4-(2-aminoethyl)phenol

Endpoint summary

Description of key information

Adsorption / desorption

Adsorption study was conducted for determining the adsorption capacity of test chemical 4-(2-Aminoethyl)phenol (CAS no. 51-67-2) on the surface of albumin-modified silica

(N. N. Vlasova, et. al; 2011). Albumin-modified finely dispersed silica samples were prepared via protein adsorption from an aqueous solution. BSA (6 g) was dissolved in water (500 ml), finely dispersed silica (10 g) was added, the system was stirred, and pH was brought to 5. In 1 h, the obtained suspension was centrifuged and silica was separated, washed three times with water, filtered off, and dried at room temperature.In the residual equilibrium solution and the filtrates, the concentration of albumin was determined based on an UV absorption band (λ= 268 nm) using the calibration plot constructed preliminarily. In this way, a silica sample was obtained with an albumin content of 430 mg/g sorbent (300 mg protein per 1 g sample). Tyramine adsorption was studied at room temperature (20±2°С). Amine solutions (10 ml, 1 mmol/l) were added to weighed portions of protein-containing silica (0.1 g) and the pH values of the systems were brought to desired values in the range of 2–8. The samples were stirred for 1 h (as was shown previously, this time is sufficient for the adsorption equilibrium to be established), with the pH values being repeatedly controlled using an EV-74 pH meter. After centrifugation (8000 rpm, 20 min), silica was separated and amine concentrations were determined on a Specord M-40 spectrophotometer. The UV absorption spectra of both amines were preliminarily studied depending on the concentration and pH of their solutions. It was found that, for tyramine, the positions and intensities of absorption bands are independent of pH; for tyramine,λmax= 275 nm,ε= 1560 (l mol–1 cm–1). The absorption bands of the amines almost coincide with the absorption spectrum of BSA; therefore, the equilibrium concentrations of the amines were determined from their absorption band intensities, which were estimated by subtracting the absorption corresponding to the concentration of the protein desorbed into a solution at a given pH. The adsorption values of amines were determined from the difference between the initial and equilibrium concentrations and expressed in percents.The adsorption values calculated from the difference between the initial and equilibrium concentrations were expressed in mmol/g.The adsorption constant value was calculated using the Langmuir equation. The maximum adsorption value of test chemical 4-(2-Aminoethyl)phenolon finely dispersed silica and albumin-modified finely dispersed silica was determined to be 0.20 & 0.23 mmol/g, respectively and percentage adsorption of chemical 4-(2-Aminoethyl)phenolat pH 7.0 and a temperature of 20 ± 2⁰C was determined to be approx. 5 and 25%, respectively. Thus based on the %adsorption, it indicates that the substance 4-(2-Aminoethyl)phenol has a negligible to low sorption tosoil and sediment and therefore have rapid to moderate migration potential to ground water.

Additional information

Adsorption / desorption

Various experimental key and supporting study for the target compound4-(2-Aminoethyl)phenol(CAS No. 51-67-2) and supporting study for its structurally similar read across substance were reviewed for the adsorption end point which are summarized as below:

 

