fallout monitoring of waters

5
M. SenegaSnik and ~. Paljk: Fallout Monitoring of Waters 375 wendung einer 0,0001 M Mal~lSsung ist die Genauig- keit verst/~ndlicherweise geringer. Aul~erdem ist hier nicht zu fibersehen, dal~ der Endpunkt ers~ bei einem bestimmten ]~berschul~ erkennbar wird. Schliel~lich seien noch einige Analysen auf Eisenge- halt an Standardmustern des Bureau of Standards, Washington, mitgeteilt (Tab. 4). Tabelle 4. Eisenbestimmungen in Standardmustern des Bureau o/Standards, Washington Muster, Nr. und Gefimden (~ Sollwerte (~ Bezeichnung Fe 1%~03 1% F%0 a i a Argillaceous 1,62 Limestone -- 1,66 J 1,64 1,63 5,81 } 69a Bauxite -- 5,85 5,83 5,82 158 Silicon 1,53 Bronze 1,52] 1,53 -- 1,48 -- 164a Aluminium 4,04 Bronze 4,06 J 4,05 4,05 -- Die Genauigkeit mit der die Sollwerte wiedergefunden werden, entspricht den Erwartungen. Lediglich die Eisenwerte der Siliciumbronze Nr. 158 liegen hSher. Mehrfache Wiederholungen ergaben immer wieder den hSheren Wert. Einen Grund daffir kSnnen wir nicht angeben. Die Versuche des experimentellen Teils lagen in den H~nden des Herrn Chemotechnikers Wortmann, die Testtitrationen und die statistische Auswertung besorgte Herr stud. chem. Kopka. Beiden sei fiir ihre wertvolle Mitarbeit auch an dieser Stelle bestens gedankt. Literatur 1. Bashkirtseva, A.A., u. E.M. Yakimets: Trudy Uralsk Politcchn. Inst. 1960, 110. 2. Bicdermann, W. : Dissertation, Z/irich 1947. 3. Doll, W., u. H. Specker: diese Z. 161, 354 (1958). 4. Liteanu, G., J. Luk~cs u. C. Strusievici: Anal. Chim. Acta 24, 200 (1961); vgl. diese Z. 187, 45 (1962). 5. Lydersen, 0., u. O. Gjems: diese Z. 138, 249 (1953). 6. Schwarzenbach, G. : Schweiz. Chemiker-Ztg. 1945, Iqr.9. 7. Wehber, P., u. W. Johannsen: diese Z. 158, 7 (1957). Dr. R. Wickbold Chemische Werke Hills A.G. 4370 Marl, Postfach 1180 Z. Anal. Chem. 244, 375--379 (1969) Fallout Monitoring of Waters II.* Radiochemical Determination of Cerium-144, Caesium-137, Strontium-89,90 and Barium-140 by Ion-Exchange IV[. S~N~GA~Nn~ and 8. PALJ~ Nuclear Institute "J. Stefan", Ljubljana and Department of Mining and Metallurgy, The University of Ljubljana, Yugoslavia Received July 20, 1968 Summary. A method for the rapid determination of 144Ce, laTCs, SgSr, 9~ and lt~ in surface-waters and atmos- pheric water precipitations by ion-exchange is presented. It can be applied to samples with total calcium- magnesium content up to 110 meq. The limit of detection amounts to 0,005 pCi/] for ~44Ce, 0.006 pCi/1 for ~87Cs, 0.004 pCi/1 for s~ and 0.006 pCi/1 for 14~ with a 30 1 sample. These sensivities can be improved for a further few times using a battery of columns. Zusammen/assung. Zur Bestimmung yon 1~4Ce, 137Cs, 898r, 9~ und 14~ in Oberfis und atmosph/~ri- schen Wasser-Niederschl~gen wird eine schnelle Ionenaustauschermethode vorgeschlagen, die auf Proben mit einem Ca-Mg-Gesamtgehalt bis zu 110 reval anwendbar ist. Bei Anwendung einer 30 1-Wasserprobe betrs die untere Iqachweisgrenze 0,005 pCi/1 ffir 14aCe, 0,006 pCi/1 ffir 137Cs, 0,004 pCi/1 fiir 9~ nnd 0,006 pCi/1 ffir 140Ba. Mit einer Batterie yon Kolonnen kSnnen diese Iqachweisgrenzen noch herabgesetzt werden. * I. Mitteilung: diese Z. 244, 306 (1969).

