Isothiazolinones Testing Standards

Isothiazolinones (e.g., MIT, CMIT, BIT, OIT) are widely used as biocides in cosmetics, paints, detergents, and industrial water treatment. Due to their potential skin sensitization and toxicity, strict regulations and testing standards apply. Below are key global testing methods and regulatory limits for isothiazolinones.

1. Common Isothiazolinones Tested

Compound Full Name Common Use Regulatory Concerns

MIT Methylisothiazolinone Cosmetics, paints Skin sensitizer (EU restricts to 15 ppm in leave-on products)

CMIT Chloromethylisothiazolinone Industrial biocides Strong irritant, usually used with MIT (3:1 CMIT:MIT ratio)

BIT Benzisothiazolinone Paints, adhesives Less allergenic but restricted in cosmetics

OIT Octylisothiazolinone Wood preservatives Limited to industrial uses

2. Key Testing Standards by Application

(1) Cosmetics & Personal Care (EU, US, China)

Regulatory Limits:

EU Regulation (EC) No 1223/2009

MIT: Max 15 ppm (0.0015%) in leave-on products, 100 ppm in rinse-off.

CMIT+MIT mix: Banned in leave-on cosmetics, max 15 ppm in rinse-off.

US FDA & CIR (Cosmetic Ingredient Review)

No explicit ban, but industry avoids MIT in leave-on products.

China (GB/T 37625-2019)

MIT: Max 100 ppm in cosmetics.

Testing Methods:

HPLC (High-Performance Liquid Chromatography) – Most common (e.g., GB/T 37625-2019).

LC-MS/MS (Liquid Chromatography-Tandem Mass Spectrometry) – Higher sensitivity.

GC-MS (Gas Chromatography-Mass Spectrometry) – For volatile derivatives.

(2) Paints & Coatings (ISO, ASTM, GB Standards)

Regulatory Limits:

EU Biocidal Products Regulation (BPR) – MIT/CMIT restricted in certain paints.

China GB 18582-2020 – Limits MIT+CMIT ≤ 500 ppm in interior wall coatings.

Testing Methods:

ISO 18416:2015 – Microbiological testing of preservatives.

ASTM D6869 – Standard test for isothiazolinones in water-based formulations.

(3) Industrial Water Treatment (EPA, ISO)

EPA Methods 8321B – LC-MS/MS for BIT, MIT, OIT in water.

ISO 11348-3 – Bacterial inhibition test for biocide efficacy.

(4) Textiles & Household Products (OEKO-TEX, REACH)

OEKO-TEX Standard 100 – Bans MIT in baby textiles.

REACH (ECHA) – Requires safety assessments for MIT/BIT in detergents.

3. Sample Preparation & Detection Limits

Method Detection Limit Sample Type Applicable Standard

HPLC-UV 0.1–1 ppm Cosmetics, water GB/T 37625-2019

LC-MS/MS 0.01–0.1 ppm Paints, industrial fluids EPA 8321B

GC-MS 0.05–0.5 ppm Volatile derivatives ISO 17234-1

4. Compliance & Safety Recommendations

✔ For cosmetics: Prefer BIT or OIT over MIT/CMIT due to lower sensitization risk.

✔ For industrial use: Follow BPR (EU) or EPA (US) guidelines for biocidal products.

✔ Testing frequency: Batch testing for high-risk products (e.g., baby shampoos).

Conclusion

Isothiazolinones testing follows HPLC, LC-MS/MS, or GC-MS methods, with strict limits in cosmetics (15–100 ppm MIT), paints (500 ppm max), and industrial applications. Compliance with EU, US EPA, China GB, and ISO standards is essential for market access.

For precise testing, consult accredited labs using ISO 17025-certified methods.