Bottle-calibration static head space method for the determination of methane dissolved in seawater

In this paper we describe a simple technique for simultaneously calibrating serum bottles for both gas and liquid phases to better than plus or minus 0.1 mL. Once calibrated, the bottles may be reused without recalibration and volume changes due to temperature and salinity can be calculated. These bottles can serve for sample collection, preservation, gas concentration, incubation, and possibly as a reaction vessel in other analytical sequences. With this calibration technique and the static head space method, we have collected up to 100 samples during a profiling run, equilibrated them, and analyzed them for CH sub(4) by gas chromatography (GC) in a single day.