1. ASTM D5558 - 95(2011). Standard Test Method for Determination of the Saponification Value of Fats and Oils.

2. ASTM E1758 - 01(2015). Standard Test Method for Determination of Carbohydrates in Biomass by High Performance Liquid Chromatography.

3. Proteins can be seen in a Spectophotometer at 294-297 nm range.

4. ASTM D5555 - 95(2011). Standard Test Method for Determination of Free Fatty Acids Contained in Animal, Marine, and Vegetable Fats and Oils Used in Fat Liquors and Stuffing Compounds.

http://bioinfopublication.org/viewhtml.php?artid=BIA0002994

You can follow the AOAC official standard methods of analysis, 18th ed., 2006 for carbohydrate, protein and lipid analysis from any sample.

Thanks Vijayanand and Shouvik. Actually, I already quantified the lipid, protein and carbohydrate in  my biomass. But I need to make a qualitative analysis and identify the compounds presents (for instance what kind of fatty acids/ amino acids are present). I was considering to carry out a GC-MS analysis but I'm not sure whether it would work out or be the best way to a complete qualification of the sample  (one of the problems would be getting the feces completely dissolved in the solvent). 

Below are the methods we used to quantify proteins, lipids, and carbohydrates in the mixed liquor of reactors fed domestic wastewater (Petropoulos et al., 2017; Petropoulos et al., in preparation). These are robust methods that should also be applicable to the analysis of manure.  

Proteins: The protein content of the manure mixed liquor can be measured via the Bradford protocol (Bradford, 1976), based on the interaction between protein and Coomassie Brilliant Blue G-250, providing a blueish-brown solution.

Lipids: The lipids content of the biomass can be estimated gravimetrically using a methanol:chlorophorm extraction protocol (Bligh and Dyer, 1959) at a ratio 1:2.

Carbohydrates: Carbohydrates content can be estimated by the anthrone method, a simple colorimetric method firstly reported by Hedje and Hofreiter (1962). Polysaccharides are firstly hydrolysed to monomers by digestion via hydrochloric acid and heat. Then the solution reacts with the anthrone reagent, yielding a greenish-blue colour.

References

Bligh, E.G., Dyer, W.J., 1959. A rapid method for total lipid extraction and purification. Canadian Journal of Biochemistry and Physiology 37, 911-917.

Bradford M. 1976 A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding.  Analytical Biochemistry 72, 248-254

Hedje J.E., Hofreiter B.T. (eds) 1962 (R.L. Whistler and J.N. Be Miller) - Carbohydrates Chemistry 17th edition; Academic Press, New York, 1962

Petropoulos et al. 2017.  Developing cold-adapted biomass for the anaerobic treatment of domestic wastewater at low temperatures (4, 8 and 15 °C) with inocula from cold environments. Water Research in press. http://dx.doi.org/10.1016/j.watres.2016.12.009

Thanks Jan for your kind answer and appointed methods. I'm sure it will be helpful as a reference for future analysis. However, my need is much more about the qualitative than quantitative analysis. I just rewrote my question to be more clear about my meaning. 

You can try FTIR-ATR analysis to get a detailed data on every component in the fecal samples as it displays all the functional groups present in the sample.

How about combining the two approaches:

(1) use the first steps of "my" robust methods outlined above, but refrain from using the final colorimetric or drying step;

(2) use the extract(s) thus obtained for subsequent analysis in a GC-MS (or LC-MS).

This should get you most, if not all, of your suspended solids in solution and into the GC/LC.  

Thanks Jan for your valuable suggestion. I'll check it out. 

Dear Raquel de Souza, 

You may also aware that human excretory material (faeces) composition is not always constant and is diet dependent. Hence, the whole exercise to analyse at component level of each class of metabolites can be less useful until and unless you are working on human waste of select group whose diet is controlled.