Orthoperiodic acid

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 April 2018 to 28 November 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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))

Version / remarks:

2016

Deviations:

no

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))

Version / remarks:

2001

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EC Technical Guidance Document on Risk Assessment Part III Chapter 4.3: Use of (Quantitative) Structure Activity Relationships ((Q)SARs) - Soil and Sediment Sorption.

Version / remarks:

2003

Deviations:

no

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

soil

Radiolabelling:

no

Test temperature:

35 °C

Details on study design: HPLC method:

BUFFER SOLUTIONS
Acetate buffer pH 4, 0.01 M: Solution of 16.7 % 0.01 M sodium acetate in water and 83.3 % 0.01 M acetic acid in water. Buffer contained 0.0009 % (w/v) sodium azide.

PERFORMANCE OF THE STUDY
The principle of the test method is similar to that of the OECD guideline no. 117: "Partition coefficient (n-octanol/water), high performance liquid chromatography (HPLC) method". While passing through the column along with the mobile phase the test material interacts with the stationary phase. As a result of partitioning between mobile and stationary phases, the test material is retarded. The dual composition of a cyanopropyl stationary phase, having polar and non-polar sites allows for interaction of polar and non-polar groups of a molecule in a similar way as is the case for organic matter in soil or sewage sludge matrices. This enables the relationship between the retention time on the column and the Koc on organic matter to be established.
According to the guidelines, the determination of the Koc for test materials that are ionized for at least 10 % within pH 5.5 to 7.5 should be performed with both the ionized and non-ionized form. The test material is a strong inorganic acid and therefore no calculations were performed. The HPLC method was performed at the lowest environmentally relevant pH from the hydrolysis study; pH 4.
Solutions of one reference substance based on soil adsorption data and the test material were analysed. Based on the retention times of the compounds the Koc and log Koc values of the test material were determined.

ANALYTICAL METHOD
Analytical Conditions:
Instrument: Acquity UPLC system (Waters, Milford, MA, USA).
Detector: Acquity UPLC TUV detector (Waters)
Column: Acquity UPLC HSS Cyano, 100 mm x 2.1 mm i.d., dp = 1.8 µm (Waters)
Column temperature: 35 °C ± 1 °C
Injection volume: 5 µL
Mobile phase: 55/45 (v/v) methanol/buffer pH 4
Flow: 0.4 mL/min
UV detection: 210 nm

PREPARATION OF SOLUTIONS
Reference Substance Solution:
- A stock solution of the reference substance at a concentration of approximately 1 g/L in methanol was used. The stock solution was diluted to obtain an end solution of 55/45 (v/v) methanol/buffer pH 4.
- The blank solution for the reference substance was 55/45 (v/v) methanol/buffer pH 4.

Reference Substance:
- Acetanilide (purity 99.8 %). logKoc value according to OECD 121 = 1.26

Test Solution:
- A 2 500 mg/L stock solution of the test material was prepared in buffer pH 4. The stock solution was 100 fold diluted with 55/45 (v/v) methanol/buffer pH 4. The final concentration of the test material solution was 25.0 mg/L.
- The test material blank solution was 55/45 (v/v) methanol/buffer pH 4.

Sample Injections
Reference substance and test material solutions were injected in duplicate. Blank solutions were analysed by single injection.

Sample No.:

#1

Type:

log Koc

Value:

< 1.26 dimensionless

pH:

7

Temp.:

35 °C

Matrix:

HPLC method based on soil-adsorption reference data

Sample No.:

#1

Type:

Koc

Value:

18 L/kg

pH:

7

Temp.:

35 °C

Matrix:

HPLC method based on soil-adsorption reference data

Details on results (HPLC method):

One peak from the test material was observed with a retention time of 0.571 minutes and one carry-over peak from the acetanilide standard. Under the same analytical conditions, the retention time of acetanilide (log Koc = 1.26) was 0.914 minutes. It was concluded that the log Koc of the test material was < 1.26 (Koc < 1.8 x 10^1).

Koc of the Test Material

Substance	Retention time (min)			log Koc	Koc
	tr,1	tr,2	mean
Acetanilide	0.913	0.915	0.914	1.26
Test material	0.570	0.571	0.571	< 1.26	1.8 x 10^1

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the test the Koc of the test material was 1.8 x 10^1, log Koc < 1.26.

Executive summary:

The soil adsorption coefficient of the test material was assessed according to EC Guideline C.19. and OECD Guideline 121 in accordance with the principles of GLP using an HPLC method.

One peak from the test material was observed with a retention time of 0.571 minutes and one carry-over peak from the acetanilide standard. Under the same analytical conditions, the retention time of acetanilide (log Koc = 1.26) was 0.914 minutes.

Under the conditions of the test the Koc of the test material was 1.8 x 10^1, log Koc < 1.26.

Description of key information

Under the conditions of the test (at 35°C) the Koc of the test material was 1.8 x 10^1, log Koc < 1.26.

Key value for chemical safety assessment

Koc at 20 °C:

18

Additional information

The soil adsorption coefficient of the test material was assessed according to EC Guideline C.19. and OECD Guideline 121 in accordance with the principles of GLP using an HPLC method. The study was assigned a reliability score of 1 in accordance with the principles for assessing data quality as outlined by Klimisch et al. (1997).

One peak from the test material was observed with a retention time of 0.571 minutes and one carry-over peak from the acetanilide standard. Under the same analytical conditions, the retention time of acetanilide (log Koc = 1.26) was 0.914 minutes.

Under the conditions of the test the Koc of the test material was 1.8 x 10^1, log Koc < 1.26.