Sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate

Endpoint summary

Description of key information

Hydrolysis

In accordance with column 2 of Annex VIII of the REACH regulation, testing for this endpoint is scientifically not necessary and does not need to be conducted since the substance sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate is readily biodegradable.

Biodegradation in water

Biodegradation study was conducted for evaluating the percentage biodegradability of test substancesodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4 -hydroxynaphtha lene-2 -sulphonate (CAS no. 57741 -47 -6) at a temperature of 30°C and pH of 7.3 ± 0.2 (Frank P. van der Zee, et. al; 2001). Anaerobic granular sludge (non-adapted) was used as a test inoculums for the study. Concentration of inoculum i.e, sludge used was 1500 mg/l (1.5 g/l) volatile suspended solids and initial test substance conc. used in the study was 100-300 mg/l, respectively. Basal medium was used as a test medium for the study. The composition of medium includes 2.8 g NH4Cl/l, 0.057 g 0CaCl2 /l, 2.5 g KH2PO4/l and 1 g MgSO4.7H2O/l and the medium was buffered at a pH of 7.3 ± 0.2 with NaHCO3 (5 g/l). The biological dye decolourisation assay was performed in 120 ml serum bottles containing 50 ml of medium and an overlying headspace composed of N2/CO2 (80%/20%) which was sealed with a butyl rubber stopper. The primary electron donating substrate of the medium was composed of 2 g/l chemical oxygen demand (COD) of an NaOH-neutralised volatile fatty acids (VFA) mixture containing acetate, propionate and butyrate in a COD-based ratio of 1:10:10. Non-adapted anaerobic granular sludge was added to the medium at a concentration of 1500 mg/l volatile suspended solids (VSS). The medium was flushed with the N2/CO2 (80%/20%) and preincubated with the sludge for 2-3 days. The background level of sulphide in the medium was 0.7 ± 0.02 mM. The test chemical acid red 266 was added to a final conc. of approx. 0.3 mM (100-300 mg/l) with a syringe from a concentrated stock solution. The serum bottles were incubated at 30°C in a rotary shaker at 50 rpm.At selected intervals, colour was measured spectrophotometrically at the dye’s wavelength of maximum absorbance (ƛ max). For this purpose, samples were centrifuged after dilution to less than 1 absorbance unit (AU) in a phosphate buffer (10.86 g/l Na2HPO4.2H2O; 5.38 g/l Na2HPO4.H2O) that contained ascorbic acid (200 mg/l) to effectively prevent auto-oxidation. The background light absorbance of the control medium in the buffer was less than 0.5% of the absorbance due to dye containing medium in the buffer and could therefore be neglected. The percentage decolourisation of test substance sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate was determined to 95%. Thus, based on percentage decolourisation,sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate is considered to be readily biodegradable in nature.

Bioaccumulation: aquatic / sediment

From CompTox Chemistry Dashboard using OPERA (OPEn (quantitative) structure-activity Relationship Application)  V1.02 model in which calculation based on PaDEL descriptors (calculate molecular descriptors and fingerprints of chemical), the bioaccumulation i.e BCF for test substance sodium 6 -amino-5 -[[4 -chloro-2 -(trifluoromethyl)phenyl]azo]-4 -hydroxynaphthalene-2 -sulphonate was estimated to be 11.3 dimensionless . The predicted BCF result based on the 5 OECD principles. Thus based on the result it is concluded that the test substance sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate is non-bioaccumulative in nature.

