Microbeads in toiletries: method 445.0

Introduction
Scope and application
Interferences
Sample collection, preservation and handling
Reagents and materials
Apparatus
Procedure
Calculations and reporting
Quality assurance / quality control
Method performance and validation
Safety precautions
References
Deviations from reference method

1. Introduction

Microbeads have been determined to be toxic to the environment under the Canadian Environmental Protection Act. The Microbeads in Toiletries Regulations prohibit the manufacture and import of microbead-containing toiletries in Canada. This method is used to support the analysis of microbeads in toiletry products. The method uses water, a mixture of water and organic solvents, or pure organic solvents to dissolve the non-plastic components of the product and by using sieving and/or filtration the undissolved components are isolated. The presence of plastics is confirmed using Fourier Transform Infrared Radiation (FT-IR).

2. Scope and application

This method is applicable to the identification of plastic microbeads in consumer products, specifically, toiletries. This method is used in support of the Microbeads in Toiletries Regulations. Microbeads in products are extracted and analyzed to determine the composition of the beads. FT-IR is used in this determination and provides confirmation of the presence or absence of plastic microbeads.

This method is qualitative only. Due to the limitations of the FT-IR, quantification is not possible; it requires isolating all plastic materials and weighing these materials.

Samples applicable to this regulation are consumer products and will be submitted either in the original product container or as a subsample from a bulk product. The sample matrix will be liquid or solid and have various viscosities and water solubility. The procedures described in this method are applicable as noted in section 7 and to liquids and solids.

The method is fit for the intended use as described in this section with the method performance data as specified in this document and other related documents.

3. Interferences

3.1 Water insoluble compounds require dissolution in organic solvents which may also degrade the plastic microbeads.
3.2 Fine clays and water insoluble oils and fats may clog pores in filter paper and sieves or not pass through smaller pore size platforms.

4. Sample collection, preservation and handling

4.1 Collect samples in original product containers.
4.2 Bulk samples can be collected in plastic or glass containers.
4.3 No preservation is required.
4.4 The minimum quantity required to analyze one sample is 10 g.

5. Reagents and materials

Use reagent grade chemicals unless otherwise specified.

5.1 Iso-propanol
5.2 Acetone
5.3 Hexane
5.4 Reagent water
5.5 Reference material

6. Apparatus

6.1 Vacuum filtration apparatus with liquid trap
- 6.1.1 Buchner Funnel, 90 mm
- 6.1.2 Filter paper, 0.7 µm pore size, 90 mm
- 6.1.3 Filter paper, 0.1 µm pore size, 90 mm
- 6.1.4 Paper funnel
- 6.1.5 One litre filtration flask with side arm
- 6.1.6 Vacuum hose with three-way stop-cock
6.2 Sieve Stack
- 6.2.1 7.3 cm (3 in.) diameter; 4760, 1000, 355, 250, 125, 74, 63, 53, and 10 µm
- 6.2.2 20.3 cm (8 in) diameter; 5000, 1000, 500, 355, 250, 125, 63, 45 and 10 µm
- 6.2.3 Glass dish; minimum size 15 cm x 15 cm and one litre
- 6.2.4 Rubber stoppers, #6, acid washed, rinsed with reagent water and dry
6.3 125 and 250 mL Erlenmeyer flasks
6.4 150, 250, and 1000 mL beakers
6.5 20 mL scintillation vial
6.6 Stirrer/Hot plates
6.7 FT-IR instrument, with the following specifications:
- 6.7.1 FT-IR capability for liquids and solids
- 6.7.2 Attached microscope and camera for particle identification
- 6.7.3 Computer and associated hardware and software for controlling the FT-IR
  - 6.7.3.1 Software must be able to access libraries containing relevant plastic spectra
- 6.7.4 Polypropylene Policeman

