- Email: [email protected]
Determination of part per billion levels of chloride in high-purity waters by co-precipitation and spectrophotometry
Analb
SHORT
t i t t: ( Ittnll~ a /1~ t o
E N e w e r Pubh,damg C o m p a n y Am~lt.rd,ma Prmlt.d in Fh~. Nt.th~.rl,tntl,,
434
COMMUNICATION
Determination of part per bUlion levels of chloride in high-purity waters by coprecipitation and spectroi~hotometry
R I~) I~,()I)ABAtJ(Jll ,tnd G "I UI'I'FI~MAN ltttl,(o~h aml W d t o \
,llhan(e l~eseat~h ( e t l t e r , Alhan~e. Ohtt~(U S" A )
(I,le~.etvetl 14lh l,ttlu,try 1972)
T h e m e r c u r y ( l l ) t h l o c y a n a t e m e t h o d ~ has b e e n w i d e l y u s e d to d e t e r m i n e c h l o r i d e c o n c e n t r a t i o n s in h i g h - p u r i t y w a t e r s i n c l u d i n g i o n - e x c h a n g e r effluents, s t c a m condensate,,,, a n d b o i l e r f e c d w a t e r s T h e p r a c t i c a l d e t e c t i o n l i m i t by this m e t h o d c a n r u n g c t'rom 10 p.p b to 50 p . p b c h l o r i d e d e p e n d i n g u p o n t h e c a r e a n d e q u i p m e n t u s e d for t h e a n a l y s i s A m o n - e x c h a n g t : r e s i n s m a y be u s e d to c o n c e n t r a t e t h e c h l o r i d e in t h e s a m p l c b c l o r e a n a l y s i s by the m e r c u r y ( l l ) t h i o c y a n a t e m e t h o d H o w c v e r , r a n - e x c h a n g e c o n c e n t r a t i o n r e q u i r e s tl largc m l t m l s a m p l e v o l u m e (severed liters o r m o r e ) b e f o r e a s i g n i f i c a n t c o n c e n t l a t i o n f a c t o r Is a c h i e v e d . A l s o t h e a n a l y s t m u s t be e x t r e m e l y c t u e f u l to a v o i d c o n t a m l n u t l o n of t h e t c s m a n d t h c s u r f a c e s t h a t c o m e in c o n t a c t w i t h the sample T h i s p a p e r d e s c r i b e s a c o p l e c l p i t a t l o n p l o c e d u r e for c o n c e n t r a t i n g c h l o r i d e w h i c h h a s t h e a d v a n t a g e s o f a r c l a t t v e l y s m a l l initial s a m p l e v o l u m e (250 m l ) a n d m l m m a i c o n t a m i n a t i o n risk C o p r e c i p l t a t i o n o f t h e c h l o r i d e is f o l l o w e d by a n a l y s i s o f t h e p r e c i p i t a t e by t h e m e r c u r y ( l l ) t h t o c y a n a t e t e c h n i q u e W i t h g o o d t e c h n i q u e a d e t e c t i o n h m l t of I p p b. c h l o r i d e m t h e o r i g i n a l s a m p l e is p o s s i b l e . A p p a r a t t¢,s
The polyethylene bottles used were "'N,dgene" narrow-mouth conventional p o l y e t h y l e n e , 8-oz sine ( n o t e t h e s e b o t t l e s a c t u a l l y h o l d a b o u t 270 ml) O t h e r e q u i p m e n t i n c l u d e d a G t l f o l d m o d e l 240 s p e c t r o p h o t o m e t e r a n d 5 0 - r a m m a t c h e d a b s o r p t i o n cells o f 15-ml c a p a c i t y , a c e n t r i f u g e ( I n t e r n a t i o n a l E q u i p m e n t C o , B o s t o n , M a s s , t y p e 1 m o d e l SB) w i t h N o . 242 c u p h o l d e r a n d N o . 373 cup~, a n d a 5-ml m l c r o b u r e t with 00l-ml divisions. Reaqents
D e m l n e m h z e d w a t e r w a s u s e d for all s o l u t i o n p r e p a r a t i o n s a n d d i l u t i o n s , u n l e s s o t h e r w i s e specified. T h e w a t e r w a s d l s t d l e d a n d d e m m e r a h z e d , a n d h a d a n e l e c t r i c a l r e s m t l v i t y g r e a t e r t h a n 10 M f L I r o n ( I l l ) n i t r a t e - n i t r i c acid s o l u t i o n D m s o l v e 8.0 g o f I r o n ( I l l ) m t r a t e n o n a h y Anal Clnm Acta, 60 (1972)
SHORT COMMUNICATION
435
