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Hydrolysis

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Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
18-04-2007 - 18-05-2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
TEST ITEM Halamid®
Batch number 0608681224
CAS RN 7080-50-4
Chemical name Sodium p-toluenesulfonchloroamide, trihydrate Content: 100.4 %
Active ingredient Chloramine-T
Chemical formula Molecular weight 281.7 g/mol
Appearance White crystalline powder
Water solubility Approx. 150 g/L
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
The samples were diluted 1:10 with HPLC water containing 0.01 % ammonia and analysed.

Samples were taken at test start and at a minimum of 9 spaced points for each pH at each test temperature.
All samples were analysed immediately (max. 30 min for preparation and analyses).
The bath temperature was checked automatically once per hour.
Buffers:
Buffer solution pH 5:
0.1 mol/L Na-phosphate dibasic adjusted to pH 5 with phosphoric acid.

Buffer solution pH 7:
296.3 ml of 0.1 mol/l NaOH were mixed with 500 ml 0.1 mol/l KH2 P04 and filled up to 1000 ml with double distilled water.

Buffer solution pH 9:
213.1 ml of 0.1 mol/l NaOH were mixed with 500 ml 0.1 mol/l H3B03 in 0.1 mol/l KCl and filled up to 1000 ml with double distilled water.

Buffers were freshly prepared from chemicals with analytical grade or better quality. Buffers were bubbled with nitrogen for 5 min. Then the pH of the test solution was checked to a precision of at least 0.1 at the required temperature and adjusted if necessary.

Origin
Chemical Origin Batch number Purity
NaOH FLUKA 60520 ≥ 97.0 %
H38Q3 FLUKA 1256645 ≥ 99.5 %
KCI MERCK A480937 501 ≥ 99.5 %
KH2P04 FLUKA 50810 ≥ 99.5 %
Na2HP04 2 H20 FLUKA 1293519 ≥ 98.0 %
Double distilled water ROTH 04784 780 conductivity: < 2.0 µSiem
Duration:
30 d
pH:
5
Temp.:
20 °C
Initial conc. measured:
100 mg/L
Duration:
30 d
pH:
5
Temp.:
30 °C
Initial conc. measured:
100 mg/L
Duration:
30 d
pH:
5
Temp.:
50 °C
Initial conc. measured:
100 mg/L
Duration:
30 d
pH:
7
Temp.:
20 °C
Initial conc. measured:
100 mg/L
Duration:
30 d
pH:
7
Temp.:
30 °C
Initial conc. measured:
100 mg/L
Duration:
30 d
pH:
7
Temp.:
50 °C
Initial conc. measured:
100 mg/L
Duration:
29 d
pH:
9
Temp.:
20 °C
Initial conc. measured:
100 mg/L
Duration:
29 d
pH:
9
Temp.:
30 °C
Initial conc. measured:
100 mg/L
Duration:
29 d
pH:
9
Temp.:
50 °C
Initial conc. measured:
100 mg/L
Number of replicates:
Single replicates, double injection
Test performance:
METHOD VALIDATION Following SANCO 3029/99 rev .4 (2000-07-11)
Linearity of detector response was checked by analysis of standard dilutions and plotting a calibration graph of peak area versus concentration. The coefficient of correlation was calculated.
Based on the calibration and the requirements of the study design, the limit of quantification (LOQ) of the analytical method was fixed at 1.2 mg/L of Halamid® and p-TSA, respectively, in buffer solution and checked by means of accuracy.
Accuracy (Fortified samples): Five replicates of buffer solution at pH 9 fortified with 1.2 mg/L (LOQ) and 12 mg/L (10 x LOQ) of Halamid® and p-TSA, respectively, and two blank replicates containing no test item were prepared.
The mean recovery of the fortified sam pies should be between 70 and 110 %.
Precision: Relative standard deviation should be lower than 20 %.
Specificity: Blank samples were used to prove specificity and blank values being < 30 % of the LOQ.

The analytical system gave linear response in the range of 1 - 16 mg Halamid®/L and 0.5 - 16 mg p-TSA/L. The coefficient of regression (r2 ) of the calibration curves was ≥ 0.9999 for Halamid® and p-TSA, respectively.
The limit of quantification (LOQ) of the analytical method was fixed at 1.2 mg/L for Halamid® and p-TSA. The LOQ and 1O x LOQ were checked by means of accuracy.
Transformation products:
yes
Remarks:
one, p-TSA
No.:
#1
% Recovery:
>= 96 - ca. 100
pH:
5
Temp.:
20 °C
Duration:
700.7 h
Remarks on result:
other: mass balance
Remarks:
Chloramine T and p-TSA
% Recovery:
>= 64 - <= 96
pH:
5
Temp.:
30 °C
Duration:
700.28 h
Remarks on result:
other: mass balance
Remarks:
Chloramine T and p-TSA
% Recovery:
>= 87 - <= 99
pH:
5
Temp.:
50 °C
Duration:
700.15 h
Remarks on result:
other: mass balance
Remarks:
Chloramine T and p-TSA
% Recovery:
>= 99 - ca. 100
pH:
7
Temp.:
20 °C
Duration:
702.58 h
Remarks on result:
other: mass balance
Remarks:
Chloramine T and p-TSA
% Recovery:
>= 96 - ca. 100
pH:
7
Temp.:
30 °C
Duration:
702.23 h
Remarks on result:
other: mass balance
Remarks:
Chloramine T and p-TSA
% Recovery:
>= 94 - <= 99
pH:
7
Temp.:
50 °C
Duration:
703.57 h
Remarks on result:
other: mass balance
Remarks:
Chlroamine T and p-TSA
% Recovery:
>= 97 - ca. 100
pH:
9
Temp.:
20 °C
Duration:
673.57 h
Remarks on result:
other: mass balance
Remarks:
Chloramine T and p-TSA
% Recovery:
>= 97 - ca. 100
pH:
9
Temp.:
30 °C
Duration:
673.92 h
Remarks on result:
other: mass balance
Remarks:
Chlormaine T and p-TSA
% Recovery:
>= 93 - ca. 100
pH:
9
Temp.:
50 °C
Duration:
673.98 h
Remarks on result:
other: mass balance
Remarks:
Chloramine T and p-TSA
% Recovery:
94
Remarks on result:
other: fortified samples 1x LOQ
Remarks:
Halamid
% Recovery:
84
Remarks on result:
other: fortified samples 10x LOQ
Remarks:
Halamid
% Recovery:
>= 100
Remarks on result:
other: fortified samples 1x LOQ
Remarks:
p-TSA
% Recovery:
>= 100
Remarks on result:
other: fortified samples 10x LOQ
Remarks:
p-TSA
Key result
pH:
5
Temp.:
20 °C
Hydrolysis rate constant:
0 s-1
DT50:
115 d
Type:
other: the determined kinetic data indicate a zero or pseudo first order kinetic. Due to the intensive spread of the data and the low reaction rate constants it could not be excluded, that a higher order kinetic is involved
Key result
pH:
5
Temp.:
30 °C
Hydrolysis rate constant:
0 s-1
DT50:
101 d
Type:
other: the determined kinetic data indicate a zero or pseudo first order kinetic. Due to the intensive spread of the data and the low reaction rate constants it could not be excluded, that a higher order kinetic is involved
Key result
pH:
5
Temp.:
50 °C
Hydrolysis rate constant:
0 s-1
DT50:
39 d
Type:
other: the determined kinetic data indicate a zero or pseudo first order kinetic. Due to the intensive spread of the data and the low reaction rate constants it could not be excluded, that a higher order kinetic is involved
Key result
pH:
7
Temp.:
20 °C
Hydrolysis rate constant:
0 s-1
DT50:
220 d
Type:
other: the determined kinetic data indicate a zero or pseudo first order kinetic. Due to the intensive spread of the data and the low reaction rate constants it could not be excluded, that a higher order kinetic is involved
Key result
pH:
7
Temp.:
30 °C
Hydrolysis rate constant:
0 s-1
DT50:
199 d
Type:
other: the determined kinetic data indicate a zero or pseudo first order kinetic. Due to the intensive spread of the data and the low reaction rate constants it could not be excluded, that a higher order kinetic is involved
Key result
pH:
7
Temp.:
50 °C
Hydrolysis rate constant:
0 s-1
DT50:
114 d
Type:
other: the determined kinetic data indicate a zero or pseudo first order kinetic. Due to the intensive spread of the data and the low reaction rate constants it could not be excluded, that a higher order kinetic is involved
Key result
pH:
9
Temp.:
20 °C
Hydrolysis rate constant:
0 s-1
DT50:
131 d
Type:
other: the determined kinetic data indicate a zero or pseudo first order kinetic. Due to the intensive spread of the data and the low reaction rate constants it could not be excluded, that a higher order kinetic is involved
Key result
pH:
9
Temp.:
30 °C
Hydrolysis rate constant:
0 s-1
DT50:
147 d
Type:
other: the determined kinetic data indicate a zero or pseudo first order kinetic. Due to the intensive spread of the data and the low reaction rate constants it could not be excluded, that a higher order kinetic is involved
Key result
pH:
9
Temp.:
50 °C
Hydrolysis rate constant:
0 s-1
DT50:
185 d
Type:
other: the determined kinetic data indicate a zero or pseudo first order kinetic. Due to the intensive spread of the data and the low reaction rate constants it could not be excluded, that a higher order kinetic is involved
Validity criteria fulfilled:
yes
Remarks:
Test temp did not differ more than ± 0.5 °C. pH values of the buffer solutions were in the range of ± 0.1 pH at test temp Sensitivity of the analytical method was sufficient to quantify concentrations at least down to 10 % of the applied test item.
Conclusions:
In general, Tosylchloramide sodium, trihydrate is seen to be relativly stable, with increasing stability at higher pH and lower temperature levels. Significant temperature dependence could only be observed for pH 5 and 7, between 30 and 50 °C. Due to the relatively high spread of the data, the half life confidence intervals are given to provide an indication of the reliability of the data. pTSA was observed as major transformation product. A mass balance was calculated involving Tosylchloramide sodium, and pTSA indicating that these two compounds are involved in the degradation process. Other degradation products could neither be analysed, with the used analytical method, nor does the mass balance data indicate another significant degradation product.
Executive summary:

Hydrolysis as a function of pH was determined according to OECD Guideline No.111 (2004) and Directive 92/69/EC Method C.7(1992) for the test item Tosylchloramide sodium, trihydrate.

The study was conducted with a test item concentration of 100 mg/L in buffer solutions of pH5 ,7 and 9 at temperatures of 20, 30 and 50°C, respectively. Samples were taken at test start(0h), test end and at least 8 spaced points between test start and end. Buffer solutions were analysed at test start and test end and there was no interference with the test item. Analyses of the test item and its transformation product p-Toluenesulfonamide (p-TSA) were performed via HPLC on a C18 column with DAD-detection. Due to the low reaction rate constants, halflives had to be calculated by extrapolation. Because of the relatively highspread of the data confidence intervals for the halflives are given, to provide an indication of the reliability of the data. In general, the test substance is seen to be relatively stable, with increasing stability at higher pH and lower temperature levels. Half lives at pH=5 and 7 were lower with increasing temperatures 115, 101, 39 days and 220, 199, 114 days for 20, 30 and 50°C, respectively. For pH=9, the half live increased with increasing temperature, 131, 147 and 185 days for 20, 30 and 50°C, respectively. p-Toluenesulfonamide (p-TSA) was determined as major transformation product. Beside p-TSA no other significant transformation product could be detected.

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
weight of evidence
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:
Method: other: HPLC determination in test media
GLP compliance:
no
Transformation products:
not specified
pH:
7
Temp.:
20 °C
DT50:
>= 1 - <= 2 d

Description of key information

Hydrolysis as a function of pH was determined according to OECD Guideline No.111 (2004)and Directive 92/69/EC Method C.7 (1992) for the test item Tosylchloramide sodium.

The study was conducted with a test item concentration of 100 mg/L in buffer solutions of pH5 ,7 and 9 at temperatures of 20, 30 and 50°C, respectively. Samples were taken at test start (0h), test end and at least 8 spaced points between test start and end. Buffer solutions wereanalysed at test start and test end and there was no interference with the test item. Analyses ofthe test item and its transformationproduct p-Toluenesulfonamide (p-TSA) were performed via HPLC on a C18 column with DAD-detection.Due to the low reaction rateconstants, halflives had to be calculated by extrapolation. Because of the relatively highspread of the data confidence intervals for the halflives are given, to provide an indication ofthe reliability of the data. In general, the test substance is seen to be relatively stable, with increasing stability at higher pH and lower temperature levels. Half lives at pH=5 and 7 were lower with increasing temperatures 115, 101, 39 days and 220, 199, 114 days for 20, 30 and 50°C, respectively. For pH=9, the half live increased with increasing temperature, 131, 147 and 185 days for 20, 30 and 50°C, respectively. p-Toluenesulfonamide (p-TSA) was determined as major transformation product. Beside p-TSA no other significant transformation product could be detected.

Key value for chemical safety assessment

Additional information

Analytical information of concentration in waters of different origin.

Weight of evidence data on stability are available for ecotoxicological test media, demineralised water and river water, some in dark and light conditions.

- From ecotox media it was concluded that the substance has a short half life of approx. 2 days (20C, pH =7). It is anticipated that this will also occur under natural conditions.

- Deminerilised water in the dark showed stability of the substance (minimal loss in 2 months), pH = 6.9, room temp

- Tap water (dark): 1/3 was lost in two months time, pH = 7.9, room temp

- River water (dark): minimal loss in two months time, pH = 7.6, room temp