Acid–Amine-Thiol Biomass Dissolution for Rapid Lignin Measurement

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Solution Overview

Problem

Existing methods for measuring lignin content in lignocellulosic biomass are labor-intensive, require hazardous reagents, and involve lengthy processes, often leading to inaccurate results due to interference from carbohydrates and other compounds.

Innovation Solution

A method involving the complete dissolution of lignocellulosic biomass in an aqueous solution comprising a strong acid and an amine-thiol, such as sulfuric acid and cysteine, followed by UV spectrophotometry to determine lignin content at 283 nm, allowing for rapid and accurate quantification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional methods (Klason, ALBTH) are used to measure lignin content, then lignin quantitation can be performed, but the process becomes labor-intensive and time-consuming

Engineering Contradiction:

Improvelignin content measurementVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent changes the chemical parameters of the dissolution system by using a specific combination of strong acid (sulfuric or hydrochloric acid) and amine-thiol reagent, allowing complete biomass dissolution under mild conditions (room temperature, short time) rather than requiring prolonged heating or complex multi-step procedures

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent extracts and eliminates the need for separate carbohydrate hydrolysis steps and complex purification procedures by using a single reagent system that selectively dissolves lignin while leaving carbohydrates intact, thereby simplifying the overall measurement process

Inventive Principle:

Principle #2Taking out (Extraction)

2Measurement precision

If strong acids are used to hydrolyze carbohydrates in Klason method, then carbohydrates can be dissolved leaving lignin as residue, but hazardous reagents and labor-intensive operations are required

Engineering Contradiction:

Improvelignin content measurementVSAvoidhazardous reagents

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an amine-thiol reagent as an intermediary substance that facilitates the dissolution process. This mediator reacts with lignin to form soluble complexes, enabling selective lignin dissolution without requiring the use of highly concentrated strong acids alone, thereby reducing the harmful effects while maintaining measurement accuracy

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If acid hydrolysis is performed to dissolve carbohydrates, then lignin can be isolated as residue, but formation of humins from sugars occurs resulting in overestimation of lignin

Engineering Contradiction:

Improvelignin content measurementVSAvoidlignin measurement accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent converts the potential harmful interaction between acids and sugars (which causes humin formation) into a beneficial selective dissolution process. By using the amine-thiol reagent system, the method exploits the selective affinity of the reagent for lignin over carbohydrates, thereby preventing unwanted side reactions and improving measurement reliability

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Productivity

If UV spectrophotometry is used to measure acid-soluble lignin, then rapid measurement is possible, but interference from furfurals present in acid-soluble lignin fraction degrades accuracy

Engineering Contradiction:

Improvemeasurement speedVSAvoidlignin content measurement

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent extracts and eliminates the source of interference (furfural formation) by avoiding the use of strong acid hydrolysis that generates these compounds. The amine-thiol based method dissolves lignin without producing furfural intermediates, thereby removing the source of spectral interference while maintaining rapid measurement capability through direct UV absorbance measurement

Inventive Principle:

Principle #2Taking out (Extraction)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method enables quick, efficient, and accurate measurement of lignin content without heating, using minimal reagents and sample sizes, with results closely correlating to established methods like the Klason method, suitable for high-throughput analysis.

Implementation Method 1

contacting an amount of biomass with an amount of an aqueous solution comprising a strong acid and an amine-thiol

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

measuring absorbance of the first solution at a wavelength of about 283 nm

Methodology Applied

Scientific EffectUV absorption: Absorption (EM radiation)

Data Source

PatentUS12358939B2Method to solubilize biomass under mild conditions

Publication Date: 2025.07.15 WISCONSIN ALUMNI RES FOUND

AI summary

A method of completely dissolving lignocellulosic biomass. The method includes the steps of dissolving a sample of biomass in an aqueous solution of strong acid and an amine-thiol to yield a first solution. A method for measuring lignin concentration in biomass via absorbance of the first solution at a wavelength of about 283 nm by comparing the measured absorbance to a standard curve of absorbance values made from solutions of known lignin concentration.