Page:NIOSH Manual of Analytical Methods - 2558.pdf/3

 ACE TO IN: MET HO D 255 8, Issue 1, dated 15 M arch 200 3 - page 3 of 3 10. Analyze a minimum of three quality control blind spikes and three analyst spikes to ensure that the calibra tion gra ph a nd D E graph are in c ontro l.

MEASUREMENT: 11. Set gas chromatograph according to manufacturer’s recomm endations and to the conditions listed on page 2558-1. Inject a 1-µL sample aliquot manually using the solvent flush technique or with an auto sam pler. Note: If peak a rea is above the linear range of the working standards, dilute with solvent, reanalyze and app ly the app ropriate dilution facto r in the c alculations. 12. Measure peak areas.

CALCULATIONS: 13. Determine the mass, µg (corrected for DE ), of acetoin found in the sam ple front (W f) and back (W b) sorbent sections, and in the average m edia blank front (B f) and back (B b) sorbent sections. Note: If W b > W f/10, report b reak throu gh a nd p oss ible sam ple loss. 14. Calculate conce ntration, C, of acetoin in the air volume sa m pled, V(L):

EVALUATION OF METHOD: This m etho d, like N MA M 2 557 (Diacetyl), was de velop ed in re spo nse to a request to identify and qua ntitate possible hazardous chemical causes of workplace lung disease occurring at a microwave popcorn packaging facility. Ac eto in, an inhalation irritan t and chem ically reactive compound, was identified as a possible suspect chem ical in the fa cility. Due to the reactivity of acetoin (under certain enviro nm ental conditions aceto in can be converted to diacetyl and vice ve rsa [2]), severa l spec ial handling re quirem ents were included in this m etho d de velop m ent. A deactivated glass inlet liner was used to retard the oxida tion of ace toin to diacetyl and to p reve nt analyte decomposition in the injection port. The Stabilwax-DA capillary was used to reduce peak tailing and decomposition of oxygenated compounds during analysis. The reactivity of acetoin was further retarded by using amber glassware and storage of stock and samples at 5°C. Application of these analytical conditions resulted in an average DE recovery of 94.9% over a range of 57 to 378 µg. T he re sults of the stora ge s tability study indicated that acetoin was stable for 7 days at 5°C with a recovery of 93.5%. A slow increase in the am oun t of diac etyl form ed d uring the study was n oted, with a m axim um of 16 -18% reco rded at 30 days. It should also be noted that the acetoin monom er (liquid) will convert to a dimer (white solid) upon standing. How ever, when dissolved, acetoin will convert back to the monom er in solution. Because of the limited solubility of acetoin some sonication may be required to fully dissolve the requ ired am oun ts in the solve nt.

REFERENCES: [1] Pende rgrass SM [2001]. Acetoin Back up Da ta Report, Oc tober. [2] Fix, G J[19 93]. D iacetyl: Form ation, R edu ction, and C ontro l, Brew ing T ech ., July/Augus t.

METHOD WRITTEN (REVISED) BY:

Stephanie M. Pendergrass, NIOSH/DART

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition