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Environmental fate & pathways

Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods
Justification for type of information:
Refer to the Quaternary ammonium salts (QAS) category or section 13 of IUCLID for details on the category justification.
Qualifier:
according to
Guideline:
other: 40 CFR 158.130 (161.1)
GLP compliance:
not specified
Analytical monitoring:
yes
Details on sampling:
Test solution preparation:
There were four test solutions and all four of them were prepared in a similar fashion: 1.0167 g of the test substance was added to a 100 mL volumetric flask and diluted to volume with deionized water giving a concentration of 0.0102 gm/mL. To each of four glass 250 mL bottles was added 3.0 mL of the test substance solution and 97.0 mL of the appropriate buffer solution (pH 5 [acetic acid/sodium acetate], pH 7 [Tris(hydroxymethyl) amino methane/HCl], pH 9 [boric acid/sodium borate] or deionized water). The final concentration in each sample was 305 µg/mL of the 32.5% active test substance or 99.1µg/mL (or 100 ppm) of 100% active test substance. Each of these bottles was then sealed with airtight polyethylene lined caps and stored in a closed water bath at approximately 25±1˚C.

Sampling and test procedure:
Test sample solutions were shaken for 20-30 seconds before sampling to ensure homogeneity. A 1 g sample was then placed in a 4 ounce jar. To the jar was added 5.0 mL of saturated (aq.) sodium chloride solution, 10.0 mL of reagent grade chloroform and 20.0 mL of a buffer solution prepared from the following: 420 parts of 0.1 M (aq.) citric acid, 580 parts of 0.2 M (aq.) disodium phosphate, 50 parts of 0.2% bromophenol blue in methanol and 50 parts of 0.2% bromocresol green in methanol.
The jar was capped and shaken for 20-30 seconds. The layers were then allowed to settle for one minute, followed by two more shake and settling periods, as before. When the final settling period had elapsed, approximately 3 mLs of the lower chloroform layer was drawn from the bottle with a plastic pipette and placed in a 1 centimeter quartz cuvette of the spectrophotometer. Sampling for analysis of the test sample was done on Day 0, 5, 12, 19, 26 and 33 of the study. The pH of each solution remained within 0.1 pH unit of the starting value throughout the 33-d sampling period. Each buffer solution was analyzed in duplicate.
Buffers:
Buffer preparation:
All solutions were prepared using reagent grade chemicals and deionized water (using a Millipore RO-15 reverse osmosis water purification system producing approximately 18 megaohms resistance water). A buffer system at pH 5 was prepared using 0.2 M (aq.) acetic acid and 0.2 M (aq.) sodium acetate. A buffer system at pH 7 was prepared using 0.2 M tris(hydroxymethyl)amino methane (aq.) and 0.2 M (aq.) HCl. A buffer system at pH 9 was prepared using 0.2 M boric acid (aq.) and 0.2 M (aq.) sodium borate. The pH of each buffer was measured using an Altex 60 pH meter with a Corning pH electrode and standard calomel reference electrode. The pH value of each buffer was adjusted to within 0.02 pH units by adjusting ratios of buffer components.
Duration:
30 d
Initial conc. measured:
100 other: ppm (i.e., 99.1µg/mL)
Number of replicates:
Each buffer solution was analyzed in duplicate.
Transformation products:
no
% Recovery:
> 90
pH:
5
Temp.:
25 °C
Duration:
33 d
Remarks on result:
other: Hydrolytically stable
Remarks:
>90% of the test substance remained intact
% Recovery:
> 90
pH:
7
Temp.:
25 °C
Duration:
33 d
Remarks on result:
other: Hydrolytically stable
Remarks:
>90% of the test substance remained intact
% Recovery:
> 90
pH:
9
Temp.:
25 °C
Duration:
33 d
Remarks on result:
other: Hydrolytically stable
Remarks:
>90% of the test substance remained intact
Key result
pH:
5
Temp.:
25 °C
DT50:
> 33 d
Type:
not specified
Remarks on result:
other: Hydrolytically stable
Key result
pH:
7
Temp.:
25 °C
DT50:
> 33 d
Type:
not specified
Remarks on result:
other: Hydrolytically stable
Key result
pH:
9
Temp.:
25 °C
DT50:
> 33 d
Type:
not specified
Remarks on result:
other: Hydrolytically stable
Details on results:
At all pH, there was less than 10% hydrolysis of the test substance.

