The patent that isn't.
A complete public breakdown of the U.S. and European patent applications filed by the Noorduin lab for methylammonium-bromide lead detection, the prior art that anticipates them by years, and the arguments their attorneys are now making to the European Patent Office to keep the application alive. Every relevant document is here, sourced and linked.
Every paper cited below has been mirrored with the most important sentences highlighted in yellow, so you can jump straight to the page in question and read it for yourself. The links below open to the exact pages where the key passages are.
Non-final office action, March 19, 2026.
Including two revivals after deemed-withdrawn lapses.
Filed at the EPO, including 4 by Eric Ritter.
After third-party prior-art submissions.
United States, rejected. Europe, defended.
The same invention is being prosecuted as two parallel applications. The U.S. and European examiners have both rejected the broad claims. The applicant has narrowed twice in Europe and is now defending the application against a wave of third-party observations.
U.S. application 18/285,431
Filed October 3, 2023 · published as US 2024/0183786 A1 · Examiner John McGuirk, Art Unit 1798.
On March 19, 2026, every single one of the 15 pending claims was rejected. The grounds: anticipation under 35 U.S.C. § 102, obviousness under § 103, indefiniteness under § 112(b), and a kit-claim anticipation by Jumonville. The applicant has not yet responded.
European application EP 22 720 443.5
PCT filed April 4, 2022 · Dutch priority April 6, 2021 · representative De Vries & Metman (Amsterdam) · originally assigned to AMOLF / NWO, transferred to Lumetallix Holding B.V. on August 5, 2025.
The application was deemed withdrawn twice and revived via paid further-processing requests. Claims have been narrowed across two amendment rounds. An intent-to-grant communication of October 2, 2025 was effectively withdrawn after a wave of third-party observations led the Examining Division to reopen prosecution on February 9, 2026. The most recent reply was filed April 24, 2026.
What they tried to patent.
A method for detecting lead by applying a methylammonium-halide reagent in a liquid medium to a solid substrate suspected of containing lead, then illuminating the substrate with ultraviolet light to observe the green photoluminescence of the lead-halide perovskite that forms.
The chemistry
Methylammonium bromide (CH₃NH₃Br) dissolved in isopropanol. When it contacts a lead-containing solid, the methylammonium and bromide combine with the lead to form methylammonium-lead-bromide perovskite (CH₃NH₃PbBr₃). Under 365 nm UV, the perovskite emits bright green light at ~530 nm.
The formulation
The application's stock solution at paragraph [0076] of US 2024/0183786 A1: "the stock solution of MABr in 2-propanol (16 mg/ml) was used." Paragraph [0095] adds: typical halide concentration ~0.16 mol/L. That is 1.6% methylammonium bromide by mass in isopropanol.
The substrate menu (as filed)
"painted surfaces, glass, metals, electronic products, soil, dust, waste, food and feed products, personal care products, cleaning products, and rock." (Claim 1, US 2024/0183786 A1.)
The substrate menu (after EP narrowing)
"painted surfaces, glass, metals, and plastics." (Amended claim 1, EP application as of July 14, 2025.) Soil, dust, waste, food, personal care, cleaning, and rock were all dropped during European prosecution. The retreat is on the public record.
The chemistry was published years before the priority date.
The earliest priority date claimed by the application is April 6, 2021 (Dutch national filing). Every reference below predates that, in some cases by years.
Holtus et al. (2018) · Nature Chemistry
"Shape-preserving transformation of carbonate minerals into lead halide perovskite semiconductors based on ion exchange/insertion reactions." Nature Chem. 2018, published June 4, 2018.
Authors include Lukas Helmbrecht (co-first author) and Willem L. Noorduin (corresponding). Helmbrecht is the named first inventor on the patent application. Noorduin is the corresponding author on the patent and the founder of Lumetallix. They published the chemistry, on a real-world solid lead-containing substrate, using the exact reagent in the exact solvent at a comparable concentration, three years before they filed for the patent.
That formulation is 1% MABr in IPA by mass, applied as drops from a pasteur pipet, illuminated with 365 nm UV, producing real-time green fluorescence. The patent application's stock formulation is 1.6% MABr in IPA. The product on the market today is the same chemistry. The inventor wrote the recipe down in 2018.
Holtus · highlighted (author byline)Holtus SI · Movie 1 description (p2)Holtus SI · Pasteur-pipet recipe (p7)
Yan et al. (2019) · Scientific Reports
Yan, He, Chen, Zhang & Yan. "CH₃NH₃Br solution as a novel platform for the selective fluorescence detection of Pb²⁺ ions." Scientific Reports 9 (2019) 15840.
