Retention and variability of hydrogen (H2) samples stored in plastic syringes.

The utility of two brands of 20 ml plastic syringes for storage of hydrogen (H2) samples as obtained in H2 breath tests were studied. Plastipak syringes were found to be significantly better with regard to the stability of the H2 concentration and the variability between the H2 samples. Storage of the H2 samples in Plastipak syringes at 5 degrees C significantly improved the H2 retention, whereas refrigeration of H2 samples stored in Once syringes did not reduce H2 loss. Storage of H2 samples in refrigerated plastic syringes is efficient and reliable for several days if syringes with minimal sample variation are used.