Joseph J. Kirkland

After receiving A.B. and M.S. degrees in chemistry from Emory University in 1948 and 1949, respectively, Joseph Jack Kirkland worked for Hercules Powder from 1949-50. He left to earn a Ph.D. in Analytical Chemistry at the University of Virginia in 1953. Jack was employed by E. I DuPont de Nemours Co. at the Experimental Station, Wilmington, DE, until 1992, when he retired as a DuPont Fellow. He then was a co-founder of Rockland Technologies, Inc., where he was Vice-President, Research and Development. This organization merged into the Hewlett-Packard Co. in 1997, where he was Manager, Research and Development, Newport Site. Hewlett Packard created and spun off Agilent Technologies, Inc. in 1999, where Dr. Kirkland remained as Senior Scientist until his retirement in February, 2001. He joined Advanced Materials Technology in 2005 where he is Vice-President, R&D. Dr. Kirkland is on the editorial advisory board of the Journal of Chromatographic Science and a past member of the advisory board of the Journal of Chromatography. He edited the book, Modern Practice of Liquid Chromatography (1971), co-authored Introduction to Modern Liquid Chromatography (1974), second edition, (1979), third edition, (2009), Modern Size-Exclusion Liquid Chromatography (1979), second edition (2009) and Practical HPLC Method Development (1988), second edition (1997). He coauthored the book, Modern Size-exclusion Liquid Chromatography in 1979, 2nd ed (2009). He was co-professor of the American Chemical Society (ACS) Short Courses, Introduction to Modern Liquid Chromatography and Practical HPLC Method Development (1971- 1996), and co-author of two taped ACS Audio Short Courses on liquid chromatography. Dr. Kirkland has authored over 160 major peer-reviewed publications, mainly in the separation sciences, and holds 32 U.S. patents. Research interests involved HPLC method development, field flow fractionation, silica chemistry and silane bonding reactions (i.e., novel HPLC columns). Dr. Kirkland received the 1972 American Chemical Society Award in Chromatography, the 1973 Delaware Section ACS Publication Award, the 1974 Dal Nogare Memorial Award in Chromatography from the Chromatography Forum of the Delaware Valley, the 1979 Anachem Award, the 1982 Torbern Bergman Medal in Analytical Chemistry from the Swedish Chemical Society, the 1988 Delaware Section ACS Award, the 1993 Eastern Analytical Symposium Award in Separation Science, DuPont's Lavoisier Medal in 1997 (DuPont’s highest technical award), the A. J. P. Martin Chromatography Award Medal in 1997, the 1999 Merit Award of the Chicago Chromatography Discussion Group, The 2009 CASSS Scientific Achievement Award, the 2013 U. D. Neue Award in Separation Science and the 2014 LCGC Lifetime Achievement in Chromatography Award. Dr. Kirkland was awarded the honorary D.Sc. degree by Emory University in 1974 and also was an Adjunct Professor of Chemistry at the University of Delaware.

Biography of an Analytical Chemist My Early Life I was born on May 24, 1925 in Winter Garden, FL, about 15 miles west of Orlando and grew up in a small-town environment. My parents ran a small hotel and later a successful restaurant. My elementary schooling history was unremarkable, except that I skipped the first grade as a result of strong kindergarten training. When I was 15 years old, the family moved to Melbourne, FL to open another restaurant. Attendance at Melbourne High School was also unremarkable, except that chemistry was fortunately taught by a teacher who actively supported interest in this subject and science in general. Perhaps as a result, I was selected as class salutatorian and winner of the Bausch and Lomb Science Award. One of my other passions was football, where I competed for two years as center and linebacker. I was deemed good enough to be offered a football scholarship at then Tampa University. However, my heart was centered on a scientific career, so this was refused. My mother was set on my attending a military college, so after high school graduation in 1942, I enrolled at Georgia Military Academy, attending for one year. During that time I took courses including chemistry and physics, but also learned close-order drill which later gave me an advantage (see below). I also competed and was chosen to be a member of the rifle team. My interest in chemistry was still growing, so in 1943 I matriculated at Emory University in Atlanta which was known as a strong teaching and research center in that subject. There I studied both science and the humanities, but had my usual trouble with languages, as German was my most difficult subject. I Enter the US Navy In 1944, at the age of 19, I received my military draft notice; World War II was still in full swing. After a summer of working on a surveying crew to build a navy fighter airplane training base (now Melbourne, FL commercial airport), I was inducted into the Navy and was shipped to Perryville, MD for boot training. My previous college experience, which included close-order drill training and rifle skills, resulted in my being selected as company scribe. So I avoided the usual onerous guard duties and other unpleasant training activities for boot trainees. During this time, I was administered the Eddy Test to determine if I qualified for electronic repair training, as at that time radio, radar, and sonar were critical topics in the Navy. The test was passed, and that opened up a new path of learning. After boot camp I was sent to Wright Junior College in Chicago for initial electronic training. About 1000 candidates were there to determine who would ultimately be qualified for training. The highly intensive program, from 7:00 AM to 7:00 PM, was difficult, but the training was excellent, with good instructors and highly technical subjects. I even learned how to use a slide rule, a new tool at that time for complex calculations. After the successful conclusion of this month of primary training, I was sent to Great Lakes, MI for a secondary school in electronics.

