2.2 Types of Sample and Sample Introduction
A basic GC of reasonable quality costs from 30,000 to 50,000 US dollars today depending on the detectors that are purchased with the GC, although more inexpensive models can be purchased for limited routine analysis. A capillary column gas chromatography-mass spectrometer (GC-MS, quadrupole) will cost slightly less than $100,000. With this relatively high price tag, students sometimes trust the results as unquestionably accurate. Reality could not be farther from this belief. Every step, including extraction of the analytes from the sample matrix, conducting serial dilutions, injection into the GC, and identification of the fragmentation pattern in MS is prone to errors. From experience, sample extraction can be the most difficult and is the source of considerable error. Samples come in a variety of forms: gaseous, liquid, solid, and biological. In order for the reader to fully appreciate sample preparation for GC analysis the following discussion will present several sample collection, extraction and sample preparation techniques.
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