Resources for LC Practitioners in 2017: What’s on Your Bookshelf and in Your Web Browser?

What are the most useful chromatography books on your bookshelf? What are the most useful web-based resources (such as websites, downloadable documents, videos) about separation science? What are the most useful tools supporting your work (such as calculators and simulators)? In this installment, Dwight Stoll compiles input from the separation science community (both individuals and vendors) to guide you to the resources that people find most useful. 

Since I started thinking several months ago about putting this installment of “LC Troubleshooting” together, my thoughts have been focused on two themes. First, the information landscape is changing very rapidly in most fields, and separation science is not immune to this trend. There are so many different vehicles for sharing information available now, including webinars, blogs, and websites, in addition to the more traditional resources of journals and books. As a result, it really is difficult-if not impossible-for any one of us to keep up with changes in the field that are important to us. I don’t think any of my chromatographer friends would say they feel confident that they have a good handle on the literature and other information at any moment in time. Second, I think that a point John Dolan made in his final “LC Troubleshooting” column installment in October (1) is astute and valuable: toward the end of that installment he noted that over the years he aimed to help readers of his column be better troubleshooters by supporting their learning about chromatography concepts and how chromatography instruments work. In other words, the more deeply we understand how the instrument works and what is going on inside the box chemically and physically, the more likely it is that we as practitioners can solve problems we encounter and make our work more efficient and effective (and enjoyable!). The more I have thought about John’s point, the more I agree with it. To that end, I am hopeful that the resources that I’ve pulled together in this installment will yield at least one gem for each reader. I hope you find one new book, website, or tool that you had not considered before, and that it helps you in your work.

Now, the problem of course is that I don’t think there is any single person in the chromatography community that has the “right” answer to the following question: Which resources are the best ones? So, the approach I have taken here is to crowdsource that information, with the hope that the cream has floated to the top. I’ve asked instrument and consumables companies that regularly contribute to LCGC to send me a list of resources highlighting those they think are most useful to the community. I’ve also reached out to more than 60 individuals in my professional network who I view as experts in their respective research areas, or at least as highly experienced chromatographers. This group is roughly composed of 60% from industry, 40% from academia, and a few folks from government laboratories. They represent six continents and eight countries. A large majority of respondents were in the age range of 31–50 years old; however, the range spanned from one person in his 20s to several over 70. I asked them to respond to the following questions, with a focus on those resources they find most helpful in whatever work they do that involves liquid chromatography (LC):

·      What are the five most useful books on your bookshelf?

·      What are the five most useful web-based resources (such as websites, downloadable documents, or videos)?

·      What are the five most useful tools supporting your work (such as calculators or simulators)?

In my presentation, discussion, and summary of the input received from individuals and suppliers I have focused the attention on those resources that people find most useful. Of course, it is impossible to summarize all of the resources available to us in a few pages, so the perspective here is not intended to be comprehensive. However, I’d love to hear from you if you think there is a gem that has been overlooked here, and I’ll be sure to call attention to it in a future article (please see contact information at the end of this article). You can also share suggestions through the commenting function at the bottom right of this page, where it says “Add new comment.”

Books

In total, 58 different books were cited by respondents as being on their list of five most useful for their work in LC. Many of these were only cited once by the group, but I’ve chosen to share them all because there is quite a lot of diversity of material represented in the list. Table I shows the list, sorted by descending frequency of mention by the group, where the “votes” column indicates the frequency of mention. Those titles receiving the fewest mentions are sorted by year of publication. A few comments come to mind after looking at this list. First, I think it makes a great shopping list for young scientists. Second, several respondents pointed out that the most useful books on their shelves are not about chromatography per se, and this observation is evident from the table. For example, the books by Reichadt and Welton (Solvents and Solvent Effects in Organic Chemistry) and Poling and Prausnitz (The Properties of Gases and Liquids) are not focused on chromatography, but contain information about solvent properties that help us understand how chromatography works. Similarly, some respondents referred to books that focus on a different mode of chromatography (for example, Berger’s Packed Column SFC), because they contain good ideas and explanations of chromatography that are generally applicable. Again, I’ve intentionally included the less frequently mentioned books. Some of the newer ones will benefit from more consideration by a wide audience (for example, Vitha’s Chromatography: Principles and Instrumentation), while some of the older ones are classics that younger scientists simply may not be aware of (for example, Snyder’s Principles of Adsorption Chromatography).

User-Identified Web-Based Resources

The books listed in Table I provide an incredible amount of information to support anyone working in LC. Increasingly, though, web-based resources provide information and tools that are difficult, if not impossible, to deliver in the form of a traditional printed book. Table II contains a summary of the web-based resources mentioned by respondents to my user survey. Again, this collection is not intended to be comprehensive. Rather, it represents a first pass at identifying those resources users find most useful in their day-to-day work with LC. The printed version of Table II only contains the resource name and a short description, but the online version of this article contains hyperlinks.. And in principle, these are discoverable with a simple web search. Many of these resources are self-explanatory, but I’d like to highlight a few things in each category.

