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Restek LC Guard Column Selector: How to Find the Right Guard Fast

Using an LC guard column is a quick, cost-effective way to maximize the lifetime of your analytical column. Guards consist of a holder and cartridge (and sometimes a filter) and install easily in front of the analytical column in order to protect it from strongly retained impurities and particulates. Guard columns are just like analytical columns, except they are shorter and are intended to be a consumable part with a limited lifetime. Understanding how to choose an LC guard column correctly can help you protect your analytical column and save money by extending analytical column lifetime.

Restek offers three guard column configurations—EXP, Roc, and Trident (direct and in-line)—that are each designed to match one of our LC column families and are intended for a specific technique. For example, if you’re performing UHPLC, you are using a smaller particle column that generates high back pressure, so you need a holder to accommodate that pressure. If you’re employing traditional HPLC using a legacy column, you want a holder that houses a legacy cartridge to match.

Step 1: Choose a LC Guard System Based on Your Technique and Analytical Column

EXP Holders and Cartridges

  • Holder is compatible with all HPLC through UHPLC instruments and cartridges (rated to 20,000 psi [1400+ bar]).
  • Choose the LC guard cartridge that matches your needs (Raptor: UHPLC, 2.7 µm, 5 µm; Force: 3 µm and 5 µm).
  • Designed for use with Raptor and Force LC columns.

Roc Holders and Cartridges

  • Compatible with traditional HPLC instrumentation.
  • Designed for use with Roc HPLC columns.

Trident Direct Holders and Cartridges

  • Compatible with traditional HPLC instrumentation.
  • Designed for use with legacy HPLC columns (Ultra, Pinnacle II, Pinnacle DB, Allure, Viva).
  • Available in three levels of protection.

Trident In-Line Holders and Cartridges

  • Compatible with traditional HPLC instrumentation.
  • Designed for use with legacy HPLC columns (Ultra, Pinnacle II, Pinnacle DB, Allure, Viva).
  • Requires a coupler to attach to the analytical column.
MSD Source
Step 1 LC Guard

While a guard cartridge is the best choice for analytical column protection, it will add some retention delay because it is a packed bed. For protection from particulates with a negligible amount of additional dead volume, choose an UltraLine in-line filter or an UltraShield filter, both of which are suitable for UHPLC pressures.

Once you know which guard column system you need, the next step is choosing an LC guard cartridge with the packing and dimensions that best match your analytical column. In order to obtain maximum protection without compromising selectivity or efficiency, you should select an LC guard cartridge that contains the same packing material—both stationary phase and silica—as your analytical column. For example, the best LC guard column to use with a Raptor Biphenyl 2.7 µm analytical column is a Raptor Biphenyl 2.7 µm guard cartridge.

In addition to choosing a guard cartridge packing that matches your analytical column, you need to select an LC guard cartridge with the correct inner diameter (ID). A good general rule is that the LC guard column cartridge ID should be the same as, or one size smaller than, the ID of the analytical column. So, a 4.0 mm ID guard cartridge should be used with a 4.6 or 4.0 mm ID analytical column, while a 2.1 mm ID guard cartridge is recommended for 3.2, 3.0, and 2.1 mm ID analytical columns.

Step 2: Choose an LC Guard Cartridge Packing
that Matches the Analytical Column


EXP Holders

• Raptor Guard Cartridges
• Force Guard Cartridges
• UltraShield Filters

LC Column Family

Column Particle Size

Analytical Column Phases

Guard Cartridge Phases

1.8 (UHPLC)

C18, ARC-18, Biphenyl, FluoroPhenyl

Raptor UHPLC guards: C18, ARC-18, Biphenyl, FluoroPhenyl

2.7

C18, ARC-18, Biphenyl, FluoroPhenyl, HILIC-Si, EtG/EtS*

Raptor 2.7 µm guards: C18, ARC-18, Biphenyl, FluoroPhenyl, HILIC-Si

5

C18, ARC-18, Biphenyl, FluoroPhenyl

Raptor 5 µm guards: C18, ARC-18, Biphenyl, FluoroPhenyl

1.8 (UHPLC)

C18, Biphenyl, FluoroPhenyl

Raptor UHPLC guard cartridge in matching phase for maximum protection, or 0.2 µm UltraShield filter for clean samples when minimal dead volume is desired**

3

C18, Biphenyl, FluoroPhenyl

Force 5 µm guards: C18, Biphenyl, FluoroPhenyl

5

C18, Biphenyl, FluoroPhenyl

Force 5 µm guards: C18, Biphenyl, FluoroPhenyl

*Restek recommends using a 0.2 µm UltraShield filter with a Raptor EtG/EtS column.

**Raptor UHPLC cartridges are packed with Raptor particles, but they are compatible with any UHPLC column so they can be used with matching phases of 1.8 µm Force and 1.9 µm Pinnacle DB UHPLC columns.


ROC Holders


• Roc Guard Cartridges

Column Family

Column Particle
Size

Column Phases

Guard Cartridge Phases

3

C18, C8, Phenyl-Hexyl, Cyano, Silica

Roc 5 µm guards: C18, C8, Phenyl-Hexyl, Cyano, Silica

5

C18, C8, Phenyl-Hexyl, Cyano, Silica

Roc 5 µm guards: C18, C8, Phenyl-Hexyl, Cyano, Silica



Trident Holders

• Ultra Guard Cartridges
• Pinnacle DB Guard Cartridges
• Pinnacle II Guard Cartridges
• Viva Guard Cartridges
• Allure Guard Cartridges

Column Family

Column Particle Size

Column Phases

Guard Cartridge Phases

Ultra

3

C18, C8, C4, C1, Biphenyl, Aromax, Aqueous C18, PFP Propyl, Cyano, IBD, Amino, Silica, Quat, Carbamate

Ultra 5 µm guards: C18, C8, C4, C1, Biphenyl, Aromax, Aqueous C18, PFP Propyl, Cyano, IBD, Amino, Silica, Quat, Carbamate

5

C18, C8, C4, C1, Biphenyl, Aromax, Aqueous C18, PFP Propyl, Cyano, IBD, Amino, Silica, Quat, Carbamate

Ultra 5 µm guards: C18, C8, C4, C1, Biphenyl, Aromax, Aqueous C18, PFP Propyl, Cyano, IBD, Amino, Silica, Quat, Carbamate

Pinnacle DB

1.9

C18, C8, Biphenyl, Aqueous C18, PFP Propyl, Cyano, IBD, Silica, PAH

Raptor UHPLC guard cartridge in matching phase for maximum protection, or 0.2 µm UltraShield filter for clean samples when minimal dead volume is desired**

3

C18, C8, Biphenyl, Aqueous C18, PFP Propyl, Silica

Pinnacle DB 5 µm guards: C18, C8, Biphenyl, Aqueous C18, PFP Propyl, Silica

5

C18, C8, Biphenyl, Aqueous C18, PFP Propyl, Cyano, Silica

Pinnacle DB 5 µm guards: C18, C8, Biphenyl, Aqueous C18, PFP Propyl, Cyano, Silica

Pinnacle II

4

PAH

Pinnacle II 4 µm guards: PAH

Viva

3

C18

Viva 5 µm guards: C18

5

C18, C8, C4, Biphenyl, PFP Propyl, Silica

Viva 5 µm guards: C18, C8, C4, Biphenyl, PFP Propyl, Silica

Allure

5

Organic Acids, AK, Silica

Allure 5 µm guards: Organic Acids, AK, Silica

**Raptor UHPLC cartridges are packed with Raptor particles, but they are compatible with any UHPLC column so they can be used with matching phases of 1.8 µm Force and 1.9 µm Pinnacle DB UHPLC columns.

Note: Trident direct holders are available in three configurations, so you can select the level of protection that is best for your application. For more details, review our Trident brochure. Trident in-line filters are also available.

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