Water guard

HPLC analyses were carried out on a Waters system (Waters 501 pump. Wisp auto-sampler 710B Waters Corporation, Milford, Massachusetts, USA) equipped with a diode array detector (Waters 996). Two systems were employed. The first used a reverse phase Cl8 column (250 x 4 mm Licrosphere 100 Merck, Darmstadt, Germany) protected by a C18 (NovaPak Waters) guard column. A binary solvent system consisting of solvent A (dilute HCl, pH 2.4) and solvent B (80% acetonitrile solution acidified using concentrated HCl to pH... 

Guard column Waters Guard-Pak with Anatech 40-60 xm glass beads... 

Mobile phase Isopropanol 100 mM pH 5.5 NaHaPOi (Use a 4 x 6 Waters Guard-Pak CIS between piunp and injector.)... 

Waters IC-Pak A HR analytical and Waters Guard Pak precolumn Dionex HPIC AG4 (50 X 4 mm ) guard and AS4 (250 X 4 mm ) analytical Metrosep A SUPP 4-250... 

Synonyms cas 142-77-8 water guard fab guard Butyl Paraben... 

GCP 501P [BetzDearborn http //www.betzdearborn.com], JM 1000 [J 8i M Labs] JM 1001 [J M Labs] Linear 2 [Sper http //www.sperchemical.com]. Liquid Poly-10 [Water Guard]... 

Liquid Poly-20 [Water Guard] Liquid Poly-30 [Water Guard] Millsperse 956 [Ashland/Drew Ind. Div. http //www.ashchem.com], MSW-600 [ONDEO Nalco http //www.ondeo-nalco.com], Nalco 519 PULV [ONDEO Nalco http //WWW. ondeo-nalco. com]... 

Consolidate the slopes, improve the hydraulic regime of the rain water (guard channels, etc.)... 

Fit a 500 ml. round-bottomed flask with a dropping-funnel, and with an efficient reflux water-condenser having a calcium chloride guard-tube at the top. 

Chill the concentrated solution of the amine hydrochloride in ice-water, and then cautiously with stirring add an excess of 20% aqueous sodium hydroxide solution to liberate the amine. Pour the mixture into a separating-funnel, and rinse out the flask or basin with ether into the funnel. Extract the mixture twice with ether (2 X25 ml.). Dry the united ether extracts over flake or powdered sodium hydroxide, preferably overnight. Distil the dry filtered extract from an apparatus similar to that used for the oxime when the ether has been removed, distil the amine slowly under water-pump pressure, using a capillary tube having a soda-lime guard - tube to ensure that only dry air free from carbon dioxide passes through the liquid. Collect the amine, b.p. 59-61°/12 mm. at atmospheric pressure it has b.p. 163-164°. Yield, 18 g. 

Dissolve 13 g. of sodium in 30 ml. of absolute ethanol in a 250 ml. flask carrying a reflux condenser, then add 10 g. (9 5 ml.) of redistilled ethyl malonate, and place the flask on a boiling water-bath. Without delay, add a solution of 5 3 g. of thiourea in a minimum of boiling absolute ethanol (about 100 ml.). The sodium salt of thiobarbituric acid rapidly begins to separate. Fit the water-condenser with a calcium chloride guard-tube (Fig. 61, p. 105), and boil the mixture on the water-bath for 1 hour. Cool the mixture, filter off the sodium salt at the pump and wash it with a small quantity of cold acetone. Dissolve the salt in warm water and liberate the acid by the addition of 30 ml. of concentrated hydrochloric acid diluted with 30 ml. of water. Cool the mixture, filter off the thiobarbituric acid, and recrystallise it from hot water. Colourless crystals, m.p. 245 with decomposition (immersed at 230°). Yield, 3 5 -4 0 g. 

Carrying out a combustion. The apparatus (Fig. 85, p. 469) will have been left with the bottle W connected to the beak of the combustion tube via the guard tube V and with all the taps shut, the combustion tube, which is dways allowed to cool down while connected to the oxygen source, will therefore be full of oxygen at slightly above atmospheric pressure, thus preventing any leaking in of carbon dioxide or water vapour from the air. 

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