Ammonium 7-(2,6-dimethyl-8-(2,2-dimethylbutyryloxy)-1,2,6,7,8,8a-hexahydro-1-naphthyl)-3,5-dihydroxyheptanoate

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption, other

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24th June 2010 to 26th November 2010

Reliability:

1 (reliable without restriction)

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))

GLP compliance:

yes

Type of method:

HPLC estimation method

Test temperature:

25oC

Details on study design: HPLC method:

The sorption behaviour of the test substance on soil can be investigated using high performance liquid chromatography (HPLC). This is performed on commercially available analytical columns packed with a solid phase containing a moderately polar stationary phase with lipophilic and polar moieties (e.g. cyano-propyl bonded phase). The chemicals injected onto the column move along it by partitioning between the mobile phase and the stationary phase. The velocity of each component thereby depends on the degree of adsorption on the stationary phase. The dual nature of the stationary phase allows for interaction of polar and apolar parts of a molecule in a similar way as is the case for soil. This enables the relationship between the retention time on such a column and the adsorption coefficient on the organic parts of the soil to be established.
Since the test substance is an ionisable substance, separate tests were conducted, as follows,
at each of pH 4, 7 and 9:
In order to correlate the measured capacity factor (k) of the test material with its Koc, six reference materials were selected from a list of recommended compounds. These reference compounds were selected to have log10Koc values between 1.3 and 5.6. An internal standard (formamide) with no retention on the HPLC column was used to determine the deadtime of the HA solution of Simvastatin ammonium salt (approximately 50 mg/l in HPLC mobile phase, and also containing I.D.S. at the same concentration as in the reference mixture) was prepared and chromatographed in duplicate, bracketed by samples of the reference mixture, using the following conditions. PLC system.

Key result

Sample No.:

#3

Type:

log Koc

Value:

1.3 <

pH:

9

Temp.:

25 °C

Key result

Sample No.:

#2

Type:

log Koc

Value:

1.3 <

pH:

7

Temp.:

25 °C

Key result

Sample No.:

#1

Type:

log Koc

Value:

2.4

pH:

4

Temp.:

25 °C

Validity criteria fulfilled:

yes

Conclusions:

Simvastatin ammonium salt was determined to have log10Koc values of 2.4, < 1.3 and < 1.3 at
pH 4, 7 and 9 respectively (equivalent Koc = 260, < 20 and < 20).

Key value for chemical safety assessment

Koc at 20 °C:

1.3