Silver nitrate

Oxidising properties

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

oxidising solids

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-07-14 to 2009-07-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: the Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria, Part 34.4.1, Test O.1: Test for oxidizing solids

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

2004-09-06

Contact with:

powdered cellulose

Duration of test (contact time):

3 min

Sample tested:

4:1 sample-to-cellulose ratio

Parameter:

mean burning time

Result:

15 s

Sample tested:

1:1 sample-to-cellulose ratio

Remarks:

mixture of test item/cellulose

Parameter:

mean burning time

Result:

100 s

Burning times of potassium bromate/cellulose mixtures

Mixture	Test 1 t [s]	Test 2 t [s]	Test 3 t [s]	Test 4 t [s]	Test 5 t [s]	mean burning time [s]
3:7	128	119	122	129	140	128
2:3	64	61	65	69	72	66
3:2	19	22	23	22	20	21

Due to the fact that both mixtures of the test item with cellulose (4:1 and 1:1) have lower mean burning times compared to the reference mixture in the ratio 3:7,it is concluded that the test item has oxidizing properties.

Due to the fact that the mean burning time of the mixture of the test item with cellulose in the ratio of 4:1 is also less than the mean burning time of the 3:2 mixture, by mass, of potassium bromate and cellulose the test item has to be classified to Packing group I

Interpretation of results:

Category 1 (strong oxidising solids) based on GHS criteria

Conclusions:

The test item silver nitrate has oxidizing properties and has to be classified to Packing group I in the sense of the Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria, Part 34.4.1 (Test O.1).

The test item silver nitrate has oxidizing properties and has to be classified in Category 1 in accordance with Regulation (EC) No. 1272/2008 on the classification, labelling and packaging of substances and mixtures (“CLP Regulation”). The according hazard statement is “H271: May cause fire or explosion; strong oxidiser.”

Reference 2

Endpoint:

oxidising solids

Type of information:

experimental study

Adequacy of study:

key study

Study period:

March 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: UN Recommendations on the Transport of Dangerous Goods, Tests and Criteria, fifth revised edition, 2009. Additionally particle size distribution was analysed.

Deviations:

no

GLP compliance:

no

Contact with:

powdered cellulose

Duration of test (contact time):

>= 9 - <= 112.6 s

Sample tested:

1:1 sample-to-cellulose ratio

Parameter:

mean burning time

Result:

96.16 s

Sample tested:

4:1 sample-to-cellulose ratio

Parameter:

mean burning time

Result:

12.76 s

Sample tested:

reference: 3:7 mixture potassium bromate + cellulose

Parameter:

mean burning time

Result:

other: not applicable

Remarks on result:

not determinable because of methodological limitations

Sample tested:

reference: 2:3 mixture potassium bromate + cellulose

Parameter:

mean burning time

Result:

49.76 s

Sample tested:

reference: 3:2 mixture potassium bromate + cellulose

Parameter:

mean burning time

Result:

13.32 s

If t1 or t2 ≤ R1, then Class 5.1, Packing group III

If t1 or t2 ≤ R2, then Class 5.1, Packing group II

If t1 or t2 < R3, then Class 5.1, Packing group II

The substance "Silver nitrate- Batch PMC 4" (II23/140110/03) fulfils the criteria for Packing Group I, because the mean burning time t2 (12.6s) of the 4:1 sample-to-cellulose ratio (by mass) is less than the mean burning time R3(13.32s) of the 3:2 mixture (by mass) of potassium bromate and cellulose.

On the basis of the test results and according to the criteria specified in the UN Recommendations on the Transport of Dangerous Goods the substance "Silver nitrate- batch PMC 4" may be classified as class 5.1, UN-Number 1479, Packaging Group I if the substances will have no subsidiary risk.

On the basis of the test results and according to the criteria specified in the GHS the substance "Silver nitrate - Batch PMC4" is an oxidising solid of Category 1.

Interpretation of results:

Category 1 (strong oxidising solids) based on GHS criteria

Conclusions:

On the basis of the test results and according to the criteria specified in the GHS the substance "Silver nitrate - Batch PMC4" is an oxidising solid of Category 1.

Reference 3

Endpoint:

oxidising solids

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-06-01 to 2010-06-16

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: the United Nations Recommendations on the Transportation of Dangerous Goods, Manual of Tests and Criteria, Test O.1.

Deviations:

no

GLP compliance:

yes

Contact with:

powdered cellulose

Duration of test (contact time):

>= 20.6 - <= 96 s

Sample tested:

reference: 3:7 mixture potassium bromate + cellulose

Parameter:

mean burning time

Result:

97.3 s

Sample tested:

reference: 2:3 mixture potassium bromate + cellulose

Parameter:

mean burning time

Result:

38.1 s

Sample tested:

reference: 2:3 mixture potassium bromate + cellulose

Parameter:

mean burning time

Result:

14.1 s

Sample tested:

1:1 sample-to-cellulose ratio

Parameter:

mean burning time

Result:

89.5 s

Sample tested:

4:1 sample-to-cellulose ratio

Parameter:

mean burning time

Result:

24.3 s

Comments:

1:1 burnt steadily with a yellow and green flame with light grey smoke.

4:1 burnt fairly rapidly with a yellow and green flame with light grey smoke.

Note:

The testing was conducted on material ‘as received’ at the request of the client. It is believed by Chilworth Technology Ltd that a repeat of this test with a finer grade sample would result in sufficient reduction of the burning time that the material would fall within Class 5.1 (Packing Group I).