This lasted for three months, and I was then transferred to the Radio Material Laboratory at Washington, DC -- the final school for repairing radio receivers, transmitters, radar and sonar. After this training I was designated as an Electronics Technician, Third Class, and first shipped to San Diego, CA, then to the Philippines for assignment. I ended up about ten miles north of Manila at a small Navy installation which featured high-tech diversity radio receiving equipment that gathered important signals from Guam, China and other locations. This assignment was typically boring, since the electronic equipment usually worked well and required little attention. The Japanese army had been moved out of this area, so the only security problems were guerillas machine-gunning the huts in our small camp at night as they passed by on a parallel road. My Schooling Resumes

I spent about a year at this Philippine location, and once the war was over, I was shipped back to San Francisco. There I was able to return home for a brief visit, and was then discharged from the Navy at the Charleston, SC naval base. Fortunately, the timing was such that I was able to re-matriculate at Emory University for the fall 1946 semester. Here I resumed studies in chemistry, physics, math and the required liberal arts. I obtained an A.B. in chemistry at Emory University in 1948. Deciding to continue my formal education, I persevered and was awarded an M.S. degree in analytical chemistry in 1949 under the direction of Emory’s Professor R.A. Day, who became a lifetime friend. Professor Day was a strong mentor in analytical chemistry and directed my M.S. research in polarography, for which I was able to publish my first peer-reviewed technical paper [1]. Life in Industry Begins

After graduation, I married Ann Winston Driskell and obtained a job at the Hercules Powder Company in Wilmington, DE. My work here involved the chemistry of terpenes using both UV and IR spectroscopy. After about two years at Hercules I decided to make chemical research my career. I then obtained a research fellowship for graduate studies at the University of Virginia under the direction of Professor John H. Yoe, a leading proponent of colorimetric analysis. In the spring of 1953 my work on the trace analysis of platinum metals by colorimetry resulted in a PhD in analytical chemistry, with appropriate publications [2, 3]. Following graduation, I accepted a position with DuPont de Nemours in the Industrial and Biochemicals Department, where I first used infrared spectroscopy and organic colorimetry analysis to solve problems, largely in the area of organic pesticide technology. Infrared spectroscopy studies of solid, non-volatile compounds led to a publication on quantitative measurements with a new KBr pellet disk technique [4].

Jack at 19

Jack in the lab (1960) My start in Chromatography

Gas chromatography In late 1954, I was introduced to gas chromatography (GC) by DuPont’s Dr. Stephen Dal Nogare, an early GC researcher. Steve had developed equipment and much insight on programmed temperature separation, and was co-author of an early GC source book. My interest in this method led me to obtain an all-glass DuPont-made instrument which resulted in solving some problems that were previously not possible. This success allowed me to start GC research studies of my own, resulting in the development of more sophisticated equipment that allowed programmed temperature separations up to 300° C., resulting in the analysis of higher-boiling compounds. In several projects, non-volatile compounds were modified chemically to volatile derivatives by suitable organic reactions so that GC separations were possible. For example, non-volatile sulfonic acid mixtures were analyzed after conversion to volatile sulfonyl chlorides [5]. One of the more interesting and challenging problems was the analysis of minor and trace impurities in anhydrous hydrochloric acid (HF). This required building a GC instrument that could resist HF (nickel, Teflon and platinum), with the development of a fluorocarbon column packing and a stationary phase that also could tolerate HF [6]. These GC analytical successes also led me into preparative GC which was useful for making compound identifications and for preparing purified standards. In 1964, I carried out studies on selective adsorbents for GC, prepared by a unique ionic-interaction-layering technique developed by Dr. Ralph Iler, a world-renowned colloid chemist; these results were reported at a symposium in England [7]. Ralph Iler actually hired me into

DuPont and fortuitously had a laboratory next to mine. Dr. Iler developed a silica sol layering technique to make light interference systems on glass plates. This approach consisted of depositing a thin film of a positively-charged organic polymer onto a negatively-charged glass plate. This step was followed by a layer of negatively-charged closely-sized silica sol, then another coating of positively-charged polymer, another layer of silica sol and so on, until the desired layer thickness was obtained. The regularity of the silica sol size resulted in a random close-packed structure that exhibited strong interference patterns whose color depended on the diameter of silica sol used. Fortunately, some of Iler’s vast experience in silica chemistry rubbed off on me (probably by osmosis), and his influence and friendship proved to be strong factors in my career. Later, in the early 1970’s, Dr. Iler had a research group working on an exciting new concept that involved reinforcing metals and ceramics with colloidal particles. This approach produced outstanding properties for the modified materials, greater strength and other enhanced properties, without changing the basic chemistry of the starting material.

The group was working on a thoria-filled nickel product and needed some analytical help. A continuous analysis was desired for simultaneously determining several different gases (methane, carbon monoxide, carbon dioxide, water vapor) emerging from a furnace with hydrogen passing over the heated medal powder containing thoria colloid. I was able to solve this problem by setting up several sensors arranged as a Rube Goldberg device on this gaseous effluent: a flame detector for methane, a differential thermal conductivity detector for carbon monoxide and carbon dioxide (after chemically converting the monoxide to dioxide), and a flame ionization detector for water vapor (after converting the water to acetylene using calcium carbide). This apparatus continuously recorded these components unattended over long periods, sometimes over the weekend. The results apparently were quite helpful in establishing the optimum conditions for the desired process so the analytical study was deemed a success.

I Discover HPLC

During a 1964 European trip, I was introduced to post-doctorate Dr. Joseph F. K. Huber in Professor Kuelemann’s lab at Eindhoven Technical University. Huber was carrying out the first

Monolayering of Silica Sol

Red: Positively charged polymer Circles: Negatively charged silica sol

experiments on what is now called high-pressure liquid chromatography (HPLC). This work excited me, as I had analytical problems at DuPont that could not be solved by GC; a separation method with a liquid mobile phase at lower temperatures seemed to be the answer. Joseph Huber’s experimental setup was quite modest, and it was clear that to make HPLC a practical general method, two advances in technology where needed: a sensitive, stable UV detector with a wide dynamic range, and better column packing materials. Joseph Huber had used large, irregular silica particles -- adapted from the GC lab -- to carry out liquid-liquid chromatographic separations. This method involves a liquid that is deposited in the porous structure of the column packing, and a partially miscible liquid as the column mobile phase. I rushed back from Europe and confronted my DuPont management with a proposed program that would allow the routine analysis of the many non-volatile compounds that were under development. Forward-looking management agreed, and research on HPLC began immediately. HPLC at DuPont The UV detector problem was quickly attacked by adapting a new highly-capable DuPont proprietary UV process monitor with a designed 20 µL-volume microcell and appropriate focusing optics. Size-wise this UV monitor was a large, massive device, but the performance was such that the problem of routinely detecting and accurately measuring UV-sensitive compounds now was solved [8]. An improved column packing was a more difficult problem. However, Dr. Ralph Iler’s colloidal particle layering technology proved useful. I realized that the random close-packed interference materials made with silica sols on plates leaves a porous structure (spaces between the silica sol nanoparticles) whose pore size could be controlled by the diameter of the silica sol. Using this approach, I was able to develop a superficially porous silica particle of about 30 µm which had a solid silica core and a 1-µm-thick shell with 100 nm pores. This material allowed the preparation of highly-efficient columns (for that time) using the liquid-liquid chromatography method successfully employed by Joseph Huber. These particles exhibited excellent mass transfer properties and fast separations as a result of the thin porous shell surrounding the solid core. A patent was obtained on these particles, and DuPont Instrument Products quickly commercialized these as Zipax® superficially porous particles for their emerging HPLC equipment business [9].

Early fast separation with Zipax (1967)

Difficulty in maintaining stable liquid-liquid systems was subsequently eliminated by altering the porous shell of these particles with stable, insoluble covalently-bound silicone polymers. This technology was quickly adapted by DuPont Instruments with patents co-authored with DuPont’s Dr. Paul C. Yates [10, 11]. This new HPLC column material was commercialized as Permaphase® chromatographic packings, available with different functional groups for separation selectivity changes. These stable particles led to the extensive development of what we now call reverse-phase chromatography; in addition, practical mobile phase gradient elution was possible. Synthesized small particles In the early 1960’s, published theoretical papers showed that HPLC separations could be best performed using columns with small particles, much smaller than the 30-100 micrometer particles used in early HPLC . This work was of keen interest to allow better, faster separations, so I used Ralph Iler’s colloidal coacervation technology to develop 7-µm totally porous silica microspheres. With this technique, closely-sized silica sol nanoparticles are collected as discrete spheres in an aqueous medium by a liquid polymer, such as that formed by the reaction of urea and formaldehyde. The organic polymer in these spheres hardens during the reaction so the resulting particles can be collected, heated to remove the polymer, leaving random close-packed totally porous silica microparticles. The pore size of these particles is controlled by the size of the silica sol used. This development was reported in 1972 which precipitated much action by column manufacturers and a huge jump in HPLC separation performance [12]. These particles were commercialized by DuPont Instruments as Zorbax® chromatographic particles which are still manufactured and used throughout the world. The instant success of this new technology quickly made obsolete the previous technology of the larger superficially porous Zipax particles. Curiously, the whole concept of superficially porous particles and their improved mass transfer effects resulting from improved diffusion effects with a thin outer porous shell then lay effectively dormant for more than 20 years before resurrection. Separations of large molecules When transferred to DuPont’s Central Research Department in 1972, I was interested in developing totally porous particles with wide pores for separating large molecules. I speculated that such structures might be useful for the HPLC of peptides and proteins, for which such applications had not been reported at that time. I knew little about peptides and proteins and needed much help in this area. Unfortunately, I was unable to establish a joint project with resident DuPont biochemists since slab electrophoresis was the characterization method of choice at that time. As a result, I turned my attention on developing wide-pore particles for the size-exclusion liquid chromatography (SEC) of synthetic polymers [13]. With this technology, Dr. Wallace W. Yau and I had a successful collaboration in developing new approaches for

improving the characterization of synthetic organic polymers [14, 15]. The wide-pore totally porous silica particles developed during this project were commercialized by DuPont Instruments with an important patent [16]. Out of this work on SEC also resulted in a 1979 book written with Dr. Yau and Dr. D .D. Bly as co-authors [17]. (A second edition of this book was published in 2009 with Dr. A. M. Striegel as main co-author [18].) Outside activities Out of the 1970s also came by a long and fruitful relationship with Dr. Lloyd R. Snyder. We initially met at the first meeting on HPLC in the U. S. at Wilmington DE. Later, we prepared chapters for the first book on HPLC published in 1971 which I edited [19]. We then collaborated in teaching a HPLC short course and preparing audio courses for the Continuing Education Department of the American Chemical Society which continued in updated forms for 21 years with more than 5000 students attending the live courses. This relationship with Dr. Snyder also generated books on HPLC method development for two editions with Dr. Joseph L Glajch [20, 21], and three editions of Introduction to Modern Liquid Chromatography source books on HPLC, the last published in 2009 with Dr. John Dolan as co-author [22-24]. During these years, Dr. Snyder and I also collaborated on several research projects. Lloyd and I still frequently correspond and our friendship has grown as the years have passed.

