Cyclic Siloxane Restrictions
Recently, the European Union (EU), the United Kingdom, and other countries have begun to restrict the use of volatile cyclic methyl siloxanes (vCMS), also called cyclic siloxanes. The three cyclic siloxanes under scrutiny are:
D4, or octamethylcyclotetrasiloxane
D5, or decamethylcyclopentasiloxane
D6, or dodecamethylcyclohexasiloxane
In 2018, The European Chemicals Agency (ECHA) formally classified D4, D5, and D6 as substances of very high concern (SVHC). Recently, these substances were also added to the EU’s REACH list. In sum, rinse-off and leave-on products with a concentration equal to or greater than 0.1% by weight of D4, D5, or D6 will not be allowed on the market in the coming years.
Similar restrictions from other countries and regulatory bodies may be on the horizon, as well as restrictions of other products. Additionally, other linear siloxanes, namely L2, L3, L4, and L5, are also being considered for regulation, namely:
- L2, or hexamethyldisiloxane.
- L3, or octamethyltrisiloxane.
- L4, or decamethyltetrasiloxane.
- L5, or dodecamethylpentasiloxane.
Cyclic Siloxane Testing Methods
ACE Laboratories has developed a methodology, based on the European regulation, for detecting and quantifying cyclic siloxanes in consumer products. We can detect both volatile cyclic methyl siloxanes (vCMS), such as D4, D5, and D6, and volatile linear methyl siloxanes (vLMS), such as L2, L3, L4, and L5, via sophisticated analytical methods.
Siloxane testing can also be performed according to ASTM F2466 (Standard Practice For Determining Silicone Volatiles In Silicone Rubber For Transportation Applications)
GC-FID vs. GC-MS for Cyclic Siloxane Testing
There are several different ways to approach cyclic siloxane testing.
The preferred analytical technique is Gas Chromatography—Flame Ionization Detector (GC-FID). GC-FID utilizes the FID as a quantitative detector. The retention times for D4, D5, and D6 are documented, making GC-FID a reliable method for detecting these molecules within a given compound.
However, there are many different molecules with retention times similar to D4, D5, and D6. If any of those molecules are also present in the compound, the result can be a false positive. If this occurs, another option is Gas Chromatography—Mass Spectrometry (GC-MS), a qualitative analytical technique. As molecules exit the analytical column of a GC-MS instrument and enter the detector, each molecule is fragmented in a specific, reproducible way, producing a “mass spectrum” that reports information on the constituents of the molecule. Analytes with the same retention time, which may have been indistinguishable to the GC-FID, produce different peaks and can be separately identified by the GC-MS instrument.
This qualitative certainty can be incredibly valuable in some contexts. GC-MS can detect interferences that cause values for analytes of interest to be greatly reduced or even eliminated.
Cyclic Siloxane Testing from ACE Laboratories
Our testing facilities in northeast Ohio are equipped for a wide range of analytical techniques, as well as sample preparation methods, so we can accommodate virtually any product for testing and deliver accurate data every time. ACE is proud to offer some of the fastest turnaround times in the industry, so you can keep your projects on schedule.