Fluorescent Reagent for Fatty Acid Analysis ADAM (9-Anthryldiazomethane)

ADAM (9-Anthryldiazomethane) is a fluorescent labeling reagent designed for high-performance liquid chromatography (HPLC) analysis of fatty acids. This crude product reacts easily with fatty acids at room temperature without requiring heat or catalysts. It is highly effective for analyzing fatty acids in biological samples and various reagents using the pre-column derivatization method.

＊The products are for research use only.

ADAM reacts with fatty acids to form highly fluorescent esters. In methanol or acetonitrile, the generated ester exhibits an excitation maximum at 365 nm and an emission maximum at 412 nm.

The reaction typically completes within 60 minutes at room temperature, with 75% to 80% of the reaction occurring in the first 5 minutes. Highly polar solvents like alcohols accelerate the reaction compared to low-polarity solvents such as ether, hexane, or benzene. Note that diazoalkanes can also react with aromatic hydroxyl groups and sulfonic acid groups.

Decomposed products of ADAM do not react with fatty acids. During HPLC, these byproducts elute before the target carboxylic acids and ADAM reaction products, minimizing analytical interference. However, for trace-level analysis, impurities might affect the results. It is recommended to run a control chromatogram using only the ADAM reagent.

A. Preparation of ADAM Reagent
Prepare a 0.05% to 0.1% (w/v) solution in methanol or acetone.

1. Dissolve the ADAM reagent to make a 0.5% to 1.0% acetone solution.
2. Dilute this solution 10-fold with methanol or acetone before use.

• Note: Do not use heat to dissolve the reagent, as ADAM is unstable against heat and light.

B. Sample Solution
Dissolve your sample in methanol or acetone. Solutions in ether, hexane, or chloroform are also acceptable. Since absolute anhydrous conditions are not required, water-containing or aqueous solutions can be used. If the sample is an aqueous solution, use a 0.1% to 0.2% (w/v) ADAM reagent solution.

The quantifiable range for carboxylic acids is approximately 0.05 μg/mL to 100 μg/mL. To ensure accuracy and avoid overlap with minor impurity peaks, measuring at concentrations of 5 μg/mL or higher is recommended.

C. Derivatization

1. Transfer 25 μL of the sample solution into a vial.
2. Add 25 μL of the prepared ADAM reagent, seal the vial, and mix well.
3. Allow the mixture to react at room temperature for about 60 minutes. For dry samples, add 50 μL of the ADAM reagent directly. (A 10-minute reaction is sufficient if using an internal standard or if strict quantification is not required).
4. Inject 5 μL of the reaction solution directly into the HPLC column.

• Note: Reaction times may vary depending on solvent conditions and the specific type of carboxylic acid. If the reaction is incomplete after 60 minutes, extend the reaction time.

D. HPLC Conditions
Reversed-phase columns offer better separation. C8 columns typically result in faster overall elution than C18 (ODS) columns. An acetonitrile–water mobile phase system provides good results. Since column performance varies by manufacturer, optimize the solvent ratio and flow rate using standard samples.