Page:NIOSH Manual of Analytical Methods - 2554.pdf/3

 GLY CO L ET HER S: ME TH OD 2554, Issue 1, dated 1 5Ma rch 2003 - Page 3 of 4 CALIBRATION AND QUALITY CONTRO L: 8. Calibrate daily with at least s ix workin g stan dards to cover the analytica l ran ge. If necessary, additional standards may be added to extend the calibration curve. a. Add known amounts of analytes to solvent solution in 10-mL volumetric flasks and dilute to the m ark. Mix well. b. Analyze together with samp les and blanks (steps 11 and 12). c. Prepare calibration graph (peak area versus :g an alyte). 9. Dete rm ine desorption efficiency (DE) at least once for each lot of Anasorb 747 used fo r sam pling in the calibration ranges (step 8). a. Prepare three tubes at each of five levels plus three media blanks. b. Inject a known amount of calibration stock solution directly onto the front sorbent section of each Anasorb 747 tube with a microliter syringe. c. Allow the tub es to air equ ilibrate for several m inutes, then cap the ends of ea ch tube a nd a llow to stan d overnight. d. Deso rb (steps 5-7) and a nalyze together with standards and blanks (steps 11 and 12). e. Prepare a graph of DE versus :g analyte recovered. 10. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration graph and D E graph are in control.

MEASUREMENT: 11. Set gas chromatograph according to manufacturer’s recomm endations and to conditions given on page 2554-1. Inject a 1-:L sample aliquot manually using the solvent flush technique or with an autosam pler. NOTE: If pea k area is abo ve the linear ra nge of the working standard s, dilute w ith solve nt, reanalyze and apply the appropriate dilution factor in the calculations. 12. Measure peak areas.

CALCULATIONS: 13. De term ine the m ass, :g (corrected for D E) of analyte found in the sam ple front (W f) and back (W b) sorbent sec tions, 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 analyte in the air volume sam pled, V(L):

NO TE : :g/L = m g/m 3

EVALUATION OF METHOD: In order to obtain improved analyte collection and recove ry results, several procedures were incorporated in the m etho d de velop m ent. These included the use of a s tain less stee l inlet liner in the injection port to reduce the possibility of degradation of analytes, lower injection port and detector temperatures to prevent thermal decomposition of a nalytes, and the use of Anasorb 747 solid sorbent tubes to reduce the possibility of the hydrolysis of the analytes. This m eth od was developed in support of a fie ld survey to iden tify and quan titate glycol ether vapors emitted from heat-cured solder mask paints. This method is applicable when levels below the REL/PEL are expected. The average desorption efficiency (DE) recovery for propylene glycol monomethyl ether was 100.6% (RSD = 1.6), for dipropylene glycol monomethyl ether, was 102.4% (RSD = 1.8), and for propylene glycol

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition