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EnzyChrom™ Free Fatty Acid Assay Kit


  • For quantitative determination of fatty acid and evaluation of drug effects on its metabolism.

Key Features

  • Sensitive. Use 10 µL samples. Linear detection range: colorimetric assay 7 – 1000 µM, fluorimetric assay 7 – 100 µM fatty acid.
  • Convenient. Room temperature “mix-and-read” procedure can be readily automated for high-throughput assay of thousands of samples per day.


  • OD570nm, or FL530/585nm


  • Serum, plasma, urine, saliva, milk, cell cultures, food, agriculture etc


  • All


  • 30 min


  • 100 tests

Detection Limit

  • 7 µM

Shelf Life

  • 6 months

More Details

Fatty acids are aliphatic monocarboxylic acids that are ubiquitously found in animal or vegetable fat, oil, and wax. Fatty Acids play important roles in cellular synthesis, and energy metabolism and are implicated in diverse disorders such as diabetes mellitus, sudden infant death syndrome, and Reye Syndrome. BioAssay Systems method provides a simple, one-step, and high-throughput assay for measuring free fatty acids. In this assay, free fatty acids are enzymatically converted to acyl-CoA and subsequently to H2O2. The resulting H2O2 reacts with a specific dye to form a pink-colored product. The optical density at 570nm or fluorescence intensity (530/585 nm) is directly proportional to the free fatty acid concentration in the sample.

Can you tell me what is the conversion factor for free fatty acids from µM to mEq/L? We are about to measure FFA with your assay (EFFA-100) but most publications in domestic animals are in mEq/L?

1 mEq/L = 1 mmole/L = 1000 µM.

I have just noticed that EDTA can interfere in this assay but, since I used Microvette CB 300 capillary tubes containing Potassium EDTA to collect the blood, I would like to know at what concentration (if known) EDTA is an inhibitor of the reaction.

EDTA in the sample will complex Mg2+ and Ca2+ ions of the assay buffer, necessary cofactors for the enzymes that are used in the assay.

Plasma EDTA tubes usually contain around 5 mM EDTA in the final volume if filled to the draw volume. Much of the EDTA will be complexed with blood Ca2+/Mg2+ ions, and thus not interfere with the assay. The EDTA concentration will be higher if the tubes are only partially filled.

Since the sample to assay buffer ratio is 1:10 and the assay buffer Mg2+ concentration is 1 mM, I would not expect any interference in samples from tubes that have been filled completely. If the collection tube had only been filled partially, I would recommend supplementing the assay working reagent with an additional 1 mM MgCl2.

Treerat, P et al. (2020). Synergism between Corynebacterium and Streptococcus sanguinis reveals new interactions between oral commensals. The ISME Journal, 14(5): 1154-1169. Assay: Fatty acid in C. durum culture supernatant.

Li, X et al. (2020). Critical role of matrix metalloproteinase 14 in adipose tissue remodeling during obesity. Molecular and Cellular Biology, 40(8). Assay: Fatty acid in rat plasma.

Kaczmarek, A et al. (2020). The interaction between cuticle free fatty acids (Ffas) of the cockroaches Blattella germanica and Blatta orientalis and hydrolases produced by the entomopathogenic fungus Conidiobolus coronatus. PLoS ONE, 15(7). Assay: Fatty acid in insect cuticle.

Lu, H et al. (2021). Hepatocyte nuclear factor 4a and glucocorticoid receptor coordinately regulate lipid metabolism in mice fed a high-fat-high-sugar diet. BioRxiv, 2021.02.06.427306. Assay: Fatty acid in mouse serum.

Carson SD, Cole AJ. (2020). Albumin enhances the rate at which coxsackievirus b3 strain 28 converts to a-particles. Journal of Virology, 94(6). Assay: Fatty acid in bovine serum albumin and culture media.

Zhang, C et al. (2020). FABP5 promotes lymph node metastasis in cervical cancer by reprogramming fatty acid metabolism. Theranostics, 10(15): 6561-6580. Assay: Fatty acid in human cells.

Tian, Q et al. (2020). Dietary α-ketoglutarate promotes beige adipogenesis and prevents obesity in middle-aged mice. Aging Cell, 19(1), e13059. Assay: Fatty acid in mouse serum.

