tag:blogger.com,1999:blog-9209375845415652006.post5235743075742535652..comments2024-01-24T09:56:18.495-05:00Comments on HPLC CHROMATOGRAPHY HINTS and TIPS FOR CHROMATOGRAPHERS [HPLC TRAINING ARTICLES] : K Prime (also known as: Capacity Factor, Ratio or Retention Factor): One of the Single Most Important HPLC Parameters of AllHPLC EXPERThttp://www.blogger.com/profile/04810178046245936465noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-9209375845415652006.post-89583782095968414122020-04-24T17:56:50.108-04:002020-04-24T17:56:50.108-04:00The larger the K prime, the longer the peak retent...The larger the K prime, the longer the peak retention time (and wider the peak width is). Good chromatography balances a reasonable total analysis time against an acceptable K prime. Optimizing the chromatographic conditions is key to developing a method which has scientifically acceptable K prime values (which demonstrate proper method selectivity has been achieved) and a reasonable run time. A "reasonable" run allows us to complete the analysis quickly, use the least amount of solvent and have the quickest turn-around time to run the next sample. *So yes, you can develop a method which has large K prime values, but the extra peak broadening and drift which are associated with long run times are not desirable (greater error).HPLC EXPERThttps://www.blogger.com/profile/04810178046245936465noreply@blogger.comtag:blogger.com,1999:blog-9209375845415652006.post-50620337400837552302020-04-24T17:50:01.445-04:002020-04-24T17:50:01.445-04:00Is a K prime of 19 too large? Is it OK to have pea...Is a K prime of 19 too large? Is it OK to have peaks with K primes of 20 or 30?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9209375845415652006.post-15174420374094501012020-04-10T10:43:05.326-04:002020-04-10T10:43:05.326-04:00As they say, better to learn now rather than than ...As they say, better to learn now rather than than later. Knowledge is power. Most training is lifelong and has no end. Stubbornness to change or excuses such as, "we always do it that way" are common reasons of failure. It is wise to always be a bit skeptical of any new information presented (e.g. HPLC methods) before use. Never assume... HPLC EXPERThttps://www.blogger.com/profile/04810178046245936465noreply@blogger.comtag:blogger.com,1999:blog-9209375845415652006.post-4742734435428309592020-04-10T10:37:47.362-04:002020-04-10T10:37:47.362-04:00We are grateful for your many articles and knowled...We are grateful for your many articles and knowledge!!!! Several methods used for purity analysis by our lab (we are Contract laboratory) come from published sources by our customers. Most have been run for many years without any problems. Now, we feel very humble. After reading your articles on column void volume and K prime, we understand that our training in HPLC has been very poor. It turns out that 6 of the regular methods we use from our clients, do not show any chromatography at all. All are reverse phase methods (C8 and 18) and we calculated K primes for the main samples and found all of them are less than 1, and a few are just 0.2. This is understood as no retention on the column and the method developed and used is junk. The scientists who provided these methods work at IVY league university, but their training was extremely poor and perhaps we now know so was ours. Our lab is now going to learn those basic chromatography fundamentals that you write about (and this website is the best place to do so) before we run any more samples. We will also do a better job of reviewing methods submitted to us. We thank you for providing this knowledge to us. Through reading and training, we have the chance to be better.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9209375845415652006.post-41485687052670142422016-12-06T10:41:55.541-05:002016-12-06T10:41:55.541-05:00GREAT POST :)
For several years, our lab has used ...GREAT POST :)<br />For several years, our lab has used a published method which we use for the determination of the purity of a clients sample. We have always wondered about the quality of the method used, but no one here is really an expert at HPLC so it is used and accepted because it is "published". After reading your post and learning more about lc, we now have evidience that the peak comes out at the VOID vol. As I understand it, that mean no separation at all. the purity values obtain are always 100% and now we know why. You are correct, just because it is published in a respected journal means ZERO. no one checks and the data and purity are worthless. Not sure what we can do, but we will not run that sample using that bad method anymore. We will find a new method. <br /><br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9209375845415652006.post-75936016416574756262016-08-15T14:12:17.308-04:002016-08-15T14:12:17.308-04:00Different regulator authorities establish differen...Different regulator authorities establish different criteria. Yes. One example of an authority which does establish an acceptance value is the US Food and Drug Administration (FDA). *K prime greater than or equal to 2.0. <br /><br />So many methods that I am asked to review have K primes of less than 1.0 ! This means that many types of potential impurities can easily co-elute or be hidden under the main peak since very little effort has been made to separate it.HPLC EXPERThttps://www.blogger.com/profile/04810178046245936465noreply@blogger.comtag:blogger.com,1999:blog-9209375845415652006.post-32769345372061778142016-08-15T13:52:58.685-04:002016-08-15T13:52:58.685-04:00Is there any reference for k prime acceptance crit...Is there any reference for k prime acceptance criteria ?Anonymoushttps://www.blogger.com/profile/01353315746711039584noreply@blogger.com