3,3'-dichlorobenzidine dihydrochloride

Phototransformation in water

Administrative data

Endpoint:

phototransformation in water

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Short and sometimes insufficient description of experimental details (e.g. intensitiy of UV-light applied not given), but overall solid experimental work with plausilbe results.

Data source

Reference

Reference Type:

other company data

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Study type:

other: Photodegradation

Principles of method if other than guideline:

A solution of 3,3´-Dichlorobenzidine (2.3 µg/mL) was prepared in 0.05 molar phosphate buffer pH 6.9. The 3,3´-Dichlorobenzidine solution was exposed to direct sunlight and long wave UV light( UV light Products Inc. Mineral Lamp) in an open beaker at different time intervals. The DCB solution was also exposed to normal day light in the laboratory (in the presence of fluorescent light, but no direct sunlight). The amount of DCB, MCB and benzidine was measured directly by HPLC.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

3,3'-dichlorobenzidine

EC Number:

202-109-0

EC Name:

3,3'-dichlorobenzidine

Cas Number:

91-94-1

IUPAC Name:

3,3'-dichlorobiphenyl-4,4'-diamine

Details on test material:

not given

Study design

Analytical method:

high-performance liquid chromatography

Light source:

sunlight

Duration of test at given test condition

Duration of test at given test condition 1

Duration:

10 min

Initial conc. measured:

2.3 other: µg/L

Duration of test at given test condition 2

Duration:

20 min

Initial conc. measured:

2.3 other: µg/L

Duration of test at given test condition 3

Duration:

30 min

Initial conc. measured:

2.3 other: µg/L

Duration of test at given test condition 4

Duration:

60 min

Initial conc. measured:

2.3 other: µg/L

Duration of test at given test condition 5

Duration:

90 min

Initial conc. measured:

2.3 other: µg/L

Duration of test at given test condition 6

Duration:

120 min

Initial conc. measured:

2.3 other: µg/L

Results and discussion

Spectrum of substance

Parameter:

not specified

% Degradation

% Degradation 1

% Degr.:

96

Sampling time:

90 min

Test condition:

sunlight

% Degradation 2

% Degr.:

47

Sampling time:

90 min

Test condition:

long wave UV

% Degradation 3

% Degr.:

> 99

Sampling time:

120 min

Test condition:

sun light

% Degradation 4

% Degr.:

57

Sampling time:

120 min

Test condition:

long wave UV

Any other information on results incl. tables

3,3´-dichlorobenzidine (DCB) is degraded by sunlight and UV. The reaction products include 3-chlorobenzidine (MCB), benzidine and several unidentified colored compounds.

The sample exposed to fluorescent light in the lab for three hours did not show any measurable decomposition . The samples exposed to sunlight and UV light source degraded rapidly. The results show that the decomposition is faster in direct sunlight than under the UV Lamp. After 2 hours exposure to sunlight more than 99% of the DCB decomposed, compared to 57% decomposition under the UV Lamp.

The amount of benzidine formed is time dependant. After 20 minutes in the sun, benzidine accounts for about 4.5% of the products. After 90 minutes the amount of benzidine increased to 10.9%, and after 150 minutes it decreased to 2.8%. The results suggest that benzidine itself is photodegraded, but at a slower rate than DCB. A similar pattern is observed with MCB but its decompositon is faster than that of benzidine.

Based an these results the order of photodecomposition rate is:

DCB >> MCB > benzidine.

Applicant's summary and conclusion

Conclusions:

3,3´-dichlorobenzidine (DCB) in aqueous solution at pH 6.9 photodegrades rapidly (70% in 10 min.) in direct sunlight to form colored products. Transient formation of monochlorobenzidine and benzidine also occurs. The highest amount of benzidine was found after 60 to 90 minutes in sunlight (10% of the products). After 2 hours in sunlight the benzidine level decreased to 3% . Photodegradation of DCB in aqueous solution did not occur in the absence of direct sunlight.

Executive summary:

In a sufficiently well documented study with plausible results (reliable with restrictions, reliability category 2)

3,3´-dichlorobenzidine was tested for phototransformation in water by exposure to direct sunlight or UV-light and tracing of decomposition products by HPLC.

3,3´-dichlorobenzidine is the base of the submission substance 3,3´-Dichlorobenzidine dihydrochloride. Thus the experimental results seen in this test are directly transferable to the submission substance.

3,3´-dichlorobenzidine (DCB) in aqueous solution at pH 6.9 photodegrades rapidly (70% in 10 min.) in direct sunlight to form coloured products. Transient formation of monochlorobenzidine and benzidine also occurs. The highest amount of benzidine was found after 60 to 90 minutes in sunlight (10% of the products). After 2 hours in sunlight the benzidine level decreased to 3% . Photodegradation of DCB in aqueous solution did not occur in the absence of direct sunlight.