GLUTARALDEHYDE: METHOD 2532, Issue 1, dated 15 August 1994 - Page 3 of 4 7. 8. 9.
Transfer back section (150 mg) with remaining glass wool plugs to a second vial. Add 3.0 mL of acetonitrile to each vial. Screw cap tightly onto each vial. Agitate vials in a mechanical shaker for at least 2 h. NOTE: The use of ultrasonic bath yields incomplete recovery.
CALIBRATION AND QUALITY CONTROL: 10.
11.
Calibrate daily with at least six working standards over the range of interest. a. Prepare and standardize glutaraldehyde stock solution. (See APPENDIX.) Make serial dilutions of the stock solution with water. b. Using a microliter syringe, add known amounts of glutaraldehyde directly onto the DNPHcoated silica gel tubes over the range of interest. Allow the tubes to stand overnight for solvent evaporation and equilibration. c. Prepare the standards as described in Steps 5 through 9 and analyze with samples and blanks. d. Prepare a calibration graph (peak area or height vs. concentration). NOTE: Because the working standards are prepared on media blanks, no additional blank correction or extraction efficiency correction is necessary. Check extraction efficiency occasionally in the range of interest. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration graph and recovery graph are in control.
MEASUREMENT: 12. 13. 14.
Set the liquid chromatograph to manufacturer's recommendations and parameters given on page 5512-1. Inject 25-µL sample aliquot. Measure peak area or height for each UV response. The two isomers of glutaraldehyde are separated using these chromatographic conditions. Sum the peak area or height of both isomers to obtain the total area of height.
CALCULATIONS: 15.
16.
Determine the mass, µg, of glutaraldehyde found in the sample front (W f) and back (Wb) sorbent sections. NOTE 1: Corrections for extraction efficiency and blanks are incorporated into the method by using spiked media as standards. NOTE 2: If Wb > Wf/10, report breakthrough and possible sample loss. Calculate concentration (C) of glutaraldehyde in the air volume sampled in liters (V):
C
(W f
W b) V
, mg/m 3.
EVALUATION OF METHOD: The pressure drop at 0.2 L/min across representative tubes was 6" 2H O, at 0.5 L/min about 14" H2O, but at 1 L/min it was about 46" H2O. This method incorporates the use of spiked media as standards eliminating recovery bias. Mechanical agitation gave better recovery and linearity of the calibration curve ranging from 0.6 to 24 µg per sample. Recoveries from tubes agitated by sonic bath decreased as the concentration increased. Recoveries of glutaraldehyde from the DNPH-coated tubes were determined by spiking 6 tubes each at concentrations of 1.2, 2.4, and 12 µg per sample. After standing overnight to allow the solvent to evaporate, the sorbent was transferred to a vial, 3 mL of acetonitrile was added, and the sample was agitated in a mechanical shaker for at least 1 h. At the same time, 6 more tubes were spiked at each of these concentrations and stored in the laboratory at ambient conditions for 42 days. The data are shown in Table 1.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition
