NEW! UPDATED! EXPANDED! A totally revised edition of the best selling single publication ever p r o d u c e d by A C S
Cleaning Our Environment Lr%[T©[p(g©U0W(: New chapters on • analysis & monitoring • toxicology • radiation Updated coverage on • air • water • solid wastes • pesticides Essential reading for: • educators • researchers • legislators • administrators • and a great refresher for environmentalists
Special Issues Sales American Chemical Society 1155 16th St., N.W. Washington, D.C. 20036 Prices: 1-9 copies 10-Λ9 copies 50 or more
$9.50 each $8.50 each $7.50 each
Enclose $1.50 per order for handling and postage. California residents add 6% state use tax.
occurring within the atom reservoir resulting in increased sensitivity. One of the most useful instrumental im p r o v e m e n t s has been the introduction of electrodeless discharge lamps. T h e increased stability and intensity of these sources have greatly improved b o t h the sensitivity and precision of analyses, particularly for As and Se. T h o m p s o n (26) and Tsujii and Kuga (23) have coupled the hydride generation technique_ with atomic flu orescence spectrometers using argon/ hydrogen flames as atom reservoirs. Solution detection limits for hydride generation sampling as well as those for conventional solution nebulization are listed in T a b l e II. Improvements in analyte detection over solution analysis are similar in magnitude to those obtained in atomic absorption experiments. Atomic emission has been used by n u m e r o u s workers employing DC plasmas (28, 29), microwave induced plasmas (MIP) (6, 22), and inductive ly coupled plasmas (ICP) (30) as exci tation sources. One commonly en countered difficulty is the instability or incompatibility of atmospheric pressure plasmas with the large quan tity of hydrogen produced during the generation reaction. T h i s phenomenon has been reported by B r a m a n et al. (28), Fricke et al. (22), Miyazaki et al. (29), and T h o m p s o n et al. (30), and may be circumvented by the use of a liquid nitrogen condensation appara t u s to separate the hydrides from the hydrogen (22, 29). Alternatively, a less efficient reaction t h a n the N a B H 4 / acid type may be used to generate the hydrides (6); or if the source has suffi cient power, the N a B H 4 reaction may be used with reduced N a B H 4 concen tration (30). Another problem t h a t has only been infrequently reported is broad band molecular emission re sulting from the presence of H 2 0 , HC1, and CO^ carried from or pro duced by the hydride generation reac tion (22). (The COs. is produced when Na-2CO:! c o n t a m i n a n t s present in t h e
Table III. Comparison of Detection Limits for Atomic Emission Spectroscopy Detection Limits, /ig/mL Inductively Inductively coupled coupled plasma/solution plasma/ nebulization a hydride b
Ge As Se Sn Sb Te Pb Bi a
0.15 0.04 0.03 0.3 0.2 0.08 0.008 0.05
Taken from ref. 46. from rel. 22.
0.0008 0.0008 0.001 0.001
Microwaveinduced plasma/ hydride
c
0.00015 0.00035 0.00125 0.002 0.0005
0.0008 6
Taken from ref. 30.
c
Taken
N a B H 1 reagent are mixed with acid.) These contaminants may be chromatographically removed as discussed below. Detection limits for hydride generation systems as well as those for conventional solution analysis are list ed in Table III. Substantial improve m e n t is observed in all available values. Detection by thermal conductivity (23, 31), flame ionization (23, 31), mass spectrometry (32, 33), radio chemical techniques (34), and molecu lar emission cavity analysis (27) has also been used with preliminary chro matographic separation of t h e various hydrides from one another and from reaction products or c o n t a m i n a n t s . Detectors amenable to simultaneous multielement detection are of increas ing interest since this is one of the most direct m e t h o d s to reduce the cost of analysis both in terms of re agents and analysis time.
Please send me copies of Cleaning Our Environment — A Chemical Perspective
Table II. Comparison of Detection Limits for Atomic Fluorescence Spectrometry Detection Limits, μς/ιτιί
Name
AF/solutlon nebulization "
Address
City State
Zip
D My payment is enclosed
894 A ·
Π Bill me
Ge As Se Sn Sb Te Pb Bi
0.1 0.1 0.04 0.05 0.05 0.005 0.01 0.005
AF/hydride
0.0001 0.00006 0.0001 0.00008
" Taken from ref. 38. " Taken from ref. 37.
A N A L Y T I C A L CHEMISTRY, VOL. 5 1, NO. 8, JULY
1979
b
Figure 3. Chromatographic separation of AsH 3 from background contaminants at 1937 Λ
