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Excellent customer service when I called. David C. Lytle ZirChrom method developers reduced our analysis turn around time from 1 hour to 10 minutes! Allyson Norman I would recommend that every research scientist have a ZirChrom® -PBD column on hand for his/her toughest separations. In our case, we had a very small hydrophilic impurity and a larger very hydrophobic pharmaceutical compound that we needed to separate. The separation on any silica-based column that we tried was poor and not very robust. One of the analytes was completely unretained (even in 100% water) while the other analyte was too well retained. We used the ZirChrom® -PBD column with phosphate in the mobile phase as a mixed-mode (reversed-phase/cation-exchange) support that easily separated the two compounds. We were able to manipulate the separation factor through the amount of organic in the mobile phase and/or through a change in the ionic strength of the mobile phase. The final optimized separation was very robust and had a unique selectivity from any other column that was tried. Senior Research Scientist After months of HPLC method development work with emamectin, I was out of ideas. I had tried many types of silica-based columns and many different mobile phases, but I could not find a system that would be suitable for scaling up to a preparative level. Every method that I had tested gave me broad, tailing peaks. Even highly endcapped, base-deactivated columns gave poor results. Knowing that the problem was with the NH-CH3 of the hydrophobic emamectin molecule interacting with the Si-OH in the HPLC columns, I started looking for alternatives to silica-based chromatography. That was when I found the ZirChrom web site and read about their zirconia-based PBD column. We purchased an analytical ZirChrom® -PBD column, and I was really impressed by the improvement that it made in my chromatography. Although the concept of "tunable selectivity" was new to me, I soon found a system using an ammonium phosphate buffer that gave rapid resolution of the emamectin and sharp, symmetric peaks. Load testing revealed that this column could handle much higher amounts of emamectin than any silica-based column that I had worked with and still give baseline resolution. With the success that we saw with the analytical column, we asked if a preparative HPLC column could be packed with the same 3µm particles. We wanted a column that was the same length as the analytical column (150 mm), but with a larger i.d. so that developed methods could be scaled up directly. Our goal was to find an efficient purification method for synthesized radio labeled emamectin. After working closely with ZirChrom technical support, we ordered a 150 mm x 22 mm i.d. preparative column along with the recommended guard column. The performance of the preparative column was even better than I had expected. We had hoped to be able to run about 10 mg of crude emamectin per injection, but I found that the column could still give baseline resolution when injecting as much as 25 mg. Our original method used a silica-based phenyl column and a multi-step solvent gradient. Using the phenyl column, we could purify 10 mg per run, and each run took 2 ½ hours. With the preparative ZirChrom® -PBD column under isocratic conditions, I was able to purify 25 mg of crude emamectin in 30 minutes. The time required to purify 300 mg of crude emamectin was reduced from weeks to a day! David A. Hunt ZirChrom® HPLC columns are very good for the separation of pharmaceutical compounds containing primary amine functional groups. No modifiers are needed in the mobile phase to sharpen the chromatographic peaks. This makes it much easier to do the semi-preparation work to prepare some pure raw material without the need of removing mobile phase modifier. Also the columns are stable at low pH, e.g. pH 2, and high pH, e.g. pH 12. Therefore the primary amine compounds can be separated as protonated and neutral molecules. This expands the capability for my separation need. Ion pair reagents, e.g. heptanesulfonate and tetrabutylammonium ions, can be added to the mobile phase to do ion pair chromatography of ionic molecules using ZirChrom® -PBD column. ZirChrom® -PBD columns are relatively more stable than the conventional silica-based reverse phase columns for this type of application. ZirChrom® columns definitely help my daily laboratory operation. Thanks for the creation of ZirChrom® columns. Assistant Technical Director ZirChrom® -PBD is vastly more stable than any silica-based reversed-phase—at any pH and at any temperature (pH 1-14, up to 200° C). And in contrast to stable polymer reversed-phase (PRP), ZirChrom’s plate count and pressure drops are excellent. The efficiency of ZirChrom® -PBD is higher than most commercial silica phases I have used and substantially better than any commercially available alumina-based PBD phases. Dr. John Blackwell ZirChrom® -CARB is an indispensable stationary phase for any chromatographer who separates diastereoisomers. We have been able to achieve separations of low molecular weight polystyrene diastereoisomers with resolutions that far exceed those obtained on conventional C18 stationary phases. The retention of the polystyrene diastereoisomers on ZirChrom® -CARB is very shape selective in comparison to the molecular weight dependence observed on conventional C18. As a consequence of the divergent retention mechanisms on C18 and ZirChrom® -CARB phases we are able to employ these columns in 2D reversed phase separations, with the added advantage of employing solvents with very high compatibilities. Another stationary phase that we find very useful is that of the DiamondBond® C18. This stationary phase offers a hybrid retention process for the diastereoisomers that are of interest in our studies. On this surface the separation of diastereoisomers can still be achieved, but with the added advantage that the separation is more molecular weight dependent than that of ZirChrom® -CARB. Consequently in 2D reversed phase separations the elution order is predictable. Dr Andrew Shalliker We have had excellent success with ZirChrom® -PBD. The separation of diastereomeric esters of Naproxen with occurs with better resolution and faster elution times (7 min vs. 40 min) than any other type of column. In fact, with 3-methylcyclohexen-1-ol, ZirChrom® -PBD is the only column that gives separation. Professor John Sowa
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