Prosecution Insights
Last updated: April 19, 2026
Application No. 18/090,163

STABILIZED N,N-DIETHYL-P-PHENYLENEDIAMINE SOLUTION AND METHOD FOR DETECTING CHLORINE

Final Rejection §102
Filed
Dec 28, 2022
Examiner
SIEFKE, SAMUEL P
Art Unit
1758
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Hach Company
OA Round
2 (Final)
63%
Grant Probability
Moderate
3-4
OA Rounds
3y 7m
To Grant
80%
With Interview

Examiner Intelligence

Grants 63% of resolved cases
63%
Career Allow Rate
651 granted / 1031 resolved
-1.9% vs TC avg
Strong +17% interview lift
Without
With
+17.0%
Interview Lift
resolved cases with interview
Typical timeline
3y 7m
Avg Prosecution
36 currently pending
Career history
1067
Total Applications
across all art units

Statute-Specific Performance

§101
1.2%
-38.8% vs TC avg
§103
30.1%
-9.9% vs TC avg
§102
47.5%
+7.5% vs TC avg
§112
11.7%
-28.3% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1031 resolved cases

Office Action

§102
DETAILED ACTION Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Claim Rejections - 35 USC § 102 The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless – (a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention. Claims 18-20 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Xia et al. (US 2015/0344333). Regarding claim 18, Xia discloses a method for detecting chlorine in an aqueous sample, the method comprising: mixing the aqueous sample with a DPD reagent to obtain a test sample (a water sample is mixed with DPD reagent, para 50-53); and subjecting the test sample to photometry (para 52, DR5000 spectrophotometer measured at 530nm), wherein the DPD reagent comprises: N,N-diethyl-p-phenylenediamine (DPD) (para 52); an inorganic chloride salt at a concentration of 0.5 M or more (para 52-53, 100 g/l); and water (liquid chamber has water therein). Regarding claim 19, the method of claim 18, wherein the test sample does not include a buffering agent (no buffer is disclosed in para. 52-53). Regarding claim 20. The method of claim 18, wherein the inorganic chloride salt is NaCl (para 52-53) or KCl. Allowable Subject Matter Claims 1-9 and 11- 17 are allowed. Claim 1 is allowed because the prior art does not teach a reagent comprising 1 M NaCl, DPD and water. Response to Arguments Applicant's arguments filed 9/30/25 have been fully considered but they are not persuasive. Applicant argues, “Thus, the sodium chloride solution of 100 g/L in Xia was not the testing reagent, but rather was the solution circulated through the electrolytic cells. The reagent used in Xia was only the N,N-diethyl-p-phenylenediamine (DPD). Moreover, that DPD reagent was used to test the free chlorine level of the output of the liquid chamber. Nowhere does Xia disclose any particular concentration of sodium chloride in the output of the liquid chamber, much less that such sodium chloride is part of the DPD reagent. Instead, any sodium chloride present is simply part of the test sample, not of the reagent.” A reagent can be any part of a system to which is used in a chemical reaction. Xia provides sodium chloride which interacts with the DPD, water and chlorine to produce a chemical reaction. Therefore sodium chloride is part of the chemical reaction. Claim 18 has not stated the reagent is a dissolvable tablet or a separate reagent in an ampoule or dropper to which consists of DPD, sodium chloride, and water. The combination of DPD reagent can be added from different droppers to a mixing container containing the aqueous sample. Conclusion THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a). A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action. Any inquiry concerning this communication or earlier communications from the examiner should be directed to SAMUEL P SIEFKE whose telephone number is (571)272-1262. The examiner can normally be reached Monday, Tuesday, Thursday, Friday, 8-6. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Maris Kessel can be reached at 571-270-7698. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /SAMUEL P SIEFKE/ Primary Examiner, Art Unit 1758
Read full office action

Prosecution Timeline

Dec 28, 2022
Application Filed
Jul 29, 2025
Non-Final Rejection — §102
Sep 30, 2025
Response Filed
Jan 21, 2026
Final Rejection — §102 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

3-4
Expected OA Rounds
63%
Grant Probability
80%
With Interview (+17.0%)
3y 7m
Median Time to Grant
Moderate
PTA Risk
Based on 1031 resolved cases by this examiner. Grant probability derived from career allow rate.

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