Test Material: S ulfentrazone 

MRID 48958901 

Title: Keenan, D.J. and A. DePompei. 2012. Anaerobic soil metabolism of 

e4CJSulfentrazone 

EPA PC Code: 129081 

OCSPP Guideline: 835.4200 

For Cambridge Environmental: 

Primary Reviewer: Dana Worcester Signature: Q~ w~· 

Date: 11112/13 

Secondary Reviewer: Kathleen Ferguson Signature: 'l(~t?frenv 

Date: 11/ 12/13 

QC/QA Manager: Joan Gaidos 

For the Environmental Protection 

Agency: 

Final Reviewer: Michael Barrett 

Signature: /--d'/{ 

Date: 11/12/13 

Date: 9/ 12/2014 
Sulfentrazone (PC 129081) MRID 48958901

Page 2 of 19

Anaerobic Degradation of Sulfentrazone in Soil

Report: MRID 48958901. Keenan, D.J. and A. DePompei. 2012. Anaerobic soil 

metabolism of [14C]Sulfentrazone. Unpublished study performed by Ricerca 

Biosciences, LLC, Concord, Ohio and sponsored and submitted by FMC 

Corporation, Ewing, New Jersey. Ricerca Study No.: 027634. FMC Study No.: 

162E2511E1. FMC Report No.: PC-0775. Experiment started September 22, 

2011 and terminated April 15, 2012 (p. 15). Final report issued September 18, 

2012.

Document No.: MRID 48958901

Guideline: OCSPP 835.4200

Statements: The study was conducted according to USEPA Principles of Good Laboratory 

Practice (p. 3). Signed and dated Data Confidentiality, GLP, and Quality 

Assurance statements were provided (pp. 2-4). The authenticity of the study 

report is certified in the Quality Assurance Statement.

Classification: This study is classified as supplemental. Redox potentials were provided only as a 

range, and pH and dissolved oxygen levels throughout the study were not 

reported. The water used to flood the soil was not characterized. The pesticide use 

history for the soil was not reported, and it was not demonstrated that the water 

and soil were pesticide-free prior to use. Limits of Detection and Quantification 

were not reported.

PC Code: 129081

Reviewer: Michael Barrett

U.S. EPA Date: September 12, 2014

Executive Summary

The anaerobic transformation of [phenyl-U14C]- and [carbonyl14C]-labeled sulfentrazone was 

studied in a sandy loam soil (pH 6.8, CEC 10.4 meq/100 g, 0.89% O.M.) from California (exact 

source or soil classification were not specified) for 120 days in a closed system in the dark at 20C

following 30 days of aerobic incubation. The soil was treated at 1.71-1.73 mg a.i./kg, equivalent to 

a field rate of 0.42 kg a.i./ha. Anaerobic conditions were established by flooding with water

(uncharacterized) plus a nitrogen gas atmosphere. The test systems were connected to individual 

continuous flow-through volatile trapping system. The soil was viable at study termination.

In soil treated with the phenyl label, overall mass balance ranged from 96.6-108.1% of the applied.

In soil treated with the carbonyl label, overall mass balance ranged from 94.8-101.8% of the 

applied.

Observed DT50 values, calculated half-lives, and information on transformation products are listed 

in Table 1.

In soil treated with the phenyl label, extractable radioactivity decreased from 99.1% of the applied 

at day 0 to 93.3% at 30 days posttreatment (pre-flooding) and was 44.7% at 120 days postflooding. 

Unextracted radioactivity increased from 0.3% of the applied at day 0 to 6.1% at 30 days

posttreatment, was a maximum 9.4% at 14 days postflooding and was 9.0% at 120 days
Sulfentrazone (PC 129081) MRID 48958901

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postflooding. Total 14CO2 increased to 0.5% of the applied at 120 days postflooding; volatile 

organics were 0.1%.

In soil treated with the carbonyl label, extractable radioactivity decreased from 98.1% of the applied 

at day 0 to 92.4% at 30 days posttreatment (pre-flooding) and was 41.1% at 120 days postflooding. 

