ANTIOXIDANTS FOR EPDM SEALS EXPOSED TO CHLORINATED TAP WATER

2014 ◽  
Vol 87 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Mio Gonokami ◽  
Yoshimasa Yamamoto ◽  
Oraphin Chaikumpollert ◽  
Yoshito Ohtake ◽  
Seiichi Kawahara
Keyword(s):  
Gas Chromatography ◽  
Weight Loss ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Mass Spectroscopy ◽  
High Performance ◽  
Tap Water ◽  
Accelerated Degradation ◽  
Poly Ethylene ◽  
Gas Chromatography Mass Spectroscopy

ABSTRACT A suitable antioxidant for a poly(ethylene-co-propylene-co-5-ethylidene-2-norbornene) (EPDM) seal in tap water applications was determined with respect to volatilization and decomposition of the antioxidants. Seals were prepared by mixing EPDM with 1 phr antioxidant and other ingredients followed by vulcanizing the mixture at 433 K for 20 min. The resulting EPDM seals were immersed into chlorinated water to investigate accelerated degradation. The change in antioxidant content was measured by gas chromatography/mass spectroscopy (GC/MS) and high-performance liquid chromatography (HPLC). The weight loss of amine antioxidants during vulcanization was quite low due to their low volatility and decomposition. Antioxidant weight loss during accelerated degradation depended on both the antioxidant's ability to trap radicals and solubility in chlorinated water.

Identification of 3β-hydroxy-5,7-pregnadien-20-one and 3β-hydroxy-5,7-androstadien-17-one as endogenous steroids in the fetal horse gonad

1983 ◽  
Vol 99 (1) ◽  
pp. 87-92 ◽  
Author(s):  
A. D. Tait ◽  
S. Santikarn ◽  
W. R. Allen
Keyword(s):  
Gas Chromatography ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Thin Layer ◽  
Mass Spectroscopy ◽  
High Performance ◽  
Synthetic Steroids ◽  
Gas Chromatography Mass Spectroscopy ◽  
Layer Chromatography ◽  
Endogenous Steroids

The 5,7-dienes, 3β-hydroxy-5,7-pregnadien-20-one and 3β-hydroxy-5,7-androstadien-17-one were extracted from fetal horse gonads and purified by solvent partition, thin-layer chromatography and high performance liquid chromatography. The isolated steroids were identified by comparison with the synthetic steroids using ultraviolet and mass spectroscopy and by gas chromatography–mass spectroscopy. The identification of these compounds as endogenous steroids, together with the data on their biosynthesis reported previously, support the proposal that in the fetal horse gonad there is a 5,7-diene pathway biosynthesizing 3β-hydroxy-5,7-androstadien-17-one, which is the proposed precursor for equilin in the placenta.

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