Acid washing procedure

A total volume of 2 L of hexane washes results, accompanied by the gradual precipitation of a yellow solid from the hexane washes. The acid-wash procedure frequently leads to emulsions and gunny yellow solid in both phases back-extraction of the "aqueous" layer with hexane may be necessary. 

Inherent in all these methodologies, which measure either absolute Sr levels or strontium isotope ratios in mineralized tissue, is the assumption that diagenesis has not altered the signal since death. This has been a matter of some considerable debate (e.g., Nelson et al. 1986), but the consensus of current opinion amongst practitioners is that the repeated acid-washing procedures used remove any diagenetic mineral, because it has a higher... 

Acid-washing Procedure in which laboratory articles are soaked overnight in 4% detergent (e.g., Contrad 70) and rinsed five times in reverse osmosis water, soaked overnight in 10% HC1 and rinsed five times in Milli-Q water and oven dried (58°C). Volume 1(6). 

The northern portion of Chesapeake Bay was studied. This upper section of the bay can be classified as a classic salt-wedge type estuary (15). The humic materials used in this study were extracted from several cores of sediments. Two one-meter cores gravity corer. The cores of sediments were then divided into sections and squeezed under nitrogen to remove most of the interstitial water. The squeezed sediments were then dried, weighed and washed with distilled water. The sediments were then washed with 0.5N KCl to remove iron hydroxides, carbonates and exchangeable cations from the clays. Some of the fulvic acids are lost in this acid wash procedure. The humic materials were then extracted from the remaining solids by a O.IN NaOH solution. 

Effects of acid-washing procedure on Th-Pb ages of zircons. In Abstracts... 

Procedure (copper in crystallised copper sulphate). Weigh out accurately about 3.1 g of copper sulphate crystals, dissolve in water, and make up to 250 mL in a graduated flask. Shake well. Pipette 50 mL of this solution into a small beaker, add an equal volume of ca AM hydrochloric acid. Pass this solution through a silver reductor at the rate of 25 mL min i, and collect the filtrate in a 500 mL conical flask charged with 20 mL 0.5M iron(III) ammonium sulphate solution (prepared by dissolving the appropriate quantity of the analytical grade iron(III) salt in 0.5M sulphuric acid). Wash the reductor column with six 25 mL portions of 2M hydrochloric acid. Add 1 drop of ferroin indicator or 0.5 mL N-phenylanthranilic acid, and titrate with 0.1 M cerium(IV) sulphate solution. The end point is sharp, and the colour imparted by the Cu2+ ions does not interfere with the detection of the equivalence point. 

Place 200 g of ion exchange resin Dowex 50W-X8, 100-200 mesh, hydrogen form into a 1-L beaker and add 600 ml of 1 M hydrochloric acid solution. Allow to stand for 24 h with occasional swirling. Decant off the liquid and filter off the resin using filter funnel and paper. Place the resin in a beaker and add 600 ml of distilled water. Stand for 24 h with occasional swirling. Decant off the liquid and repeat the washing procedure until the wash water is neutral to pH paper. 

This procedure may be employed for m-chlorobromobenzene, b.p. 191-194° from tn chloroaniline m-dibromobenzene, b.p. 215-217°, from m-bromoaniline and o-bromoanisole, b.p. 114 116°/29 mm. from o anisidine (the sulphuric acid washing is omitt in the last example). 

The chromatographic procedure may be carried out using a glass column (1.5 m x 2 mm) packed with acid-washed, silanized diatomaceous support (80-100 mesh) coated with 3% (w/w) of phenyl methyl silicone fluid (50% phenyl) (OV-17 is suitable) and maintained at 270 °C. 

By a traditional method, a- and /i-iononcs can be converted to ionene, catalyzed by HI along with small amounts of phosphorus. A cleaner cydization occurred by heating /i-ionone in water at 250 °C in the MBR [50]. In the workup the usual exhaustive washing procedures were unnecessary. Similarly, as mentioned above, carvacrol was prepared almost quantitatively, by isoaromatization of carvone in water at 250 °C for 10 min [47]. A conventional, literature method utilized acidic conditions, took a longer time and proceeded in lower conversion. The above examples show that elevated temperatures under neutral pH conditions can offer advantages over acidic (or basic) reagents at lower temperatures. 

The combined benzene filtrates from this initial washing procedure are concentrated under reduced pressure, and the washing procedure with benzene is repeated to give a second crop of the crude acid chloride which is transferred to a flask for recrystallization. 

Reaction of dichloroteUurolactones with excess NaBH regeneration of y,S-unsaturated acids (general procedure) The dichloroteUurolactone (1 mmol) in THF (10 mL) at room temperature is treated with NaBH4 (0.1 g, 2.6 mmol) in H2O (5 mL). An immediate reaction takes place and the solution turns dark red. After stirring for 10 min at room temperature, the reaction mixture is diluted with ether (30 mL) and extracted with 2 N NaOH (2x5 mL). The organic phase is washed wiUi H2O, dried (MgS04) and evaporated, furnishing bis(p-methoxyphenyl) ditelluride in a quantitative yield. The cooled aqueous... 

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