Unextracted radioactivity increased from 0.3% of the applied at day 0 to 7.7% at 30 days

posttreatment, was a maximum 9.2% at 14 days postflooding and was 8.2% at 120 days 

postflooding. Total 14CO2 was 0.1-0.3% of the applied at 90-120 days postflooding; volatile 

organics were 0.1%.

Table 1. Results Synopsis: Anaerobic Soil Metabolism of Sulfentrazone

Total System

Observed 

DT50

(days)

Calculated 

Half-life 

(days)1

Model 

Parameters

and Statistics1

Transformation Products Common Name

(maximum % of applied observed, associated interval)

Major Minor

California 

Sandy loam 

(20°C, pH 6.8) 

flooded with water

(uncharacterized)

>120 Stable ---

None

HMS (3.3% at 120 days postflooding)

DMS (1.7% at 90 days post-flooding)

SCA (3.7% at 30 days post-flooding)

CO2 (0.5% at 60-120 days post-flooding)

1 Calculated half-lives and model parameters are in accordance with the NAFTA kinetics guidance (USEPA, 2012).

I. Materials and Methods

A. Materials

1. Test Material: [Phenyl-U14C]- and [carbonyl14C]- labeled sulfentrazone (pp. 16-17, 

Appendix 5, pp. 140-141).

Phenyl

Specific activity: 22.9 mCi/mMol (p. 17)

Radiochemical purity: 98.3%

Chemical purity: Not reported

Lot No.: 54175-2-22

Carbonyl

Specific activity: 30.6 mCi/mMol (p. 17).

Radiochemical purity: 99.5%

Chemical purity: Not reported.

Lot No.: 54175-1-22

Solubility in water: Not reported
Sulfentrazone (PC 129081) MRID 48958901

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2. Reference Compounds: The following standards were used in the analysis.

Table 2. Reference Compounds

Applicant’s Code Name

(synonyms) Chemical Name Purity(%) Lot No.

Sulfentrazone N-[2,4-Dichloro-5-[4-difluoromethyl-4,5-dihydro-3-methyl-5-oxo1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamide -- E9337:19

Sulfentrazone-3-

carboxylic acid (SCA)

1-[2,4-Dichloro-5-[N(methylsulfonyl)amino-phenyl]-4-

difluoromethyl-4,5-dihydro-5-oxo-1H-1,2,4-triazol-3-carboxylic 

acid

-- SU-4

3-Desmethyl 

sulfentrazone (DMS)

1-[2,4-Dichloro-5-(N-(methylsulfonyl)amino-phenyl]-4-

difluoromethyl-1H-1,2,4-triazol-5(4H)-one

-- SU-24

3-Hydroxymethylsulfentrazone (HMS)1-[2,4-Dichloro-5-(N-(methylsulfonyl)amino-phenyl]-4-

difluoromethyl-3-hydroxy-methyl-1H-1,2,4-triazol-5(4H)-one

-- SU-29

Methyl triazole 4-Difluoromethyl-5-methyl2,4-dihydro[1,2,4]-triazole-3-one -- SU-32

Data obtained from pp. 18-20 and Appendix 1, pp. 111-115 of the study report.

-- = Not reported.

3. Soil: Soil collection and characterization are summarized in Table 3 and Table 4, respectively.

Table 3. Description of Soil Collection and Storage

Description Details

Geographic location California

Soil series Not reported

Pesticide use history at the collection site Not reported

Collection date July 26, 2011

Collection procedures Collected in accordance with ISO 10381-6

Sampling depth Not reported

Storage temperature 4 ± 2°C

Storage length Not reported.

Soil preparation Wet sieved (2 mm). 

Data obtained from p. 20 of the study report.

Table 4. Properties of the Soil

Property: Details

Soil Texture (USDA): Sandy loam

% Sand 66

% Silt 20

% Clay 14

pH [1:1 soil:water] 6.8

Organic carbon (%)1 0.52

Organic matter (%) [method not reported] 0.89

Cation Exchange Capacity (meq/100 g)

(method not reported) 10.4

CaCO3 equivalence (%) Not reported

Soil Moisture Content (%):

 At 1/3 bar 12.0

 At 15 bar 5.8

Bulk density (g/cm3, disturbed) 1.32
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Property: Details

Microbial Biomass (μg/g):

 At initiation Not tested

 At termination 48.7

Soil taxonomic classification (USDA or other) --

Data obtained from p. 28; Table 1, p. 35; and Appendix 3, pp. 129-130 of the study report. Soil texture confirmed by 

reviewer using USDA-NRCS technical support tools.

