High-sensitivity spectrophotometry - Analytical Chemistry (ACS

Identification of polychlorinated dibenzo-p-dioxin isomers by powder x-ray diffraction with electron capture gas chromatography. P. J. Slonecker , J. ...
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T. D. Harris Bell Labcratories Murray Hill, NJ. 07974

High-Sinsitivity Spectrophotomdry Quantitative analysis by solution spectrophotometry has been in continnous practice for more than a century ( I 1. Instrumental design has remained conceptually stable since the early part of this century. However, the advent of stable electronics and reliable lasers has spawned a group of techniques for measuring absorbance that provides a quantum leap in spectrophotometric sensitivity. The exceptional sensitivity available from a wide variety of methods is illustrated in Table I. This high sensitivity has not yet been aiven enouah attention bv

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I. Absorptioil

:tion Limits in Solut D.,~ion limn (M)

Method

;onventionai transmission .aser intracavity nterlerometry ahotothermai dPfleCtinn Pholoacoust~i Thermal lens

1X i O F

sx

10-6

lo-' I

x

1n-7