2,3',4,4',5-Pentachlorobiphenyl (PCB-118): Properties & Lab Use
2,3',4,4',5-Pentachlorobiphenyl (PCB-118): Properties & Lab Use
2,3',4,4',5-Pentachlorobiphenyl is a persistent organochlorine compound belonging to the polychlorinated biphenyl (PCB) congener class, widely used as an analytical reference standard in environmental monitoring, toxicological research, and method validation studies.
- IUPAC Name
- 2,3',4,4',5-Pentachlorobiphenyl
- PCB Congener Number
- PCB-118
- Molecular Formula
- C₁₂H₅Cl₅
- Molecular Weight
- 326.43 g/mol
- CAS Number
- 31508-00-6
- Classification
- Dioxin-like PCB; Persistent Organic Pollutant (POP)
- Aladdin SKU
- P1539665
Chemical Identity and Structure
2,3',4,4',5-Pentachlorobiphenyl, commonly designated as PCB-118, is one of 209 theoretically possible polychlorinated biphenyl congeners. Its molecular formula is C₁₂H₅Cl₅ with a molecular weight of approximately 326.43 g/mol, and it is registered under CAS number 31508-00-6. The compound consists of a biphenyl core bearing five chlorine substituents positioned at the 2, 3', 4, 4', and 5 positions of the two phenyl rings.
The specific chlorine substitution pattern of PCB-118 confers a degree of coplanarity to the biphenyl skeleton, enabling partial adoption of a planar conformation. This structural characteristic is responsible for its classification as a dioxin-like PCB congener, as planar or near-planar PCBs can interact with the aryl hydrocarbon receptor (AhR), triggering biological responses analogous to those of polychlorinated dibenzo-p-dioxins and furans.
Physicochemical Properties and Environmental Behavior
PCB-118 is a solid at room temperature with low water solubility and high lipophilicity, properties typical of higher-chlorinated PCB congeners. Its high octanol–water partition coefficient (log Kow) promotes bioaccumulation in fatty tissues of organisms, contributing to its biomagnification through food chains. These physicochemical characteristics, combined with strong resistance to chemical and biological degradation, underpin its classification as a persistent organic pollutant (POP) under the Stockholm Convention.
In environmental matrices, PCB-118 has been detected in air, sediments, soils, surface water, and biological tissues. Its semi-volatile nature allows long-range atmospheric transport, leading to detection in remote regions far from original emission sources. Researchers quantifying PCB-118 in environmental samples typically employ gas chromatography coupled with mass spectrometry (GC-MS) or high-resolution mass spectrometry (GC-HRMS) using certified reference standards to ensure traceability and method accuracy.
Toxicology and Regulatory Context
As a dioxin-like PCB, PCB-118 exerts its primary toxicological effects through activation of the aryl hydrocarbon receptor (AhR) pathway. AhR-mediated effects include induction of cytochrome P450 enzymes (notably CYP1A1, CYP1A2), disruption of endocrine signaling, immunotoxicity, developmental toxicity, and potential carcinogenicity. The World Health Organization (WHO) has assigned a Toxic Equivalency Factor (TEF) to PCB-118 to facilitate aggregate risk assessment of dioxin-like compounds in environmental and dietary exposure studies; however, researchers should consult the most current WHO TEF values, as these are subject to periodic revision.
Regulatory agencies including the US Environmental Protection Agency (EPA) and the European Food Safety Authority (EFSA) have established guidelines for PCB monitoring in food, feed, and environmental samples. PCB-118 is specifically included in indicator PCB and dioxin-like PCB monitoring panels mandated by European Union regulations. Its widespread historical use in industrial applications (e.g., transformer fluids, plasticizers) prior to global bans has resulted in pervasive environmental contamination that continues to be monitored today.
Laboratory Handling, Safety, and Storage
PCB-118 is a hazardous substance and must be handled in accordance with applicable national and institutional regulations for persistent organic pollutants. Laboratory personnel should wear appropriate personal protective equipment (PPE) including chemical-resistant gloves, lab coat, and eye protection. All operations with this compound should be conducted in a fume hood or under local exhaust ventilation to minimize inhalation exposure. Skin contact must be strictly avoided.