1 Determined by reviewer: organic carbon (%) = organic matter (%)/1.72.

B. Study Design

1. Experimental Conditions: Table 5 summarizes the experimental conditions.

Table 5. Experimental Design

Experimental Design Details

Duration of the test 150 days; 30 days of aerobic incubation followed by 120 days of 

anaerobic incubation

Soil condition: (Air dried/fresh) The soil was stored at 4 ± 2 ̊C and equilibrated to study 

conditions for 4 weeks prior to treatment

Soil (g/replicate) ca. 50 g (dry wt.)

Application rates:

 Nominal 1.68 mg a.i./kg (equivalent to 0.42 kg a.i./ha)

 Actual Phenyl: 1.71 mg a.i./kg

Carbonyl: 1.73 mg a.i./kg

Control conditions (if used) No sterile controls were used.

Number of Replicates:

 Controls ( if used) No sterile controls were used.

 Treatment Duplicate samples from each label treatment were collected at 

each sampling interval.

Test Apparatus:

 Type/material/volume

Glass wide mouth bottles (ca. 125 mL) containing treated soil or 

water:soil were connected to individual flow-through volatile 

trapping system and incubated in a temperature controlled room.

 Details of traps for CO2 and 

 organic volatiles ( if any)

Humidified air or nitrogen gas (postflooding) were passed 

continually through the samples and then through one bottle of 

ethylene glycol and two bottles of 1N NaOH.

If no traps were used, is the system 

closed/open? Traps were used.

Identity and concentration of co-solvent None, the test substance was dissolved in water

Test Material:

 Volume of the test solution

 used/treatment 1 mL

 Application method Glass pipette

 Is the co-solvent evaporated? Not applicable

Any indication of the test material adsorbing 

to the walls of the test apparatus? Not reported.

Experimental Conditions:

 Temperature (C) 20 ± 2oC

 Continuous darkness Yes
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Experimental Design Details

 Moisture content

Aerobic phase: prior to treatment, the soil moisture was adjusted 

to 50% MWHC.

Anaerobic phase: treated soil flooded with ca. 35 g of water (1-3 

cm water layer) after 30 days of aerobic incubation.

 Moisture maintenance method During aerobic incubation, samples were periodically monitored.

Other details (if any) None.

Data obtained from pp. 20-23, 28; Table 2, p. 36 of the study report.

 

2. Sampling during Study Period: Table 6 summarizes sampling during the study period.

Table 6. Sampling during Study Period

Criteria Details

Sampling intervals Aerobic phase: 0, 30 days posttreatment

Anaerobic phase: 14, 30, 60, 90, 120 postflooding

Sampling method Duplicate samples from each label treatment were collected at each 

interval.

Method of collection of CO2 and organic 

volatile compounds

NaOH and ethylene glycol trapping solutions of each respective 

bottle were collected at each sampling interval.

Sampling Intervals/Times

Sterility check Sterile controls were not used.

Moisture content Periodically monitored.

Redox potential, other Measured during anaerobic incubation. pH and dissolved oxygen 

were not measured.

Sample storage before analysis Water and soil were generally analyzed immediately. Soil, extracts 

and trapping solutions were stored at <5 ̊C when not in use.

Other observations (if any) None.

Data obtained from p. 23, 25 of the study report.

3. Analytical Procedures:

Separation of the water and soil: The water layer, when present, was removed by decanting (p. 

25).

Extraction Methods: Water was analyzed directly using LSC and HPLC.

Soil was extracted once with acetonitrile and twice with acetonitrile:water (80:20, v:v) by shaking at 

room temperature (p. 25). Resulting extracts were analyzed for total radioactivity by LSC. The 

acetonitrile extract was concentrated under a stream of nitrogen and analyzed by HPLC; the 

acetonitrile:water extract was apparently not further analyzed.