Results of the pH 5 study:
Day 0 = 100.9 ppm
Day 5 = 99.6 ppm
Day 12 = 101.7 ppm
Day 19 = 101 ppm
Day 26 = 99.6 ppm
Day 33 = 99.9 ppm

Results of the pH 7 study:
Day 0 = 100.1 ppm
Day 5 = 101.6 ppm
Day 12 = 103 ppm
Day 19 = 100.4 ppm
Day 26 = 97.4 ppm
Day 33 = 98 ppm
Results of the pH 7 study:
Day 0 = 99.9 ppm
Day 5 = 97.8 ppm
Day 12 = 100.3 ppm
Day 19 = 101.1 ppm
Day 26 = 96.4 ppm
Day 33 = 97.5 ppm
Results of the pH 7 study:
Day 0 = 99.1 ppm
Day 5 = 98.2 ppm
Day 12 = 99.4 ppm
Day 19 = 97.8 ppm
Day 26 = 93.8 ppm
Day 33 = 95.8 ppm

see section on details on results.

Validity criteria fulfilled:
not specified
Conclusions:
Based on the results of the read across study, the test substance can be considered to be hydrolytically stable.
Executive summary:

A study was conducted to evaluate the rate of hydrolysis of the read across substance, Coco TMAC (32.5% active in water), as a function of pH according to 40 CFR 158.130 (161.1). The study was conducted under dark conditions using three buffer solutions and one unbuffered solution (pH of approximately 6.2) at 25±1˚C: pH 5 [acetic acid/sodium acetate], pH 7 [tris(hydroxymethyl) - amino methane/HCl], pH 9 [boric acid/sodium borate], and a solution containing deionized water. The buffer solutions were spiked at approximately 100 ppm (based on 100% activity of the test substance). Each of the four solutions was sampled on Day 0, 5, 12, 19, 26 and 33 of the study. The pH of each solution remained within 0.1 pH unit of the starting value throughout the 33-day sampling period. Each buffer solution was analysed in duplicate. Under the study conditions, the read across substance was considered to be hydrolytically stable, since more than 90% of the test substance remained intact at all pH levels tested over the 30-day period (Walters ML, 1989). Based on the results of the read across study, a similar hydrolytic stability potential can be expected for the test substance.

Description of key information

Based on the results of the read across study, the test substance is considered to be hydrolytically stable.

Key value for chemical safety assessment

Additional information

A study was conducted to evaluate the rate of hydrolysis of the read across substance, Coco TMAC (32.5% active in water), as a function of pH according to 40 CFR 158.130 (161.1). The study was conducted under dark conditions using three buffer solutions and one unbuffered solution (pH of approximately 6.2) at 25±1˚C: pH 5 [acetic acid/sodium acetate], pH 7 [tris(hydroxymethyl) - amino methane/HCl], pH 9 [boric acid/sodium borate], and a solution containing deionized water. The buffer solutions were spiked at approximately 100 ppm (based on 100% activity of the read across substance). Each of the four solutions was sampled on Day 0, 5, 12, 19, 26 and 33 of the study. The pH of each solution remained within 0.1 pH unit of the starting value throughout the 33-day sampling period. Each buffer solution was analysed in duplicate. Under the conditions of the study, the read across substance was considered to be hydrolytically stable, since more than 90% of the read across substance remained intact at all pH levels tested over the 30-day period (Walters ML, 1989). Based on the results of the read across study, a similar hydrolytic stability potential can be expected for the test substance.