Sequential extraction procedures modification

Much work has been reported on the evaluation of sequential extraction procedures. The three-stage sequential extraction procedure for speciation of heavy metals proposed by the Commission of the European Communities Bureau of References (BCR) was found to be acceptable and reproducible with some modifications [29]. In another study, when applied to real soils and sediments, this (unmodified) BCR method was queried [30]. Lopez-Sanchez et al. [31 ] found that significant results can be obtained when different sequential extraction procedures are used. 

Stevenson and Preston [3] used symmetrical stop-flow flow FFF to examine proteins extracted from Katepwa, a high-quality bread wheat variety, using a modification of the traditional Osborne extraction procedure. Fractions isolated by this sequential extraction procedure included wheat proteins ex-... 

In the fields of environmental and exploration geochemistry, considerable use has been made of sequential extraction procedures in order to determine the bioavailability and geomobUity of trace metals (including V, Cr, As, Se, Cd and Pb). More recently, sequential extractions have been used to elucidate information relating to the speciation of metals in soils and sediments. The extraction protocol developed by Tessier " has traditionally been used (with modifications) and involves the sequential use of a variable cocktail of extractants including acetic acid, sodium acetate, magnesiumchloride, EDTA, acidified hydroxylamine hydrochloride, oxalic acid, sodium... 

The first two reports on the use of flow FFF for separating wheat proteins appeared in the literature in 1996 when researchers firom two independent laboratories reported characterization of wheat proteins from different varieties extracted by different methods and analyzed on two different types of flow FFF apparatus. Wahlund et al. - used asymmetrical flow FFF to examine proteins extracted firom two bread wheat varieties of different protein content using sequential extraction with increasing concentrations of dilute hydrochloric acid (HCl). Stevenson and Preston used symmetrical flow FFF to examine proteins extracted firom Katepwa, a high quahty bread wheat variety, using a modification of the traditional Osborne extraction procedure. Results from both studies showed that for the monomeric gliadin-type fractions ranged in size from 8 to... 

LO was purified from two weeks-old bovine calf aorta by a modification of published procedures (14, 15). The aortas (ca. 600 g) were cleaned and finely ground prior to protein extraction. Extractions and all subsequent procedures were carried out at 4 °C. The ground aortas were extracted with 0.15 M NaCl-16 mM potassium phosphate (KPi) (saline buffer), 16 mM KPi, and 4 M urea-16 mM KPi buffer (pH 7.8), sequentially, in the presence of protease inhibitors PMSF (1 mM) and iodoacetamide (0.04% w/v). The saline buffer and KPi extracts contained negligible activity and were discarded. The urea buffer extracts were pooled (total of 4 to 5 L) and mixed with hydroxyapatite gel (100 g, preequilibrated in 4 M urea-16 mM KPi). After batch elution from hydroxyapatite, the urea-soluble enzyme solution was concentrated (ca. 700 ml) and dialyzed against 16 mM KPi (pH 7.8) buffer. 

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