Upload: m-senegacnik

Post on 13-Aug-2016

212 views

Category:

Documents


0 download

TRANSCRIPT

M. SenegaSnik and ~. Paljk: Fallout Monitoring of Waters 375

wendung einer 0,0001 M Mal~lSsung ist die Genauig- keit verst/~ndlicherweise geringer. Aul~erdem ist hier nicht zu fibersehen, dal~ der Endpunkt ers~ bei einem best immten ]~berschul~ erkennbar wird. Schliel~lich seien noch einige Analysen auf Eisenge- halt an Standardmustern des Bureau of Standards, Washington, mitgeteilt (Tab. 4).

Tabelle 4. Eisenbestimmungen in Standardmustern des Bureau o/Standards, Washington

Muster, Nr. und Gefimden (~ Sollwerte (~ Bezeichnung Fe 1%~03 1% F%0 a

i a Argillaceous 1,62 Limestone -- 1,66 J 1,64 1,63

5,81 } 69a Bauxite -- 5,85 5,83 5,82

158 Silicon 1,53 Bronze 1,52] 1,53 -- 1,48 --

164a Aluminium 4,04 Bronze 4,06 J 4,05 4,05 --

Die Genauigkeit mit der die Sollwerte wiedergefunden werden, entspricht den Erwartungen. Lediglich die Eisenwerte der Siliciumbronze Nr. 158 liegen hSher. Mehrfache Wiederholungen ergaben immer wieder den hSheren Wert. Einen Grund daffir kSnnen wir nicht angeben.

Die Versuche des experimentellen Teils lagen in den H~nden des Herrn Chemotechnikers Wortmann, die Testtitrationen und die statistische Auswertung besorgte Herr stud. chem. Kopka. Beiden sei fiir ihre wertvolle Mitarbeit auch an dieser Stelle bestens gedankt.

Literatur 1. Bashkirtseva, A.A., u. E.M. Yakimets: Trudy Uralsk

Politcchn. Inst. 1960, 110. 2. Bicdermann, W. : Dissertation, Z/irich 1947. 3. Doll, W., u. H. Specker: diese Z. 161, 354 (1958). 4. Liteanu, G., J. Luk~cs u. C. Strusievici: Anal. Chim. Acta

24, 200 (1961); vgl. diese Z. 187, 45 (1962). 5. Lydersen, 0., u. O. Gjems: diese Z. 138, 249 (1953). 6. Schwarzenbach, G. : Schweiz. Chemiker-Ztg. 1945, Iqr.9. 7. Wehber, P., u. W. Johannsen: diese Z. 158, 7 (1957).

Dr. R. Wickbold Chemische Werke Hills A.G. 4370 Marl, Postfach 1180

Z. Anal. Chem. 244, 375--379 (1969)

Fallout Monitoring of Waters II.* Radiochemical Determination of Cerium-144, Caesium-137, Strontium-89,90 and Barium-140 by Ion-Exchange

IV[. S~N~GA~Nn~ and 8. PALJ~

Nuclear Institute "J. Stefan", Ljubljana and Department of Mining and Metallurgy, The University of Ljubljana, Yugoslavia

Received July 20, 1968

Summary. A method for the rapid determination of 144Ce, laTCs, SgSr, 9~ and lt~ in surface-waters and atmos- pheric water precipitations by ion-exchange is presented. I t can be applied to samples with total calcium- magnesium content up to 110 meq. The limit of detection amounts to 0,005 pCi/] for ~44Ce, 0.006 pCi/1 for ~87Cs, 0.004 pCi/1 for s~ and 0.006 pCi/1 for 14~ with a 30 1 sample. These sensivities can be improved for a further few times using a ba t te ry of columns.