Interpretation of results:

Category 2 (oxidising solids) based on GHS criteria

Conclusions:

For transport purposes the material Silver Nitrate (as tested in this test) should be classified as an Oxidising Solid of Class 5.1 (Packing Group II) as per UN transport regulations.
The sample Silver Nitrate (as tested in this test) is classified as a category 2 oxidising solid according to CLP.

Reference 4

Endpoint:

oxidising solids

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-06-01 to 2010-06-16

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: the United Nations Recommendations on the Transportation of Dangerous Goods, Manual of Tests and Criteria, Test O.1.

Deviations:

no

GLP compliance:

yes

Contact with:

powdered cellulose

Duration of test (contact time):

>= 11.3 - <= 65.2 s

Sample tested:

1:1 sample-to-cellulose ratio

Parameter:

mean burning time

Result:

61.6 s

Sample tested:

4:1 sample-to-cellulose ratio

Parameter:

mean burning time

Result:

12.7 s

Sample tested:

reference: 3:7 mixture potassium bromate + cellulose

Parameter:

mean burning time

Result:

97.3 s

Sample tested:

reference: 2:3 mixture potassium bromate + cellulose

Parameter:

mean burning time

Result:

38.1 s

Sample tested:

reference: 3:2 mixture potassium bromate + cellulose

Parameter:

mean burning time

Result:

14.1 s

Comments:

1:1 burnt steadily with a yellow and green flame with light grey smoke.

4:1 burnt rapidly with a yellow and green flame with light grey smoke.

Interpretation of results:

Category 1 (strong oxidising solids) based on GHS criteria

Conclusions:

For transport purposes the material Silver Nitrate (as tested in this test) should be classified as an Oxidising Solid of Class 5.1 (Packing Group I) as per UN transport regulations. The sample Silver Nitrate (as tested in this test) is classified as a category 1 oxidising solid according to CLP.

Description of key information

Silver nitrate is marketed in the form of aqueous solutions and in the form of solid crystals with various particle size characteristics. Whereas aqueous solutions do not require classification (United Nations, 2003), solid silver nitrate needs to be classified as an oxidising solid. Depending on the particles size, either classification as oxidising solid category 1 or category 2 is required. As a cut-off size between these categories, a D10 of 250 µm is proposed (see discussion).

Key value for chemical safety assessment

Oxidising properties:

oxidising

Additional information

According to Annex VI of Regulation (EC) No 1272/2008 of the European Parliament and of the Council on classification, labelling and packaging of substances and mixtures, silver nitrate is classified as an oxidising solid, category 2 (Index No. 047-001-00-2). The Precious Metals and Rhenium consortium has tried to retrieve the underlying test results for the above mentioned classification but unfortunately they were not available to any PMC Members or its experts.

Initial experimental testing (UN O.1 method) then indicated that at least for some specifications of silver nitrate, a classification as Category 1 would be applicable, and is was hypothesised that particle size could have a significant influence, particularly in respect of the content of very fine particulate fraction. Subsequently, the Precious Metals and Rhenium Consortium has conducted a total of seven experimental tests for oxidising properties (UN O.1 method) with silver nitrate. Various commercial samples were tested, either untreated, after worst-case simulated transport (to model abrasion processes which can produce fine attrition particles), or after actual grinding. An overview of these tests is given in the table below. Robust study summaries are available for four studies and are included in the technical dossier.

 

Sample description	D10	D50	D90	Resulting classification category for oxidising solids
Commercial sample from producer 1, untreated	329 µm	491 µm	727 µm	Cat. 2
Commercial sample from producer 1, after worst-case simulation of transport	272 µm	532 µm	958 µm	Cat. 2
Commercial sample from producer 2, untreated	254 µm	421 µm	677 µm	Cat. 1
Commercial sample from producer 2, after worst-case simulation of transport	154 µm	295 µm	498 µm	Cat. 1
Commercial sample, Batch PMC 4, untreated	150 µm	291 µm	457 µm	Cat. 1
Commercial sample, Batch PMC 4, after grinding	134 µm	277 µm	454 µm	Cat. 1
Commercial sample, Batch PMC 2, untreated	< 1 mm (not further specified)			Cat. 1

 

The results of this testing programme show the particles size indeed has an influence on the extent of oxidising properties of silver nitrate. Depending on the particles size, either classification as oxidising solid category 1 or category 2 is required.

As a cut-off size between these categories, a D10 of 250 µm is proposed.

Since fine particles are considered to be the most relevant to oxidising behaviour thresholds in this context, the D10 value (i.e. the particle diameter at which 10% of particle gradation mass is finer than the stated value) has been selected as a categorisation criterion. It is recognised that this threshold has its limitations since it is based on very few data points and there is reliance on only one characteristic. It is therefore used in the absence of a more comprehensive set of influencing parameters. If new and better data become available, the recommended threshold may have to be revised accordingly

 

Justification for classification or non-classification

Silver nitrate is marketed in the form of aqueous solutions and in the form of solid crystals with various particle size characteristics. Whereas aqueous solutions do not require classification (United Nations, 2003), solid silver nitrate needs to be classified as an oxidising solid. Depending on the particles size, either classification as oxidising solid category 1 or category 2 is required. As a cut-off size between these categories, a D10 of 250 µm is proposed (see discussion).