IAPSO Standard Seawater is the only internationally recognised calibration standard for the measurement of Practical Salinity as approved by all the major oceanographic bodies (ICES, IOC Unesco, SCOR,etc) and is endorsed by the International Association for Physical Sciences of the Ocean (IAPSO).
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Salinometer calibration for measurement of oceanic samples is traditionally carried out using IAPSO Standard Seawater (salinity = 35). For measurement of samples of higher and lower salinity, OSIL produce standards at salinities of 10, 30 and 38. Salinometer linearity checks provide a useful diagnostic tool in assessing the function of a salinometer and are routinely carried out at the OSIL Service Centre.
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The procedure followed by OSIL when preparing and calibrating IAPSO Standard Seawater. 
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OSIL's recommendations when using IAPSO Standard seawater particularly relating to storage, shelf-life and linearity.
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