Page 5 of the paper, on paper test strips:
That is the demonstration. The same chemistry, applied as a solution to a paper substrate, illuminated with 365 nm UV, observed with the naked eye, two years before the patent's priority date. The U.S. examiner's primary 103 reference. Eric Ritter introduced this paper to the EPO record on January 21, 2026.
Wang et al. (2021) · Sensors & Actuators B
"Highly selective fluorescence turn-on determination of Pb(II) in Water by in-situ enrichment of Pb(II) and MAPbBr₃ perovskite growth in sulfydryl functionalized mesoporous alumina film." Sensors and Actuators B: Chemical 326 (2021) 128975.
Detection setup: a 13 mm diameter sulfhydryl-functionalized mesoporous alumina film immersed in 50 mL of water containing Pb(II), 25 minutes at 55°C. MABr in DMF dropped on the film, dried, illuminated under 365 nm UV. From the abstract:
Five thousandths of a microgram per milliliter is 5 parts per billion. Below the Chinese drinking water standard of 0.01 µg/mL (10 ppb), which is also the WHO and U.S. EPA standard. Wang's published images zoom in to the perovskite crystals forming on the film. The reagent does not need to penetrate the substrate. The lead does not need to be free. The closed-surface inventive-step argument fails on Wang alone.
Zang et al. (2017) · Sol. Energy Mater. Sol. Cells
"CH₃NH₃PbI₃ converted from reactive magnetron sputtered PbO for large area perovskite solar cells."
Establishes that lead oxide reacts directly with methylammonium-halide reagent in isopropanol to form methylammonium-lead-iodide perovskite. Confirms the chemistry transfers across PbCO₃, PbO, and metallic-lead-with-oxide-skin substrates. Cited on the application's own IDS.
Concise Description of Relevance
Filed by Hovey Williams LLP under 37 CFR § 1.290 in the U.S. application, listing eight references: Yan, Yan SI, Wang, McKnight 1989, Millipore Sigma MABr data, Holtus, Holtus SI, and Zang.
The U.S. examiner relied on this record. Every document was on the file before substantive examination began.
Examiner McGuirk rejected every claim.
USPTO Examiner John McGuirk (Art Unit 1798) rejected all 15 pending claims. Three independent grounds for rejection, applied to overlapping claim sets.
| Ground | Statute | Claims affected | Primary art |
|---|---|---|---|
| Indefiniteness · 7 separate issues | 35 U.S.C. § 112(b) | 1–15 | "waste", "electronic (waste) products", missing antecedent for "the sample" in 11 & 14, "e.g." in 9, "monovalent metal cations capable of perovskite formation", "carrier of an absorbent material" |
| Anticipation | 35 U.S.C. § 102(a)(1) | 12–15 (kit claims) | Jumonville (US 2010/0086616) |
| Obviousness | 35 U.S.C. § 103 | 1–6, 8–11 | Yan 2019 + Kayano (US 2011/0177604) |
| Obviousness · oxidation step | 35 U.S.C. § 103 | 11 | Yan + Kayano (oxidation pretreatment) |
| Obviousness · solvent claim | 35 U.S.C. § 103 | 7 | Yan + Kayano + Acik (US 2019/0003074) |
"Claims 1–15 are pending in the application. Claims 1–15 are rejected."
U.S. Office Action Summary, page 1.
As of today, every claim in this patent application stands rejected in both jurisdictions.
United States: all 15 claims rejected by Examiner McGuirk on March 19, 2026. The action is non-final, which means the applicant has a statutory window to reply, but the rejection is the operative status of the file right now. The applicant has not responded.
European Union: the intent-to-grant of October 2, 2025 was effectively withdrawn when the Examining Division reopened prosecution on February 9, 2026 with a new Article 94(3) communication addressing prior art the applicant had not previously addressed. The case currently sits with the applicant's April 24, 2026 reply, awaiting the Examining Division's response. The narrowed claims are not granted; they are pending defense against fresh rejection grounds.
The most devastating part is what the U.S. examiner did not even need to use. McGuirk reached every claim with Yan + Kayano + Acik. He did not have to cite the inventor's own published paper, even though Holtus 2018 (D5–D7 in the European file, on the U.S. IDS, considered by the examiner) sits in the record. The chemistry the patent application is trying to claim was already so plainly disclosed that the examiner did not need to reach for the most damaging document available. Adding Holtus on a final action or in any continuation would only strengthen the rejection and remove any room for argument that the chemistry was non-obvious.
That is the absurd shape of this matter. The applicant published the recipe themselves. Independent groups published the same chemistry as a lead-detection method on solid substrates. The U.S. examiner rejected every claim without even needing to invoke the inventor's own paper. The European examiner reopened prosecution after a public-record wave of third-party observations introduced art the applicant could not previously distinguish. And the most recent reply is an attempt to redefine the word "paint" using two consumer-painting blog posts, in service of a novelty argument over a paper from 2019.