Zusammen/assung. Zur Best immung yon 1~4Ce, 137Cs, 898r, 9~ und 14~ in Oberfis und atmosph/~ri- schen Wasser-Niederschl~gen wird eine schnelle Ionenaustauschermethode vorgeschlagen, die auf Proben mit einem Ca-Mg-Gesamtgehalt bis zu 110 reval anwendbar ist. Bei Anwendung einer 30 1-Wasserprobe betrs die untere Iqachweisgrenze 0,005 pCi/1 ffir 14aCe, 0,006 pCi/1 ffir 137Cs, 0,004 pCi/1 fiir 9~ nnd 0,006 pCi/1 ffir 140Ba. Mit einer Batterie yon Kolonnen kSnnen diese Iqachweisgrenzen noch herabgesetzt werden.

* I. Mitteilung: diese Z. 244, 306 (1969).

376 M. SenegaSnik and ~. Paljk:

Introduction

B e c a u s e o f t h e l i m i t a t i o n o f t h e i o n - e x c h a n g e m e t h o d

for r ad io -ce r ium, r ad io -caes ium, r a d i o - s t r o n t i u m a n d

r a d i o - b a r i u m d e t e r m i n a t i o n p u b l i s h e d r e c e n t l y [4] to

t h e s amples w i t h r e l a t i v e l y low ca l c ium con ten t s , we

f o u n d i t c o n v e n i e n t to e x t e n d t h e m e t h o d g i v e n in

P a r t I [3] to i nc lude r a d i o - c e r i u m a n d r a d i o - b a r i u m

in add i t ion . T h e p r e s e n t p a p e r deals w i t h t h e des-

c r i p t i on o f th is e x t e n s i o n a n d r epo r t s t h e resu l t s o f

i ts check on samples o f su r f ace -wa te r s a n d a t m o s -

phe r i c w a t e r p rec ip i t a t ions .

Experimental

Resins and Reagents

Additionally to resins and reagents needed in ref. [3] (with the omission of 2.0 M ammonium lactate, pH 7.5 and 0.5 M ammonium citrate, pH 9-- 10) and those required in ref. [~:] (except of the eluents 3.1, 3.2 and reagent 19) 4.0 ~ ammo- nium lactate, pH 8 is necessary. This einent is prepared as ammonium lactates in reL [3] and its pH controlled with pH-paper.

Equipment

(The same as previously [2], [4].) Similarly as in Part I [3] the ion-exchange column is filled with 110 ml of settled resin.

Procedure

Preliminary Treatment and Sorption o/Samples

5 ml each of cerium, caesium 1, strontium and barium carrier solution is added to the water sample with a total calcium- magnesium content not exceeding 110 meq. and proceeded as in ref. [3], providing that the time elapsed between acidification and pH re-adjustment to 4- -5 amounts to two hours at least [4].

Separation by Elution

1.0 M ammonium lactate, pH 7.5 is passed through the column at a r~te of 5 • 1 ml/min. The first 250 ml of einate are collected for the radio-cerium determination (cerium fraction), the next 150 ml rejected and the following 350 ml collected for the radio-caesium determination (caesium fraction). Then the cinent is replaced by 0.15 M ammonium citrate, pH 7.5 and the elution continued at the same flow rate. The initial 300 ml of eluate are collected for the radio- strontium determination (strontium fraction). After discard- ing the next 250 ml, the following 600 ml are collected for the radio-barium determination (barium fraction). To regenerate the column it is washed first with 700 ml of 0.3 M ammonium citrate, p~I 9-- 10 at a flow rate of 5 =J= lm]/ min and then with 300 ml of distilled water.

