ETHYL FORMATE: METHOD 1452, Issue 1, dated 15 August 1994 - Page 3 of 3 c. 10.
11.
Prepare a calibration graph of the ratio of peak area of ethyl formate to that of n-nonane vs. mg of ethyl formate). Determine the desorption efficiency (DE) at least once for each lot of charcoal used for sampling in the calibration range (step 9). Prepare three tubes at each of five levels and three media blanks. a. Remove and discard the back sorbent section of a media blank sample. b. Inject a known amount of ethyl formate or a standard solution directly onto the front sorbent section with a microliter syringe. c. Cap the tubes. Allow to stand overnight. d. Desorb (steps 6 through 8) and analyze together with the working standards (steps 12 and 12). e. Prepare a graph of DE vs. mg ethyl formate recovered. Analyze three quality control blind spikes and three analysts spikes to ensure that the results are in control.
MEASUREMENT: 12.
13.
Set gas chromatograph according to manufacturer's recommendations and to conditions given on page 1452-1. Inject sample aliquot manually using solvent flush technique or with autosampler. NOTE: If peak area is above the linear range of the working standards, dilute with eluent reanalyze, and apply appropriate dilution factor in calculations. Measure peak area.
CALCULATIONS: 14.
15.
Determine the mass, mg (corrected for DE) of ethyl formate found in the sample front (W f) and back (W b) sorbent sections, and in the average media blank front (B f) and back (B b) sorbent sections. NOTE: If W b > W f/10 report breakthrough and possible sample loss. Calculate concentration, C, of ethyl formate in the air volume sampled, V (L):
EVALUATION OF METHOD: This method was validated over the range 171 to 666 mg/m 3 at 23 C and 766 mm Hg using 10-L samples. Overall sampling and measurement precision, SˆrT, was 0.0782, with average recovery of 104%. Desorption efficiency from charcoal was 82% in the range of 1.48 to 5.91 mg per sample. Break through volume was 14 L when sampling an atmosphere containing 666 mg/m 3 at 0.190 L/min. This corresponds to a capacity of 9.5 mg of ethyl formate. Storage stability was not determined. REFERENCES: [1] [2]
Backup Data Report for Ethyl Formate, prepared under NIOSH Contract No. CDC-99-74-45. NIOSH Manual of Analytical Methods, 2nd. ed., V. 2, S36, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-B (1977).
METHOD REVISED BY: Robert Kurimo, NIOSH/DPSE.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