Four years, two lapses, one withdrawn intent-to-grant.
Every substantive document in the EP file, in chronological order. Each link is to the original PDF served from this site.
"A paper provided with a lead bromide solution is not a painted surface."
That is the actual quoted argument from page 1 of the Lumetallix reply, signed by their European patent attorney. To support this novelty distinction over Yan 2019, two paint-definition documents were submitted as authorities. They are consumer painting blog posts.
These are the documents Lumetallix's European patent attorneys submitted to the European Patent Office as authorities for what paint is. They are reproduced here with their full first pages, as the EPO received them.
"Basic Paint Ingredients and Chemicals"
By Haseeb Jamal · February 21, 2017 · 4 pages · civil-engineering blog post. Defines paint as solvent + binder + pigment + additives.
Above: the actual first page of the document Lumetallix's representative submitted to the European Patent Office as evidence of what paint is. Author photo at top of post. Click image to view the full PDF.
"Painting 101: What Is Paint Made Of?"
By "admin" · September 21, 2018 · 4 pages · ultrafinishpainting.com. Subtitled "A primer on paint ingredients" with a consumer paint-can infographic.
Above: the title page and the consumer infographic from the second document submitted as authority for what paint is. Authored by "admin" on a residential painting company's blog. Click images to view the full PDF.
From the Lumetallix reply, with their definition of paint:
Then the conclusion they want to reach:
The argument relies on hoping the examiner does not look up their own examples.
Their own example fails their own paint definition.
The Lumetallix April 24 reply defines paint as requiring four ingredients: binder + solvent + pigment + additives. The patent application's own example 1 paint preparation, at paragraph [0087]:
That formulation has pigment and binder. No solvent. No additives. Under their April 24 definition of paint, the patent's own working example is not paint. They cannot have it both ways: either Yan's PbBr₂-impregnated paper might be paint under a broader meaning, or the patent's own example is not paint and the entire enablement argument collapses.
The "closed surface" argument is contradicted by their own data.
The reply argues at page 3 that lead in "painted surfaces, glass, metals, and plastics" is "chemically incorporated in the structure of the material; it is not present in the form of Pb ions in a freely accessible form." But the patent's own example 1 substrate table reports:
If the lead in cured lead-white paint were truly inaccessible and incorporated in the structure, the chemistry would not fire instantly with a cotton swab. The patent's own data refutes the inventive-step argument.
If crystals form, they can be seen. The light and the liquid don't have to penetrate.
The closed-surface argument confuses the substrate's interior with the substrate's surface. Methylammonium-bromide perovskite crystals form right at the surface where the reagent meets the lead-bearing layer. The crystals are what fluoresce green. The 365 nm UV does not have to penetrate, the IPA does not have to penetrate, and the green emission comes back out the same surface where the crystals sit.
Wang 2021's published images zoom directly to the crystals on the porous-alumina film surface. Holtus 2018 figure 4g shows the crystals forming on the outside of a 3.5 cm sand dollar in seconds. The chemistry has always been a surface-reaction phenomenon. The inventor wrote it that way.
They never tested plastic. Yet they claim plastic.
The April 24 amended claim 1 lists "painted surfaces, glass, metals, and plastics" as the substrate menu. The patent's example tables list dozens of tested substrates: lead carbonate powder, lead chloride, lead white, lead acetate, lead nitrate, lead oxide, lead-tin solder, lead glazing, lead-acid battery, soil samples, and so on.
No plastic substrate is tested anywhere in the patent. Not as a positive, not as a negative. The claim that the method works on plastic is not enabled by the specification. This is a § 112(a) (US) and Article 83 EPC (EP) enablement problem hiding in plain sight.
The substrates they actually tested were extreme concentrations. No real-world low-contamination paint was tested.
The substrate menu is "painted surfaces, glass, metals, and plastics." Here is what the patent actually tested for each:
| Substrate class | Pb concentration tested | What this looks like in the wild |
|---|---|---|
| Painted surfaces | Lead white paint = 1 g lead white + 0.4 g linseed oil = ~71% lead-carbonate pigment by mass · ~52% Pb by mass | Real-world consumer-product lead paint can be 0.1%–10% Pb. The CPSC limit is 90 ppm (0.009%). The patent never tested anywhere near regulated concentrations. |
| Glass | Glass with 24% PbO (≈22% Pb) | Old leaded crystal glass is 24%–32% PbO. Bottle glass is typically <0.1% Pb. The patent only tested high-Pb leaded crystal. |
| Metals | Metallic lead (100%) · Lead-Tin 60-40 solder (60% Pb) | Modern solder is <0.1% Pb (RoHS). The patent only tested pure lead and high-Pb solder. |
| Plastics | Not tested. | Lead-stabilized PVC and old painted plastic toys are real-world targets. The patent has no data. |
Inventive-step doctrine asks whether a skilled person would have a reasonable expectation of success in extending the prior art to the claimed substrates. The patent's own examples do not establish that expectation across the substrate menu. They establish it only for substrates with dominant lead loading. The "closed inaccessible surface" argument is a way of obscuring that gap.
