JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, OCTOBER 1988, VOL. 3 1013

Characterisation of Spectral Interferences in Background Correction for Arsenic, Selenium and Antimony in Electrothermal Atomic Absorption Spectrometry lvar Martinsen National Institute of Occupational Health, P.O. Box 8749 DEP, N-0033 Oslo 7, Norway Bernard Radziu k Department of Applied Research, Bodenseewerk Perkin-Elmer & Co. GmbH, Postfach 1720, 0-7770 Uberlingen, FRG Yngvar Thomassen National Institute of Occupational Health, P.O. Box 8749 DEP, N-0033 Oslo 7, Norway

Absorption spectra for Al, Co, Cu, Fe, Ni and Pt in the vicinity of As, Sb and Se resonance lines were measured directly in a heated graphite atomiser using a continuum source and a scanning monochromator. Deviations of non-analyte absorption from uniformity over the spectral band passes typically used in atomic absorption spectrometry could be correlated with systematic errors that arise when continuum source background correction is applied to this technique. Keywords: Electrothermal atomic absorption spectrometry; background correction; non-analyte absorption; interferences; arsenic, selenium and antimony

Measurement errors in atomic absorption spectrometry (AAS) occur if species other than the analyte which can also absorb the narrow-line radiation of the source are present in the observation volume during atomisation. These interfer- epces are particularly serious when electrothermal atomisa- tion is used because the concentration of the matrix relative to that of the analyte is often very high and because most such analyses are carried out in an atomiser containing an inert gas and having a non-uniform temperature.

Several approaches to the correction of such interferences have been developed and applied successfully to practical analyses. Among the most common methods are those based on the use of a continuum source, on the application of the Zeeman effect and on periodic broadening (or self-reversal) of the primary source line. Although correction based on the use of a continuum source can be effective, systematic errors will occur if there are non-uniformities in background absorption within the spectral band pass used for the measurement.’

Non-uniformities may result from absorption by molecules and radicals and also by atoms having absorbing lines within the spectral band pass. Numerous interferences have been cited in the literature, particularly for elements with resonance lines below 240 nm such as arsenic, selenium, tellurium, antimony, bismuth, zinc and cadmium in matrices containing, in particular, phosphorus, sulphur or high concentrations of transition metals.2-9 An error will always arise in continuum source background correction if nearby line absorption, due to the presence of matrix, with little or no direct overlap falls within the band pass of the monochromator. “Over-compen- sation” may be expected, characterised by a negative base-line excursion for a period during atomisation. Hohn and Jack- werthlo identified the first example of the over-compensation error in flame AAS (over-compensation from indium chloride molecular absorption in the determination of gold). Manning2 described the first identified example of the over-compensa- tion error in the determination of selenium by electrothermal atomisation in the presence of very large amounts of iron. Recently, there have also been examples shown of under- or over-compensation even with Zeeman-effect background correction for which the probability of such occurrences is in principle very much lower.11-’5 Although errors due to spectral characteristics are intrinsic to the method of correc- tion, over- and under-compensation may also be caused by imperfect matching of the measurement beams’6.17 and may not always be indicative of a spectral interference.

Reference to tables of spectral lines is helpful in explaining over-compensation, and absorption spectra have frequently been measured in flames.2.3.7 However, information concern- ing the intensity of emission lines or the oscillator strength of absorption lines is difficult to apply to the special circum- stances of a heated graphite atomiser. In this work direct measurement in the graphite furnace, by spectral scanning, of potential absorption by interfering atoms at the resonance lines of As, Se and Sb is described.

Experimental All absorption spectra were obtained using a Perkin-Elmer Model 5500 ICP spectrometer controlled by a Perkin-Elmer Model 3600 data station. The 0.408-m monochromator was equipped with an 84 X 84 mm holographic grating (2880 lines mm-1) and has a spectral band pass of 0.025 nm. Wavelength scanning was in 0.0027-nm steps. To obtain absorption spectra a deuterium-arc source, a lens and a Perkin-Elmer HGA 76 graphite furnace were positioned on an optical rail so that the radiation from the deuterium arc was imaged first at the centre of the graphite tube and again at the monochromator entrance slit. Standard ICP spectral scanning software was used to obtain scans during atomisation of large amounts (up to 1 mg) of the interfering element. Atomisation at 2500 “C for 10 s resulted in an absorption peak with a long tail, reflecting relatively constant absorption conditions. This period was sufficient to record a 1.0-nm scan (Fig. 1). Spectral scans obtained during several atomisations were combined to produce spectra covering the various band passes used. The deuterium-arc “blank” spectra were also recorded.

Scan interval

0 5 10 Timels

Fig. 1. Wavelength scans in the region of interest were made during the period of nearly constant absorbance at the tail of the atomisation peaks of large amounts of the interfering element

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1014 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, OCTOBER 1988, VOL. 3

Reference emission spectra were obtained directly from Perkin-Elmer Intensitron hollow-cathode and electrodeless discharge lamps and from the ICP source by aspirating elemental standard solutions (1 mg ml-1) made from high- purity metals (Spectrascan standard solution; TeknoLab, Norway).

Reagent solutions containing 10 mg ml-1 of cobalt, iron and nickel were prepared by dissolving high-purity metals in minimum volumes of nitric acid.

Results and Discussion

Arsenic

The absorption spectra recorded for aluminium, cobalt, iron and nickel atoms in the graphite furnace and the emission spectra of hollow-cathode lamps and of the ICP source for these elements around the two most sensitive arsenic reso- nance lines (193.70 and 197.20 nm) are shown in Figs. 2 and 3,

As I 193.696 nm

Blank Deuterium arc

As 1 193.696 nm ICP-AES 1000 mg I - ' Co

Blank

Deuterium arc Blank

0 u

Wavelengthinm +

As 1 193.696 nm ICP-AES

100 mg I-' Al

Blank

Blank Deuterium arc

Wavelength/nm -+

Fig. 2. around the 193.70-nm arsenic resonance line

Absorption spectra for aluminium, cobalt and iron and emission spectra of hollow-cathode lamps and an ICP source for these elements

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JOURNAL O F ANALYTICAL ATOMIC SPECTROMETRY, OCTOBER 1988, VOL. 3 1015

As 1197.197 nm

Blank

Deuterium arc Blank

Blank

Deuterium arc Blank

u) 0

b rn m

0 0 u u

CI) 0 9 2 7 - - c

Wavelengthinm +

Fig. 3. Absorption spectra for cobalt and nickel and emission spectra of hollow-cathode lamps and an ICP source for these elements around the 197.20-nm arsenic resonance line

I ......-.-. . . . . 0.05 . .

U Ti me/s

Fig. 4. Time-resolved Zeeman-corrected atomisation signals from the atomisation of: 1, 10 pg Al in 0.3% nitric acid; 2,10 pg Al added to 100 pg As at the arsenic 193.70-nm line; and 3, the non-specific absorption signal generated from the atomisation of 10 pg of Al. Furnace parameters: ashing temperature, 1100 "C; atomisation temperature, 2300 "C (maximum power mode); gas stop conditions. The absorbance scales for the Zeeman-corrected and the non-specific absorbance signals are 0.05 and 0.5, respectively

(a ) Serum

0.5% Ni

'u"vI e

(b) Serum

0.5% Ni

y7' II

Fig. 5. Recorder traces from the determination of selenium in human serum diluted 1 + 3 with 0.5% mlV Ni(N03)? solution using a deuterium-arc background corrector (Perkin-Elmer 5000/HGA 500). Furnace parameters: (a ) non-coated tube, 2500 "C atomisation temperature and (6) pyrolytic graphite coated tube, 2100 "C atomisa- tion temperature (maximum power mode); ashing temperature, 1150 "C; 50-ml internal gas flow

respectively. Atomic absorption of the deuterium source radiation by both iron and cobalt occurs within the spectral band pass of 0.7 nm centred at the 193.70-nm line. Over- compensation may be expected if this resonance line is applied to the determination of arsenic in a large excess of either of these two elements. Cobalt absorbs within the recommended spectral band width of 0.7 nm at the arsenic 197.20-nm resonance line whereas the nickel absorption at 197.63 nm falls outside this band pass.

