solvents
Posted: Fri Aug 18, 2006 8:17 pm
Peter wrote:
#1 "
.......Two columns in parallel is also far simpler and cheaper than comphrehensive or heartcutting 2-dimensional...... "
#2 "
........Having a huge backlog is exactly why you should change to helium now, it will double your throughput. Just remember to change the volume flow rate (best of all set the linear flow velocity at 35 - 40 cm/s)....."
#3 "
......Deans switch or valve heartcutting is cheaper to set up because you can do the plumbing yourself, but you have to do one second dimension run for every coelution on the first column - which can become very time consuming.
I would say that without a trace of doubt Peter is correct here in statement #1
and almost perfectly without doubt in statement #2 (hydrogen would be a lot cheaper and even faster than helium, as Salma's use of nitrogen indicates a company concern for the cost of helium),
but in statement #3 I have some reservations in agreeing completely.
If extremely tight heartcut timing is critical then Peter's assessment is correct, but for this application I don't think it is.
Quick, yet accurate with some extra time added (slightly larger than necessary heartcut window) heartcuts can be ascertained from a single run and once the research has been done to prove it, multiple heartcuts CAN be done on a single run, as is done daily in the process analyzer world, and can be seen in a recent Agilent publication showing multiple heartcuts using a Dean's switch in an analysis of biodiesel.
Your solvent application would be one where multiple heartcuts would be possible, depending upon the choice of columns.
and while statement #1 is still true, it is also true that research must be done to determine the coelutions on both columns and that accurate measurement of non-coelutions is possible. Even a dual parallel column analysis could be daunting for a new or inexperienced operator to interpret.
Giving considerationis for cost, greater simplicity, and ease of interpretation of results I agree with Peter that a non-multidimensional configuration is the better choice.
best wishes,
Rod
#1 "
.......Two columns in parallel is also far simpler and cheaper than comphrehensive or heartcutting 2-dimensional...... "
#2 "
........Having a huge backlog is exactly why you should change to helium now, it will double your throughput. Just remember to change the volume flow rate (best of all set the linear flow velocity at 35 - 40 cm/s)....."
#3 "
......Deans switch or valve heartcutting is cheaper to set up because you can do the plumbing yourself, but you have to do one second dimension run for every coelution on the first column - which can become very time consuming.
I would say that without a trace of doubt Peter is correct here in statement #1
and almost perfectly without doubt in statement #2 (hydrogen would be a lot cheaper and even faster than helium, as Salma's use of nitrogen indicates a company concern for the cost of helium),
but in statement #3 I have some reservations in agreeing completely.
If extremely tight heartcut timing is critical then Peter's assessment is correct, but for this application I don't think it is.
Quick, yet accurate with some extra time added (slightly larger than necessary heartcut window) heartcuts can be ascertained from a single run and once the research has been done to prove it, multiple heartcuts CAN be done on a single run, as is done daily in the process analyzer world, and can be seen in a recent Agilent publication showing multiple heartcuts using a Dean's switch in an analysis of biodiesel.
Your solvent application would be one where multiple heartcuts would be possible, depending upon the choice of columns.
and while statement #1 is still true, it is also true that research must be done to determine the coelutions on both columns and that accurate measurement of non-coelutions is possible. Even a dual parallel column analysis could be daunting for a new or inexperienced operator to interpret.
Giving considerationis for cost, greater simplicity, and ease of interpretation of results I agree with Peter that a non-multidimensional configuration is the better choice.
best wishes,
Rod