1 I t is recommended to use 20 mg of caesium carrier with samples larger than 30 liters.

Isolation and Puri/ication Procedures

Radio-Cerium. The procedure of radio-cerium isolation and purification is identical with that given in ref. [4] except that for initial precipitation of cerium peroxide hydrate 20 ml of concentrated ammonia are used instead of 6--8 g of solid sodium hydroxide. Radio.Caeslum. For radio-caesium isolation and purification see correspondent procedure in ref. [3]. Radio-Strontium. After the radio-strontium re-adsorption (see step 1 of radio-strontinm isolation in sequential scheme [4]), the radio-strontium is einted with 40 ml of 4.0 1~ ammo- nium lactate, pH 8 at a rate of 5 ml/min. To the obtained eluate 10 ml of concentrated ammonia and 10 g of solid ammonium carbonate are added. The solution is warmed to nearly 60~ and stirred until ammonium carbonate dissolves. Then the solution is removed from the hot plate and the strontium carbonate allowed to precipitate for 30 min. The further isolation and purification procedure is identical with that given in reL [3] for strontium carbonate obtained by initial precipitation from strontium einate fraction. To regenerate the column for the next radio-strontium re-adsorption it is washed first with 50 ml of 4.0 ~ ammonium lactate, pH 8 at a flow rate of 5 ml/min and then with 20 to 30 ml of distilled water. Radio-Yttrium. For its isolation see refs. [2, 3]. Radio-Barium. The radio-barium re-adsorption, re-eintion, subsequent precipitation and washing of carbonate are per- formed as with radio-strontium. The following treatment is identical with that given for steps 4, 5, 6, 7 of radio-barium isolation in sequential scheme [4]. With samples containing radium, after performing step 5, the scavenging is repeated with another 1 ml portion of ferric scavenging solution. For the next radio-barium re-adsorption the column is regenerated as in the previous case of radio-strontium.

Note. W i t h a b a t t e r y o f t w o c o l u m n s [3] t h e pro-

cedure p r o p o s e d is to be mod i f i ed in t h e fo l lowing

w a y :

The amounts of added carriers are increased to 20 mg for caesium and to 40 mg for cerium, strontium and barium, respectively. In the sorption and in the elution step the procedures indicat- ed for a single column must be followed for each column of the battery. The cerium eluate fractions arc combined and after addition of ~ i ml of hydrogen peroxide cerium peroxide hydrate is precipitated by addition of 40 m] of concentrated ammonia. The further t reatment of precipitated radio-cerium is the same as in the case of a single column einate. The modifications relating to radio-caesium isolation are given in Par t I [3]. After combining the strontium eluate fractions the steps of radio-strontium isolation procedure are identical with those given for a single eluate except that for its re-adsorption, re-eintion and subsequent precipitation the double amounts of resin, clucnt and reagents arc used. For the regeneration the resin is washed first with 70 ml of 4.0 M ammonium lactate, pH 8 at a rate of 5 ml/min and then with 30--40 ml of distilled water. For the isolation of radio-barium from the combined barium eluate fractions the same modifications must be introduced in the procedure given for a single eluate as in the preceding case of radio-strontium.

Falloub Monitoring of Waters 377

j 0 . 8

0.6

~o.~

0.2

Radiometric Determinations

For the radiometric determinations of isolated radio- nuclides see refs. [2, 4].

Discussion Separation by Elution

As the elution step by 1.0 M ammonium lactate, pH 7.5 [3] furnished satisfactory separation of radio- cerium t~om radio-caesium and separation of the bulk of (Ca ?- Mg) from radio-strontium, it was ac- cepted without changes into the pre-separation scheme to be developed. In the further elution step, which had to provide for Sr-Ba-Ra separation, 0.15M ammonium citrate, pH 7.5 was adopted as final choice [4], because ammonium lactates of various concentrations led, within reasonable eluate volumes, to complete Sr-Ba separation only. The elution course of a synthetic sample, given in Fig. 1, was followed as previously [2--4]. In some experiments where the elution curves of caesium and strontium were deter- mined flame photometrically and that of barium radiomctrically they were in good agreement with those in Fig. 1. The other most common cationic components of water samples behave in elution qualitatively similarly as reported before [2, 4]. With the determination procedure proposed the substi- tution of Dowex 50W, X-8 (50--100mesh) for Dowcx 50, X-8 (50--100 mesh)[2] is not critical though, because of broadening of radio-barium peak, 20% of radio-barium elntcs in radium fraction.

monia to avoid the abundant calcium precipitation in the cases of hard water samples.

