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Mapping and release of chemical substances from products made of chloroprene
5 Migration investigations
5.1 Chloroprene products selected for the migration investigation
According to agreement with the National Agency of Environmental Protection, the following products were selected for further migration investigation:
Figure 5.1 Selected products
| Product designation |
Sample number |
| Knee bandage |
1 |
| Dive hood |
4 |
| Premium neoprene waders |
6 |
| Dive gloves |
7 |
| Dive suit, semi-wet |
8 |
The chlorine content of the sample nos. 1, 4 and 8 was as expected when compared to published chloroprene formularies. The chlorine content of sample 6 was quite low in relation to standard formularies
and sample 7 had, as previously mentioned, a chlorine content at trace level even though these dive gloves are marketed as neoprene and thus chloroprene-based gloves.
5.2 Method descriptions for the migration investigations
5.2.1 Initial test to determine the final test plan
It was decided to select two of the products for the initial tests since, based on the screening analyses, the concentrations of organic substances to be determined by short-term exposures were expected to
be very low. Sample no. 1 (knee bandage) and sample no. 6 (waders) were selected. The knee bandage was selected because it represents a typical chloroprene product and because the temperature is
expected to be relatively high when the user is engaged in sport activities. For sample 6, the headspace analysis had identified a relatively high content of toluene in relation to the other samples, and waders
represented a product with low chlorine content.
The following exposure conditions were selected for the two products:
Figure 5.2 Exposure conditions
| Product |
Sample
number |
Exposure
time, hours |
Exposure
temperature °C |
Contact
medium |
| Knee bandage |
1 |
2 |
37 |
Artificial sweat |
| Waders |
6 |
6 |
37 |
Artificial sweat |
The GC/MS analysis conditions used on the chromatograph were the same as those used for the screening analysis of extracts. The artificial sweat was produced as prescribed by literature (DS/EN 1811).
The exposure conditions and sample preparation were as follows:
A piece of the product was cut and weighed (approx. 1.5g) for the analysis. The sample was placed in a 250ml glass with a teflon-covered screw cap and was in contact with 50ml artificial sweat. The
rubber was held down by means of metal mesh wire.
The cap was placed on the glass which was then placed in a ultrasonic bath at the exposure temperature for the time specified. Concentration was carried out by Solid Phase Micro Extraction (SPME) in the
headspace which was desorbed at the analysis. The rubber was then removed from the contact medium after it had been exposed to a physical, pumping load ("massaging"). The purpose of this load was to
pump the contact medium out of the rubber before the analysis. When the rubber was removed, the contact medium was extracted using dichloromethane. A direct GC/MS analysis of the extract was
performed.
The results of the analysis work showed that no additional information is obtained from SPME and it was therefore decided to continue the analysis work by analysing the dichloromethane extract alone.
Results of the initial tests:
Method A: SPME-GC/MS
Sample 6 (waders) was found to contain toluene. The content was quantisised against toluene-d8 and found to be 3.1µg/g. No significant content of volatile organic components could be measured in sample
1 (knee bandage).
Method B: GC/MS of the dichloromethane extracts
Two different substances were identified in the migration liquids studied. The results of the analysis are indicated in Table 5.3.
Table 5.3 Analysis results from method B [10]
| Component |
CAS no. |
No. 1 (knee bandage) |
No. 6 (waders) |
| [µg/g] |
[µg/g] |
| Dibutylformamide |
761-65-9 |
4.5 |
- |
| N-Butylbenzene sulphonamide |
3622-84-2 |
0.52 |
0.68 |
| Rt:11.04 |
- |
- |
1.1 |
| Rt:11.36 |
- |
0.39 |
- |
| Rt:11.50 |
- |
0.83 |
1.1 |
| Rt:12.24 |
- |
0.68 |
- |
| Rt:12.44 |
- |
- |
5.2 |
Identification was carried out by searching in the NIST MS library.
5.2.2 Final migration tests
The actual migration analyses were initiated on the basis of the initial migration tests. According to agreement with the National Agency of Environmental Protection, the tests were carried out under different
contact conditions. First, the test involved an analysis of migrating substances to the simulant either in the form of artificial sweat or artificial sea water. The artificial sea water was produced according to a
recipe provided in literature (Standard Methods).
Subsequently, the samples were analysed quantitatively for content of the migrants after extraction using dichloromethane.
The gas chromatographic conditions are identical to those previously listed under the method description i 5.2.2.