Determination of Unextracted Residues: Extracted soil was analyzed for total radioactivity by 

LSC following combustion (p. 26). Unextracted residues in soil were <10% of the applied and 

additional analysis was not conducted.

Determination of Volatile Residues: Aliquots of the trapping solutions were analyzed by LSC. 

The presence of CO2 was not confirmed. 
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Total Radioactivity Measurement: Total 14C residues were determined by summing the 

concentrations of residues measured in the water layers (when present), soil extracts, extracted soil 

and volatile trapping solutions (p. 28, Tables 3-4, p. 37).

Derivatization Method A derivatization method was not employed.

Identification and Quantification of Parent Compound and Transformation Products: Water 

and soil extracts were analyzed by HPLC using a Luna C 18 column eluted with a gradient mobile 

phase of (A) 0.01M ammonium acetate in water (days 0, 14, 30) or HPLC water (days 60, 90, 120) 

and (B) acetonitrile (p. 24). A second confirmatory method was not utilized.

Detection Limits (LOD, LOQ) for the Parent Compound and Transformation Products:

Limits of detection (LOD) and quantitation (LOQ) were not reported. 

II. Results and Discussion

A. Data:

Study results, including total mass balances and distribution of radioactivity, are presented in Table 

7a ([phenyl14C]sulfentrazone applied) and 7b ([carbonyl14C]sulfentrazone applied). In the water 

layer, the redox potential was +105 to +126 mV and in the soil, the redox potential was +37 to +69 

mV (p. 28). The temperature was maintained at 20 ± 2C (Appendix 4, p. 136).

B. Mass Balance:

In soil treated with the phenyl label, overall mass balance range was 96.6-108.1% of the applied 

(Table 3, p. 37). In soil treated with the carbonyl label, overall mass balance range was 94.8-101.8% 

of the applied (Table 4, p. 37). Recoveries were within guideline requirements.

C. Bound and Extractable Residues:

In soil treated with the phenyl label, extractable radioactivity decreased from 99.1% of the applied 

at day 0 to 93.3% at 30 days, then post-flooding was 44.7% at 120 days (Table 3, p. 37). 

Unextracted radioactivity increased from 0.3% of the applied at day 0 to 6.1% at 30 days, then postflooding was 6.9-9.4% at 14-120 days.

In soil treated with the carbonyl label, extractable radioactivity decreased from 98.1% of the applied 

at day 0 to 92.4% at 30 days, then post-flooding was 41.1% at 120 days (Table 4, p. 37). 

Unextracted radioactivity increased from 0.3% of the applied at day 0 to 7.7% at 30 days, then postflooding was 4.9-9.2% at 14-120 days.

D. Volatilization:

Volatile 14CO2 (identification not confirmed) was ≤0.5% of the applied for both labels (Tables 3-4, 

p. 37). Volatile organics were ≤0.1%.
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Table 7a. Transformation of [phenyl14C]sulfentrazone, expressed as a percentage of the applied radioactivity, in flooded anaerobic 

sandy loam soil following 30 days of aerobic incubation.

Sampling Interval 

(days)

Aerobic Anaerobic (postflooding (posttreatment))

0 301 14 (44) 30 (60) 60 (90) 90 (120) 120 (150)

Replicate 1 2 1 2 1 2 1 2 1 2 1 2 1 2.0

Sulfentrazone 99.1 96.3 83.3 86.1 88.1 86.4 86.4 89.3 88.3 86.0 83.0 84.8 92.6 96.9

SCA 0.0 0.0 2.4 3.2 2.6 2.1 2.6 3.2 3.3 3.3 2.5 2.8 0.8 1.1

HMS 0.0 0.0 2.7 0.0 0.0 0.0 0.0 0.0 0.3 0.6 1.1 1.1 0.0 0.0

DMS 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.7 0.0 0.0 0.0

Extractables 99.1 96.3 93.3 95.4 70.3 41.7 42.3 42.2 44.6 46.3 42.4 43.8 44.7 44.5