Radio-Strontium (Radio-Barium). For the reasons mentioned previously [4] it was felt most convenient to remove radio-strontium (radio-barium) from acidi- fied eluate by re-adsorption on a small cation-ex- change column again. In this step the sorption yields amount to 97--98o/0 for radio-strontium and more than 99.50/0 for radio-barium. After the rc-elution with 4.0 M ammonium lactate, pH 8 about 1 ~ of sorbed radio-strontium (radio-barium) remains on the column.

Chemical Yields. With the procedure proposed the chemical yields amounted to about 900/0 for radio- cerium, 800/0 for radio-caesium and 90--95o/0 for radio-strontium. Radio-barium recovery depended on the sulphate ion content in analysed samples and varied from 400/0 to 850/0 . The double exceeding of sorption capacity of resin showed no marked effect on the radio-cerium sorption yield. Its effect on the radio-barium retention is similar to that described for radio-strontium [3].

Decontamination Factors. The mutual decontami- nation factors amount for critical elements Ca-Sr- Ba-I~a to 104 at least (Fig. 1). With isolated radio- cerium and radio-barium they are of the order of 104 for e241~a daughters, l~176 + l~ 9sZr + 95Nb. In the case of isolated radio-caesium and radio-stron- tium the values of the decontamination factors are close to those given in the Table, Par t I [3].

Isolation and Puri/ication Procedures

Radio-Cerium. In initial cerium peroxide hydrate precipitation sodium hydroxide was replaced by am-

Results

The control of the efficiency of the proposed method was performed in the same way as in Par t I [3]. The

l&t'Ce § C(z 137Cs 90St 80 221,Rn

1or F\ ! \

i \ f o

�9 i \ ~ ] o

/ \o o __ ~ / ~ "t N \ , , \ . . . . '~ . . . . . . x , ~o ,

0 500 1000 15'00 2000 2500 1.0M nmmonium [actate, pH=75 ,Effluent voLume, m[0.15H ammonium citrate, pH=75 03H ammonium citrate, pH=9-10

Fig. 1. Elution course of a synthetic sample containing zr162 -~ 30 mg of Ce, 2000 mg of Ca, zs;Cs -~ 10 mg of Cs, 9~ ~oy _1_ 30 mg of Sr, 30 mg of Ba, 2eaRn in 20 liters of distilled water. Column: see ref. [2]. Resin bed: 110 ml of Dowex 50, X-8 (50--100 mesh), NH~+-form. Concentrations in elution peaks: Cm (1~4Ce + 90y) = 1200 imp./min • ml; Cm (Ca) = 18 mg/ml; Cm (laTCs) = 0.09 mg/ml; Cm (9~ = 0.30 mg/ml; Cm (Ba) = 0.10 mg/ml; Cm (e24I~a) = 1400 imp./min • ml. Sorption rate: 60--70 ml/min. Elution rate: 5 4- 1 ml/min. Temperature: 20--25~

Tab

le 1

. R

esul

ts o

/ de

term

inat

ions

el

144C

e, 13

~Cs,

S~Sr

, ~~

and

~~

in

sur

]aee

.wat

ers

wit

h ad

ded/

issi

on p

rodu

cts

r162

Sam

ple

la

dCe

con

ten

t pC

i/1

13vC

s co

nte

nt

pCi/1

sg

Sr c

on

ten

t pC

i/1

9~

con

ten

~ p

Ci/1

14

OB

a co

nte

nt

pCi/1

Ad

ded

F

ou

nd

R

eco

ver

y

Ad

ded

F

ou

nd

R

eco

ver

y

Ad

ded

F

ou

nd

R

eco

ver

y

Ad

ded

F

ou

nd

R

eco

ver

y

Ad

ded

F

ou

nd

R

eco~

r-

~ ~

~ ~

ery

~

TW

2,

tap

-wat

er

TW

3,

tap

-wat

er

~W

2,

wel

l-w

ater

RIV

W 3

,

0.00

0 0.

