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Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

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• Colorimetric<br />

• Electrochemical (anodic stripping voltametry and differential pulse polarography).<br />

The choice <strong>of</strong> analytical method today <strong>for</strong> bulk quantification is generally ICP/AES or<br />

ICP/MS (U.S. Environmental Protection Agency, 2001). Since 1986, numerous SRMs have<br />

been developed <strong>for</strong> Pb (Table AX7-1.1.2), and several significant technological improvements<br />

have been developed.<br />

Table AX7-1.1.2. National Institute <strong>of</strong> Standards and Technology <strong>Lead</strong> SRMs<br />

NIST SRM Medium<br />

Mean Pb<br />

mg/kg<br />

2710 Soil 5532<br />

2711 Soil 1162<br />

2709 Soil 18.9<br />

2587 Soil (paint) 3242<br />

2586 Soil (paint) 432<br />

2783 Filter (PM2.5) 317<br />

1648 Urban particulate 6550<br />

1649a Urban dust 12,400<br />

2584 Indoor dust 9761<br />

2583 Indoor dust 85.9<br />

1515 Apple leaves 0.47<br />

1575 Pine needles 0.167<br />

Modern spectrometry systems have replaced photomultiplier tubes with a charge-coupled<br />

device (CCD). The CCD is a camera that can detect the entire light spectrum (>70,000 lines)<br />

from 160 to 785 nm. This allows <strong>for</strong> the simultaneous measurement <strong>of</strong> all elements, as well as<br />

any interfering lines (a productivity increase), and increases precision. The detection limit <strong>for</strong> Pb<br />

in clean samples can now be as low as 40 ppb.<br />

AX7-10

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