Transdermal patch testing
A patch makes two claims: how much active it holds, and how much of that crosses over time. We measure both, plus the unit-to-unit spread that decides whether the claim holds across a batch.
- Price
- Quoted
- Turnaround
- 7–10 business days
- Family
- Product
- Agilent 1290 or 6490
- Agilent 1290 Infinity II UHPLC
- Diffusion apparatus with HPLC assay
- Incubated plates
- Agilent 7850 ICP-MS
Purchased new through authorised channels, performance-qualified by certified engineers, and the instrument ID prints on every certificate. View the bench.
What the panel measures
| Test | Method | Instrument | Reports as |
|---|---|---|---|
| Total active content | MethodExhaustive extraction then HPLC-UV or LC-MS/MS | InstrumentAgilent 1290 or 6490 | Reports asmg per patch and % of claim |
| Content uniformity | MethodReplicate assay, 10 patches | InstrumentAgilent 1290 Infinity II UHPLC | Reports asRelative standard deviation, % |
| In vitro release | MethodTimed sampling into receptor medium, 37 °C | InstrumentDiffusion apparatus with HPLC assay | Reports asCumulative mg released at each interval |
| Release profile | MethodPlotted across the stated wear time | InstrumentDerived from the assay | Reports asmg/h and cumulative percentage |
| Residual content | MethodAssay after the release study | InstrumentAgilent 1290 Infinity II UHPLC | Reports asmg remaining, mass balance closed |
| Microbial | MethodUSP <61>/<62> | InstrumentIncubated plates | Reports asCFU per patch and pathogens |
| Heavy metals | MethodICP-MS | InstrumentAgilent 7850 ICP-MS | Reports asppb: Pb, As, Cd, Hg |
Sample requirements and shipping
| Item | Requirement |
|---|---|
| Patches | Requirement12 units, unopened, in the retail packaging |
| Claim | RequirementThe stated active, dose per patch and intended wear time |
| Release study | RequirementAdd 6 patches if you want the release profile as well as content |
| Condition | RequirementRoom temperature, flat, in the original pouches. |
Order first, then ship. A prepaid label is emailed when payment lands, and the carrier scan on that label opens your chain of custody. We accept no walk-in drop-off, and we hold no DEA registration, so no Schedule I to V material.
Why the method matters
Total content and delivered dose are different numbers, and a patch can hold its full claim while releasing a fraction of it. The release study is what connects the label to what a wearer actually receives.
Closing the mass balance matters: content before, release during, residual after. When those three do not add up, the method needs work before the product does, and we say so rather than reporting a number we do not believe.
What comes back
A public certificate
Every result, the method, the instrument ID, the LOD and LOQ and the signature, verifiable by accession number with no login.
The filmed route
Your package opened on camera, a photograph of each container, and the footage retained for three years. Released to you on request.
A retained sample
Held 90 days, so any result can be rechecked by us or by an accredited laboratory of your choosing.
Questions about transdermal patch testing
Is this a regulatory bioequivalence study?
No. This is in vitro release into a receptor medium, which is a quality and consistency tool. Bioequivalence requires a clinical study we do not perform.
Why 7–10 days rather than 5–7?
The release study runs in real time across the stated wear period, then the residual assay follows. The schedule sets the turnaround.
Can you test content only?
Yes, and it is the cheaper starting point. Content and uniformity are quoted per submission, and the release profile is quoted on top and needs the extra units.
What receptor medium do you use?
Phosphate buffer at 37 °C as standard, or a medium you specify. Whichever runs, it is named on the certificate, because a release figure is meaningless without it.
Submit a sample
Order in the builder, pay, and a prepaid label is emailed to you. The certificate publishes to the database the moment it is signed.