NPE (NP-n) Selection Guide: How EO Number Affects Solubility, HLB, Cloud Point, and CMC | With an Aladdin Product Reference Table
What are nonylphenol ethoxylates?
Nonylphenol ethoxylates (NPEs, also commonly written as NP-n) are a class of nonionic surfactants produced by ethoxylation of nonylphenol (NP) with ethylene oxide (EO) under catalytic conditions. A key feature of NPEs is that the EO (ethoxy) chain length is variable, resulting in a homologous product series whose properties can be tuned across a wide range.
What does NP-n mean?
(1) NP-n / NPE-n is commonly used to describe products with an average degree of ethoxylation of approximately n (this does not mean every molecule contains exactly n EO units; a distribution is typically present).
(2) Therefore, NPE is not a single, discrete compound, but rather a series/mixture of ethoxylated oligomers:
(a) A representative structure can be written as C₉H₁₉–C₆H₄–O–(CH₂CH₂O)ₙ–H (a nonionic surfactant; n is an average value and reflects a distribution).
(b) The average molecular weight also varies with n.
(3) CAS 9016-45-9 is often used as a generic CAS number for “nonylphenol ethoxylates (series/mixture)”.
(4) Some “representative substances” with a fixed/specified EO number may be registered under different CAS numbers (differences arise from registration scope and product definitions).
Terminology and Naming Reference Table
Term/Notation | Meaning | Common Misunderstanding | Notes |
NPE / NP-n | Nonylphenol ethoxylate series; n ≈ average EO number | Mistaken as a single pure compound | Emphasize “series/distribution”; n is an average value |
9016-45-9 | Often used as a general CAS for the series/mixture | Assuming all NP-n share one CAS | In addition to 9016-45-9, CAS numbers such as 127087-87-0 are also commonly seen on the market. Different registration/definition approaches can result in multiple CAS numbers for similar products; refer to the specific SDS/TDS. |
NP-40 / NP-40 substitute | “NP-40-type nonionic detergents” commonly referred to in laboratories | Assuming it equals a fixed pure substance | In lab usage, “NP-40” often refers to Nonidet P-40 or its substitutes (e.g., IGEPAL CA-630). It is in the same broad category as Tergitol “Type NP-40”, but should not be assumed to be fully identical; refer to the specific SDS/TDS. |
Key Property Parameters
Core Parameter | Definition/Key Points | Relationship to EO Number/HLB (Typical Trend) | Typical Uses / Why It Matters |
HLB (Hydrophilic–Lipophilic Balance) | Indicates whether a surfactant is more hydrophilic or more lipophilic; can help predict whether it tends to stabilize W/O or O/W emulsions | For poly(ethylene oxide) nonionic surfactants, increasing EO chain length typically increases hydrophilicity, making HLB tunable and often higher | Rule of thumb: HLB ≈ 4–6 more often for stabilizing W/O; HLB ≈ 8–18 more often for stabilizing O/W (formulations still require experimental optimization) |
Cloud point | Characteristic temperature at which an aqueous solution of a nonionic surfactant becomes turbid or shows phase separation as temperature increases (concentration should be specified) | Longer EO chains / higher hydrophilicity often lead to higher cloud point (strongly affected by concentration and electrolytes) | (1) Evaluate formulation stability over temperature; (2) Basis for cloud point extraction (CPE) and related separation/pre-treatment methods |
CMC (Critical Micelle Concentration) & Surface Tension | CMC is the concentration threshold above which micelles form extensively; surface tension reflects the ability to lower interfacial energy | Different EO numbers/structures lead to different CMC and surface tension | Estimate “effective concentration” and solubilization/cleaning window; in research, also affects lysis/solubilization efficiency and background |
NP Series: EO Number vs. “Use/Solubility”
Overall trends of how changes in EO number affect NPE performance.
