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FOREWORD

When I moved from university to an NMR laboratory in the chemical industry at the end of the 1980s, I wanted to apply my experience with quantitative NMR from my graduate studies to real laboratory operations. For this purpose, I had quantitatively evaluated some of the results of the normal NMR spectra and presented them to colleagues from other areas of analysis, mainly chromatography. A dear colleague replied to me as follows:

"An analyst would rather use his colleague's toothbrush than his method."

For more than 30 years I have been successfully applying quantitative NMR spectroscopy in a professional setting, but still have the feeling that not much has changed regarding the above statement. Understandably, there is still a distrust of qNMR on the part of mainstream methodologists from the HPLC laboratories and specialists in elemental analysis, but surprisingly also from within the ranks of NMR spectroscopy itself. Even the term “qNMR” is a pleonasm because NMR always has the potential to be interpreted quantitatively – only the precision is affected by the details of the experiment and analysis. NMR spectroscopists often take for granted important, distinguishing points about NMR that deserve restating: the method is non-destructive, and no physical separation of chemical species is required.

This book is intended to give everyone the opportunity to make friends with qNMR as a reliable method that offers the solution to a variety of problems in pharmaceutical analysis, food analysis, or even environmental analysis or diagnostics. For some of us – by which I mean pioneers and advocates of qNMR – the method clearly is most discussed in the metrology discipline, alongside primary methods such as weighing or coulometry. Through logical considerations and unambiguous experiments, all quantitative measurements can, in principle, be traced back to a uniform standard, e.g., water.

One does not have to solve all analytical quantitative problems using NMR spectroscopy, but a lot can be achieved. Let's turn this statement around: you don't have to solve everything with HPLC or titration, even if you have always done so. Technical and financial efforts must be considered to decide on the right method. In addition, there is always the need to consider the principle of traceability to SI, or to judge the robustness of the method under GxP.

This book is not a collection of methods, but it is intended to lay the foundations for a general acceptance of NMR in the canon of classical organic and inorganic analysis. It will hopefully be an eye-opener for many readers, as well as a blueprint for successful and confident adoption and use of NMR for myriad quantitation tasks.

In April 2023, my mentor, Prof. Dr. Stefan Berger, passed away. He was not only my teacher but also a role model and friend. His practical application of NMR spectroscopy in daily work is accessible at every NMR workstation, notably through his books"100 and 200 Experiments." In the early 80s, he introduced an automated NMR system with sample changer and multiple access points.

Allow me to share an anecdote from the mid-80s. At that time, a complete research group