Gas Chromatography (GC)

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Introduction

Gas chromatography (GC) is a laboratory technique used to separate, identify, and quantify compounds in a mixture that can be vaporized. It works by passing a sample through a column with a stationary phase, while an inert gas carries the sample through. Different compounds travel at various speeds, allowing them to be separated and detected, often using devices like flame ionization detectors or mass spectrometers.

Key Feature

Separation Efficiency: GC provides high resolution and effective separation of complex mixtures based on volatility and interaction with the stationary phase.
Sensitivity: Detects trace components down to parts per billion (ppb) or lower.
Speed & Efficiency: Analyses are typically fast (minutes to tens of minutes).
Wide Applicability: Ideal for volatile/semi-volatile organics in fuels, environmental samples, flavors, fragrances, forensics, and pharmaceuticals.

Principle

The fundamental principle of GC is based on the differing partitioning behaviors of substances between a mobile phase (gas) and a stationary phase (solid or liquid). In GC, a sample mixture is introduced into a chromatographic column, where the components interact with the stationary phase to varying degrees. These differences in adsorption affinity cause the components to travel through the column at different rates, resulting in their separation. The separated components are then detected and recorded by a detector. GC is widely used for the quantitative analysis of complex mixtures containing small-molecular-weight compounds.

Inconsistent sample injection, leading to large deviations.
Peak shifting caused by changes in other peak shapes.
Baseline interference.
Changes in instrument system parameter settings; parameters should be standardized and regulated.
Changes in chromatographic column performance.

Injector temperature is too high.
The column head is uneven; use diamond sand to cut it flat.
The polarity of the stationary phase does not match the sample; use a compatible column.
Cold spots exist in the sample flow path; eliminate areas with excessively low temperatures.
Injection time is too long.
Split ratio is too low; increase the split ratio (at least greater than 20:1).
Injection volume is too high; reduce the injection volume or dilute the sample.

Improper column installation.
Sample injection leakage.
High injection volume; increase vaporization temperature.
Low split ratio; increase the split ratio.
Low column temperature.

Application

Applicable industries

Applicable materials type

Volatile organic compounds (VOCs): Such as solvents, alcohols, hydrocarbons, and aromatics.
Gases: Including air pollutants, natural gas components, and industrial gases.
Small-molecular-weight substances: Like pesticides, flavors, fragrances, and some drugs.
Thermally stable compounds: Substances that do not break down at the temperatures used in GC.

Applicable materials type

Industrial Application

Petrochemical Industry: fuels, natural gas, and lubricants, ensuring product quality and process optimization.
Environmental Monitoring: detects and quantifies pollutants such as volatile organic compounds (VOCs) in air, water, and soil samples for regulatory compliance and environmental protection.
Food and Beverage Industry: flavors, fragrances, additives, and contaminants, supporting quality control and food safety.
Pharmaceutical Industry: analyzes raw materials, monitors impurities, and verifies the purity of pharmaceutical products during manufacturing and quality assurance.
Chemical Industry: quality control, process monitoring, and the analysis of complex chemical mixtures in various chemical manufacturing processes.

Liquid or Powder Samples: Whenever possible, place liquid or powder samples in a 1.5 mL sample vial.
Gas Samples: Collect gas samples in a 200 mL gas sampling bag.
Water-Based Samples: GC generally cannot analyze water-based solvents directly. Extraction is required.
Note: Please specify the extraction reagent used, or submit the sample after extraction.

Test Procedure

Sample Preparation: The sample is prepared, often by dilution or filtration, to ensure it is suitable for injection and can be vaporized without decomposition.
Instrument Setup: The GC instrument is set up by selecting the appropriate column, stationary phase, carrier gas (mobile phase), and detector. The temperature program and flow rates are also configured.
Sample Injection: A small amount of the prepared sample is injected into the injection port, where it is vaporized and carried into the column by the carrier gas.
Separation in the Column: As the sample travels through the column, its components interact differently with the stationary phase, causing them to separate based on their volatility and affinity.
Detection: The separated components exit the column at different times and are detected by a detector, such as a flame ionization detector (FID) or mass spectrometer (MS).
Data Analysis: The detector produces a chromatogram, which displays peaks corresponding to different components. The retention time and peak area are used to identify and quantify the compounds present in the sample.

Aspect	Gas Chromatography (GC)	Gas Chromatography-Mass Spectrometry (GC-MS)
Principle	Separates volatile compounds based on volatility and interaction with stationary phase	Combines GC separation with mass spectrometry for identification
Detection	Uses detectors like FID or TCD; provides quantitative data	Uses mass spectrometer; provides both quantitative and structural data
Identification	Can separate and quantify, but limited in identifying unknowns	Can separate, quantify, and accurately identify compounds using mass spectra
Sensitivity/Specificity	Sensitive for known compounds; limited for complex/unknown samples	Higher sensitivity and specificity; ideal for trace and unknown analysis
Applications	Routine analysis, quality control, known compound mixtures	Forensics, environmental monitoring, drug testing, research, complex mixtures

Gas chromatography (GC) is an analytical technique used to separate and analyze vaporized compounds. It involves passing a sample through a column with a stationary phase while an inert gas acts as the mobile phase. Components are separated based on their volatility and affinity, and detected by devices like flame ionization detectors or mass spectrometers. GC is widely used in fields such as environmental monitoring, food analysis, and pharmaceuticals for its sensitivity and speed.

Regulatory testing

Environmental testing

Data analysis

Regulatory testing

Environmental testing

Data analysis

Sample Requirements

Application Case

Example Result

What our customers are saying

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Frequently Asked Questions

Variant (SKU)

Introduction

Introduction

Key Feature

Principle

Principle

Application

Applicable industries

Applicable materials type

Applicable materials type

Industrial Application

Heat treatment: Carburizing

Typical GC Graph Analysis

Test Procedure

Test Procedure

Comparison between GC and GCMS

Regulatory testing

Environmental testing

Data analysis

Regulatory testing

Environmental testing

Data analysis

Sample Requirements

Application Case

Example Result

What our customers are saying

Need precise analysis? Contact us – we'll help you choose the best solution for your needs.

Frequently Asked Questions

Gas Chromatography (GC)

Variant (SKU)

Introduction

Introduction

Key Feature

Principle

Principle

Why Are Gas Chromatography Peak Heights and Areas Not Reproducible?

Causes of Peak Tailing in Gas Chromatography?

Causes of Solvent Peak Broadening in Gas Chromatography?

Application

Applicable industries

Applicable materials type

Applicable materials type

Industrial Application

Heat treatment: Carburizing

Typical GC Graph Analysis

Test Procedure

Test Procedure

Comparison between GC and GCMS