Water na na na na 20.5 46.8 46.7 50.3 48.0 47.9 49.6 48.8 50.5 54.0

Unextracted residues 0.3 0.2 6.1 4.9 8.7 9.4 8.7 7.0 9.2 8.8 7.6 8.5 6.9 9.0

CO2 na na 0.3 0.3 0.2 0.2 0.1 0.1 0.5 0.5 0.5 0.5 0.5 0.5

Volatile organics na na 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.1

Mass balance 99.4 96.6 99.8 100.6 99.7 98.1 97.7 99.6 102.4 103.5 100.0 101.6 102.7 108.1

Data obtained from Table 3, p. 37 and Table 15, p. 43 of the study report.

1 Prior to flooding.1

na = not applicable
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Table 7b. Transformation of [carbonyl14C]sulfentrazone, expressed as a percentage of the applied radioactivity, in flooded 

anaerobic sandy loam soil following 30 days of aerobic incubation.

Sampling Interval 

(days)

Aerobic Anaerobic (postflooding (posttreatment))

0 301 14 (44) 30 (60) 60 (90) 90 (120) 120 (150)

Replicate 1 2 1 2 1 2 1 2 1 2 1 2 1 2

Sulfentrazone 98.1 95.2 88.1 89.2 83.3 90.3 89.3 88.6 84.5 89.2 85.8 86.8 84.9 85.8

SCA 0.0 0.0 1.5 1.2 2.1 1.7 2.4 3.7 2.7 2.1 1.3 1.6 1.5 0.3

HMS 0.0 0.0 1.4 1.9 0.0 0.0 1.3 0.6 1.0 1.2 1.2 1.1 3.3 1.7

DMS2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3 0.0 0.0 0.2 0.0 0.0

Extractables 98.1 95.2 91.1 92.4 65.2 45.2 53.2 54.9 47.1 46.2 49.3 53.5 41.1 40.2

Water na na na na 20.2 46.8 39.7 38.0 47.3 47.2 39.6 36.8 49.2 48.0

Unextracted residues 0.2 0.3 7.7 7.7 9.2 8.3 4.9 6.2 5.6 8.2 6.7 8.7 8.2 7.8

CO2 na na 0.1 0.1 0.2 0.2 0.2 0.2 0.2 0.2 0.3 0.3 0.1 0.1

Volatile organics na na 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.1 0.0 0.0 0.0 0.0

Mass balance 98.3 95.5 98.7 100.2 94.8 100.5 98.1 99.3 100.2 101.8 95.9 99.4 98.5 96.0

Data obtained from Table 4, p. 37 and Table 17, p. 44 of the study report. The study author stated that methyl triazole was not detected at any time during the study 

(“0%”: pp. 14, 33; Table 17, p. 44).

1 Prior to flooding.

2 DMS was detected only in the water layer (Table 9, p. 40 and Table 13, p. 42).

na = not applicable
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E. Transformation of Parent Compound: Transformation kinetics of the parent compound 

(combined labels) in the total systems are summarized in Figure 1. Since the concentrations of 

sulfentrazone for the phenyl treatment at 120 days appeared to be skewed by the high recoveries

and since inclusion of these samples resulted in a negative value, the half-life was determined 

without these samples. Sulfentrazone was nearly stable, with an estimated half-life approaching 10 

years (very little transformation occurred over the 100 days of anaerobic incubation). 

Transformation product information summarized in Table 8. 

The study authors determined that the 120 day data were outliers and therefore, determined a halflife both including and excluding the day 120 values (p. 33). Using first-order linear regression 

analysis, the study authors determined a half-life 4,149 days for the phenyl label and 956 days for 

the carbonyl label with the 120-day data included. The half-life of the phenyl label without the 120 

day data was 665 days. 

Figure 1. Kinetic model fitting for sulfentrazone in anaerobic sandy loam soil.

Table 8. Transformation Products of Sulfentrazone in Anaerobic Sandy Loam Soil

System Transformation 

product(s)

Maximum 

% AR 

Observed

Associated 

Interval

(days)

Final % AR 

Observed

Final Interval

(days)

California Sandy loam 

(20°C, pH 6.8) flooded 

with water

HMS 3.3 120 3.3

DMS 1.7 90 0.0 120

SCA (3-Carboxylic) 3.7 30 1.5

Data obtained from Table 15, p. 43 and Table 17, p. 44 of the study report.

