Using the GC Method Translator

Answer

This Information Applies To: Use of the Agilent GC Method Translator

Issue

How to correctly use the GC Method Translator to convert a method to suit a different GC configuration or to optimize a method.

Background

The GC Method Translator is an application to help optimize or convert a GC method from one configuration environment to another. From a given original GC method, the translator computes a new translated method in such a way that the chromatograms resulting from both methods (original and translated), look like scaled versions of each other. More specifically, the Method Translator is a calculation tool used to find the new conditions to apply for different column sizes, average linear speeds, carrier gases, and detectors while maintaining the same elution order. 

Requirements

You will need the GC Method Translator software. You can get access to this software through any of the following ways:

1. Use your GC and GC/MS User Manuals and Tools DVD. You will find the software under the Method Developer Tools.
2. Download the software from the Agilent.com website.
3. Access the software through the GC Method Editor from the current Agilent GC software products.

Resolution

Converting GC Methods

Optimizing GC Methods

Method Translation Modes

Translating Methods using the GC Method Translator

Figure 1. GC Method Translator Tool

Converting GC Methods

If there is a change in the method environment prompting a need for translation, then method translation can be viewed as converting the existing method environment to a new environment.

For example, you need to substantially reduce the time of a GC analysis without losing the resolution.

• One way to accomplish this objective is to choose a shorter, narrower column.

The GC Method Translator computes the parameters for the new method, by that avoiding the lengthy method development process, which may otherwise, be necessary when switching to a new column.

Optimizing GC Methods

Frequently, users can achieve an improved separation, or an increased speed and reduced time for analysis without changes to the method environment.

In this case, the improvement can come from optimizing pneumatic conditions of the carrier gas and/or changes in the oven temperature program.

The GC Method Translator allows you to choose several method optimization criteria this way, including: Reduction of the analysis time, and optimizing methods without changing the column, retention time locking, etc.

Method Translation Modes

Figure 2. Mode selection panel in the Method Translator 

Speed Gain

In this mode, enter a value to multiply the original outlet carrier gas flow by, with the intention of decreasing (or increasing) the run time of your method.

• The tool calculates the new temperature and pressure for your current column and carrier gas to meet the new desired outlet flow. As always with method translation, the elution order in your current method will hold constant.

Generally, increasing the flow rate compared to its optimum value can substantially reduce the analysis time compared to the maximum efficiency time, with a minor loss in the resolution of chromatographic peaks.

However, if during its prior development the original method has already been optimized for the best compromise between the speed of analysis and the resolution, the Translate mode can probably yield better results compared to the Fast Analysis or Speed Gain mode.

Translate

In this mode, the tool translates the current method to a new one based on change of column dimensions, carrier gas type, outlet pressure, and/or phase ratio.

If phase ratios of the columns in both methods are the same, then this translation mode maintains its relative position on the van Deemter curve. The relative retention times of the peaks are locked, so the order of elution is preserved.

Use this translation mode:

• If during its prior development, the original method has already been optimized, or
• To convert an established method for use with a column of different dimensions or a different phase ratio, or
• To change to a detector with a different outlet pressure

This translation mode provides the tightest link between the properties of the original and translated methods.

Best Efficiency

In this mode, the tool calculates new conditions (using your current column) that correspond to the theoretical optimum gas flow rate for the greatest separation efficiency for most compounds.

When this mode is selected, enter your current conditions and the program will adjust the temperatures and flow rate to match the theoretical optimum. The elution order of the peaks will stay the same, but the retention time will probably change.

Generally, the flow rate in the Best Efficiency mode is expected to provide the best compromise among the conflicting requirements affecting column efficiency and peak resolution.

• However, if during its prior development, the original method has been optimized for the best resolution for the most critical peak pairs, the Translate mode can probably yield better results compared to the Best Efficiency mode.

Translating Methods using the GC Method Translator

See the following article for details on Translating Methods using the GC Method Translator.

Learn how to effectively operate your Agilent GC: GC-MULTI-2190e - GC Calculators: An Introduction, e-learning course available from Agilent Education