Hi all,
I am trying to elucidate the exact composition (closest approximation) of a mixture consisting of at least 4 constituent materials. My sample is suitable to XPS analysis but as far as I know I will only be able to elucidate the chemical composition (fundamental composition). Perhaps, LC-MS-MS is also an option, or even maybe combine both. As a remark, I have a slight (but really weak) idea of the chemical structure of the components, so maybe NMR is also an option... I really have no clue.
Thank you so much
As a student, you should request the assistance of your teachers in the analytical chemistry department. Depending on the types of instrumentation available and the properties of your mixture, you should be able to determine which techniques may be appropriate. Read up on basic analysis techniques and also discuss the sample mixture with others at your school to get ideas.
Some basic questions which should be asked about your mixture are: Where did the mixture come from and what are its properties? Is the mixture in a solid or liquid form? Is it volatile? Does it absorb light at any notable wavelengths (UV/VIS)? What does it dissolve in (100 % solubility)? If it is stable and volatile, then some type of GC/MS analysis might be appropriate. If it is not, then LC/MS (or LC/MS/MS) may be appropriate. *HPLC analysis has the advantage that no heat is used so less chance of degrading the material. NMR may also provide some clues, but because it is a mixture, that data may have limited value. Same may be true for IR and other techniques too.
What! Your taking a course in 'black box' chemistry! I thought they got rid of that course >40 years ago. Try a description like color, smell... then FTIR and NIR.
Organic or inorganic? Large molecule or small? Ionizable or non-ionizable? Volatile or thermally decomposed? There is no single method that will work for everything. Do you need quantitation or just identity? Some techniques (e.g., MS and MS/MS) will give you identity, but are non-quantitative without the standard addition of stable isotope controls. Other techniques (e.g., H-NMR) can be quantitative once the identities of the compounds are known and assuming that non-overlapping proton signals can be identified. Chromatography can be used to separate the compounds, but there you have lots of choices as well from TLC, LC, GC, CE, SEC, CEC. The reason all these techniques exist is because no one technique does it all. This sounds like a good Senior Project for a Senior Analytical Chemistry student.
Try Google it, you may be lucky and find the answers, no just kidding.
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