1、How to determine the concentration of humic acid in solution?
One of the methods that is widely used in research is the Kullmann and Freitag method. It allows us to determine the optical density of humic substance extracts at different wavelengths, as well...
2、A New Standardized Method for Quantification of Humic and Fulvic Acids
Here we present a thoroughly validated method, the new standardized method for determination of HA and FA contents in raw humate ores and in solid and liquid products produced from them.
3、An efficient approach to the quantitative analysis of humic acid in
Based on the grayscale images of three-dimensional fluorescence spectra, the linear model with two selected Zernike moments was established for the determination of humic acid, and applied to the quantitative analysis of the real sample taken from the Yellow River.
Quantification of humic acids in surface water: effects of divalent
The aim of this study was to compare two methods to assess humic acids (HAs) in surface water namely absorbance of ultraviolet light at 254 nm (UV 254) and total organic carbon (TOC), as well as to evaluate the effects of calcium and magnesium concentrations, pH and sample filtration on the methods' results.
Introducing a Modified Method for Quantitative Determination of Humic
A modified method was developed for the quantitative determination of humic acid in humic-based commercial fertilizers by optimizing the factors affecting humic acid extraction and purification.
Determination of Organic Compounds, Fulvic Acid, Humic Acid, and Humin
The goal of this study was to identify the main organic compounds and determine fulvic acid, humic acid, and humin concentration in different peat and sapropel extracts from Lithuania.
Quantification of Humic and Fulvic Acids in Humate Ores, DOC
The purpose of this method is to provide an accurate and precise concentration of humic (HA) and/or fulvic acids (FA) in soft coals, humic ores and shales, peats, composts and humic substance-containing commercial products.
Water
Two automated methods for the determination of humic acids (HAs) in natural water samples are presented. Flow injection systems were developed based on the formation of a complex between humic acid...
Standard Humic Acid Testing Protocols – A Review
Humic substances can be broken down into Humic Acid, Fulvic Acid, and Humin. Currently, humic substance testing has been centered on methods for quantifying Humic Acid content in soil and product samples, which will be the focus of this discussion.
Video: Quantification of Humic and Fulvic Acids in Humate Ores
To determine the final mass of the pure humic acid, use the formula to correct for the ash content. Then use the formulas to determine the pure humic acid concentration.
Humic acid is a natural organic substance found in soil, water, and sediments. It is a product of microbial activity in the biosphere, primarily derived from the decomposition of plant residues. Humic acid plays multiple roles, including improving soil structure, enhancing fertility, and promoting plant growth. understanding how to determine its concentration is crucial for agricultural production and environmental protection.
1. Definition and Classification
Humic acid can be classified into two categories based on its chemical composition and properties:
- Water-Soluble Humic Acid: This type has high solubility in water and is easy to extract and use. Common examples include humin and humic acid.
- Non-Water-Soluble Humic Acid: This type has low solubility in water and requires chemical methods for extraction. Examples include fulvic acid and black humic acid.
2. Determination Methods
a. Aqueous Solution Method
This is one of the most common methods for determining humic acid concentration:
- Take a sample (e.g., soil, sediment, or water) and place it in a centrifuge tube, adding distilled water or another solvent.
- Use a high-speed centrifuge to separate humic acid from impurities.
- Collect the supernatant and measure its absorbance using a UV-Vis spectrophotometer.
- Calculate the humic acid concentration in the sample based on a standard curve.
b. Adsorption Method
This method involves adsorbing humic acid onto a specific adsorbent to remove impurities:
- Select an appropriate adsorbent (e.g., activated carbon, diatomaceous earth).
- Mix the sample with the adsorbent and heat it to enhance adsorption.
- Filter out unadsorbed humic acid, leaving the adsorbent with humic acid.
- Release the adsorbed humic acid using pyrolysis or oxidation, then measure its absorbance.
- Calculate the concentration using a standard curve.
Advantage: Effectively removes impurities for more accurate results.
c. Electrophoresis Method
This method uses electric fields to separate humic acid molecules in a gel:
- Prepare a polyacrylamide gel.
- Mix the sample with buffer and load it into gel wells.
- Apply an electric field to drive humic acid toward the negative electrode.
- Collect the migrated sample and measure its absorbance.
- Calculate the concentration using a standard curve.
Application: Suitable for studying the molecular structure and distribution of humic acid.
3. Influencing Factors
Key factors affecting measurement accuracy include:
- Sample processing: Different treatments may lead to loss or retention of humic acid.
- Experimental conditions: Temperature, pH, and time impact results.
- Instrument precision: Equipment performance directly affects accuracy.
- Calibration curve selection: Using the right standard curve improves reliability.
4. Practical Applications
Determining humic acid concentration is vital in fields such as:
- Agriculture: Guiding fertilization and soil management.
- Environmental monitoring: Assessing pollution levels in water or sediments.
- Resource development: Optimizing extraction processes and environmental protection.
Accurately determining humic acid concentration is essential for understanding its environmental and agricultural impacts. By selecting appropriate methods and addressing influencing factors, precise measurements can support research and practice in related fields.