Resources, Broadly Defined

Many users commented on the usefulness of John Dolan’s past “LC Troubleshooting” articles. These are all accessible through the LCGC website, but they have also been organized into John’s “LC Troubleshooting Bible.” The web version of this resource is searchable by keyword and enables rapid discovery and access to the troubleshooting ideas you need most.

Tutorials, Primers, and Guides

Much of the information cited in this box did not exist five years ago, and certainly not 10 years ago. The resources listed here are incredibly rich, with accurate information that is relevant to modern high performance liquid chromatography (HPLC). ChromAcademy was mentioned by users most frequently, and it is an excellent tool for learning about HPLC and related technologies. I personally use it extensively in my own teaching-both for classroom teaching and with my research students-in addition to the excellent primers on various topics offered by Waters and Agilent.

Tools for LC Simulation and Calculation

When we get to the tools in this column, the value of web-based resources really becomes apparent. It is said that a picture is worth 1000 words. A video or animation, then, must be worth at least 20,000 words. The tools listed here, like animations in ChromAcademy, enable users to explore and study the complex physical relationships that are central to the way chromatography works. The HPLC simulators listed in this box offer users a number of different options for simulating HPLC separations with varying degrees of sophistication. There are also dedicated tools to assist users with transferring methods from one instrument to another (2), or to improve analysis time by taking advantage of recent improvements in particle and instrument technology. The commercial product DryLab was mentioned frequently as an aid to method development. This sophisticated tool was originally developed by LC Resources, and is currently available from the Molnar Institute.

Tools for Molecular Properties

Effective and efficient method development in HPLC usually benefits from a detailed understanding of the physical and chemical properties of the compounds we are trying to separate. Users pointed to a number of tools that are useful for this purpose. I’ve only listed two in this box, because the ChemSpider website actually leverages several individual tools for molecular property prediction. For example, ChemSpider allows the user to predict (for free) properties such as dissociation constants (pK_a) and partition coefficients (log P) using the EpiSuite algorithms from the U.S. Environmental Protection Agency (EPA), tools from ACD Labs, Inc., and ChemAxxon (for example, www.chemicalize.com). As someone who also spends quite a lot of time teaching acid-base chemistry in the context of quantitative chemical analysis, I find these tools invaluable.

Tools for HPLC Column Comparison and Selection

Finally, several web-based resources were mentioned by users as being useful for the purpose of understanding the relationships between different column chemistries and columns from different vendors. To some extent these tools also support column selection, especially in cases where a column is very similar to, or very different from, a column already in hand.

Vendor-Identified Web-Based Resources

In addition to my survey of individual experienced chromatographers, I also asked several vendors of chromatography instrumentation, consumables, and software to send me references for up to five web-based resources that they believe are particularly useful to the community. Of these, I selected up to four in each case, and organized those into the categories presented in Table III. 

Surprisingly, there is not too much overlap between Tables II and III. Perhaps some of the resources identified by vendors have been a bit hidden, and users will find them useful now that they have been brought to light. I think most of the items in Table III are self-explanatory, especially given the prior discussion of Table II, and I will not comment further on them here. However, there is one item that I found to be unique-the Phenomenex blog post “What is USP Chapter 621?”-which may be of particular value to many readers. In conversation with many users and vendors I find there is a lot of confusion around United States Pharmacopeia (USP) Chapter 621 (3), part of which is concerned with allowable changes to a USP method. I hope that resource will bring some clarity to this topic.

Closing Thoughts

I hope this installment achieves two things. First, I hope that all readers find a resource identified here that they were not previously familiar with, and helps them in their work on LC. Second, I expect that identifying these resources will lead to conversation that uncovers other gems, and perhaps even inspires individuals or groups to develop new resources that address existing gaps in these materials. If you know of a useful resource that you would like to see discussed, please let me know and I will draw attention to it in the future.

Two final points are worth mentioning here. First, a few respondents pointed to online discussion groups such as www.chromforum.org as resources for questions that the chromatography community might have answers to. Second, some respondents pointed out the value of hands-on training in learning about chromatography. Although the paper and web-based resources discussed here are very useful, I would certainly agree with the idea that there is no more effective way to learn about the practice of LC than through hands-on experience, recognizing that this can also involve significant upfront cost.

Acknowledgments

I want to extend a sincere and hearty thank you to all of the individuals and vendors who took the time to respond to my questions.

References

1. J.W. Dolan, LCGC North Am. 35(10), 746–751 (2017).
2. D.R. Stoll and T. Taylor, LCGC North Am. 35(11), 802–809 (2017).
3. General Chapter <621> “Chromatography-System Suitability” in United States Pharmacopeia 39-National Formulary 34 (United States Pharmacopeial Convention, Rockville, Maryland, 2016).

Dwight Stoll is the editor of “LC Troubleshooting.” Stoll is an associate professor and co-chair of chemistry at Gustavus Adolphus College in St. Peter, Minnesota. His primary research focus is on the development of 2D-LC for both targeted and untargeted analyses. He has authored or coauthored more than 50 peer-reviewed publications and three book chapters in separation science and more than 100 conference presentations. He is also a member of LCGC’s editorial advisory board. Direct correspondence to: LCGCedit@ubm.com