328

0.00

0 0.

228

0.00

0 0.

000

--

0.00

0 0.

108

0.00

0 0.

000

0.34

2 0.

600

89.6

0.

525

0.69

0 91

.6

0.00

0 0.

000

--

0.11

0 0.

215

98.6

0.

048

0.05

2 10

8.3

0.00

0 0.

109

0.00

0 0.

036

0.00

0 0.

000

0.00

0 0.

026

0.00

0 0.

000

1.61

1,

87

108.

8 0.

121

0.15

8 10

0.6

0.45

0 0.

499

110.

9 0.

111

0.12

8 93

.4

2.40

2.

36

98.3

0.00

0 0.

070

0.00

0 0.

037

0.00

0 0.

000

0.00

0 0.

086

0.00

0 0.

000

0.33

1 0.

443

110.

5 0.

047

0.09

1 10

8.3

0.60

1 0.

553

92,0

0.

049

0.12

6 93

.3

0.21

4 0.

224

104.

7

0.00

0 0.

050

0.00

0 0.

036

0.00

0 0.

000

0.00

0 0.

385

0.00

0 0.

000

riv

er-w

ater

0.

000

0.05

4 0.

000

0.03

7 --

--

0.

000

0.41

8 --

--

1.

15

1.14

94

.8

0.17

7 0.

230

107.

7 1.

80

1.65

91

.7

0.18

2 0.

645

110.

5 0.

374

0.33

7 90

.1

Tab

le 2

. R

esul

ts o

] co

mpa

rativ

e de

term

inat

ions

el

laa

Ce,

laTC

s, S

"Sr,

~~

and

la~

in a

tmos

pher

ic w

ater

pre

cipi

tati

ons

spik

ed w

ith

]iss

ion

prod

ucts

Sam

ple

14

4Ce c

on

ten

t pC

i/1

137C

s co

nte

nt p

Ci/1

sg

Sr c

on

ten

t pC

i/1

"~

con

ten

t pC

i/1

Pre

sen

t R

efer

- D

evi-

P

rese

nt

Ref

er-

Dev

i-

Pre

sen

t R

efer

- D

evi-

P

rese

nt

Ref

er-

Dev

i-

met

ho

d

ence

at

ion

m

eth

od

en

ee

atio

n

met

ho

d

ence

at

ion

m

eth

od

en

ce

atio

n

met

ho

d

~ m

eth

od

~

met

ho

d

~ m

eth

od

0/

0

la~

co

nte

nt p

Ci/1

Pre

sen

t E

x-

Dev

i-

met

ho

d

loec

ted

atio

n

~

5r

0~

RW

10,

ra

in-w

ater

10

5 10

3 ~

- 1.

9 12

.0

11.2

-~

- 7.

1 4.

68

5,23

--

10.

5 39

.0

38.4

~

- 1.

6

RW

11~

ra

in-w

ater

27

.9

26.4

-{

- 5.

7 18

,6

20.8

--

10.

6 65

.3

64.4

-~

1.

4 5.

71

5,63

~

1.4

SW

6,

sno

w-w

ater

35

.9

34.8

-~

3.

2 7.

72

7.70

-~

0.

3 2.

30

2.49

--

7.

6 4.

02

4.00

-[

-0.5

CW

5,

cist

ern

-wat

er

40.5

38

.7

-~

4.7

8.78

8.

21

-~

6.9

1.53

1.

62

--

5.6

15.4

15

.7

--1

.9

CW

6,

cist

ern

-w~

ter

12.7

11

.5

~ 10

.4

5.82

5.

40

~ 7.

8 19

.0

19.5

--

2.

6 6.

52

6.78

--

3.8

16.7

17

.5

--

4.6

3.33

3.

