Price problems

[liamomo]

Hello, i'm an outsider to chromatography but i need a quote on the annual use of a GC-MS spectrometer for a 24hr period 365 days a year. I'm reviewing the cost-effectiveness. We use a hydrogen carrier gas. If possible the cost per sample analysis would be useful i know it varys. but an apporximation would be useful. We're investigating pharmaceuticals. Thank you sincerely for any help.

[Don_Hilton]

You largest costs will be sample preparation and staffing. Add in a service contract, if you will purchase one (For the inexperienced user, I reccomend it.). For consumables beyond carrier gas, a bottle of compressed gas can last 6 to 12 weeks on an instrument. The rest depends on the type of analysis you are doing. A chromatographic column can last from just a few weeks to years and can range in price from about $250 to over $2000 each. In some types of analysis, inlet maintantace needs to be done daily, with replacement of inlet liner ($10 to $20), septum ($1) and inlet seal ($20-$30). In other cases, this maintanance can be spread out over longer periods of time. In my work, I estimate that I use about $1000 (US) columns and inlet parts per year on one GC/MS system.

If you give some indication of the type of analysis and type of laboratory environment, someone familiar may be able to give you a better estimate.

[liamomo]

thank you for the reply
i am not too worried about the capital costs, i am more concerned at the per per analysis of hydrogen gas, electricity etc.

i was also concerned about how quickly samples can be done.

an example would be finding out the concentration of paracetemol in a one analysis, then following finding the quantity of aspirin in a different analysis.

i was concerned about the time adjustments between samples, in terms of temperature, given samples for injection are prepared before hand

any help greatly appreciated.

[Don_Hilton]

For carrier gas, you can use my estimate of use and gas prices in your area. For electrical cost, contact the vendor of the instrumentation considering. They can give you an estimate of typical use. Analysis time depends on the analytical technique you use. I have seen methods with a cycle tye as short as three minutes (isothermal GC of a simple misture) to about half an hour for several anaytes in a complex matrix. And, times can take longer.

Again change between methods can be quick (essentially no time at all) - if the two methods can use the same chromatograpic column and inlet liner. If you have to change columns between analysis, the down time can be as short as about a half hour (if the no-vent systems work as advertised) to overnight to allow background moisture to clear from the mass spectrometer.

You also have to consider the effect of making changes on our ability to maintain calibration. If you work under a regulated system you may need to recalibrate the instrument very time you change columns. This makes changing back and forth between methods quite expensive. At a minimum, you will have to demonstrate that the calibration is valid after the column change.

If you plan to use a single instrument for a number of different analysis, I would suggest that you consider employing an experienced GC/MS person who is familiar with the instrument and working under any regulatory environment you are under - at least as a consultand to get you started. Some of the questions you raise involve some considerations that are not trivial.