POLYNUCLEAR AROMATIC HYDROCARBONS by GC: METHOD 5515, Issue 2, dated 15 August 1994 - Page 3 of 7
S P E C I A L P R E C A U T I O N S : T r e a t b e n z e n e , m e t h y l e n e c h l o r i d e , a n d a l l p o l y n u c l e a r a r o m a t i c h y d r o c a r b o n s a s c a r c i n o g e n s . N e a t c o m p o u n d s s h o u l d b e w e i g h e d i n a g l o v e b o x . S p e n t s a m p l e s a n d u n u s e d s t a n d a r d s a r e t o x i c w a s t e . R e g u l a r l y c h e c k c o u n t e r t o p s a n d e q u i p m e n t w i t h " b l a c k l i g h t " f o r f l u o r e s c e n c e a s a n i n d i c a t o r o f contamination by PAH.
SAMPLING: 1. 2.
3.
4. 5.
Calibrate each personal sampling pump with a representative sampler in line. Take personal samples at 2 L/min for a total sample size of 200 to 1000 L. Take a concurrent set of eight replicate area samples at 2 to 4 L/min on preweighed, 2-µm PTFE filters in an area of highest expected PAH concentration. NOTE: The area samples are needed for solvent selection (step 7). Immediately after sampling, transfer the filter carefully with forceps to a scintillation vial. Hold filter at edge to avoid disturbing the deposit. Cap the scintillation vial and wrap it in aluminum foil. NOTE: This step is necessary to avoid loss of analytes due to sublimation and degradation by light. Cap the sorbent tube and wrap it in aluminum foil. Ship to laboratory in insulated container with bagged refrigerant.
SAMPLE PREPARATION: NOTE: UV light may degrade PAH. Use yellow, UV-absorbing shields for fluorescent lights or use incandescent lighting. 6. Refrigerate samples upon receipt at laboratory. 7. Determine optimum extraction solvent. a. Allow the preweighed area filter samples to equilibrate 24 h with the laboratory atmosphere. b. Weigh the area filters. Determine total weight collected on each. c. Extract the first pair of area filters with acetronitrile, the second with benzene, the third with cyclohexane, and the fourth with methylene chloride, according to step 8. NOTE: Use alternate solvents, if appropriate. PAH of interest may be entrained within, and adsorbed by, particulate matter collected on the filter. It is necessary to determine the solvent which maximizes recovery of the PAH from each sample matrix. For example, methylene chloride [3,4] and benzene:ethanol (4:1 v/v) [5] have been recommended for extraction of PAH from diesel exhaust particulate. d. Analyze the extracts for the PAH of interest (steps 10 through 18). Normalize the total mass of PAH found to the mass of sample collected. e. Choose the solvent which gives the highest recovery of PAH of interest. Use the solvent chosen to extract the personal filter samples. 8. Extract filters. a. Add 5.0 mL of the solvent chosen in step 7 to each scintillation vial containing a filter. Start media and reagent blanks at this step. b. Cap and let stand 15 to 20 min in an ultrasonic bath. NOTE: Soxhlet extraction may be required when large amounts of highly adsorptive particulate matter (e.g., fly ash or diesel soot) are present. 9. Desorb PAH from sorbent. a. Score each sorbent tube with a file in front of the primary (larger) sorbent section. Break tube at score line. b. Transfer front glass wool plug and front sorbent section to a culture tube. Transfer back NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