Degradation Pathway for Sulfentrazone in Soil A transformation pathway was not provided by 

the study authors.
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III. . Study Deficiencies, Reviewer's Comments, and Data Needs

1. The study author reported that redox potentials were measured in the soil and water at each 

sampling interval, but provided only ranges with no associated time intervals for minimum and 

maximum (p. 28). Detailed data should have been provided for each sampling interval. The pH 

of the water and soil throughout the study, and the dissolved oxygen levels in water were not 

reported.

2. The source of the water was not reported, and it was not characterized.

3. Pesticide use history at the site from which the soil was obtained was not provided. The soil is 

typical of an agricultural soil, but the land usage was not reported. It was not confirmed that the 

soils were free of pesticide residues. 

4. Limits of Detection (LOD) and Quantitation (LOQ) for sulfentrazone and its transformation 

products were not reported.

5. The details of the soil collection were not reported. The only information provided identifying 

the source of the soil was that it was from California.

6. In the soil treated with the phenyl label, the final sampling interval showed a concentration 

(92.6-96.9%) higher than the anaerobic time 0 concentration (83.3-86.1%; Table 15, p. 43). 

Since inclusion of these samples resulted in a negative half-life (see below), the half-life 

reported in this study was generated without data from this set of samples.

7. The study was conducted using one soil. Under current OCSPP guidelines, rates of 

transformation should be determined in at least four soils.
Sulfentrazone (PC 129081) MRID 48958901

Page 12 of 19

8. The viability of the soil was not determined prior to study initiation. The soil was tested at 

termination (p. 28). It was therefore not possible to determine if the activity of the soil 

microflora decreased as a result of treatment or over time.

9. The analytical methods suggest that the acetonitrile:water extracts of the soil were analyzed only 

using LSC (p. 25). The concentration of residues in this fraction was not reported, so it is 

unknown if failure to analyze these residues by HPLC had any impact on the reported 

concentrations of identified residues.

The following are required to potentially upgrade this study from “supplemental” to “acceptable” 

status:

1. Detailed redox data are needed for each sampling interval. Please provide the pH of the water and 

soil throughout the study, and the dissolved oxygen levels in water.

2. The source of the water used to flood the soil needs to be reported and characterized. 

3. Pesticide use and land use history at the site from which the soil was obtained should be provided.. 

Confirmation must be provided that the soils were free of pesticide residues that might alter soil 

bioactivity and also that no residues related to sulfentrazone were present prior to the initiation of the 

study.

4. The exact collection location and the taxonomic classification of the test soil should be provided. In 

the registrant’s report, the only information provided identifying the source of the soil was that it was 

from California.

5. Limits of Detection (LOD) and Quantitation (LOQ) for sulfentrazone and each of its transformation 

products for all soil and water samples should be reported (on page 28 of the registrant’s report there 

is an implication that soil detection limits were at or below 1% of the 1.68 ug/g application amount, 

generally a better sensitivity than this is desired in laboratory metabolism studies).

6. Can the registrant provide any further information on why the residues of parent sulfentrazone 

increased at the final sampling interval back to approximately the levels observed at the time of 

application (30 days before flooding)? From the available data it appears that complete stability of 

sulfentrazone in anaerobic soils needs to be assumed.

7. The viability of the soil was not determined prior to study initiation. Further information is needed to 

determine if the activity of the soil microflora was normal at the time of application and on whether 

bioactivity decreased over the course of the experiment.

