Cyclic Siloxane Testing

ACE Laboratories offers the testing solutions you need to qualify the presence of cyclic siloxanes—namely D4, D5, and D6—in your products, so you can remain compliant with siloxane restrictions in the European Union and around the world.

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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
D4 is used in leave-on cosmetics, such as lotion, deodorant, and hair conditioner. Studies have shown that octamethylcyclotetrasiloxane is toxic to marine life. D4 may also be toxic to reproduction. As a result, D4 is classified as Persistent, Bioaccumulative and Toxic (PBT) and very persistent and very bioaccumulative (vPvB).
D5, or decamethylcyclopentasiloxane
D5 is used as an emollient and protective barrier in beauty products. Like D4, D5 is classified as PBT and vPvB. Some studies suggest that D5 may be harmful to the reproductive, immune, and nervous systems.
D6, or dodecamethylcyclohexasiloxane
Because D6 has low viscosity and high volatility, it is often used in hair, skincare, and personal care products. D6 may have long-lasting, negative effects on aquatic life and is classified as PBT.

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.

vials in a rotating machine

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.

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