92 / P4 1982 CSCC ABSTRACTS

compounds were also present in the atmosphere. Ilowever, thlrty-four of these compounds were found In slgnflcantly higher concentration in human breath, or were not detected in the atmosphere at all. These include chlorinated hydrocarbons, (e.g., chloroform), aromatic compounds (toluene and furan), some alkanes and alkenes and a l a rge number of a l c o h o l s , aldehydes and kecones ( i n the C 3 t o C17 range) . The s i g n i f i - cance o f these r e s u l t s w i l l be d iscussed.

14 ~"E IFCC ASPARTATE AMINOTKANSFERASE (AST) METIIOD MODIFIED FOR USE ON A CENTRIFUGAL FAST ANALYZER AT 37*C. D.W. Grlsley I dr., J.B. Marx, A.J. Brlgandl, N. Creenberg and R.N. Rand (Eastman Kodak Company, Rochester, New York 14650)

The IFCC method for aspartate amlnotransferase (Bergmeyer, H . , e t . a l . , [ 1 9 7 8 ] C l i n . Chem. 2_~4, 720) was m o d i f i e d f o r u s e w i t h the Rotochem-lla (~u~inco) a t 370C. A similar study at 30°C has been reported (Bruns, D., et.aI., [1981] Clin. Chem. 2_77, 156). S a m p l e was i n c u b a t e d w i t h a l l c o m p o n e n t s o f t h e reac t ion m i x t u r e e x c e p t a - k e t o g l u t a r a t e a t 30"C f o r 30 m i n u t e s p r i o r t o t h e r e a c t i o n w h i c h was r u n a t 37*C f o r 160 s e c o n d s a f t e r a 90 s e c o n d l a g t i m e , F i n a l c o n c e n t r a t i o n s o f t h e r e a c t a n t s w e r e a l m o s t I d e n t i c a l w i t h t h e IFCC m e t h o d ; an e x c e p t i o n was t h e s a m p l e v o l u m e f r a c t i o n o f 0 . 0 4 3 .

Up t o 550 U / L , t h e r e a c t i o n was h i g h l y l i n e a r w i t h t i m e . Long t e r m p r e c i s i o n f o r c o n t r o l f l u i d s a t t h r e e l e v e l s o f a c t i v i t y was e x c e l l e n t ; (× U / L ) , t o t a l CV (:~)) ~ 7 . 6 , 3 . 2 , n = 2 2 3 ; 1 7 3 . 1 , 2 . 0 , n = 226; 5 2 8 . 9 , 1 . 6 , n = 35 .

V a r i a t i o n o f c o n t r o l m e a n s a t two l e v e l s in=3) d u r i n g n i n e m o n t h s was n e g l i g i b l e ; ( o v e r a l l X, Range ( U / L ) ) : 4 7 . 6 , O.2; 1 1 3 . 1 , 1 . 3 .

R e f e r e n c e i n t e r v a l s f o r t h e m e t h o d a t 37"C and a t 30°C w e r e r e s p e c t i v e l y 13-47 U/L ( d e t e r m i n e d by r e g r e s s i o n v s m e t h o d w i t h d a t a b a s e o f n = 3 7 0 0 ) , an d 4 - 3 0 U/L (n = 205) .

For a number o f n o r m a l p a t i e n t s a m p l e s (n ~ 205) t h e mean r a t i o (~) and r a n g e (R) o f 37"C t o 30"C v a l u e s was x7 = 1 . 5 2 , 95%(R) = 1 . 1 7 - 1 . 8 9 . The r a t i o a g r e e s c l o s e l y w i t h t h e d a t a of (ReJ, R., [1981] Clln. Chem. 27, 217).

It iS concluded that this method is convenient, hEghly automated and has performance characteristics comparable to the IFCC procedure.

p a t i e n t s may h a v e p r o t e i n s t h a t cause a t u r b i d i t y e f f e c t d i f f e r - e n t f r om t h e e f f e c t o f h e p a r i n .

3) At pH v a l u e s o f 3 . 5 t o 4 . 1 , a n d a c e t a t e c o n c e n t r a t i o n s o f 0 . 0 5 t o 0 . 2 m o l / L , t h e t u r b i d i t y e f f e c t i s n e g l i g i b l e on a l l t h e a b o v e c a t e g o r i e s o f s p e c i m e n . A d d i t i o n a l s t u d i e s a r e i n p r o g r e s s .

17 SUSCEPTIBILITY OF COMMERCIAL KIT PROCEDURES FOR SERUM

IRON TO INTERFERENCE FROM SERUM COPPER, Hinberg, I.H., Tieman, K. and Chiu-Siy, 0., Bureau of Medical Devices, Environmental Health Centre, Tunney's Pasture, Ottawa, Ontario, KIA OL2.