Variable Change | Common Overall Trend | Direct Implication for Selection | Key Notes |
Higher EO number (n↑ in NP-n) | Hydrophilicity ↑; water solubility ↑; HLB tunable and often ↑; cloud point often ↑ | Better suited for high-water-phase systems, O/W emulsification, solubilization, mild detergency/wetting | These are “typical trends.” Specific values must follow supplier TDS/COA and test conditions (concentration/salt/temperature can change performance). |
Lower EO number (n↓) | More hydrophobic; more oil-soluble; poorer solubility in water | Better suited for oil phase/low-HLB systems, W/O or oily-soil dispersion | The distribution for the same “NP-x” may vary among manufacturers; small-scale validation is recommended before use. |
Quick Selection Table
NP Series | Hydrophilicity Trend | Typical Behavior (Common Trend) | Common Use Directions (Examples) |
NP-4 ~ NP-6 | More hydrophobic | Often oil-soluble; water-dispersible or only limitedly soluble | Oil-phase emulsification, oily-soil dispersion, some solvent-based cleaners/additives |
NP-7 ~ NP-10 | Medium | More likely to form stable dispersions/solutions in water; wetting/penetration and detergency often prominent | Cleaning/detergency, wetting/penetration, O/W emulsification, textile printing & dyeing auxiliaries, laboratory nonionic detergents |
NP-12 and above | More hydrophilic | More water-soluble; cloud point often higher, suitable for a wider temperature window | High-water-phase emulsification/solubilization, formulations for higher temperature or higher electrolyte systems |
Typical Application Scenarios: From Industry to the Laboratory (Research Use)
1. Industrial and Teaching Examples (Understanding “What Surfactants Do”)
As nonionic surfactants, NPEs commonly provide wetting, emulsification, dispersion, solubilization, and detergency, and are therefore widely used in cleaning agents, textile printing and dyeing, papermaking, coatings, and formulation systems.
2. Research/Laboratory Use: Understanding NPE as a “Nonionic Detergent”
In life science and chemical analysis, the role of detergents/surfactants is very typical:
(1) Lyse cells and release soluble proteins;
(2) Solubilize membrane proteins and lipids;
(3) Serve as additives in immunoassays/affinity purification to reduce nonspecific adsorption;
(4) Act as auxiliaries in electrophoresis, crystallization, and sample pretreatment.
Among these, NPEs with medium HLB such as NP-9/NP-10 are often used in biochemical and formulation research as mild nonionic surfactants/detergents (detergent type and concentration windows can be highly experiment-dependent and should be optimized for the target protein/sample system).
Note: Many detergent types are used in membrane protein research (nonionic, zwitterionic, ionic, etc.). The final choice typically depends on protein stability and downstream analytical requirements; NPE is only one option.
Safety, Health, and Environmental Considerations
1. Safety and Protection (Refer to SDS/Regulatory Classification)
Common hazard statements for NPE/NP-n may include skin/eye irritation or serious eye damage, and hazardous to aquatic environments, etc. (differences may exist across EO numbers and registered substances; always refer to the SDS of the specific product).
Laboratory recommendations: wear gloves and safety goggles, avoid inhaling aerosols/mists, wash hands after handling, and prevent release into drains/the environment.
2. Regulatory and Compliance Notes (Especially for Textiles/Export)
In EU REACH Annex XVII, NPE (Entry 46a) is explicitly restricted in textiles that are expected to be washed in water during their lifecycle: from 2021-02-03, textiles (or textile components) with NPE ≥ 0.01% (w/w) (100 mg/kg) must not be placed on the market. Similar surfactants may be subject to restrictions in different regions and industries.
3. Environmental Fate: Why NPE Is Closely Scrutinized
Studies and reviews commonly indicate that APEO/NPE can be transformed/degraded in the environment, potentially generating metabolites of greater concern (e.g., nonylphenol), and may be associated with aquatic toxicity and endocrine-disrupting effects.
Nonylphenol Ethoxylates (NPE/NP Series) and Related Nonionic Detergents for Research — Aladdin Product List
The following table summarizes Aladdin products related to nonylphenol ethoxylates (NPE/NP series), including NPE/NP series surfactants, NP-40-type detergents and lysis buffer systems, as well as other commonly used nonionic detergents/surfactants in laboratories (e.g., the Triton X series, IGEPAL, and Tween/polysorbates) for convenient product selection and reference.
