Citrate Colorimetric/Fluorometric Assay Kit

Details for Product No. ABIN411649, Supplier: Log in to see
Detection Range
0.1-10 nM
Minimum Detection Limit
0.1 nM
Biochemical Assay (BCA)
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Sample Type Cell and Tissue Culture Supernatant, Plasma, Serum, Tissue Samples, Biological Fluids
Detection Method Fluorometric, Colorimetric
Specificity Citrate Assay Kit provides a simple, sensitive and rapid means of quantifying citrate in a variety of samples. In the assay, citrate is converted to pyruvate via oxaloacetate. The pyruvate is quantified by converting a nearly colorless probe to an intensely colored (lambda max =570 nm) and fluorescent (E x /E m, 535/587 nm) product. The Citrate Assay Kit can detect 0.1 to 10 nmoles (approx. 2 ?M-10 mM) of citrate in a variety of samples.
Characteristics Citrate Assay Kit: Colorimetric & Fluorometric Assay for detecting Citrate in variety of Samples within 40 min. Rapid, Convenient & Reliable.
Components Citrate Assay Buffer
Citrate Probe
Citrate Enzyme Mix
Citrate Developer
Citrate Standard (10 μmol)
Target Type Chemical
Background Citric acid (HOOC-CH₂-C(-OH)(-COOH)-CH₂-COOH) is a key intermediate in the TCA cycle which occurs in mitochondria. It is formed by the addition of oxaloacetate to the acetyl group of acetyl-CoA derived from the glycolytic pathway. Citrate can be transported out of mitochondria and converted back to acetyl CoA for fatty acid synthesis. Citrate is an allosteric modulator of both fatty acid synthesis (acetyl-CoA carboxylase) and glycolysis (phospho- fructokinase). Citrate is widely used industrially in foods, beverages and pharmaceuticals. Citrate metabolism and disposition can vary widely due to sex, age and a variety of other factors.
Application Notes The Citrate Assay Kit can detect 0.1 to 10 nmoles (~2 μM-10 mM) of citrate in a variety of samples.

Further details regarding sample type: Cell and tissue culture supernatants, urine, plasma and serum, as well as many other biological fluids

Assay Time < 1 h
Protocol 1. Standard Curve Preparations: Colorimetric Assay: Dilute the Citrate Standard to 1 nM/µL by adding 10 µL of the Standard to 990 µL of dH2O, mix well. Add 0, 2, 4, 6, 8, 10 µL into a series of standards wells on a 96 well plate. Adjust volume to 50 µL/well with Assay Buffer to generate 0, 2, 4, 6, 8, 10 nM/well of the Standard. Fluorometric Assay: Dilute the Citrate standard to 0.1 nM/µL by adding 10 µL of the standard to 990 µL of dH2O, mix well, then further dilute by adding 10 µL to 90 µL of dH2O. Add 0, 2, 4, 6, 8, 10 µL into a series of standards well on a 96-well plate. Adjust the volume to 50 µL/well to generate 0, 0.2, 0.4, 0.6, 0.8, 1.0 nM/well.
2. Sample Preparation: Tissue (20 mg) or cells (2 x 10^6 ) should be rapidly homogenized with 100 µL of Citrate Assay Buffer. Centrifuge at 15,000 g for 10 minutes to remove cell debris. Enzymes in samples may interfere with the assay. We suggest deproteinizing samples using a perchloric acid/KOH protocol or 10 kd molecular weight cut off spin columns. Add 1-50 µL samples into duplicate wells of a 96-well plate and bring volume to 50 µL with Assay Buffer. We suggest testing several doses of your samples to ensure readings are within the standard curve range.
3. Develop: Mix enough reagent for the number of samples and standards to be performed: For each well, prepare a total 50 µL Reaction Mix containing: Colorimetric Assay Fluorometric Assay Sample Bkgd Control* Sample Bkgd Control* Citrate Assay Buffer 44 µL 46 µL 44 µL 46 µL Citrate Enzyme Mix 2 µL ---- 2 µL ---- Developer 2 µL 2 µL 2 µL 2 µL Citrate Probe** 2 µL 2 µL 2 µL 2 µL *Samples may contain oxaloacetate or pyruvate which can generate a background and need to be subtracted from the sample background signal. **For the fluorometric assay, dilute 10X with DMSO to reduce fluorescent background.
4. Add 50 µL of the Reaction Mix to each well containing the Citrate Standard and test samples. Add 50 µL of the sample background control mix to background control wells.
5. Incubate for 30 minutes at room temperature, protect from light.
6. Measure OD at 570 nm or fluorescence at E x /E m 535/587nm.
Calculation of Results

Calculation: Correct background by subtracting the value of the 0 Citrate Standard from all readings. Next subtract the value of the Sample Background Control from the test sample. Plot the standard curve. Apply corrected sample readings to the standard curve to get Citrate amount in the sample wells. The Citrate concentrations in the test samples: C = Ay/Sv (nM/µL, or μM/mL, or mM) Where: Ay is the amount of citrate (nmol) in your sample from the standard curve. Sv is the sample volume (µL) added to the sample well. Citric acid molecular weight: 191 g/mol. Citrate standard curve generated using this kit protocol

Restrictions For Research Use only
Storage -20 °C
Expiry Date 12 months
Product cited in: Ding, Liu, Chen, Di, Xu, Zhou, Deng, Wu, Yang, Lan: "Metabolic sensor governing bacterial virulence in Staphylococcus aureus." in: Proceedings of the National Academy of Sciences of the United States of America, Vol. 111, Issue 46, pp. E4981-90, 2014 (PubMed).

Weiner, Leader, Bedford, Verlander, Ellis, Kalita, Vos, de Jong, Walker: "Effects of chronic lithium administration on renal acid excretion in humans and rats." in: Physiological reports, Vol. 2, Issue 12, 2014 (PubMed).

Hung, Wang, Yu, Chen, Srivastava, Petrovics, Kung: "A long noncoding RNA connects c-Myc to tumor metabolism." in: Proceedings of the National Academy of Sciences of the United States of America, Vol. 111, Issue 52, pp. 18697-702, 2014 (PubMed).

Frawley, Crouch, Bingham-Ramos, Robbins, Wang, Wright, Fang: "Iron and citrate export by a major facilitator superfamily pump regulates metabolism and stress resistance in Salmonella Typhimurium." in: Proceedings of the National Academy of Sciences of the United States of America, Vol. 110, Issue 29, pp. 12054-9, 2013 (PubMed).

Jones, Wildermuth: "The phytopathogen Pseudomonas syringae pv. tomato DC3000 has three high-affinity iron-scavenging systems functional under iron limitation conditions but dispensable for pathogenesis." in: Journal of bacteriology, Vol. 193, Issue 11, pp. 2767-75, 2011 (PubMed).

Gaglio, Metallo, Gameiro, Hiller, Danna, Balestrieri, Alberghina, Stephanopoulos, Chiaradonna: "Oncogenic K-Ras decouples glucose and glutamine metabolism to support cancer cell growth." in: Molecular systems biology, Vol. 7, pp. 523, 2011 (PubMed).