DL-α-(aminomethyl)-p-hydroxybenzylic alcohol hydrochloride

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:

02-Jul-2018 to 25-Feb-2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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:

yes

Remarks:

None of the deviations were considered to have impacted the overall integrity of the study or the interpretation of the study results and conclusions.

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

soil

Specific details on test material used for the study:

Identification: Octopamine hydrochloride
Batch (Lot) Number: D151-1710037
Physical Description: White to off white powder (determined by Charles River Den Bosch)
Storage Conditions:
Stable under storage conditions until: At room temperature protected from light
26 October 2019 (retest date)

Radiolabelling:

not specified

Test temperature:

35°C +/- 1°C

Details on study design: HPLC method:

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 item interacts with the stationary phase. As a result of partitioning between mobile and stationary phases, the test item 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 items 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. Therefore, the pKa values of the test item were calculated using the Perrin calculation method (pKalc 5.0, module in Pallas 3.0, CompuDrug International San Francisco, CA, USA). Based on the calculations, the HPLC method was performed at neutral pH 7.5.
Solutions of reference substances with known log Koc values based on soil adsorption data and the test item were analyzed. The capacity factor (k') of each compound was calculated from its retention time. The log k’ values of the references substances were plotted against the known log Koc values. A linear regression program was used to calculate the calibration curve. Linear regression analysis was performed using the least squares method. The coefficient of correlation (r) was calculated. The log Koc value for the test item was calculated by substituting its mean log k’ in the calibration curve. The value of log Koc obtained from duplicate measurements was within +/- 0.25 log units.

Key result

Sample No.:

#1

Type:

log Koc

Remarks:

Main Peak

Value:

ca. 2.81

pH:

7.5

Temp.:

35 °C

Details on results (HPLC method):

pKa Values
The pKa values in the logarithm range of 1 - 14 for acidic and basic groups in the molecular structure of the test item were calculated using the Perrin calculation method. The results are given in Table 18.

Table 18
pKa Values of the Test Item
Acidic Basic
Phenol pKa 9.6 RCH2NH3+ pKa 10.2

Koc HPLC Method
In the chromatogram of the test solution, one major peak and several small test item peaks were observed.

The equation of the regression line was: log k’ = 0.307 ´ log Koc – 0.877 (r = 0.98, n = 16).

Table 19
Koc of the Test Item
Substance Retention time (min) log Koc Koc Peak area
(%)
tr,1 tr,2 mean
Formamide (t0) 0.704 0.703 0.704
Acetanilide 0.892 0.891 1.26
Monuron 1.073 1.072 1.99
2,5-Dichloroaniline 1.187 1.187 2.55
Naphthalene 1.374 1.375 2.75
Benzoic acid phenylester 1.616 1.616 2.87
Fenthion 2.029 2.031 3.31
Phenanthrene 2.254 2.254 4.09
4,4’-DDT 4.965 4.957 5.63
Test item – major peak 1.381 1.381 1.381 2.81 6.4 x 10e2 99.8
Test item – peak 2 2.326 2.331 2.329 4.05 1.1 x 10e4 0.076
Test item – peak 3 2.621 2.626 2.624 4.28 1.9 x 10e4 0.096

Validity criteria fulfilled:

yes

Conclusions:

The HPLC method using soil-adsorption-reference data was applied for the determination of the adsorption coefficient (Koc) of Octopamine hydrochloride.
The Koc and log Koc values of the test item at pH 7.5 were:
Koc log Koc Peak area(%)
Test item – major peak 6.4 x 10e2 2.81 99.8
Test item – peak 2 1.1 x 10e4 4.05 0.076
Test item – peak 3 1.9 x 10e4 4.28 0.096

Executive summary:

The objective of this study was to determine physico-chemical properties for Octopamine hydrochloride.

The summary of the results is listed below: Adsorption coefficient EC C.19 OECD 121 log K_ocat pH 7.5 :2.81 (major peak) HPLC method based on soil-adsorption-reference data listed below:

Information       Guideline(s)       Result                     Comment

Information

Guideline(s)

Result

Comment

Adsorption coefficient

EC C.19 OECD 121

log Kocat pH 7.5 :2.81 (major peak)

HPLC method based on soil-adsorption-reference data

Description of key information

The Adsorption coefficient for the substance determined in acordance with EC C.19 OECD 121 was log K_oc=2.81 (major peak)

at pH 7.5 by HPLC method based on soil-adsorption-reference data.

Key value for chemical safety assessment

Koc at 20 °C:

640