IV. References

1. U.S. Environmental Protection Agency. 1982. Pesticide Assessment Guidelines, Subdivision N, 

Chemistry: Environmental Fate, Section 162-2, Anaerobic Soil Metabolism Studies. Office of 

Pesticide and Toxic Substances, Washington, DC. EPA 540/9-82-021.
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2. U.S. Environmental Protection Agency. 2008. Fate, Transport and Transformation Test -

Guidelines, OPPTS 835.4200, Anaerobic Soil Metabolism. Office of Prevention, Pesticides and 

Toxic Substances, Washington, DC. EPA 712-C-08-017.
Sulfentrazone (PC 129081) MRID 48958901

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DER ATTACHMENT 1. Sulfentrazone and Its Environmental Transformation Products. A

Code Name/ Synonym Chemical Name Chemical Structure Study 

Type MRID Maximum %AR (day)

Final %AR 

(study length)

PARENT

Sulfentrazone IUPAC: 2′,4′-Dichloro-5′-(4-

difluoromethyl-4,5-dihydro-3-

methyl-5-oxo-1H-1,2,4-triazol1-yl)methanesulfonanilide

CAS: N-[2,4-dichloro-5-[4-

(difluoromethyl)-4,5-dihydro-3-

methyl-5-oxo-1H-1,2,4-triazol1-yl]phenyl]methanesulfonamide

CAS No.: 122836-35-5

Formula: C11H10Cl2F2N4O3S

MW: 387.1 g/mol

SMILES: 

CLc1cc(CL)c(NS(=O)(=O)C)cc

1N2N=C(C)N(C(F)F)C2(=O)

835.4200

Anaerobic 

soil 

metabolism

48958901 Sandy 

loam 99.1% (0 d) 96.9% (150 d)

MAJOR (>10%) TRANSFORMATION PRODUCTS

No major transformation products were identified.

MINOR (<10%) TRANSFORMATION PRODUCTS

Sulfentrazone 3-

carboxylic acid (SCA; 

3-Carboxylic)

IUPAC: 1-(2,4-Dichloro-5-(N-

(methylsulfonyl)amino)-pheny]-

4-difluoromethyl-4,5-dihydro-5-

oxo-1H-1,2,4-triazol-3-

carboxylic acid

CAS: N-[2,4-dichloro-5-[4-

(difluoromethyl)-4,5-dihydro-5-

oxo-1H-1,2,4-triazol-1-

yl]phenyl]methanesulfonamido3-carboxylic acid

CAS No.: 134391-01-08

Formula: C11H8Cl2F2N4O5S

MW: 417.18 g/mol

SMILES: 

835.4200

Anaerobic 

soil 

metabolism

48958901 Sandy 

loam 3.7% (60 d) 1.5% (150 d)
Sulfentrazone (PC 129081) MRID 48958901

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Code Name/ Synonym Chemical Name Chemical Structure Study 

Type MRID Maximum %AR (day)

Final %AR 

(study length)

CS(=O)(=O)Nc1cc(c(cc1Cl)Cl)n

2c(=O)n(c(n2)C(=O)O)C(F)F

3-Hydroxymethylsulfentrazone (HMS)

IUPAC: 1-(2,4-Dichloro-5-(N-

(methylsulfonyl)amino)-pheny]-

4-difluoromethyl-3-hydroxymethyl-1H-1,2,4-triazol-5(4H)-

one

CAS No.: 134390-99-1

Formula: C11H10Cl2F2N4O4S

MW: 403.19 g/mol

SMILES: 

CS(=O)(=O)Nc1cc(c(cc1Cl)Cl)n

2c(=O)n(c(n2)CO)C(F)F

835.4200

Anaerobic 

soil 

metabolism

48958901 Sandy 

loam 3.3% (150 d) 3.3% (150 d)

3-Desmethyl 

sulfentrazone (DMS)

IUPAC: 1-(2,4-Dichloro-5-(N-

(methylsulfonyl)amino)-pheny]-

4-difluoromethyl-1H-1,2,4-

triazol-5(4H)-one

CAS: N-[2,4-dichloro-5-[4-

(difluoromethyl)-4,5-dihydro-5-

oxo-1,2,4-triazol-1-

yl]phenyl]methanesulfonamide

CAS No.: 134391-02-09

Formula: C10H8Cl2F2N4O3S

MW: 373.17 g/mol

SMILES: 

CS(=O)(=O)Nc1cc(c(cc1Cl)Cl)n

2c(=O)n(cn2)C(F)F

835.4200

Anaerobic 

soil 

metabolism

48958901 Sandy 

loam 1.7% (120 d) 0.0% (150 d)