7. Procedure

7.1 Clean all glassware, filtering equipment (except filter paper) and sieves by the following method:
- 7.1.1 Wash with hot water and laboratory grade soap. Macroscopic material adhering to the surface of the equipment can be scrapped off or use an appropriate solvent to wash it off.
- 7.1.2 Rinse three times with tap water
- 7.1.3 Rinse three times with reagent water
- 7.1.4 If using non-polar solvents, the equipment must be dried before use
7.2 Record pertinent information as per worksheet 445.0.1 (Microbeads) (see Appendix 4)
7.3 Consumer products may contain many chemicals that cause interferences in the process so a single procedure for all products cannot be relied upon. The methods below are presented as means to reduce these interferences and one or more may need to be used in the determination to recover and isolate any plastic microbeads.
7.4 Potential plastics can be found in Appendix 1.
7.5 The instrument to use for the determination of the type of plastic that may be in the sample is a FT-IR as specified in section 6.7. This instrument consists of a module for liquid determination using reflectance or transmittance; an Attenuated Total Reflectance (ATR) module for solid samples using reflectance; or the microscope module that can measure individual particles using reflectance, an ATR, or, for thin particles, transmittance. Refer to the manufacturers instructions for further information and use of these modules.
- 7.5.1 In this method reference the use of the term FTIR refers to the measurement of the particles of interest using an appropriate instrument using any of the processes described above.
7.6 Points to follow for best results:
- 7.6.1 Start with extraction procedure #1 (section 7.7) using reagent water.
- 7.6.2 In the event poor resolution of the Infrared (IR) scan due to interferences or a score (correlation) of less than 0.9; use one of Extraction Procedures #2 (section 7.8), #3 section 7.9) or #4 (section 7.10) as follows:
  - 7.6.2.1 Use Extraction Procedure #2 when the interfering substances are potentially polar and immiscible in water. Heating aids in the solubility of the substances.
  - 7.6.2.2 Use Extraction Procedure #3 when the interfering substances can be physically separated from the beads in the solution by suspension, floatation, precipitation or dissolution of the interferences in a solvent leaving the beads either at the bottom or top of the solution. Refer to Appendix 2 to determine the appropriate solvent to use for the expected plastic in the sample.
  - 7.6.2.3 Extraction Procedure #4 is used when a gelatinous substance forms in smaller volumes of solvent and causes difficulty in sieving or filtering.
- 7.6.3 If any microbeads do not separate out from the solution through sieving or filtering and other material is collected, then use solvents to remove the interfering material. Solvents may affect different kinds of plastics from no observable effect to dissolution. Refer to Appendix 2 to determine appropriate solvents or solvent mixtures for use with potential plastic microbeads.
- 7.6.4 Above 100 µm beads can be seen as small semi-spherical objects. At less than 100 µm to 10 µm the beads will appear as a fine film covering the sieve mesh.
  - 7.6.4.1 Beads on filter paper can be very hard to see. Gently drag a plastic spatula across the surface of the filter paper to determine if there is any material adhering to it.
- 7.6.5 When IR scanning any potential hits will be given a score. With obvious beads or pure material scores above 0.9 provide good results. Scores less than 0.9 may be due to mixtures which mask some peaks and a strong correlation with the reference library may be difficult. Potential plastics can be determined by comparing the obtained IR spectra with reference spectra. The IR spectra of common plastics can be found in Appendix 3.
  - 7.6.5.1 Use methods and solvents as described in sections 7.6.2 and 7.6.3 to isolate plastic material.
- 7.7 Extraction Procedure #1 - Small volume procedure for microbead extraction
  - 7.7.1 This is the preferred method of extraction. This section applies to most samples, with the exception of samples containing immiscible mineral or other oils and fats; or other organic solvent soluble compounds.
  - 7.7.2 Create a sieve stack consisting of the 3 inch sieves listed in section 6.2.1. Use a minimum of the 4760, 125 µm and 10 µm sieves. Interfering particulate of various sizes can be separated from the microbeads by using the appropriate size sieves (see sections 6.2.1 and 6.2.2).
  - 7.7.3 Collect the filtrate in a glass dish by placing the sieve stack on three rubber stoppers (section 6.2.4) in the glass dish (section 6.2.3).
  - 7.7.4 If no beads are evident in the sample the liquid portion in the glass dish can be measured directly using the liquid IR cell on the FTIR or further filtering can be done using a 0.45 µm filter paper and vacuum filtration for further separation. The liquid portion can be dried for determination using the solids FTIR and/or microscope.
    - 7.7.4.1 When dried the filtrate may form a plastic-like film or cake on the dish which can be scrapped into a scintillation vial.
  - 7.7.5 Weigh 1 to 10 grams of sample into a 250 mL Erlenmeyer flask. Add 100 mL solvent or solvent mixture (as determined in section 7.6.3).
  - 7.7.6 Add a magnetic stir bar and heat on a magnetic stirrer/hot plate until almost boiling (> 90°C for most solutions without organic solvents) with stirring at medium speed. Caution: Do not allow to boil as the solution will foam and spill over.
  - 7.7.7 Using heat resistant gloves pour the near boiling solution through the sieve stack slowly. Due to the tight seal between some sieves the solution may back up at the smaller sieve sizes. If necessary, lightly pull the sieves apart to allow air into the system.
  - 7.7.8 Rinse the stack with the solvent or solvent mixture.
  - 7.7.9 Separate the sieves, rinse each one with solvent or solvent mixture. If a scum appears, rinse with acetone and/or isopropanol. If particulate is evident in the sieve then tip the sieve at a 45° angle and use the solvent or solvent mixture to move the particulate to the bottom side of the sieve.
  - 7.7.10 Quantitatively transfer the particulate in each sieve to separate 150 mL beakers with solvent or solvent mixture and evaporate off the liquid to dryness on a hotplate at less than 40°C.
  - 7.7.11 Using a flat-edged spatula, scrape the material into a 20 mL tared scintillation vial through a paper or small glass funnel. Measure the weight of the scintillation vial and sample to obtain the sample weight by subtraction of the tared weight of the empty vial. Make a note if there appears to be a mixture of beads and other material.
- 7.8 Extraction Procedure #2 - Low volume with polar interferences
  - 7.8.1 Weigh 1 - 10 g of sample into a 125mL Erlenmeyer flask
  - 7.8.2 Add 20 mL isopropanol (section 5.1)
  - 7.8.3 Add 80 mL 70°C reagent water. Swirl to mix.
  - 7.8.4 Additional heating may be provided up to 80°C
  - 7.8.5 Filter through the filtering apparatus using 0.7 µm filter paper
  - 7.8.6 If there is no unfiltered material or it is suspected that microbeads may be in the filtrate, filter the filtrate through a 0.45 µm filter paper.
  - 7.8.7 If there is unfiltered material on the filter paper then transfer the unfiltered sample to a scintillation vial through a paper or small glass funnel. Use the flat edge of a spatula to assist in the removal of the material from the filter paper.
  - 7.8.8 The filtrate can be measured using the liquid modules of the FTIR or dried and measured using the solids portion of the FTIR.
- 7.9 Extraction Procedure #3 - Decanting
  - 7.9.1 Certain products may be composed of chemicals that dissolve in water or other solvents leaving microbeads undissolved. If the microbeads are denser than the solvent used, the solvent can be decanted.
  - 7.9.2 Weigh 1 – 10 g of product into a 150 mL beaker, add 80 mL solvent and a stirbar. Mix until all the product is dissolved except for insoluble particles.
  - 7.9.3 Decant the supernatant, retaining the particles at the bottom.
  - 7.9.4 Rinse the particles with the solvent used to remove traces of potential contaminants and air-dry the samples.
  - 7.9.5 Using a rubber or plastic policeman or spatula, quantitatively transfer the particulate to a 20 mL scintillation vial.
- 7.10 Extraction Procedure #4 – Large volume extraction with water
  - 7.10.1 Samples may become gelatinous with the quantity of water added in sections 7.7 and 7.8. Proceed as per sections 7.7.5 to 7.7.11 substituting the beakers with one litre beakers and using one litre of reagent water.
  - 7.10.2 Use the 8 inch sieve stack when using this procedure.
- 7.11 Immiscible fats, oils and other compounds will require solvents instead of water. The process for separation is similar to the procedures in sections 7.7 and 7.8 using an appropriate solvent to dissolve the water immiscible compounds. Refer to The American Institute for Conservation website (see reference 12.10) for a discussion of determining the appropriate solvents to dissolve liquids insoluble in water.
  - 7.11.1 Use the same solvent throughout the procedure due to the immiscibility of some compounds in other solvents.
- 7.12 Determine the presence or absence of plastic using ATR FT-IR. The most likely plastics to be found in samples are listed in Table 1 in Appendix 1. Other potential plastics are listed in Table 2 in Appendix 1. These two lists are not exhaustive. Spectra of most of the common plastics can be found in Appendix 3.
- 7.13 Operation of FT-IR
  - 7.13.1 Refer to the FTIR manufacturers instruction manual for setup and use of the FTIR.
  - 7.13.2 Complex spectra resulting from mixtures of compounds may be observed. Familiarity with the most common spectra is useful to determine whether a mixture contains polymer microbeads. Review comparisons of spectra with reference materials to gain a better idea of the composition of the mixture.
    - 7.13.2.1 If a mixture is suspected to contain plastic microbeads further purification may be required using other solvents and heating to remove non-plastic material.
  - 7.13.3 Use the camera on the FT-IR microscope to confirm the presence of microbeads. If using a solvent other than water the microbeads may dissolve and cause difficulty identifying microbeads.

