Headspace sampling is an effective method for the analysis of volatile components in liquid samples or solid samples, such as the analysis of volatile VOC components in plastic food packaging bags, and the analysis of toxic components in body fluids after people work in toxic environments.

　　headspace samplerFrom the current point of view, it can be divided into three types: manual type, semi-automatic type, and fully automatic type.

1. manual type

It has a constant temperature furnace with several heating holes and an air-tight glass syringe with a thermal insulation sleeve. This device is characterized by low price, usually the price should be several thousand yuan, but the repeatability of sampling results depends entirely on the experience and level of the operator. In addition, the temperature range is limited by the glass syringe material and cannot be too high.

2. semi-automatic type

With a thermostatic furnace, the top empty bottles need to be manually placed in the thermostatic furnace one by one by the user to balance. When the balance time is up, there must be a process of manually or manually inserting the sampling needle into the top empty bottle. The sampling and injection process is completely controlled by the machine's own sequence. The sampling and injection system can set the temperature to prevent condensation of samples during transmission.

3. fully automatic

After the top empty bottle is sealed, it is manually placed on the conveyor belt or turntable. The top empty bottle will enter the constant temperature furnace according to the time sequence compiled by the user. After the constant temperature time arrives, the manipulator will automatically sample and the system will automatically sample.

　　headspace samplerSelection should pay attention to the following two points:

Repeatability of sample injection results: I .e. RSD calibration sample concentration is less than 3. This index is the key index for evaluating the headspace sampler. The basic RSD of qualified headspace sampler should be less than 3%. Therefore, the user should ask the manufacturer for the original spectrum and technical data of factory inspection when selecting and purchasing.

Temperature gradient is also a key indicator. The temperature control range and control accuracy (including temperature stability and the deviation between the set value of temperature gradient and the actual value) of the headspace flask thermostatic furnace can be 180 ℃ for slightly higher ones, and 200 ℃ for higher ones, which is a bit far-fetched for headspace sampling beyond 200 ℃. The temperature range is commonly 10 ℃ to 150 ℃ above room temperature.