Sodium 1H-benzotriazolide

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Experimental Starting Date: 15 October 2012 ; Experimental Completion Date: 12 December 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not effect the quality of the relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Test material

Test material information

Constituent 1

Reference substance name:

Sodium 1H-benzotriazolide

EC Number:

239-269-6

EC Name:

Sodium 1H-benzotriazolide

Cas Number:

15217-42-2

Molecular formula:

C6H5N3.Na

IUPAC Name:

sodium 1H-1,2,3-benzotriazol-1-ide

Details on test material:

Identification: Sodium Benzotriazole
CAS number: 15217-42-2
EC number: 239-269-6
Description: extremely pale yellow solid
Sample reference: O151O-NaBZT
Expiry / retest date: not available
Storage conditions: room temperature, in the dark

Radiolabelling:

no

Study design

Test temperature:

Column temperature: 30 ºC

HPLC method

Details on study design: HPLC method:

Performance of the Test:
Preparation of sample solution:
Test item (0.1023 g) was diluted to 100 mL with methanol. This solution was further diluted by a factor of 4 with methanol to give a concentration of256 mg/L.

Preparation of dead time solution:
The dead time was determined by measuring the retention time of formamide (purity* 99.94%, 647 mg/L solution in mobile phase).

Preparation of reference standard solutions:
Solutions of reference standards (see table 3.20) within the any other information on materials and methods incl. tables section below) were prepared in methanol.

Determination of retention time:
The sample, dead time and reference standard solutions were injected in duplicate using the following HPLC parameters:

HPLC System: Agilent Technologies 1050 incorporating autosampler and workstation
Column: Xselect HSS cyano 5 µ (150 x 4.6 mm id)
Column temperature: 30ºC
Mobile phase: Methanol:phosphate buffer solution (55:45 v/v)
pH of mobile phase: 7.5
Flow-rate: 1.0 mL/min
Injection volume: 10 µL
UV detector wavelength : dead time and reference standards: 210 nm
sample: 245 nm

Results and discussion

Adsorption coefficient

Adsorption coefficient 1

Type:

log Koc

Value:

0.774

Temp.:

30 °C

Adsorption coefficient 2

Type:

Koc

Value:

5.95

Temp.:

30 °C

Results: HPLC method

Details on results (HPLC method):

See any other information on results incl. tables section.

Any other information on results incl. tables

Calibration

The retention times of the dead time and the retention times, capacity factors (k') and log₁₀ K_oc values for the reference standards are shown in the two following tables:

Table 3.21

Dead Time	Retention Time (mins)		Mean Retention Time (mins)
	Injection 1	Injection 2
Formamide	2.000	2.000	2.000

Table 3.22 

Standard	Retention Time (mins)		Mean Retention Time (mins)	Capacity Factor (k')	Log10k'	Log10Koc
	Injection 1	Injection 2
Acetanilide	2.733	2.750	2.742	0.371	-0.431	1.25
Phenol	2.633	2.617	2.625	0.313	-0.505	1.32
Atrazine	3.800	3.783	3.792	0.896	-4.78 x 10^-2	1.81
Isoproturon	4.100	4.083	4.092	1.046	1.95 x 10^-2	1.86
Linuron	5.667	5.667	5.667	1.833	0.263	2.59
Naphthalene	4.983	4.983	4.983	1.492	0.174	2.75
Endosulfan-diol	6.983	6.983	6.983	2.492	0.396	3.02
Fenthion	8.500	8.517	8.508	3.254	0.512	3.31
a-Endosulfan	12.217	12.233	12.225	5.113	0.709	4.09
Phenanthrene	9.267	9.250	9.258	3.629	0.560	4.20
Diclofop-methyl	13.083	13.083	13.083	5.542	0.744	4.09
DDT	26.067	26.033	26.050	12.025	1.080	5.63

Adsorption coefficient of sample

The retention times, capacity factor and log₁₀K_oc value determined for the sample are shown in the following table:

 

Table 3.23 

Injection	Retention Time (mins)	Capacity Factor (k')	Log10k'	Log10Koc	Mean  Log10Koc	Adsorption Coefficient
1	2.667	0.333	-0.477	0.774	0.774	5.95
2	2.667	0.333	-0.477	0.774

 

Mean log₁₀ K_oc:  0.774       

Adsorption coefficient: 5.95               

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The adsorption coefficient (Koc) of the test item has been determined to be 5.95, log10 Koc 0.774, under the experimental conditions of pH 7.5, i.e. which at which the degree of ionisation would be minimized within the pH range relevant to the test method. No further determination was performed at the lower region of the pH range as the test item would be fully ionised in a cationic form under such conditions. Cationic substances have been demonstrated to be retained by the HPLC column stationary phase by mechanisms other than partitioning; attributed to secondary ionic interactions with residual silanol groups. As such, and in the absence of any suitable cationic calibration standards in either method guideline, assessment of the fully ionised form of the test item was not considered valid by the HPLC estimation method. Finally, due to potential ionic interaction with soils, sludges and sediments in the environment, consideration of potential mobility in soils normalised to the organic carbon content present may not be appropriate for cationic species.

Executive summary:

Method

The determination was carried out using a HPLC screening method designed to be compatible with Method C19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001.

Conclusion

The adsorption coefficient (K_oc) of the test item has been determined to be 5.95, log₁₀ K_oc 0.774, under the experimental conditions of pH 7.5, i.e. which at which the degree of ionisation would be minimized within the pH range relevant to the test method. No further determination was performed at the lower region of the pH range as the test item would be fully ionised in a cationic form under such conditions. Cationic substances have been demonstrated to be retained by the HPLC column stationary phase by mechanisms other than partitioning; attributed to secondary ionic interactions with residual silanol groups. As such, and in the absence of any suitable cationic calibration standards in either method guideline, assessment of the fully ionised form of the test item was not considered valid by the HPLC estimation method. Finally, due to potential ionic interaction with soils, sludges and sediments in the environment, consideration of potential mobility in soils normalised to the organic carbon content present may not be appropriate for cationic species.