Needle-based extraction techniques with protected sorbent as powerful sample preparation tools to gas chromatographic analysis: Trends in application.

Microextraction techniques are widely applied for sample preparation to gas chromatographic analysis of target compounds in samples with a complex matrix. Recently, needle-based microextraction techniques have been developed in order to improve performance of the extraction. The main advantages of these techniques are miniaturization, automation, high performance, environmentally friendliness and on-line coupling with analytical instruments. This review focuses on the three needle-based microextraction techniques including solid-phase dynamic extraction (SPDE), in-tube extraction (ITEX) and needle trap device extraction (NTD). The core of the aforementioned techniques is an extraction phase protected in the stainless steel needle. The application of the sorbent-protected needle extraction techniques for the gas chromatographic analysis of environmental, biological and food samples is discussed. The fundamental aspects and development over the years are also summarized.