Atomization of synthetic and real samples using heated graphite atomizers for atomic absorption spectroscopy : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University

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Copyright is owned by the Author of the thesis. Permission is given for

a copy to be downloaded by an individual for the purpose of research and

private study only. The thesis may not be reproduced elsewhere without

the permission of the Author.

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ATOMIZATION OF SYNTHEI'IC .AJ'ID REAL SAMPLES

USING HEATED GRAPHITE ATOMIZERS

FOU!QMIQ ABSORPI'ION SP&;TROSCOPY.

A thesis presented in partial fulfilment of the requirements for the degree of

Master of Science in Chemistry at Massey University

MARK WILLIAM PRITCHARD February 1 975

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AC KNOWLED G-E MEHTS

The author would like to express his approbation and gratitude to his supervisor,

Dr. R.D. Reeves, for the many stimulating discussions he has initiated in the course of this work and is indebted for the personal interest shown and the guidance given. Sincere thanks are also due to Mrs .• J .D. Thirkell for the formidable task of

transcribing the original script into a more readable form. Appreciation is expressed to Miss. S. Sherriff for typing the references.

"But, my son, be warned: there is no end of opinions ready to be expressed. Studying thera can go on forever, and become very exhausting. Here is my final conclusion:

fear G-od and obey His conunandments, for this is the entire duty of man." (King Solomon 977 B.C.)

1 •

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ABSTRACT.

The interference effects caused by a number of mntrices includ:u1,:5 compounds such as NaCl, HCl, I<Br, mro

3, rr

3^{R\_, H}²so 4 ^on Cu, Pb, Cd and .Al atomic absorption sii;nnls when the elements are ntomized from three non-flame ti;rnphite atomizers (furnac·e, cup .'.'Ind

rod) arc studiec. over severnl concentration rrmc;e~. Investicn tioT'!s show that most of the interferences found occur in the vapour phase.

A comprehensive literature survey has been done and from this survey and the experimental work carried out, discussions are presented on

the postulated mechanisms of interfereroe.

given for the vapour phase interference,

Two main theories are

i) entrapment of the atom in the matrix particle forming in the vapour,

ii) rapid molecular condensation in the vapour phase.

Several degrees of interference (both enhancement and depression) were obtained for the different chemical and atomization systems used.

Attempts were made at rationalizing the degree and type of interference in terms of the postulated models. Supporting evidence for the atom entrapment theory was gained from an investieation of the nature of the non-atomic absorption peak obtained mainly when alkali halides are present in the sample. Evidence is produced showing that the absorption spectra obtained from alkali halides here and by other workers are charge-transfer spectra.

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An investigation into the use of a graphite atomizer for zinc analysis in bovine serum is presented and compared to

determinations using flame atomic absorption on the same samples.

iii.

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TABLE . m,, CONTENTS.

ACKNOrlLEDGEMENTS ABSTRACT

AP?EITDIX I

. . . ...

¹⁰⁹

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FIG. II. 1.

FIG. II. 2a.

Ji'IG. II. 2b.

FIG. II. 2c.

Copper.

FIG. III. 1-1.

PIG. III. 1-2

FIG. III. 1-3.

Fig. III. 1-4.

Fig. III. 1-5.

Fig. III. 1-Ga.

Fig. III. 1-6b.

Fig. III. 1-7a.

Fig. III. 1-7b.

View of the v,orkhead of the Varian Techtron Carbon Rod Atomizer UocJ.el GP.A 63

Sketch of the rod atomizer.

Sketch of the furnace atomizer. Sketch of the cup atomizer.

Ashing voltage determim tion curve Series of analytical curves of Cu at various atomize voltages

The eff'ect of various anions and correspondu1g cations 1,000 ppm concentration on copper ,molytical curves on the CM.

...

. . .

Effect of NaCl and KBr on Cu (2 .5 pp:n) on the rod, furnace and cup.

Peak profi le~ of copp~r

'l'he effect of Hl~) on Cu on the ro:3.

and furnace. 4

•••

. . .

The combined effect of H P0

1 and NaCl on Cu signals on the furflac~, cup aml rod. The effect of interferents on Cu signals using separate cavities in the rod. . .•

The effect of interferents on Cu sit i1E.ils when mixing of the two species is for a

limited t ine.

Fi g. III. 1-7c. The effect of interferents on Cu sienal s usu-ig separate cavities in the furnace ••

vii.

p. p. 41/42

p. p. 43/44-

p.p. l¼-3/44-

p.p. 49/50

P•P•

p.p • 50/51

p. p. 50/51

p.p • 51/52

p.p. 54/55

p.p. 54./55

p. ::,. 57/58

p.p. 57/58

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viii.

LIST OF FIGURES.

FIG. III. 1 -8a • Analytical curves of Pb in H

2o at several

atomization volta80S on the rod. • •• p.p. 66/67

FIG. III. 1-Sb.

FIG. III. 1-9.

Fig. III. ·1 -1 O.

Fig. III. 1 -1 ·1 • Cadmium.

J\.nalytic?.l curves of Pb in 2U }IN0

3 ^a^t several atomization vol taces on t:10 r cxl.

Annlytical curves of Pb at low concentrati ons in 2t! HCl nml IIIfo_

obtained ni th the furnace J

Double cavity experiuents with with Pb in the furnace £-nd .on the rod.

Peak p:i.•ofiles for Pb.

. . .

• ••

Fig. III. 1-12a. i.shi1~ volta~e cu1·ve for Cc1.

. ..

...

. ..

Fig. III. 1 -·1 2'u • Effect of i'ToCl and ILPO on Cc1. £",bsorption si[;nnls rtith lhe ftU'riac~, rod nrd cup. . ..

Fig. III. 1-13. Penk r,rofiles for

ea .

R:esidual A_nalyses.

Fig. III. 1-148. Standard curve for Cl- analysis. Fig.

Fig.

III. 1-14b. Cation Graphs for the Na, Cu, Pb e.ncl AL III. 1-14c. Cl residues from CuC1

2, PbC1

2, AlC1

3,

NaCl.

Fie. III. 1 -1 5 • NaCl . ashing voltage and time

Fig. III. 1-16.

Fie. III. 1-17a.

Fig. III. 1-17b.

determination curves.

The molecular absorption peaks of KBr and NaCl as a function of concentration.

I'IaCl molecular absorption wavelength dependence curve us ins the furnace, cup

am

^rod^a^t or.tlzers.

KBr molecular absorption wavelength dependence curve usi~ the ftu¹nace, cup and rod etomizers.

. ..

...

. ..

p.p. 66/67

p.p. 67/68

p.p. 69/70 p. p. 71/72

p.p. 74/75

;:,. p. 711--/75

p. p. 75/76

p.p. 8?./83 p.p. 82/83

p.p. 82/83

p.p. 87/88

p.p. 88/89

p.p. 89/90

p. p. 89/90

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Pig. IJI. 1-18.

PiG. III. 1-15.

Fig. III. 1-20.

Zinc .\mlysis. :r'ie. III. 2-1a.

III 2-·lb.

~J;S.T OF FIGURES.

Comparison of NaCl moleculnr nbsorption vraveJ.ength dependence curve obtnined in

this nor]-: with that obtcinod. by

ix.

Eoirtyohnnn and Pickett an:1 f.luller. • •• p. p. 91/92

Comparison of KBr molc,cular absorption

·:r.::wel ength dependence curve obt.'."!ined in this rrork with tlwt obtoincLl by

Koirt;yorw.nn and Pickett awl tiille1•. • •• p.p. 91/92

i'fovelength dependence curve of the 'scotterec1¹ rc:.d:iotion c:.nwed by the

atomization of' a 1 O, OOO ppm lbCl solution •• p.p. 93/94

Annlyticel curve of zinc 011 c~rbon rod nton:izer.

.'\.112lytical curve of zinc by fJ .'.:!rr.e :!tor.:ic nbsorption.

• •• p.p~ 97/98

p.p. 97/98

Atomization of synthetic and real samples using heated graphite atomizers for atomic absorption spectroscopy : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University

Copyright is owned by the Author of the thesis. Permission is given for

ABSTRACT.

TABLE OF CONTENTS

AP?EITDIX I

~J;S.T OF FIGURES.