Technical Guide: IRMS Reference Materials

We are often asked by customers about our reference materials for IRMS. To help explain these points we have prepared a technical guide on these materials.

All IRMS data should be traceable to Primary reference standards. These primary references are materials that have been selected and assigned definitive delta (δ) values for the light elements H, C, O, N and S and are isotope ratio scale defining.

These standards may be considered as analogous to the CHNOS elemental primary standards certified and issued by NIST e.g. NIST SRM 141d Acetanilide.

At this time the only primary IRMS standards available are those issued by IAEA Vienna (International Atomic Energy Authority). Typical references from IAEA Vienna include:

Element	IAEA reference (example)	Material	Delta value (‰) wrt zero points	Scale zero point
Nitrogen	IAEA-N-1	Ammonium sulphate	0.4	Air
Hydrogen	IAEA-CH-7	Polyethylene	-100.3	V-SMOW
Oxygen	NBS-18	Calcite	-23.3	V-SMOW
Carbon	IAEA-CH-3	Cellulose	-24.72	V-PDB
Sulphur	IAEA-SO-5	Barium sulphate	0.5	V-CDT

Two methodologies developed regarding the use of these primary standards:

1. The use of these to generate individual in-house secondary reference materials to be used as calibration materials.

2. The continued use of the (expensive) IAEA primaries as calibration standards with (and sometimes without) the use of secondary (check) references which also would have been generated in-house.

The problems with the above are:

• The consumption of the expensive IAEA materials, both within individual laboratories, and in general. The demand of these has been such that the more popular ones are now out of stock with replacements taking often years to become available. In addition to this, to conserve stocks, purchases are restricted to one unit per laboratory per three years.

• The reliance on the accuracy of intra-laboratory generated references without any inter-laboratory checks.

• The increased recognition that quality control references should be of a similar matrix to those samples being analysed.

In most analytical techniques, secondary reference materials traceable to a primary reference (NIST, IAEA) are commonplace.

Elemental Microanalysis have a range of IRMS standards which are made available to customers to allow cross-checking, reduce the reliance on in-house generated references and satisfy the above.

1. Interlaboratory comparison Certified.

An International study involving 6 to 25 laboratories.

2. Certified reference materials.

Derived from data from two or more instruments in a single testing organisation on two or more runs on different days.

3. Uncertified working standards.

Using data from a single instrument and intended as “in-run” reference only.

IRMS reference materials available from Elemental Microanalysis:

Values are approximate: refer to certificate of analysis for current values.

Inter-laboratory comparison Certified Isotopic reference materials

Part No	Material	Pack	δ 13C ‰	δ 2H ‰	δ 15N ‰	δ 18O ‰	δ 34S ‰	% C	% H	% N	% O	% S
B2203	IRMS EMA P1	3g	-28	-25		21	-3	61.5	3.5		20.9	13.9
B2205	IRMS EMA P2	3g	-28	-88	-2	27		68.4	2.9	7.5	19.9
B2207	Silver Phosphate	1g				22
B2214	Carrara marble	0.5g	2			-2

Certified Isotopic reference materials

Part No	Material	Pack	δ 13C ‰	δ 2H ‰	δ 15N ‰	δ 18O ‰	δ 34S ‰	% C	% H	% N	% O	% S
B2153	Low Organic Soil	5g	-27		7			1.6		0.1		0.0
B2155	Protein (Casein)	5g	-27		6		6*	46.5		13.3		0.8
B2157	Wheat Flour	5g	-27		3		1*	39.4		1.4		0.1
B2159	Sorghum Flour	5g	-14		2		10*	41.3		1.5		0.1
B2215	Gelatin	2g	-23		4	7	1		7

*Not certified value - for reference only*

Uncertified working standards

Part No

Material

Pack

δ 13C ‰

δ 2H ‰

δ 15N ‰

δ 18O ‰

δ 34S ‰

% C

% H

% N

% O

% S

B2190

High enriched water

25ml

1702

267

B2191

Medium enriched water

25ml

843

109

B2192

Zero natural water

25ml

B2193

Medium natural water

25ml

-98

-12

B2194

Low natural water

25ml

-269

-34

B2195

Set of 5 water working standards (B2190 to B2194)

B2172

Olive Oil

-29

B2174

Urea

-43

-1

B2213

Spruce (Wood) powder

-25

-3

50.0

6.3

0.1

40.0

Additional Information available: IRMS Refs Tech Bulletin - June 2017.pdf

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Technical Guide: IRMS Reference Materials

We are often asked by customers about our reference materials for IRMS. To help explain these points we have prepared a technical guide on these materials.

IRMS reference materials available from Elemental Microanalysis:

Inter-laboratory comparison Certified Isotopic reference materials

Certified Isotopic reference materials

Uncertified working standards

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