In Table 1, emission lines detected in the ICP and hollow-cathode lamps and absorption lines measured in the graphite furnace are listed, together with wavelengths obtained from the literature. A serious spectral interference on arsenic at the 193.70-11111 line is reported in the analysis of certain types of suspended materials in natural waters.21 This interference resulted in an erroneously high concentration of arsenic reported for this type of matrix. Riley22323 demon- strated later that this interference may be due to absorption by aluminium ions in the graphite furnace. The presence of several unresolved absorbing aluminium ion lines as shown in Fig. 2 in the range 193.30-193.90 nm confirms Riley's suggestions. It is interesting, however, that this example consists of both a nearby absorption causing an over-compen- sation and a direct spectral overlap. The effect of the spectral overlap is much larger than the effect of the absorbing ions on the deuterium-arc intensity, thus explaining the effect of large amounts of aluminium in the determination of arsenic at the 193.70-nm line. When using an instrument equipped with a

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1016 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, OCTOBER 1988, VOL. 3

Se I 196.026 nm

ICP-AES

&A !;jk\. )Ld\ 1000 mg 1-1 Fe */1,--

Blank

Deuterium arc Blank

200 pg Fe

. ' " - A / - --,

ICP-AES 10 000 Se I 196.026 nm

Deuterium arc Blank

N N

'? (D Q) 2 : 7

.- .- z z

ICP-AES 1000

mg 1-l Se I 196.026 nm

Blank

n /-\ Co HCL

Blank

Wavelengthinm +

Fig. 6. Absorption spectra for cobalt, iron and nickel and emission spectra of hollow-cathode lamps and an ICP source for these elements around the 196.0-nm selenium resonance line

1 fl Ni HCL

m

c-7 0 ? 1 : N N

N 7

d: 0 cu

.- .- .- z z z

Co HCL n

Wavelengthinm +

Fig. 7. Absorption spectra for cobalt and nickel and emission spectra of hollow-cathode lamps and an ICP source for these elements around the 204.0-nm selenium resonance line

Zeeman-effect background corrector this interference is absent at the arsenic 193.70-nm line, as shown in Fig. 4. These data were obtained using a Perkin-Elmer Zeeman/5100 atomic absorption spectrometer equipped with an HGA-600 graphite furnace.

Selenium Spectral interferences due to nickel and chromium in the determination of selenium at 204.0 nrn and due to cobalt at 196.0 nm have been reported.6 We have also experienced an interference due to nickel at the primary selenium wavelength (196.0 nm). These interferences, although correctable by means of the Zeeman effect, are of significant practical importance because nickel is one of the most effective and hence commonly used matrix modifiers for the prevention of the loss of selenium during thermal pre-treatment. An example of over-compensation recorded during the determi- nation of selenium in serum is given in Fig. 5. The matrix modifier, which contains 0.2% Triton X-100 and 0.5%

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JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, OCTOBER 1988, VOL. 3 1017

Deuterium arc Blank

Sb 1217.581 nrn ICP-AES II n 500 mg I Co

s Blank

Deuterium arc Blank

.hV.%4QQ

v i

p x : 2 N

0 9 ? cv

- Sb 1217.581 nm

I C P-AE S 10 mg I-’ Ni

Blank

Ni HCL

Deuterium arc

Blank

h

Sb 1217.581 nrn ICP-AES

Deuterium arc

Blank

Wavelengthhm +

Fig. 8. Absorption spectra for cobalt, copper, iron and nickel and emission spectra of hollow-cathode lamps and an ICP source for these elements around the 217.60-nm antimony resonance line. For practical reasons the spectra for platinum at this antimony line are presented in Fig. 10

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1018 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, OCTOBER 1988, VOL. 3

I Sb 1206.833 nm

Blank

Deuterium arc Blank

,w 1 m g N i

a - l n

0 0 0 CJNN

z z z

Sb 1206.833 nm

Blank

Deuterium arc Blank

' 0 )

2 0 N

0 u

Wavelengthinm -+

Fig. 9. Absorption spectra for cobalt and nickel and emission spectra of hollow-cathode lamps and an ICP source for these elements around the 206.80-nm antimony resonance line

Ni(NO&, gives over-compensation signals with both non- coated and pyrolytic graphite coated graphite tubes. The suppression of the over-compensation signals by the serum matrix eliminates this interference , particularly when non- coated tubes are used.

