Trace Analysis in End-Exhaled Air Using Direct Solvent Extraction in Gas Sampling Tubes: Tetrachloroethene in Workers as an Example

Table 1

Example pipetting scheme for the preparation of the calibration samples; concentration range 2 to 20 μg tetrachloroethene/L exhaled air.

Number	Calibration solutions				Calibration samples
	Conc. stock solution II (mg/L)	𝑉 stock solution II (μL)	𝑉 final (mL)	Conc. (µg/L)	𝑉 calibration solution (µL)	𝑉 gas sampling tube (mL)	Mass (µg)	Conc. (µg/L)
1	93.9	40	10	376	200	37.433	0.0751	2.0
2	93.9	80	10	751	200	37.668	0.1502	4.0
3	93.9	120	10	1127	200	37.639	0.2254	6.0
4	93.9	160	10	1502	200	37.524	0.3005	8.0
5	93.9	200	10	1878	200	37.573	0.3756	10.0
6	93.9	240	10	2254	200	37.486	0.4507	12.0
7	93.9	280	10	2629	200	37.544	0.5258	14.0
8	93.9	320	10	3005	200	37.593	0.6010	16.0
9	93.9	360	10	3380	200	37.598	0.6761	18.0
10	93.9	400	10	3756	200	37.661	0.7512	19.9