Hi to all,
Are there someone how knows the difference between HP and DB columns?
e.g. HP-35 and DB-35 has the same stationary phase and the same characteristics but in Agilent catalogue has two different part number or code.
thank's you
They are very similar columns and are mostly interchangable. However,some customers may use one or the other and have developed methods based on those that they depend on. There can be small differences between brands. In fact,a DB-35 is "equivalent" to not only a HP-35,but also a ZB-35 from phenomonex or a RTX-35 from Restek. However,if you depend on having the same chromatography,your not going to want to change to a different brand,becuase you would have to do some work to verify that everything was the same,or do testing to understand exactly what small differences there were. There are also other brands available as well. Be carefull though,and make sure its the same kind of column,becuase some of the part numbers are not that simple. For instance,DB-624,and DB-1301 are both 6% cyanopropylphenyl columns,essetially the same phase.RTX-Volatiles is very similar,perhaps even the same. Similarly,CP-Sil 8 is the same phase as DB-5 (5% diphenyl,95% dimethyl polysiloxane),and CP-Sil 5 ,rather than being equivalent to DB-5 (or HP-5,RTX-5,etc) is actually equivalent to DB-1. Additonally,sometimes a company will list a SIMILAR phase,as a replacement,when its really not the same,just similar,becuase they dont offer something that is exactly like that product,but would like to sell you a column anyway. Just to make things even harder,there are special variants of the standard columns. For instance,there are special versions of the DB5 for amines,special wax columns for acidic compounds ,columns that are made to be especially low in contaminants such as sulfur or halogens for trace analysis of those compounds,etc. Chance are you will know if you need one of those.
If your going to be doing one thing mostly,and following someones method exactly,then just get that exact column. Makes your life simpler. If your flows are calibrated and your temperatures are right,then your going to get the same chromatogram whoever wrote the method got from his instrument.
On the other hand,if your job is like mine,when you run a vast number of different compounds,often ones you only see once every few years,and the methods that they were originally run on used packed columns on instruments with mechancal regulators (and not only are you not required to use that old method verbatim,but you dont even have any instruments capable of running those old packed columns even if you could find one laying around) then get whatevers cheapest,that has the dimensions you need. My experience has been,all the different brands work just fine. I do particularly like the ones that tie the column to the cage with string though becuase they are easier to handle.
