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How to Use US EPA EPI Suite to Predict Chemical Substance Properties

By Little Pro on 2017-09-14 Views:  Update:2017-09-19

The EPI (Estimation Programs Interface) Suite™ is a suite of physical/chemical property, aquatic toxicity and environmental fate estimation programs jointly developed by US EPA and Syracuse Research Corp. (SRC). It has now become one of the most frequently used QSAR models in the world. In this article, we will show you what EPI Suite can do and how to use it.

Which Chemical Properties Can Be Predicted by EPI Suite

EPI Suite™ consists of the following estimation programs.It only requires a single user input to predict all chemical properties listed below.

Programs

Predicted properties

KOWWIN™

Log octanol-water partition coefficient, log KOW

AOPWIN™

Gas-phase reaction rate for the reaction between the most prevalent atmospheric oxidant, hydroxyl radicals, and a chemical

HENRYWIN™

Henry’s law constant

MPBPWIN™

Melting point, boiling point and vapor pressure of organic chemical substances

BIOWIN™

Aerobic and anaerobic biodegradability of organic chemical substances

BioHCwin

Biodegradation half-life for compounds containing only carbon and hydrogen (i.e. hydrocarbons).

KOCWIN™

Organic carbon-normalized sorption coefficient for soil and sediment

WATERNT™

Water solubility

BCFBAF™

Fish bioconcentration factors

HYDROWIN™

Aqueous hydrolysis rate constants and half-lives

STPWIN™

This program predicts the removal of a chemical in a typical activated sludge-based sewage treatment plant. Values are given for total removal and three processes that may contribute to removal: biodegradation, sorption to sludge, and air stripping. 

LEV3EPI™

This program contains a level III multimedia fugacity model and predicts partitioning of chemicals among air, soil, sediment, and water under steady state conditions for a default model "environment". 

ECOSAR™ 

Short-term and long-term aquatic toxicity

How to Use EPI Suite

EPI Suite is free of charge. It can be downloaded via this link. You will need to download and install Microsoft .NET Framework 2.0 Service Pack 2 first before you can install EPI Suite on your computer and run it. Currently, EPI Suite only works with Windows operation system. 

After you have successfully installed EPI Suite on your computer, you shall be able to see the following screen. To start using EPI Suite to predict chemical substance properties, you only need to input chemical name, CAS no. and Smiles code and then click "calculate" button. 

EPA EPI Suite

Example: Ethanol, 2-((2-nitrophenyl)amino)-

Let's assume that we need to use EPI Suite to predict the physio-chemical properties and environmental behavior of a chemical substance due to lack of test data. The following info is all that you need to input to the EPI Suite.

  • Chemical name:  Ethanol, 2-((2-nitrophenyl)amino)-
  • CAS no.: 4926-55-0
  • Smiles: O=[N+]([O-])c1c(NCCO)cccc1

After you have clicked "calculate" button, you should be able to see the following result window popping up.

EPI Suite LogPow

EPI Suite Fugacity Model

If you wish to see more than results, you can change output mode from "summary" to "full".

What Can We Learn from Abov Estimations

With above estimations, we can learn many things about the substance Ethanol, 2-((2-nitrophenyl)amino)-:

  • Estimated logPow is only 1.04. Its bio-accumulation potential must be very low since bio-accumulation is usually associated with large logPow.
  • Estimated melting point is 102 celcius degrees (high). It must be a solid substance under room temperature (25 celcius degrees). 
  • Water solubility is not low. 
  • STP cannot effectively remove this substance from waster water. 
  • The substance will largely end up in water and soil if released to the enviroment (as predicted by fugacity model). 

What Is SMILES and How to Find It

SMILES (Simplified Molecular Input Line Entry System) is a molecular text code of displayed chemical STRUCTURE. It is required as input by many QSAR models. For a big majority of chemical substances, you may find SMILES via the links below.

For a brand new chemical substance, you usually need to draw its chemical structure using commercial software. The software will then give you the SMILES code.

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