Lumetallix's European attorneys filed sworn-equivalent claims against Eric Ritter on April 24, 2026.
The April 24 reply from De Vries & Metman attempts to delegitimize the third-party observations by attacking the submitter. The relevant passage, reproduced verbatim from page 4:
As background information, it may be helpful to note that Mr Ritter and Spirochaete are contractual counterparties of Lumetallix, have obtained confidential information concerning the present subject-matter under NDA, and went on to incorporate Fluorospec, which now sells products the production could not have happened without knowledge of the confidential information. As a result, the applicant has a commercial and legal dispute with Mr Ritter and his two companies, including for breach of NDA, unlawful use of confidential information and misappropriation of trade secrets."De Vries & Metman, reply to ED communication, April 24, 2026, page 4.
This is now part of the public European patent file under application EP 22 720 443.5. It can be downloaded directly from the EPO file inspection portal.
Three things to note about it:
- It is a sworn-equivalent representation by counsel of record. It binds Lumetallix to the position they have stated.
- Holtus 2018 — the inventor's own paper on the same chemistry and the same formulation — was published five years before any NDA between Eric and Lumetallix. The chemistry is in the public scientific literature, available to anyone who reads Nature Chemistry. There is no "confidential information" to misappropriate when the inventor's own group already published the recipe.
- The accusation that Eric is the source of the "unusual number" of third-party observations is contradicted by the table in the same reply: TPO10 (filed January 22, 2026) was filed by NLO, a Dutch patent attorney firm acting for a third party. Lumetallix's own filing acknowledges this.
Every relevant document, sourced and downloadable.
All documents below are mirrored from the corresponding USPTO Patent Center / EPO file inspection records. They are the authoritative public files.
United States · Application 18/285,431
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US Application Publication · US 2024/0183786 A1Download PDF
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Non-Final Office Action · March 19, 2026Download PDF
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Concise Description of Relevance · Third-Party SubmissionDownload PDF
Prior Art · Cited in Both Files · with key passages highlighted in yellow
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Holtus et al. (2018) · Nature Chemistry · highlightedDownload PDF
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Holtus et al. (2018) · Supplementary Information · highlightedDownload PDF
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Yan et al. (2019) · Scientific Reports · highlightedDownload PDF
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Wang et al. (2021) · Sensors & Actuators B · highlightedDownload PDF
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Zang et al. (2017) · Sol. Energy Mater. Sol. CellsDownload PDF
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Holtus et al. (2018) · Nature Chemistry · originalDownload PDF
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Holtus et al. (2018) · Supplementary Information · originalDownload PDF
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Yan et al. (2019) · Scientific Reports · originalDownload PDF
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Yan et al. (2019) · Supplementary Information · originalDownload PDF
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Wang et al. (2021) · Sensors & Actuators B · originalDownload PDF
European Application EP 22 720 443.5
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Description as filed (PCT, April 4, 2022)Download PDF
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Claims as filedDownload PDF
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WO publication of international applicationDownload PDF
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International Search Report (October 13, 2022)Download PDF
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International Preliminary Report on Patentability (October 23, 2023)Download PDF
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Amended claims · round 1 (July 18, 2024)Download PDF
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Letter accompanying amended claims · round 1Download PDF
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First EPO Examination Communication (October 28, 2024)Download PDF
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Annex to first EPO Examination CommunicationDownload PDF
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Reply to ED · round 2 (July 14, 2025)Download PDF
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Amended claims · round 2 (July 14, 2025)Download PDF
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Amended description · round 2Download PDF
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Communication of intent to grant (October 2, 2025)Download PDF
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Text for grant (clean)Download PDF
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Annex to intent-to-grantDownload PDF
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ED communication (February 9, 2026)Download PDF
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Annex to ED communicationDownload PDF
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Reply to ED (April 24, 2026) · the paint-definition argumentDownload PDF
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Cover letter to April 24 replyDownload PDF
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Citation A · paint definitionDownload PDF
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Citation B · paint definitionDownload PDF
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FluoroSpec vs Lumetallix
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Trace-Detection Patent Disclosure
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Lead Test Patent Record (USPTO summary)
A focused summary of the U.S. examiner's findings.
What Public Disclosure Does
Why publishing the chemistry openly matters for the public record.
Trace Lead Detection · history
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Last updated 2026-05-09 · maintained by Eric Ritter · contact eric@fluorospect.com · 631-461-1838