[zcore]

Hello, I'm medical student, and I work on a problem of child age-related changes in concentration of different chemical compounds of female milk.
I'm looking for all-in-one solution, or for a solutions, that cover measurement of concentration of previously known fats, fat acids, hydrocarbonates, proteins, etc. components of a female milk.
I looked on a Wikipedia, there about 100 of different methods of spectroscopy, chromatography, spectrometry. It's hard to compare them by sensitivity, budget, detected chem. comp. etc.
So I have next situation: by default a liquid with a many known components with known spectre, which concentration I need to know.
Thank you very much for you time, that you spend on reading and, possibly, answering, I hope, that my research will be great with you help with choosing of methods.

[Arkcon]

You may not realize it, but your question, as posted, is very nearly impossible.  You going to have to way reduce the requirements, if you want the task to be moderately complicated, or moderately complicate the tests, for a reasonable subset of the analytes you want.  Analyzing "everything" with a simple spectrometric method is just simply impossible.

Fats and carbohydrates are notable for not having a chromaphore in the UV-Vis, so a spectrophotometric method is plain out, in that case.  We may derivitize some subset for visualization, but that's adding a variety of complications.  Total protein may be doable, but mammalian milk contains the opaque protein casein, and that will just wreak havoc with optical methods.

Now, IR methods might work, but you will just get a jumble of peaks from related compounds, so that may not be what you want.

Now, chromatographic methods, either HPLC or GC, may be useful.  Gas chromatography may be especially useful for fats and fatty acids.  And if you can get a separation of a variety of components, on GC or HPLC, then you may generate a "fingerprint" -- a series of peaks that you can use to see changes in the sample over time.  Even though, this fingerprint doesn't tell you exactly what's happening, you can use it to infer what phsiological changes you're trying to understand by this analytical assay.  And can say where you're going to focus on for further research.

Possibly, the saddest part is that you have a very complex set of analyses, an extremely vague question, and your best research is Wikipedia.  You're really like the proverbial absent minded professor, who didn't know how to drive, but was sure they could get the gist by reading the automobile instruction manual.  Simply put, when performing an analysis that we hope to have work, we focus on removing the interference of the matrix.  Your sample is simply too complex for the best analytical method, and spectrophotmetric assays are too simple even for moderately complex samples.

[zcore]

Hello, It' my first day of research on that problem, please, don't think that I put links to Wikipedia in my study as a reference. But I still think, that Wiki is not bad to get a simple view on a problem. I know from the start, that there a almost impossible problem, but there will be great benefits in a level of study. if it will be solved. Also I looked on some articles on physics.StackExchange, reddit, and some first links on Google. Not too bad for a first day, how I think.
I know, that a one of a problem that peaks of some compounds may lay nearby or even merge on spectrometry, and it's hard to understand, how to fix that.
On one hand, how I think, we can prepare sample in different ways and get different subset of data.
On another hand, we can use combination of different analyzes, to make it less complicated and get a different points of view.
Thanks for you advice, today I will look into HPLC and GC technology and data output.
Can you advice what type of http://en.wikipedia.org/wiki/High_performance_liquid_chromatography you think best in that case?
P.S. So, how do you think, what is a best way, combination of what preparing methods and analyzes should be appropriate in that question?

[kriggy]

I suggest this:
a) make a list of specific compounds you want to analyze in the milk.
b) look into literature -  and I mean things like journal of analytical chemistry or any number of journals because you will not find it on wikipedia - and look for methods to determine your selected compounds. There is a big chance that someone already tried that. Then, there might be some compounds that none tried to determine in milk  and for those you need to develop your own method.

[MOTOBALL]

This would be my approach...

1) make a list of all of the analytical techniques that you can think of; for example HPLC, GC, UV, IR, MS, NMR, CE & CZE etc..

2) Google search for the manufacturers of instruments that are used for these techniques; for example Agilent, Waters, Shimadzu, Perkin Elmer, Thermo Scientific, Sciex, Bruker, Jeol, Varian etc..

3) Go to the website of each of these companies & find their applications pages.  These consist of analyses performed in their technical support center by their chemists on their instrumentation.  You will find applications for all of the biomolecules (carbohydrates, peptides & proteins, nucleosides etc...) of interest to you.

4) More importantly, you will discover (by careful reading) those types of compounds that cannot be readily analyzed by any given technique. They will be ABSENT from the applications literature.

Motoball

[Irlanur]

I guess the only technique to give a very broad picture is MS. maybe coupled to some LC system.

please, don't think that I put links to Wikipedia in my study as a reference

Why not? Wiki is great, especially if it comes to things that are just facts. Like some general buffer recipes or whatever. but it seems to me that you have absolutely no idea where to start and it's quite hard to imagine that any Prof. would give you this task without any suggestions.

[Arkcon]

Using our good friend Wikipedia again, I'm beginning to suspect most of what you're interested in is changes in breast milk composition over time, as shown in various images here:  http://en.wikipedia.org/wiki/Breast_milk  In that case, maybe you do want an optical method.  However, instead of a spectrophotometer, what you want is a turbidity meter, or a colorimeter.  You can then track changes.  Still however, you're not going to get a though fat content, fatty acid composition, protein content and protein composition, all in one test.