Jack Joe Lloyd Awards sent my way during the 1970’s included the 1972 American Chemical Society Award in Chromatography. Of special pleasure was the D.Sc degree awarded by Emory University in 1974, undoubtedly spearheaded by my mentor and friend, Professor R. A. Day. I also was honored in 1997 as the recipient of the Lavoisier Medal, DuPont’s highest technical award. HPLC optimization During the 1980’s, I continued HPLC research, strongly focusing on technology for optimizing separation selectivity or band spacing changes. For example, with Joseph Glajch and Lloyd

Snyder, procedures were developed for optimizing solvent strength and selectivity for both reversed-phase and liquid-solid (adsorption) chromatography [25-27]. Interactive mixture-design techniques were used to computerize the optimization so that the least number of experiments were required for “best” separations [25]. This technology was used by DuPont Instruments to develop a commercial HPLC instrument (“Sentinel”) that would automatically and systematically search solvent mixtures for superior separations. To my knowledge, this was the first commercial attempt to use an automatic computer-directed approach for optimizing HPLC separations. Field flow fractionation In the late 1980’s my attention became focused on field flow fractionation (FFF), a separation method that is especially attractive for characterizing very large molecules, polymers and particles such as colloids. Dr. Wallace Yau participated in much of this activity, and we were able to construct and report on a sedimentation FFF instrument that was capable of force fields up to about 100,000 gravities [28-31]. Studies on the separation of biological materials such as DNA, plasmids, proteins, etc. were reported with visiting post-doctorate Dr. Luke Shallnger using this equipment [32]. Patents resulted in design features [33, 34], and DuPont Instruments subsequently commercialized a 35,000-gravity sedimentation FFF instrument that was directed towards characterizing colloids and other particles. Thermal FFF equipment was also constructed in my laboratory, and papers on synthetic polymer characterizations by this technique were published [35, 36]. A new method for force field programming was devised with Dr. Yau which allowed a wide range of molecular weights to be accessed and characterized in a single analysis, eventually using refractive index, viscometric and light-scattering detectors [37]. Cross-flow FFF proved to be a superior separation method for proteins and other large biomolecular systems. Equipment and special techniques for flow force-field programming were developed [38]. This technique was verified as a superior approach for separating very large, sensitive molecules that are difficult or impossible to analyze by HPLC. In 1983, I married Karin Ruth Monson, then a chemist at AstraZeneca, who remains my true love and staunch supporter. New column technology During the 1980’s, my HPLC research was also focused on improving the chemistry of the silica support for columns. A fortunate sabbatical in my laboratory by post-doctorate Dr. Jürgen Köhler from the Max Plank Institute in Mülheim, Germany, resulted in fundamental studies of the silica surface [39] with practical applications. We found that silica for HPLC could be much improved if the metal impurities normally present in the commonly used Type A commercial silica supports were eliminated by exhaustive acid treatment. The resulting silica was rehydroxylated to create less-acidic silanol groups on the silica surface. Later, I determined that, rather than cleaning-up available commercial silica, it was more desirable and practical to form the desired porous silica microspheres directly using ultra-pure silica sol in a coacervate reaction. In this way, highly purified silica with appropriate rehydroxylation and a “friendly” surface (Type B) for separating basic compounds was developed. This material produced columns that exhibited superior properties as an HPLC support. Patents were obtained on this technology [40, 41], and DuPont Instrument Products commercialized this material as Zorbax Rx® silica for separating polar compounds, particularly organic bases.

During the late 1980’s, DuPont invested heavily in establishing technology and a business in the life sciences. I was requested to support this area with some new separations technology. As a result, with Dr. Joseph L. Glajch, we embarked on a program to develop better columns for separating peptides and proteins. The columns used at that time were relatively inefficient and unstable to the low pH mobile phases typically used for separating these materials. So, a search was initiated to find better stationary phases and to develop more efficient columns. As a result, we were able to identify that monofunctional-silane stationary phases with large functional groups adjacent to the silica support provided steric protection for the silane against hydrolysis and stationary phase loss at low pH [42]. This steric protection technology results in very stable columns at low pH, accompanied by excellent mass transfer for efficient separations. DuPont Instruments produced commercial columns (StableBond) with this technology, and this approach now is used extensively in the HPLC column industry for many separation applications. Creating a New Business