In an experimental key study from peer reviewed journal (N. N. Vlasova, et. al; 2011),adsorption experiment was conducted for determining the adsorption capacity of test chemical 4-(2-Aminoethyl)phenol (CAS no. 51-67-2) on the surface of albumin-modified silica. Albumin-modified finely dispersed silica samples were prepared via protein adsorption from an aqueous solution. BSA (6 g) was dissolved in water (500 ml), finely dispersed silica (10 g) was added, the system was stirred, and pH was brought to 5. In 1 h, the obtained suspension was centrifuged and silica was separated, washed three times with water, filtered off, and dried at room temperature.In the residual equilibrium solution and the filtrates, the concentration of albumin was determined based on an UV absorption band (λ= 268 nm) using the calibration plot constructed preliminarily. In this way, a silica sample was obtained with an albumin content of 430 mg/g sorbent (300 mg protein per 1 g sample). Tyramine adsorption was studied at room temperature (20±2°С). Amine solutions (10 ml, 1 mmol/l) were added to weighed portions of protein-containing silica (0.1 g) and the pH values of the systems were brought to desired values in the range of 2–8. The samples were stirred for 1 h (as was shown previously, this time is sufficient for the adsorption equilibrium to be established), with the pH values being repeatedly controlled using an EV-74 pH meter. After centrifugation (8000 rpm, 20 min), silica was separated and amine concentrations were determined on a Specord M-40 spectrophotometer. The UV absorption spectra of both amines were preliminarily studied depending on the concentration and pH of their solutions. It was found that, for tyramine, the positions and intensities of absorption bands are independent of pH; for tyramine,λmax= 275 nm,ε= 1560 (l mol–1 cm–1). The absorption bands of the amines almost coincide with the absorption spectrum of BSA; therefore, the equilibrium concentrations of the amines were determined from their absorption band intensities, which were estimated by subtracting the absorption corresponding to the concentration of the protein desorbed into a solution at a given pH. The adsorption values of amines were determined from the difference between the initial and equilibrium concentrations and expressed in percents.The adsorption values calculated from the difference between the initial and equilibrium concentrations were expressed in mmol/g.The adsorption constant value was calculated using the Langmuir equation. The maximum adsorption value of test chemical 4-(2-Aminoethyl)phenolon finely dispersed silica and albumin-modified finely dispersed silica was determined to be 0.20 & 0.23 mmol/g, respectively and percentage adsorption of chemical 4-(2-Aminoethyl)phenolat pH 7.0 and a temperature of 20 ± 2⁰C was determined to be approx. 5 and 25%, respectively. Thus based on the %adsorption, it indicates that the substance 4-(2-Aminoethyl)phenol has a negligible to low sorption to soil and sediment and therefore have rapid to moderate migration potential to ground water.

 

Another adsorption study was conducted for determining the adsorption capacity of test chemical4-(2-Aminoethyl)phenol (CAS no. 51-67-2) on the surface of highly dispersed silica. The adsorption of biogenic amines was studied at room temperature (20±2°C). Mix equal volumes of initial silica suspension (20 g/l) prepared in the presence of 0.002 or 0.02 M sodium chloride, and 1 mM amine solutions so that concentrations of silica and amines in prepared suspensions were 10 g/l and 0.5 mM, respectively, and their ionic strength was 0.001 or 0.01. Then, suspension samples (10 ml) were taken, their pH was adjusted to the required pH values within the pH 4–8 range by adding alkali or acid solutions, and were stirred for 1 h. It was established preliminarily that this time is sufficient to attain an equilibrium adsorption. The values of suspension pH were checked periodically (with an EV-74 ionomer). After centrifugation (8000 rpm, 20 min), silica was separated and amine concentration was determined on a Specord M-40 spectrophotometer (Germany). The values of adsorption were calculated by the difference between final and equilibrium concentrations. Preliminarily, we measured absorption spectra of amines in the UV region as a function of the concentration and pH of their aqueous solutions. It was found that, for tyramine, the positions of absorption bands and intensities are almost identical of pH; for tyramine, λmax= 275 nm,ε= 1560 (l mol–1 cm–1).The percentage adsorption of chemical 4-(2-Aminoethyl)phenol on highly dispersed silica at pH 7.0 and a temperature of 20 ± 2⁰C was determined to be approx. 8%, respectively. Thus based on the %adsorption, it indicates that the substance 4-(2-Aminoethyl)phenol has a low sorption to soil and sediment and therefore have rapid migration potential to ground water.

 

 

In a supporting weight of evidence study from authoritative database (HSDB, 2017) for the read across chemical p-cresol (CAS no. 106-44-5),adsorption experiment was conducted in a brookston clay loam soil for determining the adsorption coefficient (Koc) value of read across chemical p-cresol (CAS no. 106-44-5) using the Batch Equilibrium Method. The study was performed according to OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method). The adsorption coefficient (Koc) value of test substance p-cresol was determined to be 49 (Log Koc = 1.69). This Koc value indicates that the substance p-cresol has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

On the basis of above overall results for target chemical4-(2-Aminoethyl)phenol(from peer reviewed journals) and for its read across substance (from authoritative database HSDB), it can be concluded that the test substance4-(2-Aminoethyl)phenolhas a negligible to low sorption to soil and sediment and therefore have rapid to moderate migration potential to ground water.