dratem300mlofwater, a d d 5 8 5 ml o f c o n c e n t r a t e d m t r l c , l c l d ( s g 1.42) a n d d i l u t e to 1 1 with water. L e a d m t r , t t e s o l u t i o n P r e p a r e a 2 " , , ( w / v ) s o l u t t o n m w m e r a n d s t o r e m a 500ml p o l y e t h y l e n e s q u e e z e b o t t l e M e r c u r y ( l l) t h l o c y a n a t e s o l u t i o n P r e p a r e a 0 3 ",, (w/v) s o l u t i o n ira metlaanol, s t o r e m an a m b e r glass b o t t l e a n d l e a v e for 12 h b e l o r e u~e S o d i u m p h o s p h a t e s o l u t i o n l)ts,,olve 16 7 g o f ,,odium d f l a y d r o g e n p h o s p h a t c m o n o h y d r a t e a n d ! 6 2 g o f d l s o d m m h y d r o g e n p h o s p h a t e h e p t a h y d r a t e in w a t e r a n d d i l u t e t o 1 I w i t h w a t e r S t o r e m 5 0 0 - m i p o l y e t h y l e n e Stluee~'e b o t t l e s S o d m m c h l o r i d e .,,tandard s o l u t i o n D i s s o l v e 0 ! 65 g of sodtuna c h l o r t d e (drted at 110 ° for 2 h) m w a t e r a n d dilute t o I ! D i l u t e I'urther to p r o d u c e 10 p.p.m a n d 5 p p na chloride ,;olutlons
Prepttr(ltt(m o/ ,S(lmplc's /or andl3'sls S o a k the 8-oz p o l y e t h y l e n e s a m p l e b o t t l e s m 10",, (v/v) m t r i c a c i d at r o o m t e m p e r a t u r e o v e r m g h t b e f o r e use R~nse the b o t t l e , , t h o r o u g h l y w~tla d c m m e r a h z e d w a t e r m a m e d m t e l y b e f o r e use. P r e p a r e k n o w n c h l o l l d e m w a t e r s a m p l e s b y a d d i n g the a p p r o p r i a t e v o l u m e o f the 5 p p.m or 10 p p m c h l o r i d e s o l u t i o n to d e m l n e r a h ; , e d w a t e l m the s a m p l e b o t t l e a n d t h e n d i l u t i n g the s o l u t i o n to 250 ml P r e p a r e solutions c o n t a i n i n g a k n o w n a m o u n t of a d d e d chloride and contam i n a n t s p e c i e s b y a d d i n g a p p r o p r m t e v o l u m e s o f the 5 p p m . c h l o r i d e s t a n d a r d s o l u t m n a n d the c o n t a m i n a n t s t o c k s o l u t i o n to a s a m p l e b o t t l e a n d t h e n d ~ l u t m g the v o l u m e t o 250 mi. A h a l v.s t s proc e d m ' e
S a m p l e s w e r e a n a l y z e d f o u r at a t i m e O n e o f t he fou r,,a naple,, wa~; a d e m m e r a l i z e d w a t e r b l a n k T h e o t h e r three c o n t a i n e d , l d d e d c h l o r t d e c o n c e n t r a t i o n s with o r w i t h o u t c o n t a m i n a n t s T h e f o l l o w i n g p r o c e d u r e w a s used to z m a l y / e e a c h set o f f o u r samples. W e i g h 5 0 g o f lead n i t r a t e s o l u t i o n i n t o e a c h s a m p l e , c a p the s a m p l e s a n d mix A f t e r 2 m t n , w e i g h 5 0 g o f s o d i u m p h o , , p h a t e s o l u t m n into e a c h s a m p l e , c a p t h e s a m pie .'rod mix L e a v e the s a m p l e s for 5 m m b e f o r e c e n t r f f u g a t i o n C e n t r i f u g e at 1500 r p m for 5 m m D e c a n t the s u p e r n a t c f r o m e a c h s a m p l e t m m e d t a t e l v a f t e r c e n t r i f u g a t i o n . P i p e t t e 15 ml o f the w o n ( I l l ) s o l u t m n into e a c h b o t t l e a n d swirl unttl the p l e c i p l t a t e d i s s o l v e s P i p e t t e 1 0 tril o f t h e m e r c u r y ( l l ) t h l o c y a n a t e s o l u t i o n i n t o e a c h bottle A f t e r 10 mln, m e a s u r e t h e a b s o r b a n c e o f e a c h o f t h e f o u r s a m p l e s a g a i n s t d m t d l e d w a t e r at 463 n m in 5 0 - m m c e l l s ( T h e 5 0 - m m cell h o l d s 15 ml a n d the c o l o r l m e t r i c s o l u t i o n v o l u m e is 16 ml By r i n s i n g a 5 0 - m m cell with d e m m e r a h z e d w a t e r a n d t h e n s h a k i n g it, it w a s d e t e r m i n e d t h a t less t h a n 100 mg w a t e r is left r e s i d e T h e d i l u t i o n effect o f thin o n the c o l o r e d s o l u t i o n w o u l d be less t h a n 1/150. F o r p r a c t i c a l p u r p o s e s , this is n e g h g l b l e . T h e r e f o r e , d r y i n g t h e cell b c f o i ¢ use Is u n n e c e s s a r y . ) Re.sult,s a n d dt.sctt,s~ton A h s o r b a n c e v.s c ' o n c e n t r a t t o n a n d p h o t o m e t r t c
Amd Chin1 Acta, 60 (1972)
setlSitlVlt v. A c u r v e o f a b s o r b a n c e
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water ,,olutlons cont.unmg
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v.s.chlorldc c o n c e n t r a t i o n is s h o w n m F i g 1 T h e c u r v e m n e a r l y h n e a r ttp t o 100 p p b c h l o r t d e At h i g h e r c h l o r i d e c o n c e n t r a t t o n s the c h a n g e m a b s o r b a n c e w t t h r e s p e c t t o c o n c e n t r a t t o n b e c o m e s less t h a n h n e a r . T h e e m p i r i c a l p h o t o m e t r i c s e n s l t l w t y o f t h e m e t h o d i s 0 0030 a b s o r b a n c e / p p . b c h l o r t d e in t h e o r i g i n a l s a m p l e . T h e s e n s i t i v i t y o f the m e r c u r y ( l l ) t h t o c y a n a t e m e t h o d w i t h o u t a c h l o r i d e c o n c e n t r a t i o n p r o c e d u r e is 0 0002 a b s o r b , ' m c e / p p b in t h e o r l g m a l s a m p l e . T h e p h o t o m e t m c s e n s l t t w t y m c r e a s e for the c o p r e c l p m t t l o n c o n c e n t r , ' t t ~ o n p r o c e d u r e is t h u s 15 t t m e s . Prect,stOlh T a b l e 1 s h o w s the a n a l y t i c a l p r e c i s i o n for d e m l n e r a h z e d w a t e r samples contamlng dtflerent amounts of added chloride. The prectston indicates that 1 p p.b. c h l o r i d e c a n be d e t e r m m e d . Ab,sorbcmce o/ the blatli~. T h e a v e r a g e a b s o r b a n c e for t h e d e m m e r a h z e d w a t e r TABLE
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DEMINERAI~IZED .
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Added p p I~ C i -
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WATER .
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SAMPLES .
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N u m h e l ol s a m p l e s c
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16
2 4 10 20 40 60 80 100 120
10 5 2 I~ 5 3 I 2 I
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205 0 246 0
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I 2 + 0 4 t' 2 2.+_O 3 42+03 102 202+_05 41 6 + _ 0 3 61 9 80 7 100 8 !170
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p p I, c h h o . l e [ot~nd"
240 320 .
CONTAINING
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a Based upon the hnear relatlonshtp a b s o r b a n c e t,s d t s t l l l e d w a t e r ) t, C a l c u l a t e d s t a n d a r d d e v i a t i o n A n M Chm~ A c t a . 60 (1972)
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p p b C I - = 333 ( s a m p l e a b s o r b a n c e
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COMMUNICATION
TABLE
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ANALYSIS
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WATER
437
SAMPLES
CONTAINING
20 p p b
CI-|LORIDE
p p b ~ ontamttlatlts a d d e d
p p h chlortde found
