Enhanced range of syringe filters

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Selective transport o f alkali a n d alkaline earth metallic ions M a n y t r a n s p o r t s y s t e m s for m e t a l l i c i o n s t h r o u g h a s u p p o r t e d l i q u i d m e m b r a n e (SLM) c o n t a i n i n g a chelating agent as a carrier have previously been s t u d i e d . However, r e p o r t s o n t h e t r a n s p o r t o f a l k a l i a n d / o r a l k a l i n e e a r t h m e t a l l i c i o n s u s i n g a n SLM h a v e r a r e l y a p p e a r e d b e c a u s e t h e a b i l i t i e s for c o m p l e x f o r m a t i o n o f t h e i r i o n s a r e v e r y low. A s e l e c t i v e t r a n s p o r t s y s t e m for a l k a l i a n d a l k a l i n e earth metallic ions with a perchlorate ion as a pairing i o n s p e c i e s t h r o u g h a n SLM c o n t a i n i n g t r i p e n t y l p h o s p h a t e (TPP} a s c a r r i e r is d e s c r i b e d in Sep. Scl. Technol., 28, p p 1 6 2 9 - 1 6 4 0 , 1993. T h e SLM u s e d w a s a p o r o u s p o l y p r o p y l e n e m e m b r a n e i m p r e g n a t e d w i t h TPP s o l u t i o n in o - n i t r o p h e n y l o c t y l e t h e r . T h e effects of t h e p a i r i n g i o n species, the initial perchlorate concentration, and the TPP c o n c e n t r a t i o n o n m e t a l l i c i o n t r a n s p o r t a b i l i t y were examined under various experimental conditions. The permeation velocities of the metallic ions in t h e t r a n s p o r t s y s t e m foUowed t h e s e q u e n c e Li + >> Na + > K + > Mg2+; t h a t is a h i g h l y s e l e c t i v e t r a n s p o r t for Li + i o n w a s o b s e r v e d . It w a s c o n c l u d e d t h a t t h i s p r o p o s e d t r a n s p o r t s y s t e m m i g h t b e a p p l i c a b l e to t h e s e p a r a t i o n , r e c o v e r y , a n d c o n c e n t r a t i o n of Li ÷ ion from aqueous solution samples such as wastewater, g r o u n d w a t e r , etc.

Further information from: Takashi Salto, Department of Chemlcal Technology, K a n a g a w a Institute of Technology, 1030, Shlmooglno, Atsugi, Kanagawa, 243-02, Japan.

N e w ca ules retain Mycoplasma G e l m a n S c i e n c e s h a s i n t r o d u c e d d i s p o s a b l e 0.1 ~m CritiCapTM-M filter c a p s u l e s t h a t offer a b s o l u t e r e t e n t i o n of M y c o p l a s m a s p e c i e s w h e n s t e r i l l s i n g l a r g e volumes of biological and tissue culture solutions. A l t h o u g h i n d u s t r y s t a n d a r d s still c o n s i d e r 0.2 ~tm f i l t r a t i o n d e v i c e s to b e a c c e p t a b l e for s t e r i l i s i n g g r a d e , the company says that research has indicated that s p e c i e s of M y c o p L a s m a c a n e a s i l y p e n e t r a t e a 0.2 ~tm p o r e size m e m b r a n e a t r e l a t i v e l y low p r e s s u r e . The double-Layer membrane capsule configuration u s e s G e h n a n S c i e n c e s p a t e n t e d 0. I ~m S u p o r

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m e m b r a n e . T h i s is d e s i g n e d to give a h i g h flow r a t e a n d h i g h t h r o u g h p u t , to r e d u c e t h e n u m b e r of filters required. The c a p s u l e s a r e Cell C u l t u r e M e d i a Certified. G a m m a i r r a d i a t i o n s t e r f l i s a t i o n , a s well a s t h e t h e r m a l b o n d i n g m e t h o d of a s s e m b l y , e l i m i n a t e s t h e p o t e n t i a l for l e a c h i n g c y t o t o x l c e x t r a e t a b l e s i n t o t h e filtrate.

Further Information from: Gelman Sciences, BrackmlUs B u s i n e s s Park, CasweU Road, Northampton NN4 0EZ, UK. Tel: +44 (0)604 765141. Fax: +44 (0)604 761383.

Enhanced range o f s y r i n g e filters W h a t m a n I n t e r n a t i o n a l h a s e x p a n d e d its r a n g e of 13 m m a n d 4 m m s y r i n g e filters, w h i c h a r e i n c r e a s i n g l y p r e f e r r e d for s m a l l s a m p l e p r e p a r a t i o n . T h e d e v i c e s h a v e a fine t u b e tip o u t l e t , a n d u s e r s c a n n o w c h o o s e filters c o n t a i n i n g c e l l u l o s e a c e t a t e m e m b r a n e s . C e l l u l o s e a c e t a t e is a u s e f u l filter m e d i u m b e c a u s e it e x h i b i t s v e r y low p r o t e i n b i n d i n g , a n d it is a l s o s o l v e n t r e s i s t a n t to a n u m b e r of low m o l e c u l a r w e i g h t a l c o h o l s . The t u b e t i p s w e r e p r e v i o u s l y o n l y a v a i l a b l e o n d e v i c e s c o n t a i n i n g y l o n a n d PTFE filter m e m b r a n e s in b o t h 0 . 2 ~rn a n d 0 . 4 5 ~tm p o r e sizes.

Further Information from: Whatman International Ltd, Whatman House, St Leonard's Road, 2 0 / 2 0 Maidstone, Kent ME16 OLS, UK. Tel: +44 (0)622 676670. Fax: +44 (0)622 677011.

H o l l o w fibre modules made w i t h h o l l o w fibre fabric R e s e a r c h e r s in t h e USA h a v e s t u d i e d t h e c o r r e l a t i o n s for m a s s t r a n s f e r a c r o s s b o u n d a r y l a y e r s a d j a c e n t to h o l l o w fibre m e m b r a n e s (J. Membrane Sci., 84, 1993, p p 1-14). T h e y m e a s u r e d t h e overall m a s s t r a n s f e r coefficient of o x y g e n from w a t e r a c r o s s a h o l l o w fibre membrane into nitrogen. The membranes were m i c r o p o r o u s , so t h e overall m a s s t r a n s f e r w a s c o n t r o l l e d b y t h e i n d i v i d u a l coefficient i n t h e water. The m e m b r a n e s w e r e i n c o r p o r a t e d i n t o m o d u l e s in w h i c h t h e f i b r e s w e r e c a r e f u l l y s p a c e d , i n c l u d i n g m o d u l e s m a d e f r o m h o l l o w fibre fabric. At low flows, t h e s e m o d u l e s gave m a s s t r a n s f e r w h i c h w a s u p to t e n t i m e s f a s t e r t h a n in c o m m e r c i a l m o d u l e s b a s e d o n

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