Dear all,
I am currently working with a GC-MS/MS system, and I've used HPLC-grade solvents in my experiments. Recently, I came across the availability of GC-MS-grade Dichloromethane (DCM). I'm curious to understand the primary distinctions between HPLC-grade and GC-MS-grade Dichloromethane. Additionally, I'd like to know if it is acceptable to use HPLC-grade DCM in my research?
Thank you in advance for your insights.
Best regards,
Diako
You probably can, but your questions suggest you really need to contact an experienced chromatographer at your school for help to insure the instrument is not damaged. *It takes many years of full-time experience to learn the basics of GC-MS analysis and we can not teach the technique in a class or forum. Please contact a local expert to help you use the system, and plan your methods so valid data is collected and the experiments follow good chromatography principles. Here are a few comments which address your questions about solvents...
"GC-MS Grade" solvents are of very high purity usually containing far less residual materials than may be found in HPLC grade solvents. HPLC analysis (and the detectors used) have different requirements than Mass Spec systems (or even FID etc detectors). *Without additional information, for GC-MS analysis, use GC-MS grade solvents where possible (this is good advice and protects the instrument and column). BTW: Specific solvent grades are usually offered to minimize certain potentially interfering compounds (e.g. Pesticide residue grade; MS grade, less particulate, less water, lower UV abs etc ...). The REAL differences, if any, will be found when you read the actual solvent analysis specification sheet provided by the manufacturer. It is on this sheet that THEY will specify which purification procedures were used and what test results were found for the batch. Different manufacturers often have different specifications and/or different definitions of "purity" so you must COMPARE the different specifications. If no 'MS grade' solvent is available, HPLC grade may be fine. Depending on your specific application(s) and instrumentation, you can select the solvents which are best.
Regarding methylene chloride (HPLC or GC-MS grade) for GC-MS (I assume injection solution), well that depends on the EXACT method used (of which their are millions...). I can think of a few where it could damage the system so please speak with a professional chromatographer before moving forward.
Yes, you can. It is very difficult to obtain MS-grade GC solvents and very often the HPLC/GC grade are used. Many of these solvents are infact not very different in terms of purification methods, but the companies do not test the HPLC/GC grade solvents for purity in an MS, which is the main difference I think.
I would first check the purity and the trace elements found, I would say it should be atleast 99.8 %. Many of the impurities in GC-MS will not make it past the inlet liner, as they are not usually volatile at the temperatures used. Pesticide or other organic residues are usually so trace they won't be noticed. But make sure you run solvent blanks as well, and check the baseline for the solvent blank, that it is not too noisy.
Just make sure you regularly clean the liner, and change the liner packing material, also stay safe while handling DCM, use a fume hood/chemical hood!
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