4 0 0 0 F e z" + 3460 N t t , ~ + 13760 S ( ) ] 2(R-)O F c 3 ' + 6 6 0 0 N O ~ 101)11 F'e ~ " 4- 3300 N ( ) { 1001) C u 2 * + 1520 ~JOaz 5 0 0 ( ' u 2 * + 760 'S().{ 2 5 0 1 u 2" + - 3 8 0 S ( ) ~ 8 3 0 ( r~()~ 4- 300 K " 415 CrzO~ +150K' 208{r2(}~ +75 K' 2(1.0{}(} S(}~. 4 960(} N , t ' 4 (RIO K ' -I- 4 9 0 0 S ( ) ~ 2.000 K " 4- 2450 ~ ( ) ~ 4.01)0 LA ' F 9 9 0 0 ()11 2 0 0 0 l.t* 4-49511 ( I l l 4000 Nail 4 5.1(R) S J ( ) ~ - ~ - ~ 1 0 0 N a ' a.8011SK)~ + 2~00 N,t ' 2,550St(){ + 1540 N , t ' 2,000 N~ 2 ' 4 ~ 2 7 0 %().~ 4 0 ( R ) l - + 380t) NFI.~ 2,O00 F - + 1900 N H ~ . 1,0011 l" 4 9 ' q ) N I I . ~ 5 0 0 I" + 4 7 5 N l l g 4 0 0 l" + 3 8 0 N l t , ~ 200 F + 1 9 0 N 1 1 ~ 1 ~.O00.OOl~ ! I ,~BO ~ 8 . 0 0 0 000 H ~B()~ 5.O00 N i I ~
20. 20 23, 2"~ 20. 20 "~8 39 27. 28 I t) 19 47 29,27.28 20 20 20. 20 20 20 17 16 19, 20 6. 2 20. 21 23 20 21 17 2 I. 20 17 20. 21 20, 21 5 12 17 211 19.21 20 21 24, 24 25 21. 22 20. 22
+CONTAMINANTS
s a m p l e s c o n t a i n i n g n o a d d e d c h l o r i d e w a s 0 090 v,s distilled w a t e r O n e p p.b chloride p r o d u c e d ,'m increase o f 0 003 a b s o r b a n c e umts, or a 3.3 ",,, relative a b s o r b a n c e increase wsth respect to the blank InterJerences T a b l e ! I s h o w s the effect o f c o n t a m m a n t species on the d e t e r m i n a t i o n o f 20 p p b c h l o r i d e Chlortde recocery br coprectpttattot~. A chloride r e c o v e r y test w a s run to determ i n e ff c o p r e m p s t a t m n o f c h l o r i d e is quantitative. T w o s a m p l e s o f d e m m e r a h z e d w a t e r and t w o s a m p l e s o f d e m m e r a h z e d water c o n t m n m g 40 p p.b. a d d e d c h l o r i d e w e r e carrmd t h r o u g h the c o p r e m p l t a t m n procedure. T h e ~ron(llI) a n d rnercury(ll) s o l u t m n s were then a d d e d to the four prempltates D e m m e r a h z e d w a t e r (1 trli) w a s a d d e d to the t w o s a m p l e s h a v i n g the 40 p.p b. added c h l o r i d e a n d to o n e o f t h e d e m m e rahzed water s a m p l e s C h l o r i d e s o l u t i o n ( e n o u g h to p r o d u c e 40 p.p.b, a d d e d chloride m a 2 5 0 - m l s a m p l e ) w a s added to the other d e m m e r a h z e d w a t e r s a m p l e The a b s o r b a n c e s o f the three s o l u t i o n s c o n t a i n i n g c h l o r i d e w e r e m e a s u r e d against the u n s p l k e d d e m m e r a h z e d w a t e r s a m p l e T h e a b o v e p r o c e d u r e was carrmd o u t twine and in b o t h c a s e s 98'2, c h l o r i d e recovery w a s o b t a i n e d . Chotce o] ,sample bottles. The centrifuged lead p h o s p h a t e preclpltate a d h e r e d w e l l e n o u g h to c o n v e n t i o n a l p o l y e t h y l e n e bottles to a l l o w c o m p l e t e d e c a n t i n g o f the A n a l C h o n A c t a . 60 11972)
438
SI40R'F
COMMUNICATION
s u p e r n a t a n t hcluid. T e f l o n bottles p r o v e d uns~ltlsfactory b e c a u s e the p r e c i p i t a t e did n o t a d h e r e well e n o u g h to p e r m i t d e c a n t i n g w i t h o u t prec~pitate loss EJJect o/varymq, lead and phosphate concentratton,s. T h e c o n c e n t r a t i o n o f lead in the 2 5 0 - m l s a m p l e after a d d i t i o n o f t h e lead n i t r a t e s o l u t m n is 0 012 M. T h e c o n c e n t r a t m n o f p h o s p h a t e w h e n 5 g o f s o d i u m p h o s p h a t e s o l u t i o n is i n t r o d u c e d i n t o a 250ml s a m p l e is 0.012 M H P O 2- a n d 0 024 M H2PO~, T h e s e l e a d a n d p h o s p h a t e c o n c e n t r a t x o n s give a p r e c i p i t a t e w h i c h a d h e r e s well t o t h e p o l y e t h y l e n e a f t e r c e n t r f f u g a t m n . W h e n 5 g o f lead s o l u t i o n a n d 2 g or 15 g o f p h o s p h a t e s o l u t i o n w e r e used, the p r e c t p l t m e did not a d h e r e well to the p o l y e t h y l e n e R I - t I I~.1- N(.'I" I 4',;7,X! Stamhwds P~trt 2~. N o v
