Page:NIOSH Manual of Analytical Methods - 5029.pdf/5

 4,4'-METHYLENEDIANILINE: METHOD 5029, Issue 2, dated 15 August 1994 - Page 5 of 5 Table 3: Recoveries of MDA from Gauze Pads and Smear Tabs Samples & Loading 0 day

Average Recovered after 1 day 7 days

30 days

Acid-treated Gauze Pads 9.3 µg 0.93 µg 0.09 µg

96 98 97

89 90 85

87 86 85

86 85 87

Untreated Gauze Pad 9.3 µg 0.93 µg 0.09 µg

97 98 93

73 70 62

70 63 60

53 46 55

Smear Tab 9.3 µg 0.93 µg 0.09 µg

93 87 85

64 62 56

53 48 44

51 46 42

Solutions 9.3 µg 0.93 µg 0.09 µg

98 95 98

97 96 97

98 95 94

96 97 98

MDA was extracted with greater than 90% extraction efficiency from all the media tested. The extraction efficiency did not decrease when the analyte was isolated from the media by extraction or media elimination. However, upon evaporation of the solvent from the spikes, the MDA begins to react with the media and loss of MDA begins immediately. This is shown by the decrease in recovery and the appearance of a yellow discoloration of the white medium. Although the recovery stabilizes, the addition of sulfuric acid to the pads does not prevent the loss of about 7% of the analyte during the first day. Addition of the 0.1 N methanolic KOH serves as an efficient stabilizer when added to the sample with no recovery loss. The improved recovery following field extraction, the imprecise mode of treated media preparation, and safety considerations of using acid-treated media for wipe samples were factors in using field extraction for surface and dermal samples.

REFERENCES: [1] [2]

[3] [4] [5]

Neumeister, C. E. Method Development for 4,4'-Methylenedianiline, Sequence #4752, NIOSH/MRSB, Cincinnati, OH., (NIOSH, unpublished, November 20, 1986). Anderson, C. C. and E. C. Gunderson, Methods Validation Study of High Performance Liquid Chromatographic Technique for Determining the MPDA and MDA Content of Air samples, SRI International, Menlo Park, CA (1986). Elskamp, C. J. Method 57 (4,4'-Methylenedianiline), Organic Methods Evaluation Branch, OSHA Analytical Laboratory, Salt Lake City, UT (1986). Federal Register 29, Part 2, CFR Parts 1910 and 1926 (May 12, 1989). NIOSH Current Intelligence Bulletin #47, 4,4'-Methylenedianiline (MDA), U. S. Dept. of Health and Human Services (NIOSH) Publication No. 86-115 (1986).

METHOD WRITTEN BY: Charles Neumeister, NIOSH/DPSE.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94