41

--

2.3

6.85

7.

22

--

5.1

0.65

7 0.

736

-- 1

0.7

0.34

0 0.

377

--

9.8

L

5 ~

H. Thaler und W. Sturm: Zur Bestimmung yon Ammoniak in Lebensmi~teln 379

results are given in Tables 1 and 2. In analysed samples the original content of radio-barium was negligible. As in the reference method [1] providing for Ba-Ra separation is not made, the results for radio-barium in Table 2 are compared with those calculated from the amount of radio-barium added. In the chemical yield determinations the correction for the original content of carrier was made for stron- t ium in the case of surface-waters only. The decay measurements of isolated radio-nuclides showed tha t within statistical counting errors no strange activ- ities were present.

Conclusion

A comparison of data in Tables i and 2 shows tha t they agree satisfactory within experimental errors. From this fact it may be concluded tha t the developed method may be successfully used for the determina- tion of 144Ce, laTCs, sDSr, 9~ and 14~ in waters. Generally, with parallel determinations the deviations of results from respective mean values are not greater than 5 % with picocurie levels per liter and 10% with tenth pieocurie levels per liter. The limits of

detection of the proposed method for surface-waters were estimated in the manner described in Par t I [3], accepting in addition 65 ~ average barium yield and no 14~ growth, and amounted to 0.005 pCi/1 for 144Ce, 0.006 pCi/1 for 137Cs, 0.004 pCi/1 for 9~ and 0.006 pCi/1 for 14~ As already mentioned [3] these sensivities can be improved for a few times by using a ba t te ry of columns, which makes possible the ana- lysis of larger samples.

Acknowledgements. The authors wish to thank Mr. J. Koro~in for performingflame-photometric determhmtions and Mrs. H. Kobal for her valuable assistance.

References

1. Osmond, 1~. D. G., T. W. Evett, J. W. Arden, M. B. Lo- vett, and B. Swenney: A.E.R.E.-AhI 84, Harwell 1961.

2. SenegaSnik, M., and 8. Paljk: Z. Anal. Chem. 232, 409 (1967).

3. -- -- Z. Anal. Chem. 244, 306 (1969). 4. -- -- and K. Ju~niS: Z. Anal. Chem. 288, 81 (1968).

Pros Dr. M. SenegaSnik 1Nuclear Institute '~ Stefan" Ljubljana, Jamova 39, Yugoslavia

Z. Anal. Chem. 244, 379--388 (1969)

Zur Bestimmung von Ammoniak in Lebensmitteln

I. l~berpriifung des Verfahrens der Wasserdampf-Destillation

H. Tt~ALE~ und W. STU~M*

Institut fiir Lebensmittelchemie der Technischen UniversitEt Braunschweig und Analytisches Laboratorium der H. Bahlsens Keksfabrik KG, Harmover

Eingegangen am 22. Juli 1968

Determination o/Ammonia in Food. Part I. Examination of the Steam-Distillation Method. Controlling the steam distillation which was used for ammonia determination applying normal pressure, we could state tha t food containing protein did release ammonia even in the presence of very little alkali (pH 7,4). By using s team distillation with magnesium oxide, for mild alkalisation, the amounts of ammonia were lower than with buffer solutions of the same alkalinity; comparatively, with buffer solutions of lower alkalinity magnesium oxide causes a higher amount of ammonia. These effects are mainly caused by the influence of the (boiling-)temperature of 100~ besides of this the amounts of ammonia obtained are depending not only on the type of substance and alkalinity of the solution, but also on the intensity of heating and the duration of the distillation. Variations in the relationship between the amount of sample and the solution for alkalisation effect a change of alkalinity and by this always different yields of ammonia. Therefore, this method cannot be acknow- ledged for determinations of ammonia in substances containiT~g easily decomposable protein compounds, even not under fixed conditions.

* Auszug aus der Dissertation W. Sturm: Zur Bestimmung yon Ammoniak in Getreidemehlen und Backwaren. Techn. Univ. Braunschweig 1967.