Anal Cimn A¢ta. 60(1972)
1969
W a t e r , atmosplaert~ analysts p p
29 31
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t i t t: ( Ittnll~ a /1~ t o
E N e w e r Pubh,damg C o m p a n y Am~lt.rd,ma Prmlt.d in Fh~. Nt.th~.rl,tntl,,
434
COMMUNICATION
Determination of part per bUlion levels of chloride in high-purity waters by coprecipitation and spectroi~hotometry
R I~) I~,()I)ABAtJ(Jll ,tnd G "I UI'I'FI~MAN ltttl,(o~h aml W d t o \
,llhan(e l~eseat~h ( e t l t e r , Alhan~e. Ohtt~(U S" A )
(I,le~.etvetl 14lh l,ttlu,try 1972)
T h e m e r c u r y ( l l ) t h l o c y a n a t e m e t h o d ~ has b e e n w i d e l y u s e d to d e t e r m i n e c h l o r i d e c o n c e n t r a t i o n s in h i g h - p u r i t y w a t e r s i n c l u d i n g i o n - e x c h a n g e r effluents, s t c a m condensate,,,, a n d b o i l e r f e c d w a t e r s T h e p r a c t i c a l d e t e c t i o n l i m i t by this m e t h o d c a n r u n g c t'rom 10 p.p b to 50 p . p b c h l o r i d e d e p e n d i n g u p o n t h e c a r e a n d e q u i p m e n t u s e d for t h e a n a l y s i s A m o n - e x c h a n g t : r e s i n s m a y be u s e d to c o n c e n t r a t e t h e c h l o r i d e in t h e s a m p l c b c l o r e a n a l y s i s by the m e r c u r y ( l l ) t h i o c y a n a t e m e t h o d H o w c v e r , r a n - e x c h a n g e c o n c e n t r a t i o n r e q u i r e s tl largc m l t m l s a m p l e v o l u m e (severed liters o r m o r e ) b e f o r e a s i g n i f i c a n t c o n c e n t l a t i o n f a c t o r Is a c h i e v e d . A l s o t h e a n a l y s t m u s t be e x t r e m e l y c t u e f u l to a v o i d c o n t a m l n u t l o n of t h e t c s m a n d t h c s u r f a c e s t h a t c o m e in c o n t a c t w i t h the sample T h i s p a p e r d e s c r i b e s a c o p l e c l p i t a t l o n p l o c e d u r e for c o n c e n t r a t i n g c h l o r i d e w h i c h h a s t h e a d v a n t a g e s o f a r c l a t t v e l y s m a l l initial s a m p l e v o l u m e (250 m l ) a n d m l m m a i c o n t a m i n a t i o n risk C o p r e c i p l t a t i o n o f t h e c h l o r i d e is f o l l o w e d by a n a l y s i s o f t h e p r e c i p i t a t e by t h e m e r c u r y ( l l ) t h t o c y a n a t e t e c h n i q u e W i t h g o o d t e c h n i q u e a d e t e c t i o n h m l t of I p p b. c h l o r i d e m t h e o r i g i n a l s a m p l e is p o s s i b l e . A p p a r a t t¢,s
The polyethylene bottles used were "'N,dgene" narrow-mouth conventional p o l y e t h y l e n e , 8-oz sine ( n o t e t h e s e b o t t l e s a c t u a l l y h o l d a b o u t 270 ml) O t h e r e q u i p m e n t i n c l u d e d a G t l f o l d m o d e l 240 s p e c t r o p h o t o m e t e r a n d 5 0 - r a m m a t c h e d a b s o r p t i o n cells o f 15-ml c a p a c i t y , a c e n t r i f u g e ( I n t e r n a t i o n a l E q u i p m e n t C o , B o s t o n , M a s s , t y p e 1 m o d e l SB) w i t h N o . 242 c u p h o l d e r a n d N o . 373 cup~, a n d a 5-ml m l c r o b u r e t with 00l-ml divisions. Reaqents
D e m l n e m h z e d w a t e r w a s u s e d for all s o l u t i o n p r e p a r a t i o n s a n d d i l u t i o n s , u n l e s s o t h e r w i s e specified. T h e w a t e r w a s d l s t d l e d a n d d e m m e r a h z e d , a n d h a d a n e l e c t r i c a l r e s m t l v i t y g r e a t e r t h a n 10 M f L I r o n ( I l l ) n i t r a t e - n i t r i c acid s o l u t i o n D m s o l v e 8.0 g o f I r o n ( I l l ) m t r a t e n o n a h y Anal Clnm Acta, 60 (1972)
SHORT COMMUNICATION
435