At this point, events occurred that resulted in my becoming an entrepreneur. DuPont decided not to invest in a viable commercial process to make the new silica, Zorbax Rx, and approached Dr. Joseph J. DeStefano (ex-DuPont Instruments), my longtime friend, associate and supervisor. DuPont wanted to determine if there was interest by HPLC-experienced people in taking over this commercial business, so that their existing customers would not be at a loss for this new, currently-used product. As a result, four DuPonters, including myself, formed Rockland Technologies, Inc. to take over this Zorbax Rx business. Facilities were set up manufacture the new highly-purified Type B Zorbax Rx silica in small-lots for columns. The other Rockland partners resigned from DuPont, but I remained and was allowed to be a consultant for this new company on my personal time. This arrangement was successfully carried out for about a year, with excellent commercial prospects for Zorbax Rx. Then, DuPont decided to completely abandon manufacturing all analytical columns for HPLC. We were contacted to determine if there was interest in taking over the entire DuPont column line for manufacturing and supplying analytical HPLC columns to DuPont customers. This opportunity was too great to be ignored, so we arranged a leveraged deal to take over the entire business. New facilities were obtained, some DuPont equipment bought and installed, and Rockland Technologies entered the HPLC column business in a big way. After about 40 year’s service, I retired in 1992 as a DuPont Fellow, and then was designated as Vice-President R&D for Rockland Technologies. In my last years with DuPont, two technologies that are in wide use today were researched and reported. During his sabbatical in my DuPont laboratory as a visiting scientist, Professor Neil Danielson and I prepared 2-µm wide-pore totally porous particles to carry out very fast separations of larger compounds such as proteins [43]. Resurrection of the old superficially porous particle technology also took place. Six-micrometer silica particles with a very thin wide-pore outer shell were obtained by a spray-drying method. These particles showed superior mass transfer which resulted in fast separations for peptides and proteins [44].

Rockland is sold During the following years after acquiring the DuPont HPLC business, many new column products were developed at Rockland Technologies using the new Zorbax Rx silica as a basis. Business was good, so good, that in 1997 Rockland Technologies was bought by Hewlett-Packard (HP), which was making HPLC instruments at that time, but did not have a viable column business. Two years later, HP separated a part of their business, which included all HPLC technologies, to form a new independent company, Agilent Technologies, Inc. I worked as a director and later a senior technologist at HP/Agilent Technologies. During Rockland Technology days, a successful method was developed (supported by a Small Business Innovation Research grant) for preparing high-purity silica particles by spray-drying. Unfortunately, this project was not continued when HP became the owner of Rockland Technologies. However, more importantly, during the Rockland Technology/HP/Agilent technology period, 5- µm wide-pore superficially porous particles (now called Poroshell 300) were developed for the fast separation of peptides and proteins [45]. This was the first commercial superficially-porous particles in over 30 years, and was the catalyst for the rebirth of this technology. And our old business was revived After retiring from Agilent Technologies in 2001, I gave little attention to HPLC, resigned all of my official ties with various societies, and attempted to really retire, although I did some technical writing. After a while this retired life became quite boring, but in 2005, I was contacted by Dr. Joseph DeStefano who was interested in starting a new company. He wanted to know if I might be interested in again heading up an R&D effort. I was enthusiastic about this, so a company called Advanced Materials Technology Inc. was formed by Dr. DeStefano and Timothy A. Langlois, the latter a chemical engineer whom I had hired for the spray-drying project during Rockland Technology days. I was designated as Vice-President, R&D, and we started looking for new products. I obviously had a previous interest in superficially porous particles and was aware of their separation potential. After a few false starts, a project was proposed to prepare very small particles with this structure for the fast separation of small molecules. After months of hard work, we were able in late 2006 to commercialize columns of 2.7 µm silica particles with solid silica cores and 0.5 µm-thick outer shells with 90 Å pores [46]. These materials with bonded organic stationary phases were given the commercial name of Halo® superficially porous particles. The Halo particles proved unexpectedly efficient – much higher plate numbers than expected, and there was immediate interest (and commercial success) in this new material for the rapid, high-efficiency separation of small molecules at modest pressures. Unfortunately, these columns were quickly cloned by competing manufacturers.

