A set of bottled waters from a single natural spring distributed
worldwide in polyethylene terephthalate (PET) bottles has been used to
examine the effects of storage in plastic polymer material on the
isotopic composition (delta(18)O and delta(2)H values) of the water. All
samples analyzed were subjected to the same packaging procedure but
experienced different conditions of temperature and humidity during
storage. Water sorption and the diffusive transfer of water and water
vapor through the wall of the PET bottle may cause isotopic exchange
between water within the bottle and water vapor in air near the
PET-water interface. Changes of about +4 parts per thousand for
delta(2)H and +0.7 parts per thousand for delta(18)O have been measured
for water after 253 days of storage within the PET bottle. The results
of this study clearly indicate the need to use glass bottles for storing
water samples for isotopic studies. It is imperative to transfer
PET-bottled natural waters to glass bottles for their use as calibration
material or potential international working standards. Copyright (C)
2008 John Wiley & Sons, Ltd.