A gas chromatograph analyzes compounds that remain detectable after being vaporized. Before, a sample has been injected into a chromatograph by hand, but now, an auto sampler-an apparatus that automatically manages and injects the sample-is used to help preserve sample integrity and produce the chromatography process more efficient. The sort of auto sampler such a unit needs depends upon the nature of this analysis. When samples are analyzed for non-toxic chemicals, a purge and trap auto sampler is the standard option. Unlike other kinds of auto samplers, this sort of auto sampler can isolate chemicals which exist in the low parts per billion ppb levels.
Common Kinds of Analysis
Purge and trap Auto samplers are commonly known for their role in Volatile Organic Compound VOC analysis. VOCs are naturally occurring chemicals that vaporize at room temperature. Inhaling VOCs can lead to temporary maladies like stomach nausea and sickness, and long-term maladies like decreased respiratory function and nerve damage. Frequent examples of substances which are analyzed for VOCs using a gas chromatograph are harvest soil, processed water, foodstuffs, and cleaning solutions. Purge and trap Auto samplers are also utilized in the analysis of less ominous compounds, such as odor chemicals which influence the taste of foods and drinks, and the odor of perfume and beauty products. Oftentimes, achieving the ideal balance of substances without the assistance of what is hplc GC is hopeless. Just like VOC analysis, this sort of auto sampler helps with the analysis of aroma compounds by discovering them in the low ppb levels.
The Purge and Trap Process
The purge and trap GC Process comprises the following steps which are intended to isolate non-toxic substances:
- Purge gas eliminates the chemicals from the sample matrix
- The chemicals are sequestered at a solid sorbent from the concentrator
- The concentrator is heated until the chemicals vaporize
When the compounds Vaporize, they are transported by carrier gas mobile phase to the pillar of the gas chromatograph, where they experience a liquid column filling stationary phase. The chemicals exit at different rates from the column to the analyzer, where they are electronically identified and detected. After the chromatography process is done, the results of the analysis can be saved in a database and published.
Choosing a Purge and Trap Auto sampler
Not all of this kind of auto sampler is equivalent, and the model one chooses can have a considerable influence on sample integrity, the efficacy of the chromatography procedure, and the value of investing in the equipment. For all these reasons, auto samplers are evaluated using the following criteria:
- Analytical superiority
- Mechanical robustness
- Ease of use