dratem300mlofwater, a d d 5 8 5 ml o f c o n c e n t r a t e d m t r l c , l c l d ( s g 1.42) a n d d i l u t e to 1 1 with water. L e a d m t r , t t e s o l u t i o n P r e p a r e a 2 " , , ( w / v ) s o l u t t o n m w m e r a n d s t o r e m a 500ml p o l y e t h y l e n e s q u e e z e b o t t l e M e r c u r y ( l l) t h l o c y a n a t e s o l u t i o n P r e p a r e a 0 3 ",, (w/v) s o l u t i o n ira metlaanol, s t o r e m an a m b e r glass b o t t l e a n d l e a v e for 12 h b e l o r e u~e S o d i u m p h o s p h a t e s o l u t i o n l)ts,,olve 16 7 g o f ,,odium d f l a y d r o g e n p h o s p h a t c m o n o h y d r a t e a n d ! 6 2 g o f d l s o d m m h y d r o g e n p h o s p h a t e h e p t a h y d r a t e in w a t e r a n d d i l u t e t o 1 I w i t h w a t e r S t o r e m 5 0 0 - m i p o l y e t h y l e n e Stluee~'e b o t t l e s S o d m m c h l o r i d e .,,tandard s o l u t i o n D i s s o l v e 0 ! 65 g of sodtuna c h l o r t d e (drted at 110 ° for 2 h) m w a t e r a n d dilute t o I ! D i l u t e I'urther to p r o d u c e 10 p.p.m a n d 5 p p na chloride ,;olutlons
Prepttr(ltt(m o/ ,S(lmplc's /or andl3'sls S o a k the 8-oz p o l y e t h y l e n e s a m p l e b o t t l e s m 10",, (v/v) m t r i c a c i d at r o o m t e m p e r a t u r e o v e r m g h t b e f o r e use R~nse the b o t t l e , , t h o r o u g h l y w~tla d c m m e r a h z e d w a t e r m a m e d m t e l y b e f o r e use. P r e p a r e k n o w n c h l o l l d e m w a t e r s a m p l e s b y a d d i n g the a p p r o p r i a t e v o l u m e o f the 5 p p.m or 10 p p m c h l o r i d e s o l u t i o n to d e m l n e r a h ; , e d w a t e l m the s a m p l e b o t t l e a n d t h e n d i l u t i n g the s o l u t i o n to 250 ml P r e p a r e solutions c o n t a i n i n g a k n o w n a m o u n t of a d d e d chloride and contam i n a n t s p e c i e s b y a d d i n g a p p r o p r m t e v o l u m e s o f the 5 p p m . c h l o r i d e s t a n d a r d s o l u t m n a n d the c o n t a m i n a n t s t o c k s o l u t i o n to a s a m p l e b o t t l e a n d t h e n d ~ l u t m g the v o l u m e t o 250 mi. A h a l v.s t s proc e d m ' e
S a m p l e s w e r e a n a l y z e d f o u r at a t i m e O n e o f t he fou r,,a naple,, wa~; a d e m m e r a l i z e d w a t e r b l a n k T h e o t h e r three c o n t a i n e d , l d d e d c h l o r t d e c o n c e n t r a t i o n s with o r w i t h o u t c o n t a m i n a n t s T h e f o l l o w i n g p r o c e d u r e w a s used to z m a l y / e e a c h set o f f o u r samples. W e i g h 5 0 g o f lead n i t r a t e s o l u t i o n i n t o e a c h s a m p l e , c a p the s a m p l e s a n d mix A f t e r 2 m t n , w e i g h 5 0 g o f s o d i u m p h o , , p h a t e s o l u t m n into e a c h s a m p l e , c a p t h e s a m pie .'rod mix L e a v e the s a m p l e s for 5 m m b e f o r e c e n t r f f u g a t i o n C e n t r i f u g e at 1500 r p m for 5 m m D e c a n t the s u p e r n a t c f r o m e a c h s a m p l e t m m e d t a t e l v a f t e r c e n t r i f u g a t i o n . P i p e t t e 15 ml o f the w o n ( I l l ) s o l u t m n into e a c h b o t t l e a n d swirl unttl the p l e c i p l t a t e d i s s o l v e s P i p e t t e 1 0 tril o f t h e m e r c u r y ( l l ) t h l o c y a n a t e s o l u t i o n i n t o e a c h bottle A f t e r 10 mln, m e a s u r e t h e a b s o r b a n c e o f e a c h o f t h e f o u r s a m p l e s a g a i n s t d m t d l e d w a t e r at 463 n m in 5 0 - m m c e l l s ( T h e 5 0 - m m cell h o l d s 15 ml a n d the c o l o r l m e t r i c s o l u t i o n v o l u m e is 16 ml By r i n s i n g a 5 0 - m m cell with d e m m e r a h z e d w a t e r a n d t h e n s h a k i n g it, it w a s d e t e r m i n e d t h a t less t h a n 100 mg w a t e r is left r e s i d e T h e d i l u t i o n effect o f thin o n the c o l o r e d s o l u t i o n w o u l d be less t h a n 1/150. F o r p r a c t i c a l p u r p o s e s , this is n e g h g l b l e . T h e r e f o r e , d r y i n g t h e cell b c f o i ¢ use Is u n n e c e s s a r y . ) Re.sult,s a n d dt.sctt,s~ton A h s o r b a n c e v.s c ' o n c e n t r a t t o n a n d p h o t o m e t r t c