Following this development, we were able to develop similar superficially porous silica particles with wider pores for separating peptides and other molecules up to about 15 kDa molecular weight [47]. Columns of these particles were commercialized and designated as Halo® Peptide columns. Similar silica particles then were developed and commercialized in Halo® Protein columns with particles 3.4 µm in size and a 0.20 µm-thick porous outer shell with very wide (400 Å) pores. These were specifically designed for separating proteins and other very large biomolecules up to about 500 kDa in molecular weight [48]. Some of the latest technology in my career has involved the development of superficially porous particles with 1000 Å pores for separating very large molecules such as DNA fragments, monoclonal antibodies, etc. All of these efforts were based on the premise that particles with different and optimum pore sizes should be developed for solutes with different sizes (hydrodynamic volumes).

Some of the latest technology in my career has involved the development of 2.0 µm superficially porous silica particles designed to provide very fast separations of proteins with modest pressures and practical operating separation techniques [49]. Superficially porous particles may have again revolutionized the way that HPLC separations are conducted, and the future looks bright for this old but new technology.

Looking Back

In summary, some of the column highlights include: 1969 Zipax Porous-layer silica 30 µm) 1972 Zorbax porous silica microspheres (7 µm)

1.64 µ

1972 Permaphase Silane phase (7 µm) 1988 Zorbax Rx-silica Type-B 1989 StableBond Stable bonded phases 2007 Halo Fused-core particles (2.7 µm)

At this writing (2016), I am still working (half-time), and enjoying the opportunity to be challenged by separations problems that remain to be solved. Editor’snote[50]But what counts as “real” achievement? Publications, awards and research facilitation are at best indirect measures of scientific “success”, and are often more relevant to workers in academia than to workers in industry. We would all like to believe that “real” respect comes as a result of our contributions to society through the development of new ideas, information, or products. The relative value of such achievements is determined by how much they advance a particular area of science, and in turn how much this contributes to human welfare. An accurate assessment of people in this way may require more effort than just adding up publications, awards, and so on. Over the next five decades (1975-2015), the further development of column theory became a cottage industry, yet these added insights have played a relatively minor role in the actual preparation of better columns. Columns mainly improved as a result of successive advances in the laboratory, including: • Procedures for the direct synthesis of small, uniformly sized particles, as opposed to size

classification methods • Successive improvements in the way small particles are packed into the column • The use of highly-pure silica particles • The development of more stable and reproducible bonded phases, especially for use in

reversed-phase chromatography • The preparation of so-called “superficially porous”, “fused-core” or core-shell particles While several names are now associated with present-day column theory, one name stands out for corresponding practical improvements of the column. This person pioneered each of the above five laboratory advances, and for the past 50 years he has been a major factor in making HPLC the valuable tool it is today. It is clear that Jack Kirkland deserves “real” respect. The widespread use of his columns, with all of their related benefits, more accurately describes Jack’s contributions to science than his impressive list of publications, patents, awards and other honors. Selected References Cited

1. J. J. Kirkland, R. A. Day, Jr., J .Amer. Chem. Soc., 72, 2766 (1950) 2. J. J. Kirkland, J. H. Yoe, Anal. Chem. 27, 1335 (1954) 3. J. J. Kirkland, Anal. Chem. 27, 1340 (1954) 4. Ibid, Anal. Chem. 27, 1537 (1955) 5. Ibid, Anal. Chem. 32 , 1388 (1960) 6. Ibid, Gas Chromatography (1958), Academic Press, N.Y., p. 203

