Page:NIOSH Manual of Analytical Methods - 3800.pdf/2

 ORGANIC AND INORGANIC GASES by FTIR Spectrometry: METHOD 3800, Issue 1, dated 15 March 2003 - Page 2 of 47 REAGENTS:

EQUIPMENT:

1. Nitrogen gas (N 2) or zero air, HP or be tter. 2. Calibration Transfer Standard (CTS) Gas, 2% accuracy or better. The proper concentration depends on both the compound used and the system absorption pathle ngth. F or ethylene in nitrogen, a standard concentration leading to a concentration - absorption pathlength product of 100 to 400 ppm-m is recomm ended. (For example, a standard of 10 ppm to 40 ppm ethylene in nitrogen is recomm ended for a 10 m eter a bso rption cell). 3. Liquid nitrogen* (LN 2) for cooling the infrared detector, if required.

1. FTIR spectrometer system (source, interferometer, sample absorption cell, and dete ctor) con figure d with a bso rption. A minimum instrumental linewidth (MIL) 2 cm -1 or lower is recomm ended. NOT E:A lower or higher MIL may be required or suitable for specific gas matrices. Choose internal abs orption ce ll ma terials to m inim ize surface/analyte interactions. 2. Com puter system with hardware, software, and required reference spectra for acquisition, s torage, and analysis of sam ple spectra. (A data backu p syste m is recom m end ed.) 3. Sam pling pum p, 0.1 to 10 L/m in, with appropriate particulate filters. 4. Non-reactive gas regulators and sam ple tubing. 5. Rota m ete rs or o the r de vices, 20% accuracy, for measuring flow rates of sample and calibration gases. 6. Tem perature measurement and/or control equ ipm ent fo r all sam pling system elem ents and IR absorption cell. NOT E:Temperature control equipment required if ambient temp. <10 °C or >30 °C. 7. Pressure gauge for measuring absolute gas pressure in absorption cell, 5% accuracy at one atm osp here (760 m m Hg) abs olute pressure. 8. For system tests (but not for normal operation): Vacuum pum p and gauge capable of 100 mm Hg abs. pressure; midinfrared attenuating filters (50% and 25% ); impinger.


 * See SPECIAL PRECAUTIONS

SPECIAL PRECAUTIONS: This m eth od req uires the use of com pressed gases and/o r cryogenic liquids and/or toxic chemicals. These m aterials are dangerous and should be handled only by experienced personnel and according to relevant safety standards. This method does not address all of the safety conc erns ass ociated w ith its use. It is the res pon sibility of the user to establish app ropriate safety and hea lth prac tices and to determ ine the app licability of regulatory limitations.

NOTE: Please refer to the Appendices for explanation s of the term inology used in this docum ent (Appendix A) and several FTIR system tests which m ust be com pleted before any tes ting is perform ed (Appendix B). Appendices C, D, and E provide (respectively) a general description of FT IR spectrom etry, considerations for preparing reference libraries, and examples of calculations req uired for performance of this method.

NIOSH Manual of Analytical Methods, Fourth Edition