2.1 Apparatus

Samples are collected using a personal sampling pump calibrated, with the sampling device attached, to within ± 5% of the recommended flow rate.

Samples are collected with 7-cm × 4-mm i.d. × 7-mm o.d. glass sampling tubes packed with two sections (100/50 mg) of Chromosorb 106. The sections are held in place with foam plugs with a glass wool plug at the front. For this evaluation, commercially prepared sampling tubes were purchased from SKC, Inc. (catalogue no. 226-110 lot 2573).

2.2 Reagents

None required.

2.3 Technique

Immediately before sampling break off the ends of the flame-sealed tube to provide an opening approximately half the internal diameter of the tube. Wear eye protection when breaking the tube. Use tube holders to minimize the hazard of broken glass. All tubes should be from the same lot.

The smaller section of the adsorbent tube is used as a back-up and is positioned nearest the sampling pump. Attach the tube holder to the sampling pump so that the adsorbent tube is in an approximately vertical position with the inlet facing down during sampling. Position the sampling pump, tube holder, and tubing so they do not impede work performance or safety.

Draw the air to be sampled directly into the inlet of the tube holder. The air being sampled is not to be passed through any hose or tubing before entering the sampling tube.

After sampling for the appropriate time, remove the adsorbent tube and seal it with plastic end caps. Seal each sample end-to-end with an OSHA-21 form as soon as possible.

Submit at least one blank sample with each set of samples. Handle the blank sample in the same manner as the other samples except draw no air through it.

Record sample air volumes (liters), sampling time (minutes), and sampling rate (L/min) for each sample, along with any potential interferences on the OSHA-91A form.

Submit the samples to the laboratory for analysis as soon as possible after sampling. If delay is unavoidable, store the samples at refrigerator temperature. Ship any bulk samples separate from the air samples.

2.4 Extraction efficiency

The extraction efficiency was determined by spiking Chromosorb 106 tubes with tetrahydrofurfuryl acrylate at 0.1 to 2 times the target concentration. These samples were stored overnight at ambient temperature and then extracted with 1 mL of the extracting solvent for 30 minutes with shaking, and analyzed. The mean extraction efficiency over the studied range was 98.6%. The wet extraction efficiency was determined at the target concentration by liquid spiking the analyte onto Chromosorb 106 tubes which had 48-L humid air (absolute humidity of 15.9 mg/L of water, about 80% relative humidity at 22.2 °C) drawn through them immediately before spiking. The mean recovery for the wet samples was 98.6%.

Table 2.4 Extraction Efficiency (%) of Tetrahydrofurfuryl Acrylate
level		sample number
x Target concn	µg per Sample	1	2	3	4	5	6	mean
0.1	5.3	98.8	97.1	97.2	97.3	99.9	99.6	98.3
0.5	26.6	98.5	98.7	99.3	99.0	99.9	99.7	99.2
1.0	53.2	98.5	98.2	98.4	98.3	98.9	98.8	98.5
1.5	79.8	98.9	97.8	99.2	98.4	98.7	98.9	98.7
2.0	106	98.4	98.1	97.9	98.9	98.7	99.6	98.5
1.0 (wet)	53.2	98.8	98.4	98.1	98.9	99.9	98.2	98.6

2.5 Retention efficiency

Six Chromosorb 106 tubes had their front sections spiked with 106 µg (2.21 mg/m³) of tetrahydrofurfuryl acrylate and allowed to equilibrate for 6 h. The tubes had 48-L humid air (absolute humidity of 15.9 mg/L of water, about 80% relative humidity at 22.2 °C) pulled through them at 0.2 L/min. The samples were extracted and analyzed. The mean recovery was 99.1%. There was no analyte found on the back-up section of any of the tubes.

Table 2.5 Retention Efficiency (%) of Tetrahydrofurfuryl Acrylate
sample number
section	1	2	3	4	5	6	mean
front	99.4	100.2	98.7	99.3	99.3	98.3	99.1
rear	0.0	0.0	0.0	0.0	0.0	0.0	0.0
total	99.4	100.2	98.7	99.3	99.3	98.3	99.7

2.6 Sample storage

Fifteen Chromosorb 106 tubes were each spiked with 53 µg (1.1 mg/m³) of tetrahydrofurufryl acrylate and were allowed to equilibrate for 6 h, then 48-L of air, with an absolute humidity of 15.7 milligrams of water per liter of air (about 80% relative humidity at 22.2 °C), was drawn through them at 0.2 L/min. Three samples were analyzed immediately. The remaining samples were sealed and six were stored at room temperature (23 °C), while the other six were stored at refrigerated temperature (4 °C). On day 7 three samples from each group were analyzed, and the remaining three from each group was analyzed on day 14. The amounts recovered, indicate good storage stability for the time period studied, with an average recovery on day 14 of 97.5% for ambient storage and 98.1% for refrigerated storage.

Table 2.6 Storage Test for Tetrahydrofurfuryl Acrylate
time (days)	ambient storage recovery (%)			refrigerated storage recovery (%)
0	99.1	98.3	98.5
7	97.9	98.4	98.7	98.9	98.2	97.7
14	97.2	98.1	97.1	98.0	98.4	97.9

2.7 Recommended air volume and sampling rate

Based on the data collected in this evaluation, 48-L air samples should be collected at a sampling rate of 0.2 L/min for 240 minutes.

2.8 Interferences (sampling)

There are no known compounds which will severely interfere with the collection of tetrahydrofurfuryl acrylate.

Suspected interferences should be reported to the laboratory with submitted samples.