m-phenylenediamine

Phototransformation in water

Administrative data

Endpoint:

phototransformation in water

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

This GLP study generally follows the guideline. There are several deviations in the preparation and aging of the synthetic humic water, including no information on the measurement of DOC and the pre-aging time was seven days not three. These guideline differences and potential impacts were not discussed.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1990

Report date:

1990

Materials and methods

Study type:

indirect photolysis

Test guideline

Qualifier:

according to guideline

Guideline:

EPA OTS 795.70 (Indirect Photolysis Screening Test: Sunlight Photolysis in Waters Containing Dissolved Humic Substances)

Deviations:

yes

Remarks:

The study generally follows the guideline. There are several deviations in the preparation synthetic humic water. These guideline differences and potential impacts were not discussed.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

m-phenylenediamine

EC Number:

203-584-7

EC Name:

m-phenylenediamine

Cas Number:

108-45-2

Molecular formula:

C6H8N2

IUPAC Name:

m-phenylenediamine

Details on test material:

Purity: 99.76%

Study design

Radiolabelling:

not specified

Analytical method:

high-performance liquid chromatography

Light source:

sunlight

Details on light source:

Location: roof, 38ºN, facing south and angled at ~30º to the horizon
Time of year/month: summer/June
Other: Skies were clear during the whole exposure

Sensitiser (for indirect photolysis)

Type of sensitiser:

other: humic acid

Details on sensitiser:

synthetic humic water, pH 7

Concentration of sensitiser:

other: Absorbance (1cm cell @ 290 nm) = 0.05

Dark controls:

yes

Remarks:

No significant losses were observed with the dark controls.

Results and discussion

Preliminary study:

Because the loss of the test substance in synthetic humic acid water was considerably faster than in distilled water, a definitive study was conducted.

Screening test:
Indirect photolysis rate constant = 0.68 d-1
Direct photolysis rate constant = 0.18 d-1
Overall photolysis rate constant = 0.86 d-1
Half-life = 0.81 d

Quantum yield (for direct photolysis):

0.07

Rate constant (for indirect photolysis):

0.86 other: d-1 (Indirect photolysis)

Dissipation half-life of parent compound

Dissipation half-life of parent compound 1

DT50:

0.51 d

Test condition:

Overall photolysis half-life. These results demonstrate that the substance is readily degraded by sunlight.

Dissipation half-life of parent compound 2

DT50:

0.81 d

Test condition:

Indirect photolysis half-life.

Transformation products:

not measured

Any other information on results incl. tables

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Screening Study Results: Distilled Water (DW) and Synthetic Humic Water (SHW)

Water Type	Light Conditions	Sample	Time (PDT)	Peak Area (millions), Injection #1	Peak Area (millions), Injection #2	Peak Area (millions), Injection #3	Average Area (millions)	Test Substance (µM)	Test Substance % Reacted
DW	Start (Time 0)	A	16:30	0.712	0.721	0.782	0.738	10.5	0
DW	Start (Time 0)	B	16:30	0.709	0.727	0.777
DW	Dark	1A	17:00	0.711	0.718	N/A	0.713	10.2	3
DW	Dark	1B	17:00	0.710	0.712	N/A
DW	Dark	2A	20:15	0.758	0.746	N/A	0.744	10.6	-1
DW	Dark	2B	20:15	0.742	0.742	N/A
DW	Light	1A	17:00	0.690	0.682	N/A	0.703	10.0	5
DW	Light	1B	17:00	0.722	0.718	N/A
DW	Light	2A	20:15	0.691	0.679	N/A	0.688	9.8	7
DW	Light	2B	20:15	0.686	0.695	N/A
SHW	Start (Time 0)	A	16:30	0.722	0.723	0.773	0.736	10.5	0
SHW	Start (Time 0)	B	16:30	0.714	0.725	0.759
SHW	Dark	1A	17:00	0.722	0.719	N/A	0.716	10.2	3
SHW	Dark	1B	17:00	0.724	0.698	N/A
SHW	Dark	2A	20:15	0.750	0.748	N/A	0.743	10.6	-1
SHW	Dark	2B	20:15	0.752	0.721	N/A
SHW	Light	1A	17:00	0.664	0.662	N/A	0.665	9.5	10
SHW	Light	1B	17:00	0.678	0.654	N/A
SHW	Light	2A	20:15	0.540	0.537	N/A	0.545	7.8	26
SHW	Light	2B	20:15	0.569	0.532	N/A