7. Ibid, Gas Chromatography (1965), Academic Press, N.Y., p 285 8. Ibid, Anal. Chem., 40, 391 (1968). 9. Ibid, U. S. Patent 3,505,785, April 14, 1970. 10. J. J. Kirkland and P. C. Yates, U.S. Patent 3,772,181, March 27, 1973 11. Ibid, U.S. Patent 3,795,313, March 5, 1974 12. Ibid,, J. Chromatogr. Sci., 10, 593 (1972). 13. Ibid, J. Chromatogr., 125, 219 (1976). 14. J. J. Kirkland, W. W. Yau, H. J. Stoklosa, C. H. Dilks, Jr., J. Chromatogr. Sci., 15, 303 (1977) 15. W. W. Yau, C. R. Ginnard, J. Chromatogr., 149, 465 (1977) 16. J. J. Kirkland, U.S.Patent 3,782,075, January 1, 1974 17. W. W. Yau, J. J. Kirkland, D. D. Bly, Modern Size-Exclusion Liquid Chromatography, John Wiley and Sons, New York, 1979 18. A. M. Striegel, W. W. Yau, J. J. Kirkland, D. D. Bly, Modern Size-Exclusion Liquid Chromatography, 2nd ed., John Wiley and Sons, Hoboken, NJ, 2009 19. J. J. Kirkland ed., Modern Practice of Liquid Chromatography, John Wiley and Sons, New York, 1971. 20. L. R. Snyder, J. L. Glajch, J. J. Kirkland, Practical HPLC Method Development, John Wiley and Sons, New York, 1988. 21. L. R. Snyder, J. J. Kirkland, J. L. Glajch, Practical HPLC Method Development, 2nd ed., John Wiley and Sons, New York, 1997. 22. L. R. Snyder, J. J. Kirkland, Introduction to Modern Liquid Chromatography, John Wiley and Sons, New York, 1974. 23. Ibid, Introduction to Modern Lquid Chromatogarphy, 2nd ed., John Wiley and Sons, New York, 1979. 24. L. R. Snyder, J. J. Kirkland, J. W. Dolan, Introduction to Modern Liquid Chromatography, 3rd ed., John Wiley and Sons, Hoboken, NJ, 2010 25. J. L. Glajch, J. J. Kirkland, K. M. Squire, J. M. Minor, J. Chromatogr., 199, 57 (1980) 26. J. L. Glajch, J. J. Kirkland, L. R. Snyder, J. Chromatogr., 238, 269 (1982) 27. J. J. Kirkland, J. L. Glajch, J. Chromatogr., 255, 27 (1983) 28. W. W. Yau, J. J. Kirkland, Sep. Sci. Technol., 16, 577 (1981) 29. Ibid, J. Chromatogr. 218, 217 (1981) 30. J. J. Kirkland, W. W. Yau, Science, 218, 121 (1982) 31. J. J. Kirkland, C. H. Dilks, Jr., W. W. Yau, J. Chromatogr., 255, 255 (1983). 32. L. E. Schallenger, W. W. Yau, J. J. Kirkland, Science,.218, 121 (1984). 33. J. J. Kirkland, W. W. Yau, U.S. Patent 4,285,809, August 25, 1981 34. C. H. Dilks, Jr., J. J. Kirkland, W. W. Yau, U. S. Patent 4,448,679, May 15, 1984 35. J. J. Kirkland, W. W. Yau, J. Chromatogr., 353, 95 (1986) 36. Ibid, Macromol., 18, 2305 (1985) 37. J. J. Kirkland, S. W. Rementer, W. W. Yau, Anal. Chem., 60, 610 (1988) 38. J. J. Kirkland, C. H. Dilks, Jr., S. W. Rementer, W. W. Yau, J. Chromatogr., 593, 339 (1992) 39. J. Köhler, D. B. Chase, R. D. Farlee, A. J. Vega, J. J. Kirkland, J. Chromatogr., 352, 275 (1986) 40. J. J. Kirkland, J. Köhler, U. S. Patent 5,032,266, July 16, 1991 41. Ibid, U. S. Patent 5,108,595, April 28, 1992 42. J. L. Glajch, J. J. Kirkland, U.S. Patent 4,847,159, July 11, 1989

43. N. D. Danielson, J. J. Kirkland, Anal. Chem., 59, 2501 (1987) 44. J. J. Kirkland, Anal. Chem., 1239, 1245 (1992) 45. J. J. Kirkland, F. A. Truszkowski, C. H. Dilks, Jr., G. S. Engel, J. Chromatogr. A, 890, 3 (2000) 46. J. J. Kirkland, T. J. Langlois, J. J. DeStefano, Amer. Lab., 39 18 (2007) 47. S. A. Schuster, B. M. Wagner, B. E. Boyes, J. J. Kirkland, J. Chromatogr. Sci., 48, 566 (2010) 48. B. M. Wagner, S. A. Schuster, B. E. Boyes, J. J. Kirkland, J. Chromatogr. A., 1264, 22 (2012) 49. B. M. Wagner, S. A. Schuster, B. E. Boyes, W. L. Miles, D. R. Nehring, J. J. Kirkland, LCGC North America, 33, 856 (2015) 50. “Who’s on Top”, L. R. Snyder, Anal. Scientist, November 2013, p. 18.