Amd Chin1 Acta, 60 (1972)
setlSitlVlt v. A c u r v e o f a b s o r b a n c e
436
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F : g 1 A h , . o r b . t n c c c u r v e .tt 46"~ n m tn 5 0 - r a m cell,, l o r d e m t n e r , t h / e d
water ,,olutlons cont.unmg
chloNde
v.s.chlorldc c o n c e n t r a t i o n is s h o w n m F i g 1 T h e c u r v e m n e a r l y h n e a r ttp t o 100 p p b c h l o r t d e At h i g h e r c h l o r i d e c o n c e n t r a t t o n s the c h a n g e m a b s o r b a n c e w t t h r e s p e c t t o c o n c e n t r a t t o n b e c o m e s less t h a n h n e a r . T h e e m p i r i c a l p h o t o m e t r i c s e n s l t l w t y o f t h e m e t h o d i s 0 0030 a b s o r b a n c e / p p . b c h l o r t d e in t h e o r i g i n a l s a m p l e . T h e s e n s i t i v i t y o f the m e r c u r y ( l l ) t h t o c y a n a t e m e t h o d w i t h o u t a c h l o r i d e c o n c e n t r a t i o n p r o c e d u r e is 0 0002 a b s o r b , ' m c e / p p b in t h e o r l g m a l s a m p l e . T h e p h o t o m e t m c s e n s l t t w t y m c r e a s e for the c o p r e c l p m t t l o n c o n c e n t r , ' t t ~ o n p r o c e d u r e is t h u s 15 t t m e s . Prect,stOlh T a b l e 1 s h o w s the a n a l y t i c a l p r e c i s i o n for d e m l n e r a h z e d w a t e r samples contamlng dtflerent amounts of added chloride. The prectston indicates that 1 p p.b. c h l o r i d e c a n be d e t e r m m e d . Ab,sorbcmce o/ the blatli~. T h e a v e r a g e a b s o r b a n c e for t h e d e m m e r a h z e d w a t e r TABLE
I
ANALYSIS .
.
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OF
.
.
.
.
DEMINERAI~IZED .
.
Added p p I~ C i -
.
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.
.
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.
.
.
.
.
.
WATER .
.
.
.
.
.
.
.
SAMPLES .
.
N u m h e l ol s a m p l e s c
I
16
2 4 10 20 40 60 80 100 120
10 5 2 I~ 5 3 I 2 I
.
I
149 0
I I
205 0 246 0
.
.
.
.
.
.
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CHLORIDE
I 2 + 0 4 t' 2 2.+_O 3 42+03 102 202+_05 41 6 + _ 0 3 61 9 80 7 100 8 !170
160
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ADI)ED
p p I, c h h o . l e [ot~nd"
240 320 .
CONTAINING
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a Based upon the hnear relatlonshtp a b s o r b a n c e t,s d t s t l l l e d w a t e r ) t, C a l c u l a t e d s t a n d a r d d e v i a t i o n A n M Chm~ A c t a . 60 (1972)
.
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that
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.
p p b C I - = 333 ( s a m p l e a b s o r b a n c e
l,s d s s t t l l e d w a t e r - b l a n k
SHORT
COMMUNICATION
TABLE
!1
ANALYSIS
OF
WATER
437
SAMPLES
CONTAINING
20 p p b
CI-|LORIDE
p p b ~ ontamttlatlts a d d e d
p p h chlortde found