Quiros Cognuck, S et al. (2020). Sex differences in body composition, metabolism-related hormones, and energy homeostasis during aging in Wistar rats. Physiological Reports, 8(20). Assay: Fatty acid in rat serum.

Moorhead, SG et al. (2020). Variation of body condition and plasma energy substrates with life stage, sex, and season in wild-sampled nurse sharks Ginglymostoma cirratum. Journal of Fish Biology. Assay: Fatty acid in shark plasma.

Roquetto, AR et al. (2020). Moderate intake of BCAA-rich protein improves glucose homeostasis in high-fat-fed mice. The Journal of Nutritional Biochemistry, 80, 108332. Assay: Fatty acid in mouse serum.

Lambert, K et al. (2020). Grape polyphenols and exercise training have distinct molecular effects on cardiac hypertrophy in a model of obese insulin-resistant rats. The Journal of Nutritional Biochemistry, 108522. Assay: Fatty acid in rat plasma.

Li, X et al. (2020). Novel role of dynamin-related-protein 1 in dynamics of ER-lipid droplets in adipose tissue. FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology, 34(6): 8265-8282. Assay: Fatty acid in mouse serum and adipose.

Jiang, S et al. (2021). Associations of circulating irisin with fndc5 expression in fat and muscle in type 1 and type 2 diabetic mice. Biomolecules, 11(2). Assay: Fatty acid in mouse plasma.

Ji, Yosep, et al (2019). Amelioration of obesity-related biomarkers by Lactobacillus sakei CJLS03 in a high-fat diet-induced obese murine model. Scientific reports 9.1: 6821. Assay: Free fatty acidin mouse serum.

McCambridge, Grace, et al (2019). Saturated Fatty Acid Activates T Cell Inflammation Through a Nicotinamide Nucleotide Transhydrogenase (NNT)-Dependent Mechanism. Biomolecules 9.2: 79. Assay: Free fatty acidin human plasma.

Singh, Sudhakar, et al (2019). Buffalo liver transcriptome analysis suggests immune tolerance as its key adaptive mechanism during early postpartum negative energy balance. Functional & integrative genomics: 1-15. Assay: Free fatty acidin buffaloe serum.

Cueno, Marni E., and Kuniyasu Ochiai (2018). Gingival periodontal disease (PD) level-butyric acid affects the systemic blood and brain organ: insights into the systemic inflammation of periodontal disease. Frontiers in immunology 9:1158. Assay: Free fatty acidin rat blood cytosol.

Feng, Juan, et al (2018). IL-25 stimulates M2 macrophage polarization and thereby promotes mitochondrial respiratory capacity and lipolysis in adipose tissues against obesity. Cellular & molecular immunology 15.5: 493. Assay: Free fatty acidin mice tissues.

Hao, Jiaqing, et al (2018). Circulating Adipose Fatty Acid Binding Protein Is a New Link Underlying Obesity-Associated Breast/Mammary Tumor Development. Cell metabolism 28.5: 689-705. Assay: Free fatty acidin mice serum.

Lambert, Karen, et al (2018). Combination of nutritional polyphenols supplementation with exercise training counteracts insulin resistance and improves endurance in high-fat diet-induced obese rats. Scientific reports 8.1: 2885. Assay: Free fatty acidin rat plasma.

Lambert, Karen, et al (2018). No Additive Effects of Polyphenol Supplementation and Exercise Training on White Adiposity Determinants of High-Fat Diet-Induced Obese Insulin-Resistant rats. Oxidative medicine and cellular longevity 2018:7406946. Assay: Free fatty acidin rat plasma.

Sharma, Vandana, et al (2018). Mannose Alters Gut Microbiome, Prevents Diet-Induced Obesity, and Improves Host Metabolism. Cell Reports 24.12: 3087-3098. Assay: Free fatty acidin mice serum and feces.

Wronska, Anna Katarzyna, et al (2018). Cuticular fatty acids of Galleria mellonella (Lepidoptera) inhibit fungal enzymatic activities of pathogenic Conidiobolus coronatus. PloS one 13.3: e0192715. Assay: Free fatty acidin moth cuticle.