The susceptibi l i ty to interference from serum copper of four commercial k i t procedures for serum iron was determined by studying the effect of added ceruloplasmin-bound copper on the results.

As expected the bathophenanthro)ine k i t procedure was found to be unaffected by up to )000 ug/dl added cerulop)asmin-bound copper. The results obtained with the FerroZine TM reagent which contained thiourea as a copper masking reagent were only increased by 2.3': by the addition of 400 ug/dL ceruloplasmin bound copper.

The other two FerroZine TM kits, which did not contain a copper masking agent, were more strong)y affected by added ceru)oplasmin. The results obtained with both these kits increased linear)y with ceruloplasmin-bound copper added, up to a concentration of 500 ug/dL, but the extent to which the results increased with added cerulop]asmin differed for the two ki ts. The increase in the results observed with the ferroZine TM k i t with the milder reaction conditions was only 3.3" of the ug/dL added copper, indicating that only 33 of the ceru]plasmin bound copper interfered. In contrast, the increase observed with the other k i t was I0.4 of the ug/dL copper added, in excellent agreement with the maximum value of )0.] based on the relative molar absorptivities of Cu I FerroZine)o and Fe(II) (FerroZine) 3. This indicates that a)I the serum c6pper, not just the unsound form, interferes and is therefore a c ] in ica l ly slgnif icant source of interference with this k i t .

~ A CO~fPARISON OF METHODS FOR CK MB QUANTITATION, Meuffels w M. and Hindamrsh, J.T., Biochemistry Division, Dept. of Lab Medicine, Ottawa Civic Hospital, Ottawa, Ontario KIY 4E9.

T h r e e m e t h o d s o f CK MB q u a n t t t a t l o n h a v e b e e n c o m p a r e d u s i n g s e r u m f r o m p a t i e n t s w i t h p r o v e n t r a n s m u r a l m y o c a r d i a l i n f a r c t s ( E . K . G . d i a g n o s i s ) . T y p i c a l r e s u l t s a r e :

% CK MB % CK bib % CK MB C o r n i n g I o n E x c h a n g e Beckman P a r a g o n E l e c t r o - Co lumn

Total CK U/L Electrophoresis phoresis Technique

396 36 18 13 71 17 8 7

759 22 17 I0 917 19 19 7 615 21 19 11

All three methods gave sufflelent sensitivity to make a Lorrect diagnosis using the criterion: 6% MB or greater = myocardial infarction. Further studies wlll include norTnals and patients with high total CK due to non-cardiac disease and other methods f o r MR quantltaclon. (Du Po n t ACA and DADE t e c h n i q u e s . )

i~ IRON INTERFERENCE IN DIALYSIS PATIENT SERUM Buntln~1 Peter S. and Aggarwal, Mahesh, Dept. of Bio-

chemistry, Sunnybrook Medical Centre, 2075 Bayview Avenue, Toronto, Ontario. M4N 3M5, and Dept. of Clinical Biochemistry,

University of Toronto.

We measure serum iron by a dltect serum blank method on a discrete analyser, at pH 4.5, 0.35 mol/L sodium acetate Buffer, with ferrozine (120 mg/L or 244 omol/L) as chromogen, thiourea as copper chelator (40 g/L or 526 ramol/L) and ascorhic acid as reduetant (6.0 g/L Or 34 mmol/L). It became evident that preci- pitation in the reaction tubes caused many falsely elevated values on renal patient specimens, particularly those from haemo- dialysis patients. Subsequent investigation has led to the following results and tentative conclusions:

I) An effect similar to that observed with haemodialysls patient sertLm ks found with non-renal patient bepatinised plasma, but not with non-renal patient serum. One or more plasma proteins presumably precipitates, causing the turbidity. Since haemo- dialysis patients are anticoagulated with heparin, their "serum" more closely resembles plasma, and this probably accounts for most of the problem.

2) A much smaller turbidity effect is observed with serum and plasma from peritoneal dialysis patients (who are not anticoagu- fated), in addition, the renal patient behavlour is not identi- cal to that o f non-renal plasma. This suggests that renal

18 TIIE POSSIBLE INTEREI!RENCE OF SERUM FREE FATTY ACIDS WITII CALCIUM DETER$11NATION IN SERA OF I)IALYSIS P A T I E N T S , I , e e , Y . I . , P r a g a y , D . A . , and C h i l c o t e , M.I£. , D e p t . o f C l i n i c a l C h e m i s t r y , E r i e Count) - M e d i c a l C e n t e r and D e p t . o f B i o c h e m i s t r y , S U N Y / B u f f a l q B u f f a l o , NY 14214 .

