RoHS testing for chemical raw materials verifies that resins, pigments, plasticizers, flame retardants, and other upstream inputs comply with the hazardous substance limits established by EU Directive 2011/65/EU as amended by (EU) 2015/863. Accredited third-party laboratories apply the IEC 62321 series of methods, combining XRF screening with confirmatory techniques such as ICP-OES, ICP-MS, and GC-MS. This guide explains the technical scope, sample categories, test items, analytical procedures, and practical applications of RoHS testing for chemical raw materials.
Technical Overview
The Restriction of Hazardous Substances (RoHS) Directive, formally Directive 2011/65/EU and its amendment (EU) 2015/863 (commonly known as RoHS 3), restricts the use of ten hazardous substances in electrical and electronic equipment (EEE). Because the limits apply at the level of the homogeneous material—a material of uniform composition throughout that cannot be mechanically disjointed into different materials—compliance must ultimately be demonstrated for every constituent of a finished product, including the chemical raw materials used at the very beginning of the supply chain.
Chemical raw materials such as polymer resins, pigments, plasticizers, stabilizers, and flame retardants are among the most common sources of RoHS non-compliance. Heavy metals are deliberately added to some pigments and heat stabilizers, phthalates are the dominant class of plasticizers, and brominated flame retardants are widely used in polymers for electronic enclosures and components. Testing raw materials before they enter production allows manufacturers to control risk at the source, avoid costly rework and product recalls, and satisfy green procurement requirements from downstream brands.
Restricted substances and maximum concentration limits (by weight in homogeneous material) under RoHS 3 are:
- Lead (Pb): 0.1% (1000 mg/kg)
- Cadmium (Cd): 0.01% (100 mg/kg)
- Mercury (Hg): 0.1% (1000 mg/kg)
- Hexavalent chromium (Cr(VI)): 0.1% (1000 mg/kg)
- Polybrominated biphenyls (PBB): 0.1% (1000 mg/kg)
- Polybrominated diphenyl ethers (PBDE): 0.1% (1000 mg/kg)
- Bis(2-ethylhexyl) phthalate (DEHP): 0.1% (1000 mg/kg)
- Butyl benzyl phthalate (BBP): 0.1% (1000 mg/kg)
- Dibutyl phthalate (DBP): 0.1% (1000 mg/kg)
- Diisobutyl phthalate (DIBP): 0.1% (1000 mg/kg)
In addition to EU RoHS, comparable frameworks such as China RoHS (GB/T 30512 for requirements and GB/T 26572 for analytical determination) and similar regulations in other jurisdictions follow the same substance lists, so a single raw-material test program can generally support multi-market compliance.
Testing Samples
Polymer Resins and Compounds
Thermoplastic and thermoset resins in pellet, powder, granule, or liquid form, including PE, PP, PVC, ABS, PS, PC, PA, PBT, epoxy resins, polyurethane systems, silicone elastomers, rubber compounds, color masterbatches, and filled or reinforced compounds. These are the highest-volume sample category because they form the housings, insulation, laminates, and encapsulants of electronic products.
Pigments, Dyes, and Colorants
Inorganic pigments (for example lead chromate yellows, cadmium reds and yellows, and chrome-containing molybdate oranges), organic pigments, solvent and reactive dyes, carbon black, and titanium dioxide. Historically, cadmium- and lead-based pigments are the most frequent causes of RoHS failure in this category.
Plasticizers, Stabilizers, and Functional Additives
Phthalate and non-phthalate plasticizers, PVC heat stabilizers (including lead stearate and lead salts), organotin stabilizers, brominated and phosphorus flame retardants, antioxidants, UV absorbers, light stabilizers, lubricants, curing agents, and adhesion promoters. These additives are intentionally formulated into polymers and directly determine RoHS-relevant concentrations.
Coatings, Inks, and Adhesives
Liquid and powder coatings, printing inks, solder-mask and conformal coating resins, conductive pastes, adhesives, sealants, and potting compounds used on printed circuit boards, enclosures, cables, and labels.
Inorganic Chemicals, Metal Salts, and Fillers
Fillers and extenders such as calcium carbonate, talc, and glass fibers; catalysts and driers (cobalt, manganese, and lead salts); glass frits and ceramic precursors; electroplating and surface-treatment chemicals; and other metal-containing intermediates used in component manufacturing.
Textile and Surface-Treatment Auxiliaries
Finishing agents, flame-retardant treatments for fabrics and foams, anti-static and anti-microbial agents, and cleaning or degreasing chemicals that may leave RoHS-relevant residues on components.
