Guest Author: Ramkumar Dhandapani, Ph.D.
When it comes to gas chromatography, one of the first questions that arise is “Why Do I need Pure Gas?”. To answer this the most thorough way possible, there are several points that need to be addressed, along with solutions implemented – like gas management.
Problems Related to Gas Purity
Using chromatography as a diagnostic tool and a path for systematic elimination makes it easy to find your problem. This serves as the best troubleshooting approach for gas chromatography related issues. However, a lot of time and money is spent on fixing these gas chromatographic issues and the here are numerous problems that can be related to gas purity. These problems include but aren’t limited to:
Unstable Baseline: Primarily caused by the detector not being stabilized. Detectors like Flame Ionization Detector (FID), are sensitive to hydrocarbons, while detectors like Electron Capture detector (ECD) & Mass Selective (MS) are sensitive to moisture and oxygen content. In fact, oxygen and moisture can eventually kill these detectors resulting in expensive replacement.
Tailing Peaks: Peak tailing is commonly related to secondary interaction. The secondary interaction can also be induced in the GC inlet and detectors via depletion of deactivation in the inlet liner and creation of active spots in the column due to excessive bleed. Both depletion of deactivation in liner and column bleed are primarily caused by oxygen content in carrier gas.
Raised Baseline: Raised baseline at the end of a temperature programmed GC is an indication of column bleed. The common cause for depletion of deactivation is oxygen and moisture content in carrier gas.
Poor Sensitivity: Unstable detector leads to a noisy baseline and can result in high noise level. This will adversely affect quantitative results and detection limit of analytical method. Here again, oxygen and moisture content in carrier gas is the primary reason for issues.
Poor Column Life: There are multiple reasons for poor GC column life time. Oxygen content in carrier gas can kill the stationary phase right away. 2 pp(?) of oxygen at or above 70 0C is enough to cleave and degrade GC stationary phase. Other reasons for a poor column life time includes harsh sample matrix and extreme heating and cooling cycle that the column is exposed to.
Unlit Flame in FID: Carrier gas or detector gas with high moisture can put off detector flame in GC FID. An unlit flame in FID will provide no peaks in the chromatogram.
Represented below are the common diagnostic symptoms of impure carrier gas.
What is the Solution?
The best approach to troubleshooting is to identify the root cause of the problem, fix the problem, and then figure out how to prevent it from happening again in future. Having discussed various carrier gas related issues, it is time to go over prevention techniques to avoid having these problems again. Zebron Gas Management product serve as a solution to all carrier gas related issues. There are two styles of Zebron Gas Management System available namely:
- Plug-In GC and LC filters
2. Click-on Gas Traps.
The Plug-In GC and LC Filters: The Plug-In GC and LC filters are cartridge style filters with high capacity material that provide ultra-pure gas. These cartridge style filters are easy to order and replace as they can be connected in less than 20 seconds. The hardware is made of dual housing; bullet proof plastic outer housing and clean glass inner housing. Eliminate stabilization time by choosing pre-flushed helium specific or hydrogen specific filters. No more need for expensive gas to be wasted on stabilization. These filters are provided with sensitive color indicator. In addition Electronic indicators are available to intimate end users when it is time to change the filters.
What are My Filter Choices?
There are 5 different filters to choose from, which includes Moisture Filter, Oxygen Filter, Hydrocarbon Filter, and Universal filter, Universal filter(helium specific) and LC/MS filter.
High Capacity and Easy to Install Click-on Traps
Zebron Gas Management trap cartridge systems make changing gas traps quick and easy. Spring-loaded check valves close when the filter is removed and open only when a new filter has been locked in place. With the Zebron gas traps there is no need for loosening and tightening fittings every time a trap is changed and you can eliminate contamination during the process. These serve multiple instrument at once and are 750cc large capacity. The Click on-Gas Trap Choices are:
- Click-On Moisture trap
- Click-On Oxygen trap
- Click-On Hydrocarbon Trap
- Click-On Universal Trap
- Click-On Carbondioxide Trap
Be sure to order the brass or stainless steel Click-on connector with your first trap.
Zebron™ Electronic Indicators remind you when to replace your GC Filter or Trap. These indicators attaches directly onto gas filters and traps. These easy-to-read indicator warns when a filter is becoming saturated—allowing you enough time to order a replacement. Combined audio and visual warning system alerts you in advance to change filters and traps.
Combine Zebron Gas Filters, Gas Traps and electronic indicator to get total protection against contaminants in your GC Gas line. To learn more about this product, click the link: www.Phenomenex.com/gasmanagement