Potassium hydrogen phthalate

Endpoint summary

Description of key information

Biodegradation in water:

28-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test item. The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used for this study. 1 polyseed capsule were added in 500 ml D.I water and then stirred for 1 hour for proper mixing and functioning of inoculum. This gave the bacterial count as 10E7 to 10E8 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism.The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32 ml. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 75.3%. Degradation of Sodium Benzoate exceeds 46.38 % on 7 days & 61.44 on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 1.1 mgO2/mg. ThOD was calculated as 1.13 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 97.34 %. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

Biodegradation in water and sediment:

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound 1,2-Benzenedicarboxylic acid, monopotassium salt (CAS No. 877 -24 -7). If released in to the environment, 20% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 1,2-Benzenedicarboxylic acid, monopotassium salt in water is estimated to be 15 days (360hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is low whereas the half-life period of 1,2-Benzenedicarboxylic acid, monopotassium salt in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of the chemical into the sediment is less than 1% (i.e, reported as 0.102%), indicates that 1,2-Benzenedicarboxylic acid, monopotassium salt is not persistent in nature.

Biodegradation in soil:

The half-life period of 1,2-Benzenedicarboxylic acid, monopotassium salt (CAS No. 877 -24 -7) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 79.9% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 1,2-Benzenedicarboxylic acid, monopotassium salt in soil is estimated to be 30 days (720hrs). Based on this half-life value of 1,2-Benzenedicarboxylic acid, monopotassium salt, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

Bioaccumulation: aquatic / sediment:

Based on the predicted data by BCFBAF Program (v3.01) model of EPI suite the Bioaccumulation factor (BCF) was predicted to be 3.162 L/kg wet-wt at 25 deg.C.Based on the BCF concentration it is concluded that the test chemical hydrogen potassium phthalate in non bioaccumulative in nature as it dose not exceed the BCF criteria of 2000.

Adsorption / desorption

The adsorption coefficient Koc in soil and in sewage sludge of test chemical Potassium hydrogen phthalate (CAS No. 877-24-7) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals (Experimental study report, 2018). The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 5.4. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances were Acetanilide, 4-chloroaniline, 4-methylaniline(p-Tolouidine), N-methylaniline, p-toluamide, Aniline, 2,5-Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4- Nitrobenzamide, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichloro benzene, Pentachlorophenol, 3,5-dinitrobenzamide, Benzamide, phenanthrene having Koc value ranging from 1.25 to 4.09. The Log Koc value of test chemical Potassium hydrogen phthalate was determined to be 0.841± 0.000 at 25°C. This log Koc value indicates that the substance Potassium hydrogen phthalate has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.

Additional information

Biodegradation in water:

Various experimental study for the test compound Potassium hydrogen phthalate (CAS No. 877-24-7) were reviewed for the biodegradation end point which are summarized as below:

In the first key study from experimental report 28-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test item. The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used for this study. 1 polyseed capsule were added in 500 ml D.I water and then stirred for 1 hour for proper mixing and functioning of inoculum. This gave the bacterial count as 10E7 to 10E8 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism.The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32 ml. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 75.3%. Degradation of Sodium Benzoate exceeds 46.38 % on 7 days & 61.44 on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 1.1 mgO2/mg. ThOD was calculated as 1.13 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 97.34 %. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

First study was supported by the second from peer reviewed journal. Biodegradation study was conducted for 30 days for evaluating the percentage biodegradability of test substance1,2-Benzenedicarboxylic acid, monopotassium salt. Glucose-glutamic acid mixture was used as a reference substance for the biodegradation study. The results are compared with the chemical oxygen demand (COD) of the test chemical, which measures its maximum oxygen combining power; the results are also compared with the BOD test performed on a standard glucose-glutamic acid reference solution used for BOD caliberation. Reference substance i.e; glucose-glutamic acid mixture consumes 75 percent of its maximum oxygen requirement (COD) within 5 days and almost 100 percent in 30 days. Thus, based on this result, the reference substance is considered to be readily biodegradable. The percentage degradation of test substance was determined to be 92% by BOD parameter in 30 days. Thus, based on percentage degradation, test chemical1,2-Benzenedicarboxylic acid, monopotassium salt was considered to be readily biodegradable in nature.

Based on the above both studies, chemical consider to be readily biodegradable in water.

Biodegradation in water and sediment:

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound 1,2-Benzenedicarboxylic acid, monopotassium salt (CAS No. 877 -24 -7). If released in to the environment, 20% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 1,2-Benzenedicarboxylic acid, monopotassium salt in water is estimated to be 15 days (360hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is low whereas the half-life period of 1,2-Benzenedicarboxylic acid, monopotassium salt in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of the chemical into the sediment is less than 1% (i.e, reported as 0.102%), indicates that 1,2-Benzenedicarboxylic acid, monopotassium salt is not persistent in nature.

Biodegradation in soil:

The half-life period of 1,2-Benzenedicarboxylic acid, monopotassium salt (CAS No. 877 -24 -7) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 79.9% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 1,2-Benzenedicarboxylic acid, monopotassium salt in soil is estimated to be 30 days (720hrs). Based on this half-life value of 1,2-Benzenedicarboxylic acid, monopotassium salt, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

On the basis of available information, the test substance Potassium hydrogen phthalate can be considered to be readily biodegradable in nature.

Bioaccumulation: aquatic / sediment:

Experimental and Predicted data of Bioaccumulation endpoint for the target chemical hydrogen potassium phthalate (Cas no. 877-24-7) and its read across chemical were reviewed to summarize as follows:  

 

From predicted model EPI suite 2017 using BCFBAF Program (v3.01) indicate that Bioaccumulation factor (BCF) was predicted to be 3.162 L/kg wet-wt at 25 deg.C. Based on the BCF concentration it is concluded that the test chemical hydrogen potassium phthalate in non bioaccumulative in nature as it does not exceed the BCF criteria of 2000.

 

Whereas from PBT profiler computational model the Bio concentration factor (BCF) was estimated to be 3.2 for test substance hydrogen potassium phthalate.   

 

From HSDB database (2017); for the read across chemical Phthalic acid (Cas no. 88-99-3) an estimated BCF of 3 was calculated, using a log Kow of 0.73 and a regression-derived equation ,this BCF suggests the potential for bioconcentration in aquatic organisms is negligible.

And information from an authorative database ECOTOX (2017) for read across Benzoic Acid (Cas no. 65-85-0) indicates, on the basis of accumulation effect, the Bioconcentration factor (BCF) for test substance Benzoic acid was observed to be 21 for dose concentration 1.78 ug/L in fish Gambusia affinis (Western Mosquitofish) for exposure period of 24 hrs. Based on the result it is concluded that the test substance is non bioaccumulative in nature.

Thus based on the above all studies it is concluded that the test substance hydrogen potassium phthalate (Cas no. 877-24-7) is non Bioaccumulative in aquatic environment.

Adsorption / desorption

The adsorption coefficient Koc in soil and in sewage sludge of test chemical Potassium hydrogen phthalate (CAS No. 877-24-7) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals (Experimental study report, 2018). The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 5.4. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances were Acetanilide, 4-chloroaniline, 4-methylaniline(p-Tolouidine), N-methylaniline, p-toluamide, Aniline, 2,5-Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4- Nitrobenzamide, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichloro benzene, Pentachlorophenol, 3,5-dinitrobenzamide, Benzamide, phenanthrene having Koc value ranging from 1.25 to 4.09. The Log Koc value of test chemical Potassium hydrogen phthalate was determined to be 0.841± 0.000 at 25°C. This log Koc value indicates that the substance Potassium hydrogen phthalate has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.