ADRA Kit

ADRA is proposed to address the molecular initiating event of skin sensitization AOP (Adverse Outcome Pathway) by quantifying the reactivity of the test compounds against the model synthetic amino acid derivatives. The reaction is monitored by HPLC-analysis after 24 hours incubation at 25°C and 281 nm, determining the relative residual concentration of NAC and NAL in the reaction liquid.

• NAC and NAL are detected at a relatively long wavelength (281 nm).
  ・・・ Preventing co-elution of the test chemical and the nucleophilic reagent.
• ADRA avoids precipitation by using only 1% of reactants of the existing method.
• Variability of result values are very low.
  ・・・ In ADRA, the reaction is stopped by the addition of a fixing solution (2.5%TFA) before analyzing.
• Multiple test chemicals can be assayed in a short period of time.
  ・・・ The test procedure is performed using a single 96-well plate and a multichannel pipette.

• Components	Amount	Qty
  NAC	for 10 mL	2 vials
  NAL	for 10 mL	2 vials
  NAC Buffer (pH 8.0) premixed	for 300 mL	2 vials
  NAL Buffer (pH 10.2) premixed	for 300 mL	2 vials
  0.01 mol/L EDTA Solution	for 1 mL	2 vials

• 

1. Dissolve and prepare the buffer premix in water
2. Dissolve NAC and NAL
3. React the test compounds with 96-well plate for 24 hours
4. Analyze it by HPLC

※Buffer premix, NAC, and NAL are subdivided into small amounts for reaction. It can be used for ADRA just by dissolving it.

Reagents

* Use water with low metal content.
** Not to be used, if the test chemical dissolves in water or acetonitrile.
Phenylacetaldehyde (CAS RN® 122-78-1) is required as a positive control.

Lab ware

• Electronic balance –with a displayed precision of 0.1 mg
• Micropipette – Three micropipettes capable of distribution of 2 -10 μL, 10 - 100 μL, 100 - 1000 μL
• 12 channel pipette – capable of distribution of 50 - 150 μL
• HPLC system – equipped with a light-shielding auto-sampler for a 96-well plate capable of liquid feeding at 0.3 mL/min
• UV detector - photodiode array (PDA) detector or absorbance detector (281 nm)
• HPLC column
• pH meter – with precision of ±0.01 pH, equipped with a buffer solution for calibration
• Incubator – capable of a temperature of 25°C
• 96-well plate
• 500 mL plastic bottle
• Test tube mixer
• Plate seal*
  * Use the seal having high sealability and solvent-resistant performance.
• Plate shaker
• Plate centrifuge

Note: to avoid NAC/NAL dimerization upon metal ion contamination, all consumables (except for components for HPLC analysis) must be made of polypropylene or polyethylene.

High speed analysis (by Shimadzu Corporation)

Shimadzu Corporation showed an example of high-speed analysis of ADRA.
By using high-speed conditions, HPLC analysis can be completed in 18 hours in the test of 10 test substances, which took about 50 hours conventionally.
Please check the website of Shimadzu Corporation for the detail.