pettiness against Río de la Loza, but read the full paper to find out what happened.

Did you uncover anything particularly interesting or surprising during your work on this project?

Mariana and Gabriel:

Yes. The relation between Río de la Loza and Schaffner was never reported before, so establishing this connection and affirming that it led the way to nothing less than the first elemental analysis carried out in Mexico was interesting and surprising. Also, finding out that Río de la Loza was publicly accused in several newspapers of cheating led us to hypothesize that this was the reason for abandoning elemental analysis.

What do you think is the most important takeaway from this article?

Mariana and Gabriel:

The article is fascinating because it shows the scientific work of the most famous Mexican pharmacist in the 19th Century, Leopoldo Rio de la Loza, while it also gives hints of his biography and shows some key personal aspects of this character. These elements are rarely together in a history of science work. Also, the paper shows a new facet of another famous scientist, the German botanist William Schaffner. His work as botanist has been acknowledged, but his role as a chemist has been dismissed among the history of science community. Moreover, as the article focuses mainly on a local history of science, it also depicts a clear route of knowledge between Germany and Mexico, explaining the circumstances and consequences in which it occurred. Yet, the most important takeaway is really in the main finding: the revelation of the first elemental analysis in Mexico, and the chronicle of its his oblivion.

Is this part of a larger project? What else are you working on?

Mariana and Gabriel:

Yes, we just published a facsimile of the first edition of Rio de la Loza’s textbook of chemistry. The second edition can still be found in historic libraries, and this text mentions there was a first edition that ran out of copies. We found out that the National Library of Spain guards an original book of the lost first edition, so we elaborated on an introductory study and published a facsimile edition to disseminate the work of this pharmacist. We also wrote a paper comparing both editions.

We are also trying to uncover a physical space that once was the laboratory of Andres Manuel del Rio, a famous 18th Century scientist that discovered the chemical element Vanadium, in Mexico City. Vanadium is the only non-radioactive element discovered outside Europe. We are striving to design and create a museum in the building which once hosted the first location of the Real Seminario de Minería (Royal Mining Seminar).


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