Category | CAS No. | Aladdin Cat. No. | Product Name | Specification / Grade | Key Applications / Product Highlights |
NPE/NP Series | 127087-87-0 | Nonylphenol ethoxylate, Type NP-4 | Type NP-4 | Low-EO segment of the NPE/NP series; relatively hydrophobic/low HLB; suitable as a reference for low-HLB emulsification/dispersion and wetting/penetration applications. | |
NPE/NP Series | 127087-87-0 | Nonylphenol ethoxylate, Type NP-7 | Type NP-7 | Medium-EO segment; for wetting, penetration, washing/cleaning, emulsification and dispersion; useful for demonstrating how EO number influences performance. | |
NPE/NP Series | 127087-87-0 | Nonylphenol ethoxylate, Type NP-9 | Type NP-9 | Representative NP grade; mild nonionic surfactant/detergent; commonly used for wetting, emulsification, dispersion, and soil removal/cleaning. | |
NPE/NP Series | 127087-87-0 | Nonylphenol ethoxylate, Type NP-10 | Type NP-10 | More hydrophilic member of the series; suitable for O/W emulsification, solubilization, and cleaning systems; can serve as a mild detergent reference in research. | |
NPE/NP Series | 127087-87-0 | TERGITOL™ NP-6 Surfactant | Type NP-6 | NP-6 in the NPE/NP series; lower-EO segment; for low-HLB emulsification/dispersion and wetting/penetration; suitable for side-by-side series comparisons. | |
NPE/NP Series | -- | TERGITOL™ NP-9.5 Surfactant | – | Medium-EO segment (NP-9.5); for wetting, detergency, emulsification/dispersion, and solubilization; suitable as a continuous, tunable comparison point. | |
NPE/NP Series | – | TERGITOL™ NP-15 Surfactant | – | Higher-EO segment (more hydrophilic/higher HLB); for emulsification, dispersion, solubilization, and selection for systems requiring a broader temperature window. | |
NPE/NP Series | 9016-45-9 | Nonylphenol ethoxylate (Tergitol NP-40) | Isomeric mixture, white flakes | NP-40-type NPE; nonionic surfactant/detergent; emulsification, dispersion, solubilization; commonly used as a search entry for NP-40-type products in research. | |
NPE/NP Series | 9016-45-9 | Nonylphenol ethoxylate (Tergitol NP-40) | Isomeric mixture | Also NP-40-type; convenient for matching different physical forms/batches to specific applications. | |
NPE/NP Series | 9016-45-9 | Nonylphenol ethoxylate (Tergitol NP-40) | ~10% in H₂O | NP-40-type aqueous solution; convenient for pipetting and blending; suitable for high-throughput workflows and improved reproducibility. | |
NPE/NP Series | 14409-72-4 | Nonoxynol-9 | – | Often used as a related search term for NP-9 (Nonoxynol-9); nonionic surfactant/detergent for wetting, emulsification, dispersion, and cleaning. | |
Upstream / Reference | 104-40-5 | p-Nonylphenol | Analytical standard | Parent compound/upstream reference for NPE; suitable for teaching/research comparisons (raw material → ethoxylation → property changes). | |
NP-40-Type Detergent / Substitute | 9016-45-9 | NP-40 Substitute | Proteomics grade | NP-40-type nonionic detergent oriented to protein/proteomics workflows; for lysis, membrane-protein solubilization, and reducing nonspecific adsorption. | |
NP-40-Type Detergent / Substitute | 9016-45-9 | NP-40 Substitute | Reagent grade | General NP-40-type detergent for research/teaching; mild detergency and wetting additive. | |
NP-40 Research Buffer System | – | NP-40 Lysis Buffer (with inhibitors) | BioReagent, for western blot, for CoIP, for IP | Ready-to-use lysis system: NP-40 detergent + inhibitors; designed for WB/CoIP/IP workflows; supports standardized operation. | |
NP-40 Research Buffer System | – | NP-40 Lysis Buffer | Ultrapure grade | Ready-to-use NP-40 lysis buffer for cell lysis/protein extraction; ultrapure grade is better suited for background-sensitive assays. | |
Related Nonionic Detergent (IGEPAL) | 9036-19-5 | IGEPAL® CA-720 | average Mn ~735 | Nonionic surfactant/detergent; commonly used for cell lysis, membrane-protein solubilization, and reducing nonspecific adsorption in research. | |
Related Nonionic Detergent (Triton X Series) | 9002-93-1 | Triton™ X-100 | UltraBio™, ultrapure | Classic nonionic detergent; for cell lysis/membrane processing/reducing nonspecific adsorption; ultrapure grade suitable for high-sensitivity detection. | |
Related Nonionic Detergent (Triton X Series) | 9002-93-1 | Triton™ X-100 | Molecular biology grade | Molecular biology grade; suitable for washing/lysis steps in nucleic acid and protein workflows, or as a formulation additive. | |
Related Nonionic Detergent (Triton X Series) | 9002-93-1 | Triton™ X-100 | For electrophoresis | Intended for electrophoresis applications; used for sample handling, wetting, or reduced adsorption (method-dependent). | |
Related Nonionic Detergent (Triton X Series) | 9002-93-1 | Triton™ X-100 | Biochemical reagent | Biochemical reagent grade; for mild detergency, washing, and solubilization support in routine biochemical systems. | |
Related Nonionic Detergent (Triton X Series) | 9036-19-5 | Triton™ X-102 | – | Triton X series nonionic surfactant/detergent; for wetting, solubilization, detergency, and formulation benchmarking. | |
Related Nonionic Detergent (Triton X Series) | 9002-93-1 | Triton™ X-45 | Cloud Point 39.4–44.8 °C | Nonionic surfactant; suitable for examples related to cloud point, temperature window, and system stability. | |