Testing Items
Standard RoHS testing of chemical raw materials covers the ten restricted substances listed above, typically reported as a "RoHS 10 items" or "RoHS 2.0" package:
- Four heavy metals: lead, cadmium, mercury, and hexavalent chromium
- Two brominated flame retardants: PBB and PBDE
- Four phthalate plasticizers: DEHP, BBP, DBP, and DIBP
Depending on client requirements, the program may be extended with related screening items, for example total chlorine and bromine content for halogen-free specifications, individual PBDE congeners (such as deca-BDE), or additional SVHC-type substances under the REACH candidate list. Testing may also be scoped for China RoHS conformity assessment, which relies on GB/T 26572 determination methods.
Testing Methods
Sample Preparation
Solid samples are homogenized by cutting, grinding, or cryogenic milling to ensure representative analysis. For elemental determination, samples are digested using microwave-assisted acid digestion (typically nitric acid, hydrochloric acid, hydrofluoric acid, or hydrogen peroxide mixtures selected according to the matrix). Organic analyses require solvent extraction or thermal desorption to liberate brominated flame retardants and phthalates from the polymer or liquid matrix.
XRF Screening
Energy-dispersive X-ray fluorescence spectrometry (EDXRF) performed in accordance with IEC 62321-3-1 provides rapid screening for lead, cadmium, mercury, total chromium, and total bromine. Results are classified as pass, fail, or inconclusive; only confirmatory testing can establish final compliance, particularly for values near the limits.
Heavy Metal Confirmation
- Lead and cadmium: ICP-OES, ICP-MS, or atomic absorption spectrometry (AAS) after acid digestion, following IEC 62321-5
- Mercury: ICP-OES, ICP-MS, or cold-vapor AAS following IEC 62321-4
- Hexavalent chromium: alkaline digestion followed by UV-Vis spectrophotometry with 1,5-diphenylcarbazide colorimetric detection, following IEC 62321-7-1 and IEC 62321-7-2, with the procedure adapted for coatings, pigments, and polymers
Organic Determination
- PBB and PBDE: gas chromatography–mass spectrometry (GC-MS) following solvent extraction or pyrolysis/thermal desorption, in accordance with IEC 62321-6
- Phthalates (DEHP, BBP, DBP, DIBP): GC-MS, pyrolysis-thermal desorption GC-MS, or LC-MS following solvent extraction, in accordance with IEC 62321-8
Quality Control
Accredited third-party laboratories operating under ISO/IEC 17025 apply method blanks, duplicate determinations, certified reference materials, and spike-recovery checks to each batch, and report results with detection limits well below the regulatory thresholds so that pass/fail conclusions are defensible.
Applications
RoHS testing of chemical raw materials is applied across the electronics manufacturing supply chain and adjacent industries:
- Supplier qualification and incoming inspection of resins, masterbatches, pigments, and additives for EEE production, supporting declarations of conformity and CE marking obligations
- Cable, wire, connector, and PCB laminate manufacturing, where PVC compounds, brominated laminates, and solder-mask resins carry elevated risk
- Consumer electronics, household appliances, lighting equipment, power tools, toys, and IT products intended for export to RoHS-regulated markets
- Green procurement programs and material substitution projects, for example replacing lead-based stabilizers or phthalate plasticizers with compliant alternatives
- Multi-market compliance strategies combining EU RoHS, China RoHS (GB/T 30512 / GB/T 26572), and analogous national regulations
- Supporting documentation for customer audits, dispute resolution, and due-diligence records in business-to-business chemical trading
FAQ
What counts as a homogeneous material?
A homogeneous material is one of uniform composition that cannot be mechanically separated into different materials, such as a single resin, pigment powder, or plasticizer liquid. RoHS limits apply to each homogeneous material individually, not to the finished article or the mixture as a whole, which is why raw-material-level testing is the most reliable basis for compliance.
How much sample is required for testing?
For a full ten-substance package, laboratories typically request 10 to 20 grams of solid material or 10 to 20 milliliters of liquid. Smaller quantities can be accepted for screening only, but insufficient sample mass increases detection limits and may lead to inconclusive results.
Is XRF screening sufficient to prove compliance?
No. XRF is a screening tool that measures total chromium and total bromine rather than hexavalent chromium and specific brominated compounds, and it cannot detect phthalates or low-level results reliably near the limits. Confirmatory wet-chemistry and chromatographic methods per the IEC 62321 series are required for definitive conclusions and for reports used in formal conformity declarations.
How long does testing take and do reports expire?
A standard ten-item RoHS analysis typically takes five to seven working days after sample receipt; expedited services can shorten this. Reports are based on the tested sample and technically do not expire, but it is common practice to retest annually or whenever the formulation, supplier, or production process changes.
Which raw materials most often fail RoHS?
Common failure sources include cadmium and lead pigments, lead-based PVC heat stabilizers, legacy phthalate plasticizers, recycled resins contaminated with brominated flame retardants, and certain anti-corrosion coatings containing hexavalent chromium. Early screening of these high-risk inputs is the most cost-effective compliance strategy.