Tetrakis(phenylmethyl)thioperoxydi(carbothioamide)

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study performed according to OECD and GLP guidelines.

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))

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

soil

Specific details on test material used for the study:

Identity: TBzTD
Storate: at room temperature at about 20°C
Batch: 2041 0003
Purity: > 90%
Appearance: solid white to yellowish
Expiration date: October 31. 2006

Radiolabelling:

no

Details on study design: HPLC method:

- HPLC with UV/VIS detector
- reversed phase column
- aqueous mobile phase

The first test to determine the adsorption coefficient (Kod of TBzTD was performed with methanol as organic solvent. Methanol was not sufficient to elute the test item from the column. Referring to this, acetonitrile was used as organic solvent.

- Apparatus: Varian autosampler 9100, Varian pump ProStar 230, Varian UV/VIS detector ProStar 310, Jones column oven 7990
- Column: LiChrospher 100 CN, particle size 5 μm, 250 mm x 4 mm
- Pre-column: CN
- Mobile phase: Acetonitrile/water (55:45; v/v); pH 6.3
- Temperature: 25°C
- Injection volume: 10 μl
- Flow: 1.0 ml/min
- Run time: 10 minutes

Key result

Type:

log Koc

Value:

7.5

Temp.:

25 °C

Details on results (HPLC method):

The chromatography of the test item resulted in one main peak with a weIl-defined and reproducible retention time. The HPLC method was therefore considered to be suitable for the purpose of the study. Based on the chromatographic data, TBzTD was considered to be stable during the test procedure.

The mobility classification of TBzTD was obtained by comparing the calculated Koc value to the mobility classes according to P. J. McCall, D. A. Laskowski, R. L. Swann and H. J. Dishburger "Measurement of Sorption Coefficients of Organic Chemicals and Their Use in Environmental Fate Analysis"; 1981; Assoc. of Off. Anal. Chem., Arlington, VA; p 89 - 109.

ange of Koc	Mobility Class
0 -50	very high
50 -150	high
150 -500	medium
500 -2000	low
2000 -5000	slightly
> 5000	immobile

The test item solution was injected three times and the combined reference solution was injected six times. The log Koc of the test item was extrapolated from a regression curve (log k' vs. log Koc) to be 7.5, which is equal to a Koc value of 31 028 667. The retention time of the test item was higher than the retention time of the highest reference item used (2,4-DDT) with Koc 5.63, which is equal to a Koc value of 426 580. In the present study the reference items covered the range of log Koc 1.25 to log Koc 5.63.

The tabulated values represent rounded mean results, which were obtained by calculation using the exact raw data.

In conclusion, the log of the adsorption coefficient (Kod of TBzTD was estimated to be log Koc > 5.63 which is equal to a Koc value of > 426580 using the HPLC method. This value indicates that TBzTD is immobile and remains preferably in soil.

Table: results of the linear regression of Log k' vs Log Koc

	No. of analysis	Mean retention time (min)	k'	log k'	log Koc
Sodium nitrate (dead time)	2	1.12	-	-	-
Reference items:
Acetanilide	6	2.80	1.50	0.17	1.25
Isoproturon	6	3.22	1.86	0.27	1.86
Linuron	6	3.55	2.16	0.34	2.59
Pyrazophos	6	3.98	2.55	0.41	3.65
Diclofop-methyl	6	5.54	3.04	0.48	4.20
2.4 -DDT	6	5.57	3.96	0.60	5.63

Linear regression: slope (= 0.093), y-axis intercept (= 0.080), coefficient of regression (r = 0.994)

Table: Results of TBzTD analysis

No. of analysis	retention time (min)	k'	log k'	log Koc	mean log Koc	Koc	Mean Koc
Test Item Peak
1	7.80	5.95	0.77417	7.45		28434088
2	7.99	6.11	0.78630	7.58		38382018
3	7.75	5.90	0.77097	7.42	7.5	26269895	31028667

Conclusions:

In conclusion, the log of the adsorption coefficient (Kod of TBzTD was estimated to be log Koc > 5.63 which is equal to a Koc value of > 426580 using the HPLC method. This value indicates that TBzTD is immobile and remains preferably in soil.

Description of key information

The log of the adsorption coefficient (Koc) of the test item was extrapolated from a regression curve (log k' vs. log Koc) to be 7.5, which is equal to a Koc value of 31028667. This value indicates that TBzTD is immobile and remains preferably in soil.

Key value for chemical safety assessment

Koc at 20 °C:

31 028 667

Additional information

In the present study using the High Performance Liquid Chromatography (HPLC) estimation method on Soil and Sewage Sludge the log of the adsorption coefficient (Koc) of the test item was extrapolated from a regression curve (log k' vs. log Koc) to be 7.5, which is equal to a Koc value of 31028667. The reference items covered the range of log Koc 1.25 to log Koc 5.63. Therefore, the retention time of the test item was higher than the retention time of the highest reference item used (2,4-DDT) with log Koc 5.63, which is equal to a Koc value of 426580. In conclusion the log Koc of TBzTD was judged to be log Koc > 5.63 which is equal to a Koc value of > 426580. This value indicates that TBzTD is immobile and remains preferably in soil.

[LogKoc: 7.5]