Ethyl Formate (1452)
ETHYL FORMATE
CH3CH2COOH
MW: 74.08
METHOD: 1452, Issue 1
1452
CAS: 109-94-4
RTECS: LQ8400000
EVALUATION: PARTIAL
OSHA : 100 ppm NIOSH: 100 ppm; Group I Pesticide ACGIH: 100 ppm (1 ppm = 3.03 mg/m 3)
Issue 1: 15 August 1994
PROPERTIES: liquid; BP 54.5 °C; d 0.917 g/mL @ 20 °C; VP 26 kPa (194 mm Hg) @ 20 °C; vapor density (air = 1) 2.6; explosive range 2.8 to 16% v/v
SYNONYMS: formic acid, ethyl ester; ethyl methanoate
SAMPLING SAMPLER:
SOLID SORBENT TUBE (coconut shell charcoal; 100 mg/50 mg)
FLOW RATE:
0.01 to 0.2 L/min
VOL-MIN: -MAX:
0.3 L @ 100 ppm 10 L
SHIPMENT:
routine
MEASUREMENT TECHNIQUE:
GAS CHROMATOGRAPHY, FID
ANALYTE:
ethyl formate
EXTRACTION:
1 mL CS 2 ; stand 30 min.
INJECTION VOLUME:
5 µL
SAMPLE STABILITY:
unknown
TEMPERATURE-INJECTION: -DETECTOR: -COLUMN:
BLANKS:
2 to 10 field blanks per set
CARRIER GAS:
helium, 30 mL/min
COLUMN:
stainless steel, 10% FFAP on 80/100 Chromosorb W AW-DMCS (20 ft. x 1/8 in.)
CALIBRATION:
standard solutions of ethyl formate in carbon disulfide with n-nonane as internal standard.
RANGE:
0.1 to 6 mg per sample [1]
ACCURACY RANGE STUDIED:
171-666 mg/m 3 (10-L samples) [1]
BIAS:
7.3%
225 °C 250 °C 65 °C
ESTIMATED LOD: 0.02 mg per sample ˆ ): 0.0782 [1] OVERALL PRECISION (S rT PRECISION (Sr): ACCURACY:
0.019 @ 1.71 to 6.66 mg per sample [1]
± 21.1%
APPLICABILITY: The working range is 3.3 to 210 ppm (10 to 630 mg/m 3) for a 10-L air sample.
INTERFERENCES: Any compound having the same retention time as ethyl formate under the same analytical conditions is an interference. A different temperature program or column with a different phase may eliminate the problem.
OTHER METHODS: This revises Method S36 [2].
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 ETHYL FORMATE: METHOD 1452, Issue 1, dated 15 August 1994 - Page 2 of 3 REAGENTS: 1. 2.
3. 4. 5.
EQUIPMENT:
Ethyl formate, ACS reagent grade. Eluent: carbon disulfide, chromatographic quality, with 0.1% v/v n-nonane, ACS reagent grade (optional internal standard). Helium, purified. Hydrogen, prepurified. Air, compressed, filtered.
SPECIAL PRECAUTIONS
1. Sampler: glass tube, 7 cm long, 6-mm OD, 4mm ID flame-sealed ends with plastic caps, containing two sections of 20/40 mesh of activated (600 °C) coconut shell charcoal (front = 100 mg; back = 50 mg) separated by a 2-mm urethane foam plug. A silylated glass wool plug precedes the front section and a 3mm urethane foam plug follows the back section. Pressure drop across the tube must be less than 3.4 kPa at 1 L/min airflow. Tubes are commercially available. 2. Personal sampling pump, 0.01 to 0.2 L/min, with flexible connecting tubing. 3. Gas chromatograph, FID, integrator, and column. 4. Vials, glass, 2-mL, PTFE-lined caps. 5. Syringe, 10-µL and other convenient sizes for preparing standards. 6. Flasks, volumetric, 10-mL. 7. Pipet, 1-mL graduated in 0.1 mL increments with bulb.
SPECIAL PRECAUTIONS: Carbon disulfide is toxic and a serious fire and explosion hazard (flash point = -30 °C); work with it only in a hood. SAMPLING: 1. 2. 3. 4. 5.
Calibrate each personal sampling pump with a representative sampler in line. Break the ends of the sampler immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.01 and 0.2 L/min for a sample size of 0.3 to 10 L. Replace the caps on the sampling tube and pack securely for shipment. Obtain a small quantity (5 mL) of the bulk material in a glass container with a Teflon-lined cap. Ship to the laboratory in a separate container from the charcoal tube samples.
SAMPLE PREPARATION: 6. 7. 8.
Place the front and back sorbent sections of the sampler tube in separate vials. Discard the glass wool and foam plugs. Add 1.0 mL eluent to each vial. Attach cap to each vial. Allow to stand for 30 min. with occasional agitation.
CALIBRATION AND QUALITY CONTROL: 9.
Calibrate daily with at least six working standards covering the range 0.01 to 6 mg/sample. a. Add known amounts of ethyl formate to eluent in 10-mL volumetric flasks with a concentration equal to 70% of that of the highest standard. b. Analyze together with the samples (steps 12 and 13). NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 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