Significant differences between the emission spectra from ICP and hollow-cathode emission and also the deuterium-arc absorption spectra for cobalt, iron and nickel near 196 and 204 nm are shown in Figs. 6 and 7. It is evident that the absorption from nickel lines at 195.73 and 196.32 nm could lead to the measured over-compensation if sufficient nickel were present in the matrix or added as a matrix modifier, even when a 0.7-nm slit is used instead of the recommended 2.0 nm. It is important when working at the detection limit for selenium to

use no more nickel than is required for quantitative thermal stabilisation. In addition to the absorption adjacent to the primary selenium line, nickel atoms absorb at both 203.51 and 2'04.12 nm. This results in over-compensation at the Se 204-nm line, which, however, can be reduced by the use of narrower slits.

Fig. 6 clearly shows the cause of the over-compensation due to iron when determining selenium in matrices rich in iron. It is seen that the selenium wavelength is situated directly between two relatively strong iron lines and that the absorp- tion due to iron within 0.35 nm of the central wavelength is much greater than that due to nickel. The half-width of all the spectral lines recorded here corresponds to the instrumental band pass of 0.025 nm, whereas the actual width of an absorption line under the conditions of atomisation in the graphite furnace is less than 0.01 nm. The selenium line occurs at a minimum in the iron absorption spectrum, but the nearest iron lines are sufficiently close that the interference cannot be eliminated by any practicable choice of instrument band pass for AAS. On the other hand, the nearest iron line is 0.035 nm removed from the selenium line centre. Thus the shift of about 0.005 nm resulting from Zeeman splitting of the iron line would not cause any change in the absorption of the selenium emission line. In Table 1 an overview is given of the recorded spectral data near the two most frequently used selenium resonance lines.

Antimony A potentially important interference due to iron at the most sensitive antimony line is indicated in Fig. 8. Iron atoms absorb at wavelengths close to the 217.60-nm antimony line at 217.81 nm. Among the matrices tested, the measurements on cobalt, copper, iron, nickel and platinum indicate situations where over-compensation can be expected. The secondary antimony lines at 206.80 and 231.10 nm were also studied (Figs. 9 and 10). Nickel absorption is registered near both wavelengths, which means that the use of narrow spectral band widths to overcome the problem is not applicable.

Absorption by Ions

In some instances it was possible to detect apparent absorption by ions, e . g . , at the Fe I1 217.485, Ni I1 217.467-, Ni I1 203.535- and Co I1 231.160-nm lines and at several A1 I1 and A1 111 lines in the spectral range 193.3G193.90 nm. The absorption at the Fe I1 wavelength was more pronounced in strongly acidic solutions than that shown in Fig. 8, indicating an influence of the matrix on gas-phase population distribu- tions. Further studies are required to confirm these observa- tions, as the presence of ions in measurable amounts in the graphite furnace is not expected24 on the basis of thermo- dynamic considerations.

Conclusions The information obtained by this method is useful in the direct identification of the spectral lines causing interference in the furnace and can provide information applicable not only to the systematic elimination of these interferences and the selection of operating parameters, but also to the study of the chemical and physical processes taking place in the atomiser. The low spectral resolution and slow scanning of the present instrumentation, however, were important limiting factors. Absorption due to short-lived molecular species, e.g., phos- phate decomposition products (PO, P2) could not be success- fully investigated. When the Zeeman effect is used for background correction, spectral interferences are expected only in those instances for which the interfering line centre is within a few grating steps and the spectral line appears, because of the monochromator resolution, to overlap directly.

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JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, OCTOBER 1988, VOL. 3 1019

ICP-AES Sb 1217.581 nm 1000 mg I-1Pt

Blank

Pt HCL

A

20 ug Pt

Sb 1231.147 nm

Blank

Deuterium arc Blank

Sb 1231.147 nm

:::e

&?

Blank

Fe HCL

JA- Deuterium arc

Blank

1 0 m m 0, 03

0 m N

a, LL

-

c

d 0 c

p! c

m cv

aJ LL -

Sb 1231.147 nm

Blank

Deuterium arc Blank

Wavelengthinm -+

Fig. 10. elements at the 217.60- and 231.10-nm antimony lines

Absorption spectra for cobalt, iron, nickel and platinum and emission spectra of hollow-cathode lamps and an ICP source for these

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1020 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, OCTOBER 1988, VOL. 3

Table 1. Deuterium-arc source absorption spectra of some metal atoms and the emission spectra of hollow-cathode lamps (HCL) and the ICP source adjacent to resonance lines of antimony, arsenic and selenium. Literature wavelengths are listed in references 18-20 and 25