The compound should be stored in a tightly sealed container, away from heat, ignition sources, and incompatible materials, in accordance with the supplier's Safety Data Sheet (SDS). Waste disposal must comply with local regulations governing halogenated organic waste. Researchers are advised to consult the current SDS for Aladdin product P1539665 prior to use, as it contains specific hazard classifications, first-aid measures, and disposal guidance applicable to this material.
Research Applications and Use as a Reference Standard
High-purity PCB-118 serves as an essential reference standard and analytical calibrant in a broad range of research and regulatory testing contexts. Key applications include: environmental monitoring programs requiring quantification of PCB-118 in air, water, soil, and sediment samples; food safety and dietary exposure studies examining PCB burdens in fish, meat, dairy, and other foodstuffs; biological and toxicological in vitro and in vivo studies investigating AhR pathway activation, endocrine disruption, and immunotoxic mechanisms; and laboratory method development, validation, and proficiency testing for accredited analytical laboratories.
Aladdin Scientific offers 2,3',4,4',5-Pentachlorobiphenyl (SKU: P1539665) to support these demanding research requirements. Researchers are encouraged to verify the certificate of analysis (CoA) for purity confirmation and to ensure the product meets the specifications required for their specific application, particularly when the standard is intended for use in regulatory-compliant testing or method validation.
Frequently asked questions
What is PCB-118 and why is it classified as a dioxin-like PCB?
PCB-118 (2,3',4,4',5-Pentachlorobiphenyl) is a polychlorinated biphenyl congener whose chlorine substitution pattern allows the biphenyl rings to adopt a near-planar conformation. This planarity enables binding to the aryl hydrocarbon receptor (AhR), producing dioxin-like biological effects including enzyme induction, endocrine disruption, and developmental toxicity, hence its classification as a dioxin-like PCB.
How should PCB-118 reference standards be stored to maintain stability?
PCB-118 should be stored in tightly sealed containers, protected from light and heat, and kept away from incompatible reagents. Always consult the supplier's current Safety Data Sheet (SDS) and Certificate of Analysis (CoA) for product-specific storage conditions, as recommendations may vary by formulation or solvent system.
What analytical techniques are commonly used to detect and quantify PCB-118 in environmental samples?
Gas chromatography coupled with mass spectrometry (GC-MS) and high-resolution mass spectrometry (GC-HRMS) are the standard techniques for PCB-118 quantification in environmental matrices including air, water, sediment, and biota. Certified reference standards with traceable purity are essential for accurate calibration and compliance with regulatory method requirements.
Is PCB-118 subject to international regulatory restrictions?
Yes. Polychlorinated biphenyls, including PCB-118, are listed as persistent organic pollutants (POPs) under the Stockholm Convention, which requires parties to eliminate or restrict their production and use. Additionally, regulatory bodies such as the EU and US EPA have established maximum residue limits and monitoring requirements for PCBs in food, feed, and environmental media.
What purity grade is recommended when using PCB-118 as an analytical reference standard?
For analytical and regulatory applications, high-purity PCB-118 (typically ≥98% or as specified by the applicable method standard) is recommended to minimize interference from other congeners and ensure accurate quantification. Researchers should verify the purity stated on the Certificate of Analysis (CoA) for Aladdin SKU P1539665 before use.
References
- Van den Berg M, et al. WHO/TEF re-evaluation of human and mammalian toxic equivalency factors for dioxins and dioxin-like compounds. Toxicological Sciences. 2006.
- Stockholm Convention on Persistent Organic Pollutants. United Nations Environment Programme (UNEP). Available at: http://www.pops.int
- European Commission Regulation (EC) No 1881/2006 setting maximum levels for certain contaminants in foodstuffs, as amended.
- US EPA. Polychlorinated Biphenyls (PCBs). Available at: https://www.epa.gov/pcbs
Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.
危险品化学品经营许可证（带存储）