2.1 Apparatus

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

2.1.2 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 and with a glass wool plug at the front. For this evaluation, commercially prepared sampling tubes were purchased from SKC, Inc. (Catalog no. 226-110, lot 2573).

2.2 Reagents

None required.

2.3 Technique

2.3.1 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.

2.3.2 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.

2.3.3 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.

2.3.4 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.

2.3.5 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.

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

2.3.7 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 the front sections of Chromosorb 106 tubes with 1, 6-hexanediol diacrylate at 0.1 to 2 times the target concentration, based on a 48-L air volume, for a loading of 4.85 to 97.0 µg/sample. These samples were stored overnight at ambient temperature and then extracted with 1 mL of extracting solvent on a shaker for 30 minutes, and analyzed by GC-FID. The mean extraction efficiency over the studied range was 98.9%. The wet extraction efficiency was determined at 1 times the target concentration by liquid spiking the analyte onto Chromsorb 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 98.7%.

Table 2.4 Extraction Efficiency (%) of 1,6-Hexanediol Diacrylate
level		sample number						mean
x target concn	µg per Sample	1	2	3	4	5	6
0.1	4.85	98.7	99.3	97.9	97.6	99.0	99.1	98.6
0.5	24.3	99.8	99.9	99.4	98.7	99.9	99.7	99.6
1.0	48.5	98.9	99.0	98.3	98.0	98.5	98.2	98.5
1.5	72.7	99.0	97.9	98.7	98.3	98.7	98.9	98.6
2.0	97.0	98.7	99.2	99.0	98.9	99.1	99.2	99.0
1.0 (wet)	48.5	97.9	98.7	98.9	98.8	99.3	98.3	98.7

2.5 Retention efficiency

Six Chromosorb 106 tubes were spiked with 97.0 µg (2.02 mg/m³) of 1,6-hexanediol diacrylate in the front sections, and allowed to equilibrate for 4 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 98.7%. There was no analyte found on the back-up section of any of the tubes.

Table 2.5 Retention Efficiency (%) of 1,6-Hexanediol Diacrylate
section	sample number						mean
	1	2	3	4	5	6
front of spiked tube	99.0	98.7	99.2	98.8	97.9	98.3	98.7
rear of spiked tube	0.0	0.0	0.0	0.0	0.0	0.0	0.0
total	99.0	98.7	99.2	98.8	97.9	98.3	98.7

2.6 Sample storage

Fifteen Chromosorb 106 tubes were each spiked with 48.5 µg (1.01 mg/m³) of 1,6-hexanediol diacrylate. They were allowed to equilibrate for 6h, then 48 L of air, with an absolute humidity of 15.7 milligrams of water per liter of air (about 80% relative humidity at 23 °C), drawn through them. Three samples were analyzed immediately, and the rest were sealed. Six samples were stored at room temperature (23 °C), while the other six samples were stored at refrigerated temperature (4 °C). Three samples from each set of storage samples were analyzed after 7 days of storage and the remaining three from each set after 14 days. The amounts recovered indicate good storage stability for the time period studied.

Table 2.6 Storage Test for 1,6-Hexanediol Diacrylate
time (days)	ambient storage recovery (%)			refrigerated storage recovery (%)
0	98.5	99.0	99.4
4	98.1	98.6	97.8	98.8	99.1	98.2
14	96.9	98.0	97.0	98.2	98.9	97.8

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)

2.8.1 There are no known compounds which will severely interfere with the collection of 1,6-hexanediol diacrylate.

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