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Adsorption / desorption

The adsorption coefficient Koc in soil and in sewage sludge 4-methoxyphenylacetic acid (CAS No.104-01-8) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The reference substances were chosen according to structural similarity with the test substance and calibration graph prepared. The reference substances were xylene,ethylbenzene and toluene having Koc value ranging from 2.369 to 2.649. The Log Koc value was found to be 1.15385 ± 0.0029 at 25°C. The results indicate that the chemical 4-methoxyphenylacetic acid (CAS No. 104-01-8) is likely to show low tendency of sorption to soil and sediment and show moderate migration potential to groundwater.

Additional information

Transport and distribution

Adsorption / desorption

For adsorption in soil/sediment endpoint 5 studies for test chemical (4-methoxyphenyl) acetic acid (Cas no. 104-01-8) with read across chemical which is 60-70% structurally similar to target were summarised as follows:

Study 1:

The experiment conduct by UERL; 2017to determine Adsorption coefficient (KOC) on soil and on sewage sludge of the4-methoxyphenylacetic acid(CAS No.104-01-8) using HPLC.

According to study the adsorption coefficient Koc in soil and in sewage sludge 4 -methoxyphenylacetic acid(CAS No.104-01-8) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The reference substances were chosen according to structural similarity with the test substance and calibration graph prepared. The reference substances were xylene, ethylbenzene and toluene having Koc value ranging from 2.369 to 2.649. TheLog Kocvalue was found to be1.15385 ± 0.0029 at 25°C. The results indicate that the chemical 4-methoxyphenylacetic acid (CAS No. 104-01-8) is likely to show low tendency of sorption to soil and sediment and show moderate migration potential to groundwater.

Study 2:

The Soil Adsorption Coefficient i.e Koc value of 4-methoxyphenylacetic acid was estimated using EPI suite  KOCWIN Program (v2.00) program as Koc 18.94 L/kg(log Koc=1.277)  by means of MCI method at 25 deg.C, indicating that it is has a negligible sorption to soil and sediment and therefore have rapid migration potential to groundwater.

Study 3:

SciFinder, American Chemical Society (ACS); 2017 prediction database indicated the soil adsorption coefficient i.e Koc value of target substance (4-methoxyphenyl)acetic acid was estimated to be 112 L/Kg i.e Log Koc= 2.049 at pH 1, 111.0 i.e Koc=2.045 at pH 2, 108.0 i.e Log Koc=2.033 at pH 3, 82.4 i.e Log Koc=1.915 at pH 4, 32.1 i.e Log Koc=1.389 at pH 5, 3.06 i.e Log Koc=0.4857 at pH 6, 1.0 i.e Log Koc=0, at pH 6-10 and temperature 25 deg.C. This Koc value at all range of pH condition indicates that the substance 4-methoxyphenylacetic acid has a low sorption to soil and sediment and therefore have rapid migration potential to groundwater. 

Study 4:

Chemspider predicted database the soil adsorption coefficient i.e Koc value of test substance 4-methoxyphenylacetic acid was estimated to be 1 13.81 i.e Log Koc= 1.140 at pH 5.5 and 1.00 i.e Log Koc=0 at pH 7.4 at temp.25 deg.C .This Koc value indicates that the substance 4-methoxyphenylacetic acid has a negligible sorption to soil and sediment and therefore have rapid migration potential to groundwater.

All studies i.e 2, 3 and 4 based on the prediction results also supports the experimental study 1.

Study 5:

In final study based on the authorative database source i.e HSDB database; 2017 for read across chemical 4-chlorophenoxy acetic acid (Cas no. 122-88-3) indicate Koc of 4-chlorophenoxyacetic acid is estimated as 18, Using a structure estimation method based on molecular connectivity indices, this estimated Koc value suggests that 4-chlorophenoxy acetic acid is expected to have very high mobility in soil.

 Read across study also give assistance to experimental and predicted results of the target chemical.

Thus all above experimental and other supported reports arrive at a judgement as the test substance (4-methoxyphenyl) acetic acid (Cas no. 104-01-8) has high mobility in soil/sediment.

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