The l i t e r a t u r e s p o r a d i c a l l y m e n t i o n e d s p u r i o u s l y low C a l c i u m / C a ) l e v e l s in s e r a o f d i a l y s i s p a t i e n t s . (Two s u c h c a s e s i n t e n ) ' e a r s o c c u r r e d in o u r l a b o r a t o r i e s . ) I : ree f a t t y a c i d s (FI:A) we re s u g g e s - t ed a s a p o s s i b l e s o u r c e o f i n t e r f e r e n c e w i t h Ca d e t e r m i n a t i o n s . In o r d e r t o t e s t t h i s , v a r i o u s a m o u n t s o f FFA ( p a l m i t a t e , s t e a r a t e and o l e a t e r e s p e c t i v e l y ) we re a d d e d t o s e p a r a t e a l i q u o t s o f p o o l e d s e r a and t h o r o u g h l y m i x e d . Ca was t e s t e d in t h e s e s e r a by f o u r d i f f e r e n t m e t h o d s : A t o m i c A b s o r p t i o n AA, ( C . V . 1 . 4 % ) , EGTA t i t r a - t i o n in C o m i n g C a l c i u m T i t r a t o r (C .V . 1 . S % ) , O - c r e s o l p h t h a l e i n a s s a y i n T e c h n i c o n Sb~ 12 ( C . V . 1 . 5 - 1 . 7 % 1 and Kodak E k t a c h e m c h i p m e t h o d . Brunk and S w a n s o n ' s m e t h o d ( C l i n . C h e m . 2 7 : 9 2 4 , 1981) was u s e d t o a s s a y t h e c o n c e n t r a t i o n o f EFA in m i x t u r e s ( C . V . 4 - 1 0 % ) . R e s u l t s showed t h a t up t o a c e r t a i n " t h r e s h o l d l e v e l " ( 1 . 6 raraol/L f o r p a l m i t a t e o r s t e a r a t e o r 1 . 9 mmol / I , f o r d i e s i s ) t h e r e was no i n t e r f e r e n c e w i t h any o f t h e Ca m e t h o d s . Ahove t h e " t h r e s h o l d l e v e l , " t u r b i d s a m p l e s c o u l d be c o r r e c t l y d e t e r m i n e d by AA m e t h o d b u t n o t w i t h t h e o t h e r m e t h o d s . I f t u r b i d s a m p l e s c o n t a i n i n g h i g h l e v e l o f FI:A we re c l e a r e d by c e n t r i f u g a t i o n o r f i l t r a t i o n , t h e c l e a r e d i n f r a n a t a n t s c r a showed a d e c r e a s e d Ca c o n c e n t r a t i o n by a l l m e t h o d s . I t was d e t e c t e d t h a t t h e p a r t i c l e s s e p a r a t e d by t e n o t r i f u g a t i o n c o n t a i n e d t h e b a l a n c e o f t h e Ca in FFA c o m p l e x f o r m . T h e s e e x p e r i m e n t s showed t h a t FEA, a p h y s i o l o g i c a l m e t a b o l i t e , m i g h t i n t e r f e r e w i t h Ca a s s a y m e t h o d s . V e r y h i g h FFA c o n c e n t r a - t i o n ( 2 - 4 m m o l / L ) m i g h t r a n d o m l y he e n c o u n t e r e d in t h e b l o o d o f p a t i e n t s who u n d e r g o k i d n e y d i a l y s i s ( B e r g r e m ~ L e i v e s t a d , L a n c e t , 1978 , i i , 1160) o r r e c e i v e l i p i d i n f u s i o n . U n d e r s u c h c o n d i t i o n s one mus t be p a r t i c u l a r l y c a r e f u l o f Ca l e v e l s and m e t h o d s o f d e t e ~ m i n a t i o n . IVe a l s o c o n t i n u e o u r s t u d i e s t o e l u c i d a t e w h e t h e r o r n o t t h e FFA-Ca c o m p l e x c o n t r i b u t e s t o t h e m u s c u l a r t w i t c h i n g phenom- enon in d i a l y s i s p a t i e n t s .

i9 INFLUENCE OF HEMOLYSIS ON THE RATIO OF LACTATE

DEHYDROGENASE-I/LACTATE DEHYDROGENASE-2 (LD-I/LD-2) IN SERUM AS DETERMINED BY COLORIMETRIC AGAROSE-GEL ELECTROPHORESIS PROCEDURE. David Acheampon~-Mensah and Julian Deogracias, Humber Memorial Hospital, 200 Church Street, Weston, Ontario, Canada, H9N ]M8.

The effect of hemolysis on the ratio of LD-I/LD-2 in serum appears to depend on tile method of isoenzyme measurement (I. Papadopoulus, N., Clin. Chem. 27 624- 625, i98I; 2. Leung, F. and Henderson, A., Clln. Chem. 2__~7 1708-I711, 198l). Since this observation affects the use of thls test for the diagnosis of myocardial infarction we investigated the problem with our Cornlng Agarose-Cel Calorimetric Electrophoretlc Procedure