Page:NIOSH Manual of Analytical Methods - 2500.pdf/3

 METHYL ETHYL KETONE: METHOD 2500, Issue 2, dated 15 May 1996 - Page 3 of 4

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d. Deso rb (steps 5 through 7 ) and analyze together with working standards (steps 11 and 12). e. Prepare a gra ph o f DE vs. :g MEK recovered. Analyze three quality control blind spikes and three analyst spikes to insure that the calibration graph and D E graph are in control.

MEASUREMENT: 11.

12.

Set gas chro m atog raph acc ording to m anu facturer's rec om m end ations and to conditions given on page 25 00-1. Inject sam ple aliquot m anually using solvent flush techn ique or with autosam pler. NOTE: If pea k area is abo ve the linear ra nge of the working standard s, dilute with eluent, rean alyze and apply the appropriate dilution factor in calculations. Mea sure peak area. Divide the peak area of analyte by the peak area of internal standard on the same chromatogram.

CALCULATIONS: 13.

14.

Determine the m ass, :g (corrected for D E) of ME K found in the sam ple front (W f) and back (W b) sorbent sec tions, and in the average m edia blank front (B f) and back (B b) sorbent sections. NO TE: If W b > W f /10, report breakthrough and possible sample loss. Calculate conce ntration, C, of MEK in the air volume s am pled, V (L):

NO TE : :g/L = m g/m 3

EVALUATION OF METHOD: The method was evaluate d with spik ed sam plers and with atm ospheres generated by syringe pum p/a ir dilution, verified by infrared absorption. For Ambersorb XE-347 samplers, breakthrough (80% RH, 200 ppm, 0.3 L/min) = 16.4 L; DE (4 to 18 mg per sample) = 1.03; storage stability (0.7 to 4 mg per sample) = 90% after six wee ks at 25 °C; precision and a ccu racy as give n on pag e 25 00-1 (15 s am ples) [2]. A user ch eck g ave an estimated LOD of 4 :g M EK per s am ple [3]. Storage stability of MEK and m ethyl isobutyl ketone (M IBK) on An asorb CMS sam plers was determined for the Proficiency Analytic al Testing (PAT) program [1]. Stability of MEK (0.125, 0.622, and 2.282 mg per sample) was 94 to 99% after 90 days at -5 °C. Only the highest level (2.282 mg) was stable (96% rec overy) at ambient temperature for 30 days, and was stable for 180 days (98 % rec overy) at freezer tempe ratures (-5 °C). Results were similar for MIBK, although all concentration levels (0.103, 0.516, and 2.064 mg per sample) were stable for 30 days at ambient temperatures.

REFERENCES: [1] NIOSH [1996]. Six-month storage stability data for methyl ethyl ketone and methyl isobutyl ketone. Proficiency Analytical Testing program, Jensen Groff, unpublished data. [2] Slick, E. J. [19 83]. N IOS H, unpu blishe d da ta. [3] User c heck, UBT L, NIOS H Se q. #3990-J (un published, Augus t 29, 1983). [4] User c heck, DataChe m Labs., NIOS H Se q. #7053-L (un published, Augus t 9, 1990). [5] DataC hem Labs, NIO SH S eq. #7373-L (unpublished, Nov. 27, 199 1).

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition