N-METHYL-2-PYRROLIDINONE: METHOD 1302, Issue 1, dated 15 January 1998 - Page 3 of 3
c. d. e. 10.
solution directly onto the front sorbent bed of each charcoal tube. Allow the tubes to air equilibrate for several minutes, then cap the ends of the tubes and allow to stand overnight. Desorb (steps 5 through 7) and analyze together with standards and blanks (steps 11 and 12). Prepare a graph of DE vs. µg analyte recovered. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration and DE graphs are in control.
MEASUREMENT: 11.
12.
Set gas chromatograph according to manufacturer’s recommendations and to conditions given on page 1302-1. Inject a 1-µL sample aliquot manually using solvent flush technique or with an autosampler. NOTE: If peak area is above the linear range of the working standards, dilute with desorption solvent, reanalyze, and apply the appropriate dilution factor in the calculations. Measure peak areas.
CALCULATIONS: 13.
14.
Determine the mass, µg (corrected for DE), forN-methyl-2-pyrrolidinone found in the sample front (Wf) and back (Wb) sorbent sections, and in the average media blank front (B f) and back (Bb)sorbent sections. NOTE: If Wb > Wf/10, report breakthrough and possible sample loss. Calculate concentration, C, ofN-methyl-2-pyrrolidinone in the air volume sampled, V (L):
C
NOTE:
µg/mL
(Wf
Wb
Bf V
Bb)
, mg/m 3
mg/m3
EVALUATION OF METHOD: The method was evaluated forN-methyl-2-pyrrolidinone using GC-NPD and GC-FID over a range of 0.662 to 2066 µg/sample. Precision was determined to be 0.05 using GC-NPD and 0.01 using GC-FID. For GC-NPD, a DE graph was developed over a range of 0.310 µg to 10.8 µg. GC-FID was used to verify the results. The mean recovery was determined to be 98.8% with a pooled relative standard deviation ( r) of 0.051. An extended DE graph of the upper level of the method (0.103 to 2.07 mg) was previously determined by OSHA [2]. When spiked onto charcoal tubes at the 10.8 µg level and stored at ambient temperature, N-methyl-2- pyrrolidinone was stable on the charcoal tube for 7 days. OSHA reported that N-methyl-2-pyrrolidinone, when spiked at the 2070 µg level, was stable for 15 days at ambient temperature [2]. Refrigerated storage is recommended. REFERENCES: [1] Pendergrass, SM [1997]. Backup data report for N-methyl-2-pyrrolidinone (unpublished). Cincinnati, OH: National Institute for Occupational Safety and Health. [2] Eide M [1991]. OSHA Stopgap Method for N-methyl-2-pyrrolidinone. Salt Lake City, UT: OSHA Salt Lake City Technical Center.
METHOD WRITTEN BY: Stephanie M. Pendergrass, DPSE, NIOSH
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition
