ChemIDplus - Part 1

Welcome to Part 1 of the ChemIDplus tutorial. After completing this tutorial, you will be able to:

  • Select the ChemIDplus search option right for you
  • Locate chemicals by name/registry number, toxicity, physical properties, locator codes, or molecular weight
  • Identify where the chemical information in ChemIDplus is coming from
  • Locate biomedical data and literature about a specific chemical

View Part 2 of this tutorial to learn how to search for substances with a specific chemical structure. 

How to use this tutorial:

  • Follow along in the live ChemIDplus site in the right side frame.
  • Use the arrows below to navigate through the tutorial.
  • Jump to a specific section by clicking the menu button with three lines in the upper right-side corner.
  • Important note: Use the arrows below or the menu button to navigate backwards or to a previous section. Using your browser's back button may cause you to exit the tutorial.

Click the arrow below to continue.

About ChemIDplus

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One of the foundations of toxicology is basic chemical information, which you can find in ChemIDplus.

ChemIDplus contains more than 420,000 chemical records with information about names, structures, chemical properties, and toxicity from over 100 authoritative sources. It is updated daily.

About ChemIDplus

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ChemIDplus is a great place to start your search for chemical information because you can search by several criteria, and it links to many National Library of Medicine databases, such as PubMed and PubChem, that have information, data, and literature about a particular drug or chemical.

ChemIDplus also links to federal agencies, chemical law sites, regulations sites, and other relevant resources.

Browse ChemIDplus sources

You can download a large subset of the ChemIDplus data via the NLM Data Distribution program. 

About ChemIDplus

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ChemIDplus has three search interfaces:

  • Lite
  • Browse
  • Advanced

We've landed at the ChemIDplus Lite simple search box, which is the default.

What's the difference between the search interfaces? Review a comparison on the ChemIDplus Help page, and then answer the question below. 

You can search for substances with similar chemical structures in ChemIDplus Lite.

Searching ChemIDplus

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On the ChemIDplus page, locate the links for Browse and Advanced.

Use the Browse tool if you’re not certain how to spell a particular substance.

  • Enter the first few letters of a substance, and the database will help you drill down to possible names.
  • Browse by other fields, such as chemical formula.

Searching ChemIDplus

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We will use the Advanced search interface for the remainder of this tutorial.

Click Advanced to navigate there.

There are several search boxes on this page. They each represent a different access point to information in the database.

Important note: In the Advanced search interface, you may be prompted to download or run Java and enable Marvin to run as an applet in order for the structure search to work. For more information about the Marvin Applet, Java, or browser compatibility, see the ChemIDplus FAQs.

Searching by Substance Identification

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Name/Synonym

In the Advanced search interface, you can search by several categories. Each category has its own search box.

Try It:

Let's start with searching by a chemical name in the Substance Identification search box in the upper left-side column.

To view Substance Identification search options, click the first drop-down menu labeled automatic. Select Name/Synonym from the list that appears.

If searching by Name/Synonym, you can enter a common name, trade name, or formal chemical name.

Enter Tylenol as Name/Synonym and click the Search button.

This search should take you to the record for Acetaminophen, the preferred name for Tylenol.

We'll explore the record pages in more detail later, but for now, click the Start New Query button to return to the Advanced search interface.

Searching by Substance Identification

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Registry Number

You can also locate a chemical by registry number. Registry numbers refer to the unique identification numbers from the Chemical Abstracts Service (CAS). These numbers are up to 10 digits long and are divided by hyphens into three parts.

Try It:

In the Substance Identification box, select Registry Number from the drop-down menu and type 58-08-2. Click the Search button.

This search should take you to the record for the substance Caffeine.

The substance name may have one or more abbreviations next to it in brackets, such as USP or BAN. Read more about those abbreviations.

The Registry Number (RN) appears under the substance name and is followed by the UNII and InChIKey. Read more about the UNII and InChIKey

Searching by Substance Identification

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At the top of the full record for Caffeine, you should also see the:

  • Molecular formula
  • Molecular weight
  • Descriptive note
  • 2D chemical structure

Below are several tabs you can use to navigate to different sections including: 

  • Classifications
  • Links to Resources
  • Names & Synonyms
  • Registry Numbers
  • Structure Descriptors
  • Toxicity
  • Physical Properties
We'll explore these sections in-depth later. 

What is the source of information in the Note? 

Click the Start New Query button to return to the Advanced search interface. 

Searching by Substance Identification

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Chemical Formula

You can also search by chemical formula. A chemical formula tells us the number of atoms of each element of a substance. For example, water’s chemical formula is H2O because it contains 2 hydrogen atoms (H) and one oxygen atom (O) in each molecule.

In ChemIDplus, you can search for a chemical that exactly matches a formula or contains that formula.

Try It:

From the first drop-down menu in the Substance Identification box, select Formula. 

Enter C10-H12 with the hyphen into the search box.

From the second drop-down menu, select contains.

Click the Search button.

This will retrieve all chemicals that contain the same formula. You can also search by starts by to find chemicals beginning with this formula.

Review the results and answer the question below: 

Approximately how many substances have a chemical formula that contains C10-H12? 

Click Start New Query to return to the Advanced search interface. 

Searching by Substance Identification

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Category

Suppose you would like to find substances categorized as antacids. You can search by category in ChemIDplus

Try It:

Go to the drop-down menus in the Substance Identification box and select Category and starts with.

Enter antac into the search box. ChemIDplus will suggest searches for you. Select the antacids (31 results) option.

Click the Search button.

Read more about this autocomplete option in ChemIDplus Help.

Open the record for calcium carbonate.

Look under the Classification tab to confirm it is classified as an antacid.

Click Start New Query to start a new Advanced search interface.

Searching by Substance Identification

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Let's try a few exercises. In some cases, the answer may be approximate because new substances are added daily to ChemIDplus.

Important note: Remember to return to the Advanced search interface using the Start New Query button, rather than your browser's back button.

What substance is identified by registry number 11061-68-0? 

A researcher might be interested in finding chemicals that contain a specific formula. Approximately how many substances contain Mg-O2? 

How many substances start with the name Thiopent? 

Search by Toxicity

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The next type of search you can do is by the toxicity of a substance.

Try It:

Return to the ChemIDplus Advanced search interface.

Locate the Toxicity box. Click on the information button (the small i icon) next to Toxicity to review toxicity terms that will help you interpret your search results.

Then answer the question below. 

Which term is used to indicate the lowest dose of a substance reported to have caused death in animals or humans?

Search by Toxicity

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Suppose you wanted to answer the following question:

What substances cause death in 50% of the human population at a dose of less than 50 mg/kg through any route of exposure?

In the Toxicity box, select LD50 as the Test.

Change the second drop-down menu that says between to less than. Type 50 in the search box.

From the Species drop-down menu, select human. 

Leave the Route and Effect menus set to any.

Click the Search button.

You should have retrieved 5 results. You may recognize some of these substances as highly toxic chemicals, such as sarin or mustard gas.

Search by Toxicity

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Click on Sarin to open the full record for the substance.

Click the Toxicity tab.

In the table that appears, find the human LD50 reported dose (normalized dose) value. Notice the route of exposure, effect, and source of information. Where possible, the source is linked to its citation in PubMed.

Click Start New Query to return to the Advanced search interface.

Search by Physical Properties

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From the Advanced search interface, you can also search by several physical properties.

This can help you identify an unknown substance or generate a list of substances that share certain physical characteristics.

In the Physical Properties box, click on the drop-down menu labeled Melting Point to explore the search options.

Click on the information button (the small i icon) in that box to read a definition for each physical property.

Search by Physical Properties

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Let's search for substances with a boiling point between 200 and 202 degrees.

Try It:

In the Physical Properties box, select Boiling Point and between from the drop-down menus.

Type 200 202 into the search box. Use a space or dash between the two values.

Click the Search button.

Search by Physical Properties

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You should retrieve approximately 60 substances.

Open the record for Tetraethyl Lead.

Click the Physical Properties tab to verify that this substance meets your search criteria.

Click Start New Query to return to the Advanced search interface.

Search by Locator Code

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The next search box is for Locator Codes. Locator Codes refer to a database or resource with data present in ChemIDplus.

In the Locator Codes box, click on the first drop-down menu labeled any to see a long list of resources that can be searched from ChemIDplus, which includes resources from NLM and other agencies.

To read definitions for each code, click the information button (the small i icon) in the Locator Codes search box.

This will open the Locator Codes section of ChemIDplus Help where you'll see a link to the Alphabetical List of Locators Used in ChemIDplus that includes their full names and descriptions.

Use this list to answer the question below. 

Substances on the California Proposition 65 list, those known to the state to cause cancer or reproductive toxicity, can be found using code CA65. 

Search by Locator Code

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You can use Locator Codes combined with other criteria as a limit for your searches. For example, you may want to see only records with information from NIOSH (The National Institute for Occupational Safety and Health). They can also be used to explore the overlap between databases.

Use the Alphabetical List of Locators to answer the question below: 

How many substances are listed on Title VI of the Clean Air Act?

The search generates a list of substances from Title VI of the Clean Air Act, which added provisions to the Clean Air Act for protecting the ozone layer. 

Search by Locator Code

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Select Chlorodifluoromethane from the results list.

Click the Links to Resources tab.

These links point to additional resources, or locators, for this chemical. You can use these to find data or literature about the chemical. 

The links are divided into three categories: 

  • National Library of Medicine associated databases, such as PubMed or the Drug Information Portal.
  • Regulatory Agencies and scientific lists that contain information about the chemical, like Title VI of the Clean Air Act (CAA2) or the EPA High Production Volume chemicals (HPV).
  • Other Resources point to external federal, state, or scientific sites with information of interest for the chemical, such the National Institute for Occupational Safety and Health International Chemical Safety Cards (NIOSH ICSC).

Clicking on the information button (the small i icon) next to a locator name will provide a description of the resource.

Clicking on the locator hyperlink will open a new window with data or literature from that resource, as close to the level of the substance as possible.

Search by Locator Code

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Try It: 

Under NLM Resources (File Locators), click on the link to MeSH. It should open in a new window.

Notice that it opens to a substance called fluorocarbon 22.

Is this a synonym of Chlorodifluoromethane or did something go wrong?

Switch back to your ChemIDplus window and click the Names & Synonyms tab. Scan the list to verify that they are indeed synonyms.

Click Start a New Query to return to the Advanced search interface.

Search by Molecular Weight

You can also search by molecular weight. A researcher may want to find what substances exist within a particular molecular weight range.

Try it and then answer the question below. 

Approximately how many substances have a molecular weight between 58 and 60? 

Notice that the molecular weight appears below the structure drawing in the search results. For example, the molecular weight of acetamide is 59.0675.

Click Start New Query to return to the Advanced search interface.

Combining Searches

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You can combine search fields on the Advanced search interface, but keep in mind that ChemIDplus will automatically AND your search fields. In other words, it will narrow your search to chemicals that include all of the criteria you enter.

Try It:

Find substances that have a melting point between 212-220º AND have a molecular weight greater than 400.

You should retrieve about 24 records.

Click Start New Query to return to the Advanced search interface.

Combining Searches

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Notice that below the search box for each category, ChemIDplus indicates how many records have data available in that category. In other words, not all substances have the same data fields in the record.

Keep this in mind if you combine search fields. 

What type of data is available for the fewest records?

Combining Searches

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You've completed Part 1 of the ChemIDplus Tutorial! You should now be able to: 

  • Select the ChemIDplus search option right for you
  • Locate chemicals by name/registry number, toxicity, physical properties, locator codes, or molecular weight
  • Identify where the chemical information in ChemIDplus is coming from
  • Locate biomedical data and literature about a specific chemical

In Part 2, you'll learn about searching by chemical structure.

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