Barium titanium trioxide

Dissociation constant

Administrative data

Endpoint:

dissociation constant

Type of information:

experimental study

Remarks:

Non-guideline research in view of chemical identity.

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Justification for type of information:

Dissociation characteristics were investigated as part of estimation for solubility of ions at biological and environmental pH.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2022

Report date:

2022

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Samples of Barium Titanium Trioxide (hereafter barium titanate) were examined in order to investigate dissociation under dilute environmental and biological conditions, and determine the
concentrations of barium and titanium ions in solution under these conditions.

Five different conditions were examined; hydrochloric acid to simulate gastric fluid, spring water at pH 9, 5 and 7 (adjusted with sodium hydroxide) to simulate environmental conditions and MiliO ultrapure deionised water as a control. A sixth sample was prepared by complete digestion in concentrated nitric acid in order to examine the sample as supplied.

Dilution in each case was 25mg/ml.

Following dissolution and filtration, sample solutions were examined by ICP analysis to determine the concentration of dissociated barium and titanium.

GLP compliance:

no

Remarks:

This was special research using non-guideline methods, making GLP inappropriate.

Test material

Test material information

Constituent 1

Reference substance name:

Barium titanium trioxide

EC Number:

234-975-0

EC Name:

Barium titanium trioxide

Cas Number:

12047-27-7

Molecular formula:

Ba.O3Ti

IUPAC Name:

titanium(4+) barium(2+) trioxidandiide

Details on test material:

Test item name : Barium titanate milled ABT-O-21
Other names or
synonyms
: Barium titanate
Lot No. : 33HF-201
Product Code : 1326122
Index No. : 056-002-00-7
CAS No. : 12047-27-7
EINECS No. : 234-975-0
Quantity : 1 kg
Date of manufacture : 2011

Specific details on test material used for the study:

Nominal 100% technical grade

Results and discussion

Dissociating properties:

yes

Remarks:

Relative solubility of ions determined at different pH using different aqueous media

Dissociation constant

Remarks on result:

not determinable because of methodological limitations

Remarks:

Standard method was not possible to perform and therefore pKa could not be determined The measurement of pKa was not an intended output of the research

Any other information on results incl. tables

Results of the ICP analysis of the sample solutions are summarised below.

Sample as supplied (conc. Nitric acid) Ba 58.46 %, Ti 15.91 % (ie completely dissociated)

Simulated gastric fluid Ba 689 ppm, Ti 13 ppm (slight dissociation, pH 1.5 molar HCl)

Titanium was not detected in natural buffered water or deionised water
MilliQ DI pure water Ba 74 ppm
Buxton spring water pH 5 solution Ba 42 ppm 
Buxton spring water pH 7 solution Ba 64 ppm 
Buxton spring water pH 9 solution Ba 69 ppm 

The results for titanium are below the limit of detection of the measurement as determined by the quality control samples (1 ppm) for all samples except for the samples digested in Simulated Gastric Fluid and Conc. Nitric Acid. The concentration of these elements is therefore determined to be close to zero for all other samples.

The study has shown that Barium Titanate exhibits a very slight dissociation of the Barium ion under environmental conditions, with no dissociation of the titanium ion.  

Under simulated gastric conditions there is a higher dissociation of the barium ion, with a very slight dissociation of the titanium ion also seen.

Applicant's summary and conclusion

Conclusions:

Testing has shown that Barium Titanate exhibits a very slight dissociation of the Barium ion under environmental conditions, with no dissociation of the titanium ion.  

Under simulated gastric conditions there is a higher dissociation of the barium ion, with a very slight dissociation of the titanium ion also seen.

The titanium ions were not significantly soluble under environmental conditions and can be disregarded as having the potential to cause toxicity to aquatic and terrestrial organisms. Barium has been considered for environmental effects.

Barium and titanium were marginally soluble under gastric conditions with apparent dissociation. Therefore, for toxicological effects, barium and titanium can be considered separately because to be biologically available in solution, they will need to dissociate from each other.