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Environmental fate & pathways

Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Principles of method if other than guideline:

The hydrolysis of sodium salt solutions of 2,4,6-trihydroxy-1,3,5-triazine was studied at three concentrations and in three pH buffers using three sources of water.
GLP compliance:
no
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
- Sampling intervals for the parent/transformation products: Aliquots of the solutions were withdrawn periodically on a weekly basis
Buffers:
- pH: 5
- Composition of buffer: Potassium biphthalate in distilled water, tap water or well water

-pH: 7
- Composition of buffer: Sodium phosphate monobasic, monohydrate in distilled water, tap water or well water.

-pH: 9
- Composition of buffer: Boric acid in distilled water, tap water or well water
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks: 50 ml volumetric flasks
- Measures taken to avoid photolytic effects: Samples were covered

TEST MEDIUM

- Kind and purity of water:
Distilled water:
pH: 7.65
Alkalinity: <15 ppm
Hardness: <2 ppm
Conductivity: 3.65 µmho/cm
Total dissolved solids: 15.5 mg/l

Tap water:
pH: 7.1
Alkalinity: 110 ppm
Hardness: 120 ppm
Conductivity: 335 µmho/cm
Total dissolved solids: 201 mg/l

Well water:
pH: 7.5
Alkalinity: 130 ppm
Hardness: 140 ppm
Conductivity: 297 µmho/cm
Total dissolved solids: 186 mg/l


- Preparation of test medium: Sample solutions were prepared by diluting 0.5 ml, 1.0 ml and 2.0 ml of the stock 2,4,6-trihydroxy-1,3,5-triazine sodium salt solution with 39.5 ml, 39 ml and 38 ml of each of the buffer solutions, to generate final concentrations of 50 ppm, 100 ppm and 200 ppm, respectively.

Duration:
30 d
Temp.:
25
Number of replicates:
27 sample solutions were generated (3 solutions at each pH and in each of the 3 different water types).
Positive controls:
no
Negative controls:
no
Statistical methods:
None applied
Preliminary study:
Not performed
Transformation products:
no
Details on hydrolysis and appearance of transformation product(s):
Not applicable
pH:
5
Temp.:
25 °C
DT50:
> 30 d
pH:
7
Temp.:
25 °C
DT50:
> 30 d
pH:
9
Temp.:
25 °C
DT50:
> 30 d

Table 1: Hydrolysis of test compound

Water Type

pH

Average concentration (ppm) of 2,4,6-trihydroxy-1,3,5-triazine – First Run

Average concentration (ppm) of 2,4,6-trihydroxy-1,3,5-triazine – Second Run

Time 0

Week 2

Week 3

Week 4

Time 0

Week 2

Week 3

Week 4

Distilled

5

50

52.6

50.7

47.8

50

48.1

-

47.2

100

102.0

103.0

102.5

100

100

-

100

200

220

216.7

217.8

200

208.2

-

201

7

50

56.3

54

50.9

50

51.4

-

50.8

100

102.8

102.3

104.0

100

98.4

-

95.6

200

207.9

205.6

206.8

200

200

-

194.6

9

50

50.3

48.9

46.8

50

50.3

-

49.7

100

103.0

103.0

104.8

100

100

-

100

200

204.6

208.1

211.6

200

199.0

-

192.7

Tap

5

50

50.2

50.7

51.9

50

54.0

-

52.7

100

113.0

107.6

112.0

100

104.7

-

96.7

200

212.6

211.6

212.6

200

195.2

-

197.1

7

50

55.8

56.9

53.8

50

49.5

-

51.0

100

106.5

108.2

106.5

100

92.8

-

92.3

200

208.0

206.8

210.2

200

202.1

-

200

9

50

55.9

54.7

51.7

50

52.9

-

50.3

100

112.1

106.3

106.9

100

96.4

-

91.8

200

216.7

216.7

221.4

200

200

-

197.9

Well

5

50

51.0

52.4

51.2

50

49.5

-

47.7

100

107.9

109.5

106.8

100

99.0

-

99.5

200

218.3

216.1

219.4

200

199.1

-

192.5

7

50

50.5

51.3

51.6

50

50.5

-

48.7

100

105.8

105.8

105.8

100

100

-

96.3

200

217.4

209.3

212.8

200

200

-

191.6

9

50

50.3

53.5

51.9

50

48.2

-

48.2

100

107.8

104.5

102.8

100

99.5

-

95.3

200

214.1

216.5

217.6

200

200

-

190.2

Conclusions:
No hydrolysis of 2,4,6-trihydroxy-1,3,5-triazine occurred at any of the 3 pHs tested.

Description of key information

A study is available which gives a hydrolysis half-life > 30 days at pH 5,7 and 9.       

                    

Key value for chemical safety assessment

Additional information

The hydrolysis of sodium salt solutions of 2,4,6-trihydroxy-1,3,5-triazine was studied at three concentrations and in three pH buffers (pH 5, 7 and 9) using three sources of water ( distilled, tap and well water). The hydrolysis half-life was determined to be > 30 days.