Related Nonionic Detergent (Triton X Series) | 9002-93-1 | TRITON™ X-305 Surfactant | 70% in H₂O | High-concentration aqueous solution; convenient for formulation/lab addition; for wetting, emulsification, solubilization, and detergency. | |
Related Nonionic Detergent (Triton X Series) | 9036-19-5 | Triton™ X-114 | Reagent grade | Exhibits temperature-induced phase separation; used in phase separation/enrichment methods and membrane-related processing; also usable as a detergent. | |
Related Nonionic Detergent (Triton X Series) | 9036-19-5 | T434562 | Triton™ X-405 Solution | 70% in H₂O | X-405 solution form; for emulsification/solubilization/dispersion and detergency; solution format enables rapid preparation. |
Related Nonionic Detergent (Triton X Series) | 9036-19-5 | Triton™ X-405 Solution | 70% in H₂O | Also an X-405 solution; suitable for brand/batch comparisons and application matching. | |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-64-5 | T777478 | Tween® 20 (TWEEN® 20) | Acid Value ≤ 3.0 | Mild nonionic surfactant; widely used in wash buffers to reduce nonspecific binding (immunoassay/protein washing). |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-64-5 | Tween® 20 (TWEEN® 20) | Viscous liquid | Standard form of Tween 20; for washing, wetting, and formulation additives. | |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-64-5 | Tween® 20 | Molecular biology grade, viscous liquids | Molecular biology grade; suitable for impurity-sensitive workflows and buffer systems. | |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-64-5 | Tween® 20 | For cell culture, viscous liquid | Positioned for cell culture; mild surfactant addition (validate concentration window in your system). | |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-64-5 | Tween® 20 | Nonionic aqueous solution, 10% (w/v) | 10% solution; convenient for pipetting and reproducible preparation; suitable for high-throughput experiments. | |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-65-6 | T274282 | Tween® 80 (TWEEN® 80) | Reagent grade | Mild nonionic surfactant; for emulsification/dispersion, wetting, and system stabilization. |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-65-6 | Tween® 80 (TWEEN® 80) | For cell culture | Positioned for cell culture; for mild emulsification/dispersion and stabilization (validate in your system). | |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-65-6 | Tween® 80 (TWEEN® 80) | Pharmaceutical grade, PharmPure™ | Pharmaceutical-grade positioning; suitable for formulation/excipient research or high-requirement systems with stricter impurity control. | |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-65-6 | Tween® 80 (TWEEN® 80) | Viscous liquid | Standard form; for emulsification, dispersion, wetting, and stabilization. | |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-65-6 | T657459 | Tween® 80 (TWEEN® 80) | Animal-free, low endotoxin, for cell culture | Animal-free/low endotoxin; suitable for background-sensitive systems such as cell and immunology assays. |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-65-6 | Tween® 80 | Animal-origin-free | Suitable for origin-sensitive or compliance-driven scenarios. | |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-65-6 | Tween® 80 | Viscous liquid; preservative-free; low peroxide; low carbonyl | Low peroxide/low carbonyl; more suitable for oxidation-sensitive systems (e.g., protein stability studies). | |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-65-6 | Tween® 80 Solution | 10%, low peroxide | 10% solution + low peroxide; convenient for reproducible preparation and stability studies. | |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-64-5 | T196268 | Polysorbate-21 | 100% | Polysorbate nonionic surfactant; for emulsification/dispersion/wetting; can serve as an alternative (non-NPE) route reference. |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-65-6 | P491239 | Polysorbate-80 | Pharmaceutical grade, PharmPure™ | Polysorbate 80 (same class as Tween 80); pharmaceutical-grade positioning; for emulsification/stabilization and formulation research. |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-65-6 | T196272 | Polysorbate-80 | – | Polysorbate 80; for emulsification, dispersion, wetting, and system stabilization. |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-64-5 | Polyoxyethylene (20) sorbitan monolaurate solution | ~10% in H₂O | Nonionic surfactant solution; for emulsification/solubilization/wetting comparisons and formulation screening. | |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-64-5 | T196269 | Polyoxyethylene sorbitan fatty acid ester (dehydrated sorbitan) | – | Polyoxyethylene sorbitan ester; for emulsification, dispersion, wetting, and solubilization; can serve as a non-NPE route reference. |
Related Nonionic Surfactant (Tween/Polysorbates) | 9005-64-5 | T274277 | Polyoxyethylene sorbitan fatty acid ester (dehydrated sorbitan) | Reagent grade | Reagent-grade counterpart; for teaching/research comparative experiments on emulsification/dispersion and solubilization. |