Fatty acids-based herbicides are considered to be a green alternative to synthesized weed control products. However, the environmentally sustainable effect of those herbicides needs more investigation to be confirmed. The aim of this work was to develop a chemical analysis method that enables identification of short-chain fatty acids (SCFA´s) and medium-chain fatty acids (MCFA´s) in a commercial fatty acid-based herbicide product, and to set up extraction and gas chromatography (GC) methods that can be used to detect the exposure to the product in environmental matrices. Fatty acids (FA´s) were extracted from the herbicide by liquid-liquid extraction (LLE) using n-heptane as organic solvent. FA´s were extracted from soils spiked with the herbicide; on a supercritical fluid extraction (SFE) system using extraction solvent consisting of 90% supercritical carbon dioxide (SC-CO2) and 10% methanol (MeOH) (v/v). The extracted FA´s were derivatized under acidic conditions into fatty acid methyl esters (FAME´s) to be analysed on gas chromatography-flame ionization detector (GC-FID) system and gas chromatography-mass spectrometry (GC-MS) system. Standard solutions of known FAME´s were used to construct retention index (RI) models and internal calibration models to identify and quantify FAME´s in the samples. The herbicide product was found to contain octanoic acid, pelargonic acid, decanoic acid, and 2-methyoctanoic acid. R2 values of the calibration curves ranged between 0.992 and 0.996. Repeatabilities for the peak areas and retention times had RSD% values varied between 1.32 -7.69 and 0.011-0.783, respectively. Recoveries (R%) of pelargonic acid in the spiked soils were estimated to vary between 8% and 128%; showing that more work could be required to investigate the optimum parameters for SFE extraction method., Herbicide products are widely used as weed-controlling agents by both professionals and individuals. The formulas of some of those products contain chemicals that may have harmful impacts on the environment, which incentivized governments and health authorities to ban some of those herbicides. Researchers and producers were also encouraged to synthesize and examine weed-controlling agents that are greener and more environmentally sustainable. Some products of the modern generation of herbicides depend mainly on fatty acids and natural oils to achieve their mode of action as weed-controlling agents. Nonanoic acid, also known by its trivial name as pelargonic acid, is widely used as the main ingredient in the so-called bio-herbicides. However, the friendly environmental impact of those bio-herbicides is yet to be investigated. Research and studies that could achieve that goal, implicitly, shall include analytical methods to extract, detect and quantify those products in environmental matrices. The aim of this work was to identify the fatty acid composition in a commercial fatty acid-based herbicide product and to detect it in environmental matrices. Soils collected from different locations were spiked with different amounts of the herbicide in order to mimic the exposure to the herbicide in nature. The extractions of FA´s from the soil were performed using extraction solvent consisting of SC-CO2 and methanol as a co-solvent to tune the polarity of the extraction solvent in order to create optimal solubility conditions for the extraction of the FA´s from the soils. Qualitative and quantitative analysis’s were performed on GC-FID system and GC-MS system. The free FA´s used to construct the models as well as lipids in the extractions were derivatized under acidic conditions and then analyzed in their FAME´s form. The qualitative analysis was performed by constructing retention index models for the FAME´s to detect and identify the corresponding FA´s in the herbicide and