4 0 0 0 F e z" + 3460 N t t , ~ + 13760 S ( ) ] 2(R-)O F c 3 ' + 6 6 0 0 N O ~ 101)11 F'e ~ " 4- 3300 N ( ) { 1001) C u 2 * + 1520 ~JOaz 5 0 0 ( ' u 2 * + 760 'S().{ 2 5 0 1 u 2" + - 3 8 0 S ( ) ~ 8 3 0 ( r~()~ 4- 300 K " 415 CrzO~ +150K' 208{r2(}~ +75 K' 2(1.0{}(} S(}~. 4 960(} N , t ' 4 (RIO K ' -I- 4 9 0 0 S ( ) ~ 2.000 K " 4- 2450 ~ ( ) ~ 4.01)0 LA ' F 9 9 0 0 ()11 2 0 0 0 l.t* 4-49511 ( I l l 4000 Nail 4 5.1(R) S J ( ) ~ - ~ - ~ 1 0 0 N a ' a.8011SK)~ + 2~00 N,t ' 2,550St(){ + 1540 N , t ' 2,000 N~ 2 ' 4 ~ 2 7 0 %().~ 4 0 ( R ) l - + 380t) NFI.~ 2,O00 F - + 1900 N H ~ . 1,0011 l" 4 9 ' q ) N I I . ~ 5 0 0 I" + 4 7 5 N l l g 4 0 0 l" + 3 8 0 N l t , ~ 200 F + 1 9 0 N 1 1 ~ 1 ~.O00.OOl~ ! I ,~BO ~ 8 . 0 0 0 000 H ~B()~ 5.O00 N i I ~
20. 20 23, 2"~ 20. 20 "~8 39 27. 28 I t) 19 47 29,27.28 20 20 20. 20 20 20 17 16 19, 20 6. 2 20. 21 23 20 21 17 2 I. 20 17 20. 21 20, 21 5 12 17 211 19.21 20 21 24, 24 25 21. 22 20. 22
+CONTAMINANTS
s a m p l e s c o n t a i n i n g n o a d d e d c h l o r i d e w a s 0 090 v,s distilled w a t e r O n e p p.b chloride p r o d u c e d ,'m increase o f 0 003 a b s o r b a n c e umts, or a 3.3 ",,, relative a b s o r b a n c e increase wsth respect to the blank InterJerences T a b l e ! I s h o w s the effect o f c o n t a m m a n t species on the d e t e r m i n a t i o n o f 20 p p b c h l o r i d e Chlortde recocery br coprectpttattot~. A chloride r e c o v e r y test w a s run to determ i n e ff c o p r e m p s t a t m n o f c h l o r i d e is quantitative. T w o s a m p l e s o f d e m m e r a h z e d w a t e r and t w o s a m p l e s o f d e m m e r a h z e d water c o n t m n m g 40 p p.b. a d d e d c h l o r i d e w e r e carrmd t h r o u g h the c o p r e m p l t a t m n procedure. T h e ~ron(llI) a n d rnercury(ll) s o l u t m n s were then a d d e d to the four prempltates D e m m e r a h z e d w a t e r (1 trli) w a s a d d e d to the t w o s a m p l e s h a v i n g the 40 p.p b. added c h l o r i d e a n d to o n e o f t h e d e m m e rahzed water s a m p l e s C h l o r i d e s o l u t i o n ( e n o u g h to p r o d u c e 40 p.p.b, a d d e d chloride m a 2 5 0 - m l s a m p l e ) w a s added to the other d e m m e r a h z e d w a t e r s a m p l e The a b s o r b a n c e s o f the three s o l u t i o n s c o n t a i n i n g c h l o r i d e w e r e m e a s u r e d against the u n s p l k e d d e m m e r a h z e d w a t e r s a m p l e T h e a b o v e p r o c e d u r e was carrmd o u t twine and in b o t h c a s e s 98'2, c h l o r i d e recovery w a s o b t a i n e d . Chotce o] ,sample bottles. The centrifuged lead p h o s p h a t e preclpltate a d h e r e d w e l l e n o u g h to c o n v e n t i o n a l p o l y e t h y l e n e bottles to a l l o w c o m p l e t e d e c a n t i n g o f the A n a l C h o n A c t a . 60 11972)
438
SI40R'F
COMMUNICATION
s u p e r n a t a n t hcluid. T e f l o n bottles p r o v e d uns~ltlsfactory b e c a u s e the p r e c i p i t a t e did n o t a d h e r e well e n o u g h to p e r m i t d e c a n t i n g w i t h o u t prec~pitate loss EJJect o/varymq, lead and phosphate concentratton,s. T h e c o n c e n t r a t i o n o f lead in the 2 5 0 - m l s a m p l e after a d d i t i o n o f t h e lead n i t r a t e s o l u t m n is 0 012 M. T h e c o n c e n t r a t m n o f p h o s p h a t e w h e n 5 g o f s o d i u m p h o s p h a t e s o l u t i o n is i n t r o d u c e d i n t o a 250ml s a m p l e is 0.012 M H P O 2- a n d 0 024 M H2PO~, T h e s e l e a d a n d p h o s p h a t e c o n c e n t r a t x o n s give a p r e c i p i t a t e w h i c h a d h e r e s well t o t h e p o l y e t h y l e n e a f t e r c e n t r f f u g a t m n . W h e n 5 g o f lead s o l u t i o n a n d 2 g or 15 g o f p h o s p h a t e s o l u t i o n w e r e used, the p r e c t p l t m e did not a d h e r e well to the p o l y e t h y l e n e R I - t I I~.1- N(.'I" I 4',;7,X! Stamhwds P~trt 2~. N o v
Anal Cimn A¢ta. 60(1972)
1969
W a t e r , atmosplaert~ analysts p p
29 31