Gallagher, Austin J., et al (2017). Energy metabolism in mobile, wild-sampled sharks inferred by plasma lipids. Conservation physiology 5.1:cox002. Assay: Free fatty acidin sharks plasma.

Wang, Bo, et al (2017). Moderate alcohol intake induces thermogenic brown/beige adipocyte formation via elevating retinoic acid signaling. The FASEB Journal 31.10: 4612-4622. Assay: Free fatty acidin mice serum.

Wang, Bo, et al (2017). Retinoic acid induces white adipose tissue browning by increasing adipose vascularity and inducing beige adipogenesis of PDGFRalpha+ adipose progenitors. Cell discovery 3: 17036. Assay: Free fatty acidin mice serum.

Chung, Hea-Jong, et al (2016). Intestinal removal of free fatty acids from hosts by Lactobacilli for the treatment of obesity. FEBS Open Bio 6.1: 64-76. Assay: Free fatty acidin human lactobacillus culture.

Eastwood, Laura, Pascal Leterme, and A. Denise Beaulieu (2016). Body fat mobilization during lactation in high-producing sows fed varied omega-6 to omega-3 fatty acid ratios. Canadian Journal of Animal Science 96.1: 69-78. Assay: Free fatty acidin pig serum.

Garces-Rimon, M., et al (2016). Pepsin egg white hydrolysate ameliorates obesity-related oxidative stress, inflammation and steatosis in Zucker Fatty rats. PLoS One 11.3: e0151193. Assay: Free fatty acidin rat plasma.

Nishikido, Toshiyuki, et al (2016). Deletion of apoptosis inhibitor of macrophage (AIM)/CD5L attenuates the inflammatory response and infarct size in acute myocardial infarction. Journal of the American Heart Association 5.4: e002863. Assay: Free fatty acidin mice plasma.

Yoo, Jeong-Hyun, Yanan Liu, and Hyun-Sook Kim (2016). Hawthorn fruit extract elevates expression of Nrf2/HO-1 and improves lipid profiles in ovariectomized rats. Nutrients 8.5: 283. Assay: Free fatty acidin rat serum.

Hwang I et al (2012) Catalase deficiency accelerates diabetic renal injury through peroxisomal dysfunction. Diabetes 61(3):728-738. Assay: Free fatty acidin mouse plasma.

Jelinek D et al (2012) The Niemann-Pick C1 Gene Is Downregulated in Livers of C57BL/6J Mice by Dietary Fatty Acids, but Not Dietary Cholesterol, through Feedback Inhibition of the SREBP Pathway. J Nutr 142(11):1935-1942. Assay: Free fatty acidin mouse plasma.

Jin Kyubob et al (2012) Dysregulation of hepatic fatty acid metabolism in chronic kidney disease. Nephrol Dial Transplant. Assay: Free fatty acidin rat liver.

Lu Z et al (2012) TLR4 Antagonist Reduces Early-Stage Atherosclerosis in Diabetic Apolipoprotein E-deficient Mice. J Endocrinol. Assay: Free fatty acidin mouse serum.

Primassin, S., S. Tucci, et al. (2011). Hepatic and muscular effects of different dietary fat content in VLCAD deficient mice. Mol Genet Metab 104(4): 546-51. Assay: Free fatty acidin mouse serum.

Seo, C.W., et al. (2011). Antihyperlipidemic and body fat-lowering effects of silk proteins with different fibroin/sericin compositions in mice fed with high fat diet. J Agric Food Chem 59(8):4192-7. Assay: Free fatty acidin mouse plasma.

To find more recent publications, please click here.

If you or your labs do not have the equipment or scientists necessary to run this assay, BioAssay Systems can perform the service for you.

– Fast turnaround
– Quality data
– Low cost

Please email or call 1-510-782-9988 x 2 to discuss your projects.

Free Fatty Acid Assay Kit
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For bulk quote or custom reagents, please email or call 1-510-782-9988 x 1.

Orders are shipped the same day if placed by 2pm PST
Shipping: On Ice
Carrier: Fedex
Delivery: 1-2 days (US), 3-6 days (Intl)
Storage: -20°C upon receipt

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