NITROGEN ANALYZERS continued
vertical with no need to change connections when switching from solid to liquid samples.
Multielement analysis Nitrogen analysis is frequently combined with
other elemental analysis, typically carbon, oxy- gen, or hydrogen. Some analyzers are modular with add-ons for additional elemental analysis.
ELTRA analyzers (
www.eltra.org) are available for single elements O, N, or H, or combined ele- ments ON, OH, or ONH.
The TOC-L Series from Shimadzu (www.ssi.
shimadzu.com) has the option of adding a total nitrogen (TN) analyzer to perform simultaneous TN and TOC (total organic carbon) measurements.
Regulatory compliance Since nitrogen analysis covers a broad range
of industries, check that your chosen analyzer complies with the relevant regulatory test methods for your industry.
The FP628 from LECO for nitrogen/protein analysis in organic samples complies with Association of Official Analytical Chemists (AOAC), American Association of Cereal Chemists (AACC), and American Society of Brewing Chemists (ASBC) methods and inter- national ISO standards.
The Thermo Scientific iPRO 5000 Series TN/ TS analyzer for petrochemicals (Thermo Fisher Scientific,
www.thermoscientific. com) is compliant with ASTM D4629, ASTM D6069, ASTM D7184, ASTM D7183, ASTM
D5453, ASTM D6667, EN 20846, EN 15486, and UOP 936.
Measuring range, detection limits, and accuracy
The measuring range, detection limits, and ac- curacy vary by sample size and may be quoted as ppm or ppb, weight per gram, or a percent- age. For multielement analyzers, detection limits and accuracy vary for different elements.
The ON-900 and ONH-2000 from ELTRA use inert gas fusion to break down solid metals, alloys, and ceramics. Nitrogen is determined by thermal conductivity. For a 1-g sample, the low measuring range is 0.1 ppm–200 ppm with an accuracy of ±0.1 ppm. The high measuring range is 10 ppm–2% with an accuracy of ±2 ppm. Sensitivity is 0.01 ppm.
The EMGA-930 analyzer for inorganic materi- als (HORIBA Scientific,
www.horiba.com) has a sensitivity of 0.001 ppm and accuracy of 0.02 ppm.
The Torch Combustion TOC/TN analyzer for water samples (Teledyne Tekmar, www.
teledynetekmar.com) has a detection limit of 50 ppb and maximum measurable concentration of 2000 ppm.
Speed of analysis The speed of nitrogen analysis depends
on the method used, the sample size, and the heat of combustion. Most nitrogen analyzers take 3–4 min per analysis. Loading
Figure 2 –The ON736 analyzer from LECO measures oxygen/nitrogen in inorganic materials, ferrous and nonferrous alloys, and refractory materials. It is controlled via a touchscreen display.
procedures and postanalysis cleaning will im- pact the throughput.
Instruments that stand out as having par- ticularly fast analysis times are the HORIBA EMGA-830, quoting 40 sec from gas extraction to sample display, and the G8 GALILEO, with an analysis time of 50 sec.
Automation Many automation features are available,
including autoloading and cleaning for continuous use and autocalibration for walk- away operation.
Table 2 – Manufacturers and suppliers of nitrogen analyzers Analytik Jena
Bruker Elemental ELTRA
HORIBA Scientific LECO Skalar
Shimadzu Teledyne Tekmar
Thermo Fisher Scientific VELP Scientifica
Jena, Germany Kalkar, Germany Haan, Germany Edison, NJ
St. Joseph, MI
Breda, The Netherlands Columbia, MD Mason, OH
Waltham, MA Usmate, Italy
www.analytik-jena.com
www.bruker.com/elemental www.eltra.org
www.horiba.com www.leco.com www.skalar.com
www.ssi.shimadzu.com www.teledynetekmar.com www.thermoscientific.com www.velp.com
AMERICAN LABORATORY • 16 • MAY 2014
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