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Definitive Study Results: Distilled Water (DW) and Synthetic Humic Water (SHW)

Water Type	Sample	Time (PDT)	Peak Area (millions), Injection #1	Peak Area (millions), Injection #2	Average Area, C (millions)	ln(C0/Ct)	Test Substance (µM)
DW	Start (Time 0)	11:00	0.843	0.834	0.839	0.000	9.8
DW	Dark 1	12:15	0.773	0.841	0.807	-0.030	10.1
DW	Dark 2	13:15	0.831	0.850	0.841	-0.049	10.3
DW	Dark 3	14:15	0.864	0.838	0.851	-0.036	10.2
DW	Dark 4	15:35	0.859	0.833	0.846	-0.056	10.4
DW	Dark 5	18:00	0.843	0.846	0.845	-0.071	10.6
DW	Light 1	12:15	0.774	0.779	0.777	0.180	8.2
DW	Light 2	13:15	0.752	0.720	0.736	0.390	6.7
DW	Light 3	14:15	0.650	0.638	0.644	0.612	5.3
DW	Light 4	15:35	0.633	0.652	0.643	0.819	4.3
DW	Light 5	18:00	0.548	0.574	0.561	1.119	3.2
SHW	Start (Time 0)	11:00	0.832	0.831	0.832	0.000	9.9
SHW	Dark 1	12:15	0.838	0.807	0.823	0.011	9.8
SHW	Dark 2	13:15	0.838	0.824	0.831	0.001	9.9
SHW	Dark 3	14:15	0.826	0.848	0.837	-0.006	10.0
SHW	Dark 4	15:35	0.854	0.832	0.843	-0.013	10.1
SHW	Dark 5	18:00	0.836	0.827	0.832	0.000	9.9
SHW	Light 1	12:15	0.670	0.693	0.682	0.199	8.1
SHW	Light 2	13:15	0.606	0.590	0.598	0.330	7.1
SHW	Light 3	14:15	0.511	0.532	0.522	0.466	6.2
SHW	Light 4	15:35	0.481	0.466	0.474	0.563	5.7
SHW	Light 5	18:00	0.380	0.383	0.382	0.778	4.6

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Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The test substance has photochemical properties very similar to those of other anilines. It is very photolabile, and direct and indirect photolysis each contribute significantly to the overall photolysis. These results demonstrate that the substance is readily degraded by sunlight.

Executive summary:

Tests were conducted to determine whether natural humic acid significantly enhances the aqueous photolysis of the test substance. In the preliminary screening test, quartz tubes containing test substance and synthetic humic acid were exposed to sunlight. Because the loss of the test substance in synthetic humic acid water was considerably faster than in distilled water, a definitive study was conducted.

 

The results demonstrate that the test substance is readily degraded by sunlight. It is very photolabile, and direct and indirect photolysis each contribute significantly to the overall photolysis. Because the indirect photolysis rate constant will vary from water to water, and direct photolysis is a significant fraction of the overall photolysis, the direct photolysis rate constant is a useful estimate of the minimum photolysis rate constant. The direct photolysis quantum yield has been estimated and can be used to calculate direct photolysis constants as a function of the latitude and time of year. Such calculations for 40ºN yield minimum rate constants of 0.34, 0.5, 0.18, and 0.068 d-1 in spring, summer, fall, and winter, respectively, and maximum half lives of 2.0, 1.4, 3.8, and 10 d for the same seasons.

 

Definitive Study Results:

Indirect photolysis rate constant: 0.86 d-1

Indirect photolysis half-life: 0.81 d

Direct photolysis rate constant: 0.50 d-1

Quantum yield (for direct photolysis): 0.07

Overall photolysis rate constant: 1.36 d-1

Overall photolysis half-life: 0.51 d

 

Screening Test Results:

Indirect photolysis rate constant = 0.68 d-1

Direct photolysis rate constant = 0.18 d-1

Overall photolysis rate constant = 0.86 d-1

Overall photolysis half-life: 0.81 d