8. Calculations and reporting

8.1 Report results as positive or negative for plastic microbeads. If the analysis result is positive provide the type of plastic determined.

9. Quality assurance / quality control

9.1 Analyze at least 10% of the samples in replicate, with a minimum of one sample per work order.
9.2 Compare the IR spectrum of sample to the FT-IR library and the reference spectrum of a known plastic.
9.3 Daily and weekly maintenance checks must be done as per the manufacturers' instructions.
9.4 Contamination Checks must be done on the FTIR as per the manufacturers' instructions and the FT-IR software help if the crystal is suspected to be contaminated. If necessary wipe with a cloth or gently use a soft plastic spatula to remove any material adhering to the diamond.
9.5 The IR spectra of a reference sample must be done before any samples, after every ten samples and at the end of the use for the day.

10. Method performance and validation

10.1 For up-to-date method validation and uncertainty information, refer to the laboratories protocols.
10.2 For up-to-date control charts and trend analysis, refer to individual analytes QC control charts as per the laboratories protocols.

11. Safety and precautions

11.1 If heating the sample with a solvent or solvent mixture, do not heat above three degrees below the boiling point of the solvent or solvent mixture. Refer to Appendix 2 for the boiling point of common solvents. Heating near the boiling point may cause the mixture to foam excessively and boil over.
11.2 Use a fume hood and a grounding strap when pouring or using volatile flammable solvents.
11.3 There are no other safety hazards associated with this method, and no special protective equipment is required. THAs and SWPs for this method must be reviewed and signed-off before using this method.

12. References

12.1 PNLET, Quality Manual.
12.2 PNLET SOP 2002.0, General Laboratory Safety.
12.3 PNLET SOP 2004.0, Measurement Uncertainty for Chemistry.
12.4 PNLET, SOP 501.1, SOP for the Washing of Glassware.
12.5 Environment and Climate Change Canada publication Microbeads – A Science Summary; July 2015.
12.6 Leslie, H.A., PhD; Review of Microplastics in Cosmetics; IVM Institute for Environmental Studies, Report R14/29, July 2014.
12.7 NOAA; Laboratory Methods for the Analysis of Microplastics in the Marine Environment: Recommendations for Quantifying Synthetic Particles in Waters and Sediments; NOAA Marine Debris Program; Technical Memorandum NOS-OR&R-48, July 2015.
12.8 Mintenig, S.M.; Int-Veen, I.; Loder, M.G.J.; et al, Identification of Microplastic in Effluents of Waste Water Treatment Plants Using Focal Plane Array-based Micro-Fourier-Transform Infrared Imaging; Water Research, Vol 108, (2017) p 365-372.
12.9 Proceedings of the GESAMP International Workshop on Microplastic Particles as Vector in Transporting Persistent, Bioaccumulating and Toxic Substances in the Ocean. June 28-30, 2010, GESAMP, UNESCO-IOC, Paris, Pre-Publication copy. GESAMP Reports & Studies No. 82.
12.10 Burke, John; The American Institute for Conservation; Solubility Parameters: Theory and Application; The Book and Paper Group Annual, Volume Three, 1984. Website .

13. Deviations from reference method

13.1 This method was developed from the discussions in references 12.5 to 12.9.