Specifications

10
4.1.3 Silica Gel Tubes
Environmental (area) sampling was conducted using two personal pumps and treated silica gel
tubes. The pumps were calibrated using a mini buck calibrator, model number M-5, Serial
Number 050621 last calibrated on March 21, 2001. The pumps were field calibrated upon
arrival at the hospital and at the end of the sampling day, each time requiring three readings
within 5% to show that the pump had stabilized. The pumps were turned on for 10 minutes prior
to calibration to allow them to warm up.
The two pumps were set up on the fridge immediately adjacent to the formalin dispensing station
and the silica gel tubes were attached to the pumps using rubber tubing. The tubing was set up
on the fridge allowing the sampling tubes to be located within one foot of the nurses breathing
zone when the formalin was being dispensed. One pump was set up to sample for 317 minutes
with a flow rate of 0.204 L/min and the tubes attached to the other pump were replaced after 98,
92 and 125 minutes respectively with a flow rate of 0.203 L/min. One blank was taken for the
four tubes.
Lab analysis was conducted at the WCB lab as per WCB Analytical Method 5270 – Aldehydes
in Air. This method involves analysis with a high performance liquid chromatograph with a UV-
visible detector. This method has an error of +/- 3.3%.
4.1.4 Colorimetric Detector Tubes
Personal sampling was conducted using a Gastec pump and formaldehyde colorimetric detector
tubes. One sample was taken each time a nurse brought a tissue biopsy to the dispensing station.
The procedure for the Gastec tubes required five strokes and each stroke was drawn in the
nurse’s breathing zone. Since the pump required approximately one minute between the five
strokes the nurses always left the dispensing area during the sampling period and the sampling
continued in their breathing zone even after they had left the dispensing area.
This method has an error of +/- 10%.