Pyridine (1613)
PYRIDINE
C5H5N
MW: 79.10
METHOD: 1613, Issue 2
CAS: 110-86-1
1613
RTECS: UR8400000
EVALUATION: FULL
OSHA : 5 ppm NIOSH: 5 ppm; Group III Pesticide ACGIH: 5 ppm (1 ppm = 3.23 mg/m 3 @ NTP)
PROPERTIES:
Issue 1: 15 August 1987 Issue 2: 15 August 1994
liquid; d 0.982 g/mL @ 20 °C; BP 115 °C; MP -42 °C; VP 2.4 kPa (18 mm Hg; 2.4% v/v) @ 20 °C; explosive limits 1.8 to 12.4% v/v in air
SYNONYMS: azine; azabenzene
SAMPLING SAMPLER:
SOLID SORBENT TUBE (coconut shell charcoal, 100 mg/50 mg)
MEASUREMENT TECHNIQUE:
GAS CHROMATOGRAPHY, FID
ANALYTE:
pyridine
FLOW RATE:
0.01 to 1.0 L/min
DESORPTION:
1 mL methylene chloride; stand 30 min
VOL-MIN: -MAX:
18 L 150 L
INJECTION VOLUME:
5 µL
SHIPMENT:
routine
SAMPLE STABILITY:
TEMPERATURE-INJECTION: -DETECTOR: -COLUMN:
not determined
FIELD BLANKS:
2 to 10 field blanks per set
CARRIER GAS:
260 °C 285 °C 140 °C
N 2, 30 mL/min
COLUMN:
3 m x 3-mm OD stainless steel packed with 5% Carbowax 20M on 80/100 mesh acid-washed DMCS Chromosorb W
CALIBRATION:
standard solutions methylene chloride
RANGE:
0.3 to 4.5 mg per sample
ACCURACY RANGE STUDIED:
7.6 to 30 mg/m 3 [1] (100-L samples)
BIAS:
9.2%
ˆ rT): 0.059 [1] OVERALL PRECISION (S ACCURACY:
± 19.8%
of
pyridine
in
ESTIMATED LOD: 0.02 mg per sample [2] PRECISION (Sr):
0.014 @ 0.8 to 3.1 mg per sample [1]
APPLICABILITY: The working range is 1 to 14 ppm (3 to 45 mg/m 3) for a 100-L air sample.
INTERFERENCES: None detected. The chromatographic column or separation may be changed to circumvent interference problems (e.g., 30 m x 0.32-mm capillary column with 1 µm DB-5 at 50 °C [2]).
OTHER METHODS: This revises Method S161 [3].
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 PYRIDINE: METHOD 1613, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1. 2. 3. 4.
5. 6. 7.
EQUIPMENT:
M e t h y l e n e chloride (CH 2Cl 2) , chromatographic quality. Pyridine, reagent grade.* Hexane, chromatographic quality. DE stock solution, 300 mg/mL. Weigh 3 g pyridine (ca. 3.1 mL) into a 10-mL volumetric flask. Dilute to volume with hexane. Prepare in duplicate. Nitrogen, purified. Hydrogen, prepurified. Air, filtered, compressed.
1.
2. 3.
- See SPECIAL PRECAUTIONS.
4. 5. 6. 7. 8.
Sampler: glass tube, 7 cm long, 6-mm OD, 4-mm ID, flame-sealed ends, with plastic caps, containing two sections 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 3-mm urethane foam plug follows the back section. Pressure drop across the tube at 1 L/min airflow must be less than 3.4 kPa. Tubes are commercially available. Personal sampling pump, 0.01 to 1 L/min, with flexible connecting tubing. Gas chromatograph, flame ionization detector, integrator and column (page 1613-1). Vials, 2-mL, PTFE-lined crimp caps. Syringes, 10-µL, readable to 0.1 µL. Volumetric flasks, 10-mL. Pipet, TD, 1-mL. Balance, analytical.
SPECIAL PRECAUTIONS: Pyridine can cause liver and kidney damage, and CNS depression if it is inhaled or contacts the eyes or skin [4,5]. Methylene chloride is a suspect carcinogen [6].
SAMPLING: 1. 2. 3. 4.
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 1 L/min for a total sample size of 18 to 150 L. Cap the samplers. Pack securely for shipment.
SAMPLE PREPARATION: 5. 6. 7.
Place the front and back sorbent sections of the sampler tube in separate vials. Discard the glass wool and foam plugs. Pipet 1.0 mL CH 2Cl2 into each vial. Cap each vial. NOTE: A suitable internal standard, such as toluene, may be added at this step [2]. Allow to stand 30 min with occasional agitation.
CALIBRATION AND QUALITY CONTROL: 8.
Calibrate daily with at least six working standards. a. Add known amounts of pyridine to CH 2Cl2 in 10-mL volumetric flasks and dilute to the mark. Use serial dilutions as needed to obtain pyridine concentrations in the range 0.02 to 4.5 mg/mL. b. Analyze together with samples and blanks (steps 11 and 12). c. Prepare calibration graph (peak area vs. mg pyridine). NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 PYRIDINE: METHOD 1613, Issue 2, dated 15 August 1994 - Page 3 of 4 9.
10.
Determine desorption efficiency (DE) at least once for each batch of charcoal used for sampling in the calibration range (step 8). Prepare three tubes at each of five levels plus three media blanks. a. Remove and discard back sorbent section of a media blank sampler. b. Inject a known amount (2 to 20 µL) of DE stock solution, or a serial dilution thereof, directly onto front sorbent section with a microliter syringe. c. Cap the tube. Allow to stand overnight. d. Desorb (steps 5 through 7) and analyze together with working standards (steps 11 and 12). e. Prepare a graph of DE vs. mg pyridine recovered. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration graph and DE graph are in control.
MEASUREMENT: 11.
12.
Set gas chromatograph according to manufacturer's recommendations and to conditions given on page 1613-1. 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 CH 2Cl2, reanalyze, and apply the appropriate dilution factor in calculations. Measure peak area.
CALCULATIONS: 13.
14.
Determine the mass, mg (corrected for DE) of pyridine 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 pyridine in the air volume sampled, V (L):
EVALUATION OF METHOD: Method S161 was issued on August 1, 1975 [3], and validated with atmospheres generated by calibrated syringe pump and confirmed using a total hydrocarbon analyzer [2]. Average recovery was 109% ±3.6% (18 samples) in the range 7.6 to 30.4 mg/m 3 for 100-L samples. Breakthrough (effluent concentration = 5% of test concentration) was not observed after sampling for 240 min at 0.93 L/min from an atmosphere containing 30.4 mg/m 3 pyridine in dry air. Carbon disulfide and methanol were tested and rejected as possible desorbing solvents. Carbon disulfide gave an average DE of 0.734; methanol, 0.201. Desorption efficiency using methylene chloride for 18 spiked samples in the range 0.8 to 3.1 mg pyridine per sample averaged 0.81 with S r = 0.013.
REFERENCES: [1] Documentation of the NIOSH Validation Tests, S161, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-185 (1977), available as Stock No. PB 274-248 from NTIS, Springfield, VA 22161. [2] UBTL, Inc. Report, NIOSH Sequences 4949-K (unpublished, May 24, 1985) and 3030-K (unpublished, July 20, 1981). [3] NIOSH Manual of Analytical Methods, 2nd. ed., V. 3, S161, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-C (1977).
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94 PYRIDINE: METHOD 1613, Issue 2, dated 15 August 1994 - Page 4 of 4 [4] NIOSH/OSHA Occupational Health Guidelines for Chemical Hazards, U.S. Department of Health and Human Services, Publ. (NIOSH) 81-123 (1981), available as Stock #PB83-154609 from NTIS, Springfield, VA 22161. [5] Merck Index, 10th ed., Merck & Co., Rahway, NJ (1983). [6] NIOSH Current Intelligence Bulletin 46, U.S. Department of Health and Human Services, Publ. (NIOSH) 86-114 (1986).
METHOD REVISED BY: G. David Foley, NIOSH/DPSE.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94