Registration Dossier

Administrative data

Endpoint:
skin irritation / corrosion, other
Remarks:
Determination of pH-value and acidic reserve
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
Report date: July 20th, 2016
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report Date:
2016

Materials and methods

Principles of method if other than guideline:
Electrochemic determination of pH
Determination of the acidic reserve via titration
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
- Name of test material (as cited in study report): Samarium nitrate
No other information are available.

Test system

Details on study design:
Purpose:
The higher the buffer capacity of a mixture (solution or slurry) is, the stronger the irritating and corrosive potential is, respectively. The physiological effects of acidic or alkaline solutions are not only determined by the pH value but also by the buffering capacity. That is why it is necessary to determine the alkaline or acidic reserve of identified products.

Method:
First, the pH-value of a 10% solution (or slurry) is determined electrochemically at 20°C with a calibrated pH meter (MA 235 Mettler Toledo). This value is recorded.

Determination of the acidic reserve titration:
- For the determination of the alkaline reserve: the titration volume (in mL) of a 0.5 mol/L H2SO4 solution, which is required to achieve a pH of 10 of a 10% solution (or slurry) at 20°C, is recorded.
- For the determination of the acid reserve: the titration volume (in mL) of a 1 mol/L NaOH solution, which is required to achieve a pH of 4 of a 10% solution (or slurry) at 20°C, is recorded.

Calculations:
Titration of the 10% solution/slurry
Alkaline or acid reserve = titration volume [mL] x 0.4

A product is classified as corrosive if:
pH + 1/12 alkaline reserve >= 14.5
pH - 1/12 acid reserve <= -0.5

Results and discussion

In vivo

Results
Irritation parameter:
other: acid/alcaline reserve
Basis:
other: acid reserve
Remarks on result:
no indication of irritation
Irritant / corrosive response data:
Not corrosive (based on an acidic reserve of 0.41 and pH of 1.95, the calculation for corrosivity was 1.92 which is higher than -0.5).

Applicant's summary and conclusion

Interpretation of results:
other: not corrosive
Remarks:
Based on acidic reserve calculation
Conclusions:
The pH value of a 10% solution of Samarium trinitrate was determined to be 1.95 and the acidic reserve 0.41. Based on these data, the calculation for corrosivity was 1.92 (> -0.5). Although this information is conclusive it can not be used alone to conclude on the classification or not of the susbstance.