TraceCERT^®: Traceable Certified Standards

For certified calibration solutions, we maintained a long-standing partnership with Swiss Federal Institute for Materials Science and Technology (EMPA). However, EMPA terminated all their activities in chemical metrology in 2004 and no longer acts as a national metrological institute. Recognizing that EMPA’s exit created the need for a first class CRM supplier in the market, Sigma-Aldrich made a strategic decision to acquire the metrological competency from EMPA and transfer it to our Buchs, Switzerland site. We began in late 2005 to replicate the EMPA metrological environment in order to provide a seamless transition. First, we purchased from EMPA the unique equipment which was custom-designed to produce intercomparison samples of the highest metrological level (CCQM Key Comparisons). Second, we built a special, dedicated laboratory at the Buchs site where the high-precision weighing capabilities, homogenization and clean room bottling equipment were installed.

TraceCERT® reference materials are developed and produced in an accredited laboratory fulfilling both ISO 17025 (General requirements for the competence of testing and calibration laboratories) and ISO Guide 34 (General requirements for the competence of reference material producers).

TraceCERT^® products are characterized by

• Unique (metrological) level of accuracy and lot-specific values
• Traceability to at least two independent references (i.e. NIST, BAM or SI unit kg)
• Certification according to ISO Guide 31
• Highest-purity starting materials available
• Comprehensive documentation including proper uncertainty calculation,
  expiry date and storage data
• Certificates of ICP standards list up to 70 trace impurities
• ICP standards packaged in light- and gas-tight aluminum foil bags
• Competitively priced

Certified Element Standards for AAS and ICP

Element	Composition	Cat. no. ICP Standard	Example Certificate	Add to Cart	Cat. no. AAS Standard	Example Certificate	Add to Cart
Aluminum	Al(NO3)3 x 9H2O + HNO3	61935			39435
Antimony	Sb metal + HNO3 + HF	50360			73969
Arsenic	As2O3 + HNO3 (+ NaOH for AAS)	01969			39436
Barium	BaCO3 + HNO3	59943			90092
Boron	H3BO3 + H2O	01932			40591
Cadmium	Cd metal + HNO3	36379			51994
Calcium	CaCO3 + HNO3	19051			69349
Cesium	CsNO3 + HNO3	96664			67717
Chromium	(NH4)2Cr2O7 + HNO3	68131			02733
Cobalt	Co metal + HNO3	30329			05202
Copper	Cu metal + HNO3	68921			38996
Gold	Au metal + HCl (HNO3 traces)	38168			08269
Iron	Fe metal + HNO3	43149			16596
Lead	Pb(NO3)2 + HNO3	41318			16595
Magnesium	Mg metal + HNO3	30083			42992
Manganese	Mn metal + HNO3	74128			77036
Mercury	Hg metal + HNO3	28941			16482
Nickel	Ni metal + HNO3	28944			42242
Palladium	Pd(NO3)2 + HCl	30931			06948
Phosphorus	H3PO4 + H2O	38338			51474
Platinum	Pt metal + HCl (HNO3 traces)	19078			47037
Potassium	KNO3 + HNO3	06335			96665
Scandium	Sc2O3 + HNO3	92279			68418
Selenium	Se metal + HNO3	50002			89498
Silicon	Si metal + NaOH	94170			16259
Silver	Ag metal + HNO3	12818			39361
Sodium	NaNO3 + HNO3	00462			05201
Strontium	Sr(NO3)2 + HNO3	75267			51287
Sulfur	H2SO4 + H2O	18021			18020
Tin	Sn metal + HCl	92615			74244
Vanadium	V2O5 + HNO3	18399			02334
Yttrium	Y2O3 + HNO3	01357			40423
Zinc	Zn metal + HNO3	18562			18827

ICP standards supplied in 100 mL HDPE bottles and sealed in an aluminum bag, including certificate. AAS standards supplied in 250 mL HDPE bottles, except for Hg which is bottled in 100 mL borosilicate white glass bottle.
The following AAS standards are supplied in 100 mL HDPE bottles: Pd, Au, Pt, Sc

Certified Ion Standards for IC (TraceCERT^®)

Cat. No.	Ion	Composition	Example Certificate	Additional Information
59755	Ammonium	NH4CI in water		replaces cat. no. 95023
43147	Bromide	NaBr in water		replaces cat. no. 17355
39883	Chloride	NaCI in water		replaces cat. no. 24889
40121	Chromate	K2CrO4 in water		replaces cat. no. 27072
90157	Cyanide
77365	Fluoride	NaF in water		replaces cat. no. 47070
41271	Iodide	KI in water		new product
74246	Nitrate	NaNO3 in water		replaces cat. no. 72547
67276	Nitrite	NaNO2 in water		replaces cat. no. 77012
38364	Phosphate	Na2HPO4 in water		replaces cat. no. 79409
90071	Sulfate	Na22SO4 in water		replaces cat. no. 86126
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Production and certification of TraceCERT^® standards

To actually produce high quality CRMs, the entire development process, beginning from the selection of an appropriate starting material to the choice of a purpose-specific packaging, must be highly sophisticated.

Figure 1: Schematic representation of the production design and certification of Sigma-Aldrich TraceCERT^® products.
This approach was established for the preparation of intercomparison samples at the highest metrological stage.

Not only is the bottled solution compared to a reference material (NIST, BAM, etc.), the starting material is checked against a second, independent reference. A key step is that the weighing operation leads to direct traceability to the SI-unit kilogram. Gravimetric preparation using pure materials is a practical and, in many cases, the most accurate calculation of concentration units, through conversion of mass and mole fraction to mass fraction. As a final step, we provide detailed, lot-specific information in the Certificate of Analysis supplied with every TraceCERT® product. Our well-defined approach to CRM production leads to multiple-traceability and, as a further benefit, ensures that significant biases and systematic deviations are excluded to the fullest extent possible.

Serie of ANALYTIX articles about certified reference materials

There is much confusion and many misconceptions over traceability, uncertainty calculation and the proper use of reference materials. In the next seven issues of Analytix, we will attempt to enlighten interested readers on the meaning behind important CRM-related terms and concepts, including

• What does traceability really mean?
• The proper method to calculate uncertainty
• Characterization and purity statement of high-purity starting materials
• Production, liquid handling and packaging on a metrological level
• Certification and accreditation
• Certification of custom standards

Now available:

Part 1: Introduction - Swiss precision meets analytical competence (PDF, 104KB)
Part 2: What treaceability really means (PDF, 172KB)
Part 3: Challenges in the characterization of high-purity starting materials (PDF, 102 KB)
Part 4: Production, handling and storage of high-precision calibration solutions (PDF, 129 KB)
Part 5: Reliability is a matter of proper uncertainty calculation (PDF, 106 KB)
Part 6: Double accreditation - increasing the reliability and and value of analytical results (PDF, 168 KB)

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