GNS Stable Isotope Laboratory

Stable Isotopes - Oxygen – ¹⁸O/¹⁶O

Abundance -
¹⁶O = 99.762 % atom
¹⁷O = 0.038 % atom (not usually measured)
¹⁸O = 0.200 % atom

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Gas analysed –
CO₂, but also can be analysed as CO and O₂, but not at this facility

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Recommended Scales –
VPDB (Pee Dee Belemnite) and VSMOW for waters (Standard Mean Ocean Water, absolute isotope ratio (2005.20 ± 0.45) x 10^-6 [Baeertschi,1976])

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Equipment -
Europa Geo 20-20 dual inlet for CO₂ gas samples
GVI Isoprime coupled with AquaPrep for water and carbonate samples

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		Precision‰		Preferred		Minimum		Price
				samples		sample
				size		size
SOLIDS
18O & 13C	carbonates	0.3 & 0.1		2mg as CaCO3		0.5mg
18O	silicates	0.1		5mg		2mg
18O	sulfate minerals	0.3		50mg		20mg
18O & 34S	sulfate minerals	0.2 & 0.3		50mg as BaSO4		20mg as BaSO4
LIQUIDS
18O	water	0.1		5-20 ml		0.5 ml
18O & D	water	0.1 & 1.0		5-20 ml		0.5 ml
18O	sulfate solution	0.3		20 mg as SO4		20 mg as BaSO4
18O & 34S	sulfate solution	0.2 & 0.3		50mg as BaSO4		20mg as BaSO4
GAS
18O & 13C	CO2	0.3 & 0.1		5ml STP*		1ml STP*
*Standard Temperature and Pressure