Carbon dioxide IUPAC: Carbon dioxide

Formula: CO2

MW: 44 g/mol

SMILES: C(=O)=O

835.4200

Anaerobic 

soil 

metabolism

48958901 Sandy 

loam 

0.5% (60-150 

d) 0.5% (150 d)

REFERENCE COMPOUNDS NOT IDENTIFIED
Sulfentrazone (PC 129081) MRID 48958901

Page 16 of 19

Code Name/ Synonym Chemical Name Chemical Structure Study 

Type MRID Maximum %AR (day)

Final %AR 

(study length)

Methyl triazole IUPAC: 4-Difluoromethyl-5-

methyl-2,4-

dihydro[1,2,4]triazole-3-one

Formula: C4H5F2N3O

MW: 149.1 g/mol

SMILES: 

Cc1n[nH]c(=O)n1C(F)F

835.4200

Anaerobic 

soil 

metabolism

48958901 NA NA

A AR means “applied radioactivity”. MW means “molecular weight”. NA means “not applicable”. 
Sulfentrazone (PC 129081) MRID 48958901

Page 17 of 19

Attachment 2: Statistics Spreadsheets and Graphs
Sulfentrazone (PC 129081) MRID 48958901

Page 18 of 19

Attachment 3: Calculations

Calculations were performed by the reviewer using R software, and the following equations. 

Single First-Order (SFO) Model

(eq. 1)

where, 

Ct = concentration at time t (%)

C0 = initial concentration (%)

e = Euler’s number (-)

k = SFO rate constant of decline (d-1)

t = time (d)

The SFO equation is solved with R kinetics software by adjusting C0 and k to minimize the 

objective function (SSFO) shown in equation 9.

DT50 = natural log (2)/k (eq. 2)

DT90 = ln (10)/k (eq. 3)

Indeterminate Order Rate Equation (IORE) Model

(eq. 4)

where, 

N = order of decline rate (-)

kIORE = IORE rate constant of decline (d-1)

This equation is solved with R kinetics software by adjusting C0, kIORE, and N to minimize the 

objective function for IORE (SIORE) (See equation 9). Half-lives for the IORE model are 

calculated using equation 5, which represents a first-order half-life that passes through the DT90 of 

the IORE model. (Traditional DT50 and DT90 values for the IORE model can be calculated using 

equations 6 and 7.)

(eq. 5)

DT50 = 

k(N -1)

(C /2) -C

(1-N)

0

(1-N)

0

(eq. 6)

DT90 = 

k(N -1)

(C /10) -C

(1-N)

0

(1-N)

0

(eq. 7)
Sulfentrazone (PC 129081) MRID 48958901

Page 19 of 19

Double First-Order in Parallel (DFOP) Model

(eq. 8)

where,

g = the fraction of C0 applied to compartment 1 (-)

k1 = rate constant for compartment 1 (d-1)

k2 = rate constant for compartment 2 (d-1)

If C0 x g is set equal to a and C0(1-g) is set equal to c, then the equation can be solved with R 

kinetics software for a, c, k1, and k2 by minimizing the objective function (SDFOP) as described in 

equation 9.

DT50 and DT90 values can be calculated using equations 2 and 3, with k1 or k2 in place of k.

Objective Function: SFO, IORE, and DFOP are solved by minimizing the objective function (SSFO, 

SIORE, or SDFOP).

(eq. 9)

where, 

SSFO , SIORE, or SDFOP = objective function of kinetics model fit (%2)

n = number of data points (-)

Cmodel,t = modeled value at time corresponding to Cd,t (%)

Cd,t = experimental concentration at time t (%)

Critical Value to Determine Whether SFO is an Adequate Kinetics Model

If SSFO is less than SC, the SFO model is adequate to describe kinetics. If not, the faster of tIORE or 

the DFOP DT50 for compartment 2 should be used.

(eq. 10)

where,

Sc = the critical value that defines the confidence contours (%2)

p = number of parameters (3 in this case)

α = the confidence level (0.50 in this case)

F(α, p, n-p) = F distribution with α level of confidence and degrees of freedom p and n-p