Cyanuric acid

Hydrolysis

Link to relevant study record(s)

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- Sampling intervals for the parent/transformation products: Aliquots of the solutions were withdrawn periodically on a weekly basis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.       

                    

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.