Hydroquinone

Hydroquinone: phenol (skin lightening agent).

Hydroquinone testing at Vanguard Laboratory: identity, purity and quantity $250 per sample, with results in 3 to 5 business days.

Structure

Hydroquinone: 2D structure drawn from the PubChem record (CID 785).

Compound data

CAS number

123-31-9

Formula

C₆H₆O₂

Molecular weight

110.11 g/mol

Type

Phenol (skin lightening agent)

Structure and names

Identity: Hydroquinone

IUPAC name: benzene-1,4-diol

How Vanguard tests Hydroquinone

Method for the $250 identity, purity and quantity test: HPLC-UV purity and assay, LC-MS identity, against a reference standard, with results in 3 to 5 business days.

The USP monograph covers identity by infrared spectroscopy, TLC and UV, assay by titration, melting range, water and residue on ignition. Full testing to the USP Hydroquinone monograph is available and quoted.

What's reported

Purity, as percent of total peak area
Quantity, against the label claim
Identity, reported as match or no match against the reference standard
With monograph testing (quoted): the monograph’s tests against its limits

Tests and prices

Purity and quantity

$250

Chromatographic purity and mg per unit by the method matched to the compound, identity against a reference standard. 1 unit.

Raw powder purity

$200

Chromatographic purity on bulk powder. 50 mg.

Add-on tests

Add-on test	Price
Identity and impurities
FTIR identity	$90
CHNS elemental analysis (carbon, hydrogen, nitrogen, sulfur)	$125
Chiral purity (where a chiral method exists; new methods quoted)	$250
Water, solvents and salt form
Water content by Karl Fischer	$60
Residual solvents	$150
Counterions: chloride, acetate and TFA	$70
Assay
Assay, % w/w (with raw powder purity; $250 together)	+$50
Metals and conformity
Heavy metals: arsenic, cadmium, chromium, mercury and lead	$150
Conformity: purity and quantity on more units from the same lot	$100 per extra unit
Microbiology (injectables)
Endotoxin	$210
Sterility or bioburden	$150
Container closure integrity (CCI)	$50
Screening
Fentanyl screen	$50

10% off for 10 or more samples.

Need something else? Other tests are available on request.

Sample amount and turnaround

Purity and quantity is $250 per sample (1 unit) and raw powder purity is $200 for 50 mg, with results in 3 to 5 business days. Send the material sealed and labeled, with the label claim and the form it contains.

Salts, forms and compendial references

Hydroquinone (CAS 123-31-9)
Tell us the salt or form the label states, so quantity is reported on the same basis.

Questions about Hydroquinone testing

Is the $250 test the same as USP monograph testing?

No. The $250 test covers identity, purity and quantity by HPLC with UV detection for purity and assay, and LC-MS for identity. Full testing to the USP Hydroquinone monograph is available and quoted.

Why does hydroquinone turn brown?

Hydroquinone oxidizes in air and light to benzoquinone and darker products. The monograph calls for tight, light-resistant containers, and discolored samples often show lower assay values.

What does HPLC add over the USP titration?

Titration measures total reducing material, while HPLC separates hydroquinone from oxidation products and look-alikes such as arbutin or monobenzone. LC-MS confirms identity.

What form does hydroquinone arrive in?

As crystals or in creams and serums. Creams need extraction and should be sent in their original sealed container to limit oxidation.

Sources

https://pubchem.ncbi.nlm.nih.gov/compound/785

Identity facts from the USP monograph header for this compound.

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