If you want to quantify the content in lignin without chemical manipulation here are some methodssuch as using analytical pyrolysis or spectroscopy (FTIR, NIR). Organic solvents do not dissolve lignin due to the size of the macromolecule

Spectroscopy could be useful method for determination of lignin. For extraction (e.g. for structural study) can be used mixture dioxane-water-hydrochloric acid, however, yield is incomplete. Another way is solvent DMSO/NMI (see attachment).

That is not true. Dioxane has been used for lignin extraction for a long time.

What Dr. Helena said is correct. Follow the FT-NIR or IR method. but to ensure precise quantification of lignin, wet-lab method should be more precise and accurate. For this to obtain, a paper published by Prof. Manfred on a modified method of lignin quantification is available (Holzforschung 56: 161-166 (2002).

What Dr Kačík expained is correct. To answer the original question, there are some solvents for lignin extraction. Yes, it is difficult to obtain full yield of lignin. However, we do have two approaches to analyze lignin. One is degrade carbohydrates first by chemical or enzymatic method and obtain lignin; the other is extract lignin without removing carbohydrates. these are two general methods for obtaining lignin. Afterwards, analytical methods, such as Spectroscopy can be used for analysis. The method used in Holzforschung article is for Klason lignin analysis, which is obtained after removing polysaccharides from acid hydrolysis.

Thank you very much for your nice suggestions

A wet chemistry lignin analysis is by acetyl bromide solubilization and then UV (280 nm) reading. You may want to take a look at "FUKUSHIMA, R.S.; Kerley, M.S. 2011. Use of lignin extracted from different plant sources as standards in the acetyl bromide lignin method. J. Agric. Food Chem., 59:3505-3509. "

I hope this paper could help you:

DOI: 10.1515/hfsg.1998.52.4.391,

Additionally to earlier mentioned, I can suggest the UMSP (UV -microspectrophotometry) for lignin quantification within the cell wall (or lignin distribution within the cell wall), of course it is not the easiest and cheapest method, but clearly more informative.

NIR and solid state nmr spectroscopy are the techniques that you can estimate lignin using without any solvent.

From the above answers the easiest and precise method for lignin determination is so called "acetylbromide" method of wood dissolution followed by UV determination. We used it frequently in lignin determinations in various pulps. This method was recomended to you previously Dr. R. Fukushima.

Another simple method is based on evaluation of difference spectrum obtained as a difference between the FTIR spectra of extractive free wood meal /or wood surface/ and hollocellulose of the same wood species. It is advisible to use holocellulose sample with known contents of lignin.The absorption maxima cheracteristic for lignin are: a peak at 1423 - 25 cm-1 corresponding to sceletal aromatic ring vibr.,peak at 1505 cm-1 can be at ributed to aromat. ring vibrations and the band at 1600cm-1is a mixed /overlapped/ one corresponds to aromatic ring stretchings associated with -C-O- stretching mode in lignin, and to carboxylate anion C=O stretching, if present in the sample,

The gold standard in determining lignin is the Klason acid hydrolysis followed by acid-soluble lignin determination. Of alternatives, acetyl bromide is probably the best. As for the question as it's asked, the short answer is no. As far as it's known, there exists no solvent that dissolves 100% of all known types of lignin in their native state. However, it is possible to dissolve wood completely in [amim]Cl with very extensive (48-96 h) ball milling; this is a mild treatment, although it does(!) cleave chemical bonds in the lignin (the milled wood obviously smells of vanillin). See what Alistair King has published on this.

I am rather surprised to get this question from KTH, given their excellence in the topic. Go to Träkemi och Massateknologi; I'm sure they can help you.

Dear Muhammad,

If you refer to the book of Methods in Lignin Chemistry, you can find a chapter that explains UV microscopy and quatification of lignin content in wood cell walls. Also FTIR spectrocopy as well as FTIR-microscopy are useful methods too.

Good luck

This question isn't easy, but if you have an adjusted model using the spectroscopy infrared near (NIR) it's possible with high precision.

Hi Muhammad, If you want to work on low microgram plant samples, analytical pyrolysis for sure is a good tool. There is one close to you at Invenntia in Stockholm. I have currently two Py-GC/MS in the lab in Umeå, Sweden, for exactly the same application, mostly plant (arabidopsis and poplar) samples.

Is there any protocol available for lignin quantification form plant roots?

Please is there publication, send the link

Thank you  

I do recommend you to use FTIR or ATR technique to quantify the lignin. You can easily dry the specimens in an oven to remove water and prepare fine flours with mesh size below 60 or 80 and use ATR to prepare spectra of the solid material and look for bond assignments for especially aromatic skeletal vibration. FTIR also gives you the same results. However, you should makes pellets with KBr and dried flour. Avoid any contamination of the flour with CO2, and access of water molecules to your samples.

Good luck

I use the same routine of wood analysis. But the ash content have to be considered.

Hi, 

may be used acetyl bromide method for lignin analysis. 

See here: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0110000

Hi,

The Cupric Oxide (CuO) method is nice because you collect quantitative and qualitative data on lignin and cutin simultaneously.  This method involves oxidizing any sort of plant tissue or complex matrix containing lignin (such as soils, sediments) with CuO at high temperatures.  This breaks down the lignin macromolecule into a distribution of phenolic monomers and dimers which are quantifiable with GC/MS and provide information on total lignin, plant type, and degradation state.  Likewise, cutin is broken down into hydroxy acids whose distributions contain similar information.  We set up  labs for this type of analysis and it's been great for a number of applications - it works well for plant tissues and is also one of the only solutions in sediments or soils where lignin may be a very minor component of the total organic fraction