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