Observed emission/absorption lineshm Literature

Element linesl8-20JVnm Arsenic 197.197 nm . . . . Co* 1196.803

Co 1196.828 Co 1196.941 Co I 197.006 Co 1197.051

Co 1197.187 Co 1197.32

Co I 197.632

Ni 1197.622

Arsenic 193.696 nm . . . . Alt I1 193.172 A1 I1 193.384 A1 I1 193.405 A1 I11 193.518 A1 I11 193.529 A1 I1 193.625 A1 I1 193.860

Co 1193.593

Co 111 193.950 Co IT 194.065

Fe 1193.388

Fe 1193.661 Fe I11 193.825 Fe 1194.001

Antimony217.581 nm . . Co 11217.333 Co 1217.384 Co 1217.460

Co I1 218.060 Co1218.112

Cu 1217.176 Cu I1 217.498

Cu 1217.894 Cu I1 217.940

Fe 1217.130 Fe 1217.259 Fe 1217.321 Fe I1 217.485 Fe I1 217.545 Fe 217.640

ICP 196.81

197.01 197.05 197.11 197.19 197.33 197.33 197.37 197.44 197.51 197.64 197.71

196.82 197.63 197.71

Unresolved lines from 193.30 to 193.90

193.31 193.38 193.53 193.60 193.65 193.83 193.95 194.06 194.17

193.29 193.32 193.39 193.47 193.62 193.66

194.00

217.29 217.33 217.40 217.46

217.85

218.00 218.06 218.10

217.18

217.89 217.94

217.30 217.26 217.32 217.48 217.54 217.63

HCL D2 absorption 196.81 196.81

197.01 197.01 197.06

197.20

196.83 197.63 197.70

193.30 194.40

193.30 193.37

193.60 193.65 193.82 193.94 194.06 194.18

193.40

193.62 193.67 193.82 194.00 194.13

217.33 217.39 217.46 217.57 217.66 217.76 217.85 217.93 218.00 218.07

217.18 217.49 217.66 217.76 217.89 217.93 218.07

217.30 217.26 217.32

217.54

196.83 197.63

Unresolved absorption from 193.30 to 193.90

193.60

193.40

193.66

194.00

217.33 217.39 217.46

218.00

217.89

217.30 217.26 217.32 2 17.47$

continued

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JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, OCTOBER 1988, VOL. 3 1021

Table l.--continued Literature

Element lines18-20.25inm

Fe 1217.684 Fe 1217.809 Fe 1218.087

Ni I1 217.467 Ni I1 217.515

Ni I1 217.709 Ni I1 217.736 Ni I1 217.935

Ni I1 218.047

Pt 1217.467

Antimony 231.147 nm . . Co I1 230.786

Co I 230.902

Co I1 231.160

CoI1231.364 CoII231.404 Co I1 231.498

Fe I 230.900 Fe 230.944 Fe 23 1.026 FeI1231.129 Fe I1 23 1.202 Fe1231.310 Fe231.394

Ni 1230.735 Ni 230.817 Ni I1 230.852

Ni 231.002 Ni 1231.096

Ni 1231.234 Ni I1 231.292 Ni 1231.365 Ni 1231.398 Ni I1 231.604

Antimony 206.833 nm . . Co I1 206.376

Co I1 206.553

Ni

Observed emissiodabsorption linesinm

ICP

217.68 217.80 218.08

217.35 217.46 217.51

217.71

217.93 217.99 218.04

217.47 217.64 217.69

218.04

230.80

230.90

231.17 231.26

231.40 231.49

230.66 230.76

230.91

231.13 231.20 231.32 231.40

230.96 231.01 231.10

231.24 231.29 231.35 231.40 231.60

206.33 206.38

206.55 206.74 206.89 206.94 207.14

206.34 206.44

206.55

HCL

217.67 217.80 218.08

217.35 217.46 217.51 217.58 217.71 217.73 217.93 217.99 218.04 218.08

217.47

217.89 217.93 218.04

230.62 230.72 230.80 230.89 230.91 231.04 231.09 231.16 231.28 231.35 231.40 231.49 231.53 231.56

230.67 230.76 230.81 230.91 230.96 231.03 231.13 231.20 231.31 231.39 231.46 231.56

