Naproxen

Naproxen: nSAID (propionic acid derivative).

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

Structure

Naproxen: 2D structure drawn from the PubChem record (CID 156391).

Compound data

CAS number

22204-53-1

Formula

C₁₄H₁₄O₃

Molecular weight

230.26 g/mol

Type

NSAID (propionic acid derivative)

Structure and names

Identity: Naproxen

IUPAC name: (2S)-2-(6-methoxynaphthalen-2-yl)propanoic acid

How Vanguard tests Naproxen

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 and HPLC retention time, assay by HPLC, organic impurities and enantiomeric purity by HPLC, and loss on drying. Full testing to the USP Naproxen 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

Naproxen (CAS 22204-53-1)
Naproxen Sodium
Tell us the salt or form the label states, so quantity is reported on the same basis.

Questions about Naproxen testing

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

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

What is the difference between naproxen and naproxen sodium?

Naproxen is the free acid and naproxen sodium is its sodium salt. The salt has a higher molecular weight, so the same mass of naproxen sodium contains less naproxen, and results are reported against the form on the label.

Why does enantiomeric purity matter for naproxen?

Naproxen is the single S enantiomer. The USP monograph includes a chiral HPLC test for the R enantiomer, which a standard reversed-phase purity test does not resolve, so chiral testing is quoted separately.

Sources

https://pubchem.ncbi.nlm.nih.gov/compound/156391

Identity facts from the USP monograph header for this compound.

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