Versatile, 'Go Anywhere' Industrial pH Transmitters
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T a b l e I. F l a m e Characteristics Desirable for M u l t i e l e m e n t Flame Spectrometry Technique
Characteristics
Atomic emission
Potential f l a m e s
Good atomization efficiency for wide variety of elements
Shielded N 2 0 - C 2 H 2
Long residence time in optical
Fuel-rich oxyacetylene
path High temperature for good excitation efficiency Large variation in excitation conditions over small flame region to allow simultaneous excitation and observation of many elements Good atomization efficiency for
Atomic absorption
N20-C2H2
wide variety of elements Long residence time in optical Atomic fluorescence
path
Separated N 2 0 - C 2 H 2
Good atomization efficiency for wide variety of elements Long residence time in optical
Flame sheathed a i r acetylene
path Low background spectral radiance Low concentration of quenchers Low scattering of exciting radiation T a b l e I I . Primary Light S o u r c e s for Multielement F l a m e S p e c t r o m e t r y Technique
Atomic absorption
Approach
Limitations
Single-element hollow cathode lamps Multielement hollow cathode lamps Tandem hollow cathode lamps
Complicated optical arrangement required Number of elements which c a n be incorporated in given lamp limited Limited to three lamps by light
Time-resolved spark Continuum
Kent EIL Series 2830 pH trans mitters have lab instrument accuracy, but are rugged and waterproof. Have integral local indicators and standard 0-14 pH/0-800 mV scales —output of 4-20 mA.
Atomic fluorescence
Banks of singleelement electrodeless discharge tubes Banks of pulsed hollow cathode lamps
Optional features include .. . • high/low alarms and controls with relays • any 2, 5 or 10 pH expanded scale • 7201 flow electrode system • ultrasonic cleaning on electrodes Write for complete data to: ΛΜΨ C Î
KENT CAMBRIDGE INSTRUMENT COMPANY
^ 1 ^ Division of Kent Cambridge Corp. 73 S p r i n g S t r e e t , O s s i n i n g , N.Y. 10562 (914) 941-8100 T e l e x 137-337 IN CANADA KENT CAMBRIDGE LIMITED Thornhill, Ontario, Canada (416) 889-8330 Telex 06-217518 CIRCLE 1 1 9 O N READER SERVICE CARD 714 A ·
ANALYTICAL
CHEMISTRY,
Multielement electrodeless discharge tubes
Tunable laser Continuum
An alternative approach to the primary source problem of simultaneous multielement analysis by atomic absorption is the production of a light source which simultaneously radiates resonance lines of a variety of elements, i.e., multielement light sources. Massman (13) studied the factors involved in the production of multielement hollow cathode lamps. Concentric rings of metals retained in a copper or steel sheath have proV O L . 4 5 , N O . 8, J U L Y
1973
losses Less sensitive & less reproducible than hollow cathode lamp Low spectral radiance at short wavelengths & less sensitive than hollow cathode lamp Number of elements which can be incorporated into given lamp limitedmicrowave power supplies Multiple required
No serious limitations except system may become unwieldy for large number of lamps Very expensive at present Low spectral radiance at shorter wavelengths
duced lamps with up to four elements. Since the sputtering rates and melting points of the elements are parameters affecting the production of multielement hollow cathode lamps, it seems unlikely that this approach will yield lamps having a large enough number of elements for true multielement analysis. Strasheim and Butler (14, 15) made specially designed hollow cathode lamps which allow tandem
