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Handbook of Solvents - George Wypych - ChemTech - Ventech!

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15.2.1 Use <strong>of</strong> breath monitoring 1085<br />

End-exhaled air is becoming the standard for breath monitoring. Of the 36 chemicals<br />

with established BEIs, 7 end-exhaled air is recommended for 6, while earlier BEIs recommending<br />

mixed-exhaled air have been withdrawn. Beyond the regulatory arena, however,<br />

mixed-exhaled air continues to be used with satisfactory results.<br />

Methodologically, the difference between these two types <strong>of</strong> samples is the control<br />

over which portion <strong>of</strong> the breath is collected. Many techniques 28-32 make use <strong>of</strong> the<br />

Haldane-Prestley tube to collect the last portion <strong>of</strong> the expiration. Earlier work 6,19 used the<br />

simultaneous monitoring <strong>of</strong> CO 2 or temperature in the exhaled breath to identify the moment<br />

(CO 2 or temperature reaching a maximum) when air from the anatomical dead space<br />

has been purged and alveolar air can be sampled.<br />

A variety <strong>of</strong> sampling techniques has been tried for measuring organic vapors in exhaled<br />

air. Table 15.2.1.1 shows a classification <strong>of</strong> these techniques. The main distinction is<br />

between direct reading instruments and transportable samples that require analysis in the<br />

laboratory. The former group covers the widest range, from simple detector tubes to High<br />

Resolution Mass Spectrometry.<br />

Table 15.2.1.1. Techniques for sampling organic vapors in exhaled air<br />

Technique References<br />

A. SAMPLE COLLECTION<br />

A.1 END-EXHALED AIR<br />

Use <strong>of</strong> Haldane-Prestley tube<br />

Simultaneous CO 2 monitoring<br />

Simultaneous temperature monitoring<br />

B. SAMPLE ANALYSIS<br />

B.1 DIRECT READING INSTRUMENTS<br />

B.1.1 DETECTOR TUBES<br />

Colorimetric<br />

B.1.2 GAS CHROMATOGRAPHS with various detectors and<br />

modified injector/inlet with mouthpiece<br />

GC/FID<br />

GC/PID<br />

GC/MS<br />

B.2 TRANSPORTABLE SAMPLE COLLECTORS<br />

B.2.1 CONTAINERS<br />

B.2.1.1 Rigid containers<br />

Stainless steel tubes<br />

Glass tubes<br />

Aluminum tubes<br />

B.2.1.2 Flexible containers<br />

Tedlar bags<br />

Saran bags<br />

Mylar bags<br />

B.2.2 ADSORBENTS<br />

B.2.2.1 Tubes/cartridges containing:<br />

Charcoal<br />

Tenax<br />

Silica gel<br />

B.2.2.2 Felt/cloth<br />

23, 25, 26, 28, 29, 31<br />

6, 20, 21, 24<br />

19<br />

33<br />

52<br />

25, 26<br />

24, 41, 42, 43<br />

24<br />

9, 53, 54, 55, 61, 64<br />

28, 29, 47<br />

6, 49<br />

54, 55, 60<br />

25, 26, 28, 29, 40<br />

31, 49<br />

6<br />

48<br />

Specifically, detector tubes operating on colorimetric reaction principles have been<br />

used to determine the concentration <strong>of</strong> alcohol in breath for traffic safety. 33 Alcohol measurements<br />

in breath have been thoroughly studied and scrutinized because <strong>of</strong> the forensic

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