The 7694 Headspace Sampler
This Headspace sampler is in excellent condition. This instrument powers up goes through self-test. Purchase of this machine includes a vial crimper.
The 7694 Headspace Sampler provides an automated method to run up to 44 samples consecutively without operator attention. The sampler’s microprocessor optimizes the time spent for each run according to the values programmed in by the operator. Up to four different methods can be stored and used to analyze a series of samples.
Your headspace sampler is a tool for introducing volatiles that are contained in liquid or solid samples into a gas chromatograph. The analytical technique is called “static headspace gas chromatography.” The term “headspace” refers to the space above the liquid or solid sample that you place in a sealed vial. The term “static” means that the volatiles in the headspace of the vial are at equilibrium with the same compounds in the liquid or solid sample.
The instrument extracts a reproducible volume of the headspace and injects it into the carrier gas flowing into the gas chromatograph. Food, packaging, pharmaceutical products, soil, and water are often tested to see if they meet quality criteria or regulatory standards. Fragrances and consumer products are analyzed using headspace in order to understand their composition. Forensics laboratories use headspace for measuring the percent of ethanol in human blood to see if a driver is legally intoxicated.
The ease with which a sample forms a gaseous headspace depends on the sample’s “partition coefficient.”
After a programmed heating time, the headspace gas is extracted from the vial and injected into a GC for analysis.
There are two means of extracting the headspace gas from the vial—single or multiple headspace extraction (MHE). With single headspace extraction, only one sample of gas is taken from each sample vial. Single headspace extraction is the standard method. It is used for samples that are readily volatile or for which there are no matrix effects. Quantitative analysis can be performed by using suitable internal or external standards. MHE is available only in models G1289 and G1290. MHE is used for headspace samples for which no calibration standard can be prepared easily (for example, solid samples) or for highly volatile compounds in liquids, where the method of standard addition is difficult because of losses due to evaporation. MHE takes several headspace samples from each vial. With each extraction, the concentration of the volatile compound in both the gas phase and the sample becomes smaller, although the ratio remains constant. The logs of the peak areas versus the extraction number are plotted to obtain quantitative data about the compound of interest. MHE is often used as a calibration tool. Once the peak area versus the concentration is established for a given sample matrix, quantitative measurements of samples with a similar matrix can be carried out using a single extraction.
Models G1289 and G1290 can also be used for multiple HS extraction using multiple septum punctures, with up to 10 extractions per sample. A low-volume, highly inert, heated volatiles interface is optimized for headspace-GC analysis, preventing sample loss or degradation and reducing carryover.
It can eliminate sample preparation by letting you introduce volatile components automatically
Integrates seamlessly with HP/Agilent GCs
Features a highly inert path from the vial to the GC column head to prevent sample absorption
Constant heating time
Overlapping sample processing - automatic parameter increments for easy method development
Up to 10 headspace extractions per vial
Two levels of vial agitation