230.74 230.81 230.85 230.88 230.97 231.03 231.10 231.18 231.24 231.30 231.37

231.61

206.38 206.52 206.55

206.89

207.13

206.33 206.43 206.52

D2 absorption

217.67 217.80

217.35 217.46

217.47

230.93

231.15

230.92

231.32

230.74

231.11

231.25

231.36 231.40

206.89

206.36 206.45

con tin u ed

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JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, OCTOBER 1988, VOL. 3 1022

Table l.--continued Literature

Element line~18-2~J~/nm

Selenium 203.985 nm . . Co I1 203.658

Co I 203.995 Co I 204.1 11

Ni I1 203.535

* Co literature lines corrected to air (-0.066 nm). t A1 literature lines corrected to air (-0.066 nm). + More intense when acidic iron-solutions are atomised.

Observed emission/absorption linednm

ICP

206.64

206.85 206.90 206.94

207.21

203.67 203.87 204.00 204.11

204.30

203.45 203.50 203.59 203.67 203.73 203.84

204.12

204.40

HCL D2 absorption 206.59 206.63 206.69 206.84 206.86 206.89 206.91 206.93 206.95 206.97 207.10 207.20

203.67 203.87

204.20

203.45 203.51 203.59

203.72

203.94 204.02 204.12 204.24 204.39

203.87 204.00 204.11

203.51

204.12

The absence of such instances in this study is an indication of the relative freedom from interferences of Zeeman-effect background correction. The probability of the occurrence of a spectral interference on Zeeman-effect background correc- tion, calculated from the effective band pass for the correc- tion, should be two orders of magnitude smaller than that on continuum source background correction. This study will be continued using a more suitable device combining high resolution, rapid scanning capability and good energy throughput.

1.

2. 3. 4.

5. 6.

7 . 8.

9.

10.

References Massmann, H., and El Gohary, Z., Spectrochim. Acta, Part B , 1976, 31, 399. Manning, D. C., At. Absorpt. Newsl., 1978, 17, 107. Vajda, F., Anal. Chim. Acta, 1981, 128, 31. Saeed, K. , and Thomassen, Y., Anal. Chim. Acta, 1981, 130, 281. Fernandez, F. J., and Giddings, R., At . Spectrosc., 1982,3,61. Fernandez, F. J . , and Beaty, M. M., Spectrochim. Acta, Part B , 1984, 39, 519. Slavin, W., and Carnrick, G. R. , At. Spectrosc., 1986, 7, 9. Fernandez, F. J., Meyers, S. A., and Slavin, W., Anal. Chem., 1980, 52, 741. Martinsen, I., and Langmyhr, F. J., Anal. Chim. Acta, 1982, 135, 137. Hohn, R., and Jackwerth, E. , Anal. Chim. Acta, 1976,85,407.

11.

12.

13.

14.

15. 16. 17. 18.

19.

20. 21. 22. 23. 24.

25.

Wibetoe, G., and Langmyhr, F. J . , Anal. Chim. Actu, 1984, 165, 87. Wibetoe, G., and Langmyhr, F. J., Anal. Chim. Acta, 1985, 176, 33. Wibetoe, G., and Langmyhr, F. J. , Anal. Chim. Actu, 1986, 186, 155. Wibetoe, G., and Langmyhr, F. J. , Anal. Chim. Acta, 1987, 198, 81. Massmann, H., Talanta, 1982, 29, 1051. Siemer, D. D., Anal. Chem., 1984, 56, 1517. Nakamura, S., and Kawase, A., Bunseki Kagaku, 1979,28,86. Michaud, E., and Mermet, J. M., Spectrochim. Acta, Part B , 1982, 37, 145. Reader, J., and Corliss, C. H., “Wavelength and Transition Probabilities for Atoms and Atomic Ions. Part I: Wavelengths”, NSRDS-NBS 68, National Bureau of Stan- dards, Washington, DC, 1980. Wohlers, C. C., ZCPZnf. Newsl., 1985, 10, 593. Poldoski, J. E., At. Absorpt. Newsl., 1977, 16, 70. Riley, K. W . , At. Spectrosc., 1982, 3, 120. Riley, K. W., Analyst, 1984, 109, 181. Sturgeon, R. E., and Berman, S. S . . Anal. Chem., 1981, 53, 632. Crosswhite, H. M., J . Res. Natl. Bur. Stand., Sect. A , 1975,79, 17.

Paper 8100629F Received February 18th, 1988

Accepted April 25th, 1988

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