The results of tests and analyses are indicated in Table 5.4.
Table 5.4 Analysis results
| Chemical compound |
CAS no. |
No. 1
Knee bandage |
No. 4
Dive hood |
No. 6
Waders |
No. 7
Dive gloves |
No. 8
Dive suit,
semi-wet |
| µg/g |
µg/cm² |
µg/g |
µg/cm² |
µg/g |
µg/cm² |
µg/g |
µg/cm² |
µg/g |
µg/cm² |
Alde-
hydes and ketones |
|
|
|
|
|
|
|
|
|
|
|
3,5,5-Tri-
methyl-
2-cyclo-
hexen
-1-one (isopho-
rone) |
78-59-1 |
|
|
|
|
|
|
|
|
0.15 |
0.011 |
Aromatic hydro-
carbons |
|
|
|
|
|
|
|
|
|
|
|
| Toluene |
108-88-3 |
|
|
|
|
0.12 |
0.0046 |
|
|
|
|
| Aromatic amines and phenols |
|
|
|
|
|
|
|
|
|
|
|
| Phenol |
108-95-2 |
|
|
|
|
|
|
0.90 |
0.062 |
|
|
Form-
amide
deriva-
tives |
|
|
|
|
|
|
|
|
|
|
|
| N,N-Dibutyl formamide |
761-65-9 |
4.9 |
0.22 |
0.48 |
0.031 |
|
|
|
|
0.27 |
0.020 |
| Urea derivatives |
|
|
|
|
|
|
|
|
|
|
|
N,N`-diethyl-
thiourea |
105-55-5 |
|
|
|
|
1.8 |
0.074 |
|
|
|
|
| Other |
|
|
|
|
|
|
|
|
|
|
|
N-Butyl-
benzene
sulpho-
namide |
3622-84-2 |
0.50 |
0.023 |
|
|
0.64 |
0.026 |
|
|
|
|
The following exposure conditions were used in the tests:
No. 1 Knee bandage: 37°C, 2 hours, artificial sweat.
No. 6 Waders 37°C, 6 hours, artificial sweat.
No. 4 Dive hood, 28°C, 1½ hours, artificial sea water.
No. 7 Dive gloves: 28°C, 1½ hours, artificial sea water.
No. 8 Dive suit, semi-wet, 28°C, 1½ hours, artificial sea water.
In the table, the results are indicated as migrated amount per gram of sample and as migrated amount per exposed area. The results are indicated as the mean value of two determinations. Raw data are listed
in Annex C.
The table shows that the following substances migrated:
- Isophorone from the dive suit
- Toluene from waders
- Phenol from dive gloves
- N,N-Dimethyl formamide from knee bandage, dive hood and dive suit
- N-Butylbenzene sulphonamide from knee bandage and waders
5.2.3 Quantitative analyses of selected substances in the products
It was subsequently decided to analyse quantitatively for some of the substances in the products. Aniline was included to see to what extent the substance is present in relation to phenol.
Table 5.5 Analyses of components in products
| Substance |
CAS no. |
No. 1
Knee bandage |
No. 4
Dive hood |
No. 6
Waders |
No. 7
Dive gloves |
No. 8
Dive suit,
semi-wet |
Detection
limit |
| 3,5,5-Trimethyl-2-cyclohexen-1-one (isophorone) |
78-59-1 |
- |
1.6 |
1.0 |
8.9 |
2.4 |
1 |
| Toluene |
108-88-3 |
2.1 |
- |
74 |
- |
9.8 |
1 |
| Phenol |
108-95-2 |
- |
- |
7.7 |
36 |
- |
5 |
| N,N-Dibutyl formamide |
761-65-9 |
240 |
18 |
7.2 |
5.5 |
12 |
5 |
| N,N-diethylthiourea |
105-55-5 |
- |
- |
160 |
- |
110 |
20 |
| Aniline |
62-53-3 |
- |
- |
- |
5.4 |
6.8 |
3 |
When comparing Table 5.4 with Table 5.5, the highest concentrations in the migration tests are consistent with those in the products. Thus, this applies to:
- Toluene i waders
- Phenol in gloves
- N,N-dimethyl formamide in knee bandage
- N,N diethylthiourea in waders
Footnotes
[10] "-" means below the detection limit, 0.1µg/g.
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Version 1.0 September 2005, © Danish Environmental Protection Agency
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