Adsorption / desorption

Adsorption study was conducted for evaluating the adsorption capacity of test chemical sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate (CAS no. 57741-47-6) onto nanoclay at a temperature of 95°C (Yiqi Yang, et. al; 2005). In this study, Nanoclay Cloisites 10A, 15A, 30B and Na+were selected for dye sorption. Dye sorption onto nanoclay was performed at 95°C for 6 hours with a liquor-to-clay ratio of 100:1. A pre-study showed that dye sorption equilibrium was obtained within 6 hours. No purification was performed to either the commercial dyestuffs or the clays. Dye concentration differences in the bath before and after dyeing were used to obtain dye sorption data. A Hunterlab spectrophotometer was used to measure dye concentrations using the Beer–Lambert law.Before absorbance measurement, the clay was filtered from the dye liquor using syringe filters and a centrifuge to assure that small clay particles did not interfere with absorbance measurement. The clay treated with quaternary ammonium had a very strong sorption capability to acid red 266. This result indicated that the major contributive forces to dye sorption onto clay were van der Waals forces and hydrophobic interaction. Ionic attraction also played an important role. Nanoclay (10A, 15A, 30B and Na+) have a sorption capacity ranging from 150-700 mg dye per gram of the sorbent at a liquor-to-sorbent ratio of 100 to 1. Furthermore, it could have a sorption of 90% at an initial dye concentration of 6 g/L, or 60% based on the weight of the sorbent, indicating a very high dye affinity. This indicatesthat the substance sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate (C. I. Acid Red 266) has a very strong sorption tosoil and therefore have negligible migration potential to ground water.

Additional information

Hydrolysis

In accordance with column 2 of Annex VIII of the REACH regulation, testing for this endpoint is scientifically not necessary and does not need to be conducted since the substance sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate is readily biodegradable.

Biodegradation in water

Experimental study for the target compound sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate (CAS No. 57741-47-6) and supporting study for its structurally similar read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental key study from peer reviewed journal (Frank P. van der Zee, et. al; 2001), biodegradation experiment was conducted for evaluating the percentage biodegradability of test substance sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4 -hydroxynaphtha lene-2 -sulphonate (CAS no. 57741 -47 -6) at a temperature of 30°C and pH of 7.3 ± 0.2.Anaerobic granular sludge (non-adapted) was used as a test inoculums for the study. Concentration of inoculum i.e, sludge used was 1500 mg/l (1.5 g/l) volatile suspended solids and initial test substance conc. used in the study was 100-300 mg/l, respectively. Basal medium was used as a test medium for the study. The composition of medium includes 2.8 g NH4Cl/l, 0.057 g 0CaCl2 /l, 2.5 g KH2PO4/l and 1 g MgSO4.7H2O/l and the medium was buffered at a pH of 7.3 ± 0.2 with NaHCO3 (5 g/l). The biological dye decolourisation assay was performed in 120 ml serum bottles containing 50 ml of medium and an overlying headspace composed of N2/CO2 (80%/20%) which was sealed with a butyl rubber stopper. The primary electron donating substrate of the medium was composed of 2 g/l chemical oxygen demand (COD) of an NaOH-neutralised volatile fatty acids (VFA) mixture containing acetate, propionate and butyrate in a COD-based ratio of 1:10:10. Non-adapted anaerobic granular sludge was added to the medium at a concentration of 1500 mg/l volatile suspended solids (VSS). The medium was flushed with the N2/CO2 (80%/20%) and preincubated with the sludge for 2-3 days. The background level of sulphide in the medium was 0.7 ± 0.02 mM. The test chemical acid red 266 was added to a final conc. of approx. 0.3 mM (100-300 mg/l) with a syringe from a concentrated stock solution. The serum bottles were incubated at 30°C in a rotary shaker at 50 rpm. At selected intervals, colour was measured spectrophotometrically at the dye’s wavelength of maximum absorbance (ƛ max). For this purpose, samples were centrifuged after dilution to less than 1 absorbance unit (AU) in a phosphate buffer (10.86 g/l Na2HPO4.2H2O; 5.38 g/l Na2HPO4.H2O) that contained ascorbic acid (200 mg/l) to effectively prevent auto-oxidation. The background light absorbance of the control medium in the buffer was less than 0.5% of the absorbance due to dye containing medium in the buffer and could therefore be neglected. The percentage decolourisation of test substance sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate was determined to 95%. Thus, based on percentage decolourisation, sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate is considered to be readily biodegradable in nature.

 

For the read across chemical disodium 5-acetamido-4-hydroxy-3-(phenyldiazenyl)naphthalene-2,7-disulfonate (CAS no. 3734-67-6) from peer reviewed journal (Lata Kumari, et. al; 2016),biodegradation study was conducted for evaluating the percentage biodegradability of read across chemical Disodium 5-acetamido-4-hydroxy-3-(phenyldiazenyl)naphthalene-2,7-disulfonate by indigenous bacteria Stenotrophomonassp. BHUSSp X2. Stenotrophomonassp. BHUSSp X2 was used as a test inoculum isolated from soil collected from the carpet dyeing industries located in Bhadohi, India. Soil and effluents were collected from the carpet dyeing industries located in Bhadohi, India. One hundred milliliters of 1 % soil solution was incubated with 500-mg/l RED G dye in nutrient broth maintained at 35±2 °C for 1 week under static and shaking conditions. The resultant broth sample was streaked on nutrient agar plate having 500-mg/l RED G dye, and this was again incubated at 35±2 °C for a week. Morphologically distinct bacteria were isolated from this agar plate and were again streaked on fresh nutrient agar plate for isolation of pure bacteria. The most promising isolates selected in this manner were tested for decolorization of dye in submerged condition. The dye degrading bacteria were identified on the basis of morphological colony; Gram staining and biochemical test of isolated strain were performed according to the Bergey’s manual and on the basis of 16S rRNA gene sequence analysis. The sequence was compared using BLAST programmed at NCBI server to identify bacteria. The 16S rRNA sequence of isolated bacterial strain and related sequences of NCBI were aligned using Cluster W, and phylogenetic tree was made using neighbor-joining methods of MEGA (Version 6).The decolorization experiments were carried out in 250-ml Erlenmeyer flasks containing 100-ml nutrient broth supplemented with RED G dye (100 mg/l). The media were inoculated with respective bacterial strains by addition of inoculums with uniform cell density (O.D. 0.5). Decolorization studies were carried out under static and shaking conditions in 100-ml nutrient broth having dye concentration 200 mg/l dye. All the flasks were incubated under static and shaking (100 rpm) conditions at 35±2 °C for 24 h. Samples were periodically withdrawn after every 2 h, centrifuged (10,000 rpm) to estimate the extent of decolorization using UV-Vis spectrophotometer. The degraded metabolites were extracted with equal volumes of ethyl acetate, and this was evaporated to dryness in rotatory evaporator. The extracted metabolites were mixed with HPLC grade potassiumbromide (KBr) in the ratio of 5:95 and analyzed at mid IR region (400–4000 cm−1) by using FTIR Perkin Elmer, Spectrophotometer. The intermediates produced after degradation were analyzed by GC-MS. The presence of various groups in the GC-MS spectra of dye sample before degradation confirms the characteristics of ACID RED 1 dye, whereas GC-MS spectra of degraded samples confirms the presence of aniline (M.W. 93 peak at 93 m/z), benzene with M.W. 78 m/z 74, sodium7-amino-6-hydroxynapthalene-2-sulfonate (M.W. 261, m/z 263), 3- hydroxyphthalic acid (M.W. 182, m/z 184), and pyrocatechol (M.W.110, m/z 110).The percentage decolorization of test chemical Disodium 5-acetamido-4-hydroxy-3-(phenyldiazenyl)naphthalene-2,7-disulfonate was determined to be 95 and 45% under static and shaking conditions after 28 hrs, respectively. Thus, based on percentage decolorization, chemical disodium 5-acetamido-4-hydroxy-3-(phenyldiazenyl)naphthalene-2,7-disulfonate can be considered to be readily biodegradable in water.

 

On the basis of above results for target chemical sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate(from peer reviewed journal) and for its read across substance (from peer reviewed journal), it can be concluded that the test substance sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonatecan be expected to be readily biodegradable in nature.

Bioaccumulation: aquatic / sediment

Predicted data for the target compound sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate (CAS No. 57741-47-6) and supporting study for its structurally similar read across substance were reviewed for the bioaccumulation end point which are summarized as below:

 

From CompTox Chemistry Dashboard using OPERA (OPEn (quantitative) structure-activity Relationship Application)  V1.02 model in which calculation based on PaDEL descriptors (calculate molecular descriptors and fingerprints of chemical), the bioaccumulation i.e BCF for test substance sodium 6 -amino-5 -[[4 -chloro-2 -(trifluoromethyl)phenyl]azo]-4 -hydroxynaphthalene-2 -sulphonate was estimated to be 11.3 dimensionless . The predicted BCF result based on the 5 OECD principles. Thus based on the result it is concluded that the test substance sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate is non-bioaccumulative in nature.

 

In a supporting weight of evidence study from authoritative database (J-CHECK, 2017 and Envichem, 2018) for the read across chemical 8-amino-1-naphthol-3,6-disulfonic (CAS no. 5460-09-3),bioaccumulation experiment was conducted on test organism Cyprinus carpio for 6 weeks for evaluating the bioconcentration factor (BCF value) of 8-amino-1-naphthol-3,6-disulfonic. The study was performed according to other guideline "Bioaccumulation test of a chemical substance in fish or shellfish" provided in "the Notice on the Test Method Concerning New Chemical Substances", respectively. Cyprinus carpio was used as a test organism for the study. Test chemical nominal conc. used for the study were 2mg/l and 0.2 mg/l, respectively. Range finding study involve the TLm (48 hr) 880 mg/l (w/v) onRice fish (Oryzias latipes).The bioconcentration factor (BCF value) of substance 8-amino-1-naphthol-3,6-disulfonic on Cyprinus carpio was determined to be ≤ 0.3 L/Kg at a conc. of 2 mg/l and ≤ 2.9 L/Kg at a conc. of 0.2 mg/l, respectively, which does not exceed the bioconcentration threshold of 2000, indicating that the chemical 8-amino-1-naphthol-3,6-disulfonic is not expected to bioaccumulate in the food chain.

 

On the basis of above overall results for target chemicalsodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate(from Comptox Chemistry Dashboard,2018) and for its read across substance from authoritative database (J-CHECK, 2017 and EnviChem, 2014), it can be concluded that the BCF value of test substance sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate was estimated to be 11.3, which does not exceed the bioconcentration threshold of 2000, indicating that the chemical sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate is not expected to bioaccumulate in the food chain.

 

Adsorption / desorption

Various experimental study and predicted data for the target compound sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate (CAS No. 57741-47-6) were reviewed for the adsorption end point which are summarized as below:

 

In an experimental key study from peer reviewed journal (Yiqi Yang, et. al; 2005) for the target chemicalsodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxy naphthalene-2-sulphonate(CAS No. 57741-47-6),adsorption experiment was conducted for evaluating the adsorption capacity of test chemical sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate onto nanoclay at a temperature of 95°C. In this study, Nanoclay Cloisites 10A, 15A, 30B and Na+ were selected for dye sorption. Dye sorption onto nanoclay was performed at 95°C for 6 hours with a liquor-to-clay ratio of 100:1. A pre-study showed that dye sorption equilibrium was obtained within 6 hours. No purification was performed to either the commercial dyestuffs or the clays. Dye concentration differences in the bath before and after dyeing were used to obtain dye sorption data. A Hunterlab spectrophotometer was used to measure dye concentrations using the Beer–Lambert law. Before absorbance measurement, the clay was filtered from the dye liquor using syringe filters and a centrifuge to assure that small clay particles did not interfere with absorbance measurement. The clay treated with quaternary ammonium had a very strong sorption capability to acid red 266. This result indicated that the major contributive forces to dye sorption onto clay were van der Waals forces and hydrophobic interaction. Ionic attraction also played an important role. Nanoclay (10A, 15A, 30B and Na+) have a sorption capacity ranging from 150-700 mg dye per gram of the sorbent at a liquor-to-sorbent ratio of 100 to 1. Furthermore, it could have a sorption of 90% at an initial dye concentration of 6 g/L, or 60% based on the weight of the sorbent, indicating a very high dye affinity. This indicates that the substance sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate (C. I. Acid Red 266) has a very strong sorption to soil and therefore have negligible migration potential to ground water.

 

Another adsorption study was conducted for evaluating the adsorption capacity of test chemical sodium 6 -amino-5 -[[4 -chloro-2 -(trifluoromethyl)phenyl]azo]-4 -hydroxy naphthalene-2 -sulphonate (CAS no. 57741 -47-6) onto sewage sludge (NTRL report, Report no. OTS0514199, March 1988). Test chemical conc. used for the study was 0.5 mg/l (0.5 ppm).Three wastewater treatment were selected plants for sludge collection. These plants were coded A, B and C. All plants selected for study treated an influent containing at least 75% wastewater from textile dyeing and finishing processes. All three plants were activated sludge systems operated in extended aeration mode.Plant A is a municipal system typically processing 35 million gallons per day of wastewater. Approximately 90% of the wastewater is from industrial sources. The plant achieves 97-98% BOD reduction. Sludge obtained from this plant had been sand bed dried.Plant B is operated by atextilecompany and has a capacity of 2 million gallons per day. The influent is almost100%textile process wastewater.Plant C is a municipal plant processing 1.5 million gallons of wastewater per day with 75% of the influent from textile dyeing processes. Plant C achieves a 98% BOD removal with a 5 day residence time.For adsorption study, test solution was exposed in several experiments to sludge in a chromatography column. Sludge was obtained from the N.E. Clayton County sewage plant. This sludge contained about 0.9% dry solids. The sludge was allowed to settle, the supernatant decanted and the sludge washed with distilled H20. This was repeated to remove any water soluble chemicals from the sludge. The sludge was left in a closed container for thirty days to starve the bacteria. No bacterial count was made so it is possible that the sludge contained active bacteria.The sludge adsorption columns were prepared in 16 mm by 500 mm chromatography columns. The column was fitted with a stopcock at the lower end preceded by an inch of packed glass wool to prevent sludge from seeping out of the column, but allowing the dye solution to pass through. Approximately 500 ml of sludge solution was allowed tosettleand the top layer of H20 decanted. The column was then filled with sludge and the sludge was allowed to settle in the column. The stopcock was opened allowing excess water to drain off. This process was continued until the column was filled, leaving 1-inch at the top of the column for a glass wool plug. A Kelly infusion jar was attached to the column by a 2 inch piece of Teflon tubing. Dye solution was poured into the infusion jar and passed slowly through the sludge packed column. The effluent was collected and analyzed for dye content. Effluents were collected from the columns on a regular basis. Upon collection from the column the effluents were placed in clean freezer jars and maintained in a freezer until analyzed. Analysis was carried out using liquidchromatography and absorption spectrophotometry.Thus, it was possible by knowing the concentration of dyes and volume of the influent to the sludge column and the dye concentration and volume of the effluent to determine the actual quantity of each dye adsorbed on the sludge.The percentage recovery of the test chemical Acid Red 266 was determined to be 18.7%.These result certainly suggest that the test chemical Acid Red 266 is strongly adsorbed by waste treatment plant sludges and are very difficult to remove.This indicatesthat the substance sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate (C. I. Acid Red 266) has a strong sorption to sewage sludge and therefore have negligible to slow migration potential to ground water.

 

From CompTox Chemistry Dashboard using OPERA (OPEn (quantitative) structure-activity Relationship Application)  V1.02 model in which calculation based on PaDEL descriptors (calculate molecular descriptors and fingerprints of chemical), the adsorption coefficient i.e KOC for test substance sodium 6 -amino-5 -[[4 -chloro-2 -(trifluoromethyl)phenyl]azo]-4 -hydroxynaphthalene-2 -sulphonate was estimated to be 3640 L/kg (log Koc = 3.561).The predicted KOC result based on the 5 OECD principles. This Koc value indicates that the substance sodium 6 -amino-5 -[[4 -chloro-2 -(trifluoromethyl)phenyl]azo]-4 -hydroxynaphthalene-2-sulphonate has a strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.

 

On the basis of above overall results for target chemical sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate (from peer reviewed journal, secondary source and modelling database Comptox Chemistry Dashboard), it can be concluded that the test substance sodium 6-amino-5-[[4-chloro-2-(trifluoromethyl)phenyl]azo]-4-hydroxynaphthalene-2-sulphonate has a strong to very strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.