Monitoring chloride extraction

An aqueous extract of P. hysterophorus (collected in Puerto Rico) was partitioned into methylene chloride at pH 7, pH 10 and pH 2. Bioassays of the methylene chloride soluble fractions, using the bean second internode bioassay (13), showed that the highest activity was concentrated in the methylene chloride extract at pH 7. Extensive chromatographic purification (flash chromatography, medium pressure LC, preparative TLC) monitored by bioassay led to the isolation of the four sesquiter-... 

A solution of the aldehyde (1 mmol), the diene (1.5 mmol) and bis(trimethylsilyl) sulfide (2 mmol) in acetonitrile (0.5 ml) was treated at room temperature with a solution of CoC12.6H20 (0.2 mmol) in acetonitrile (2.5 ml). Progress of the reaction was monitored by GC/MS analysis. The reaction mixture was quenched with saturated ammonium chloride, extracted with ether and dried over sodium sulfate, and the solvent removed under vacuum. The crude reaction product was then purified by column chromatography or TLC on silica gel. For R1 = Ph a 94% yield was secured. 

Standard procedures were followed for isolation of the toxic principles from mycelium of FA 120. A methylene chloride extract of the freeze-dried hyphae was initially partitioned between hexane and aqueous methanol to separate lipids from more polar material. Bio-assay-monitored chromatographic fractionation of the hexane-soluble material led to the isolation of a fraction (ca. 5% of the hyphal weight) which could account for much of the toxicity of the hyphae of FA 120 to spruce budworm larvae. The spectroscopic and chemical properties of this material were characteristic of the enniatins, a group of cyclic hexadepsipeptide ionophore antibiotics produced by several plant pathogenic Fusarium species, including F. lateritium... 

Trials. The effectiveness of chloride extraction depends on characteristics of individual structures, such as the concrete composition, the actual chloride-penetration profile and the depth of cover. So, it may be useful to carry out a trial on an area (about 1 to 10 m ), which must be representative of the structure to be treated and should last at least 4 to 8 weeks. The results of such a trial in terms of the chloride profile before, during and after chloride extraction gives an indication of the duration required and can be used to show that chloride-extraction treatment of the particular structure will be effective under field conditions. Trials are most certainly recommended if prestressed structures are to be treated with chloride extraction. Careful monitoring of the potential of the prestressing steel should be carried out to establish the risk of hydrogen embrittlement. As a safe criterion, the potential should not become more negative than -900 mV SCE, as apphes for cathodic protection [13]. 

Monitoring after treatment. After the application of chloride extraction, non-destructive measurements may be carried out for controlling the durabihty of the structure, for example, by measuring the half-cell potential of reinforcement How-... 

Automated analyzers may be used for continuous monitoring of ambient poUutants and EPA has developed continuous procedures (23) as alternatives to the referenced methods. Eor source sampling, EPA has specified extractive sampling trains and analytical methods for poUutants such as SO2 and SO [7446-11-9] sulfuric acid [7664-93-9] mists, NO, mercury [7439-97-6], beryUium [7440-41-7], vinyl chloride, and VOCs (volatile organic compounds). Some EPA New Source Performance Standards requite continuous monitors on specified sources. 

The two-phase titration is based on the reaction of anionic surfactants with cations—normally large cationic surfactants—to form an ion pair. The preferred cationic is benzethonium chloride (Hyamine 1622, 1) because of the purity of the commercially available product. On neutralization of the ionic charges, the ion pair has nonpolar character and can be extracted continuously into the organic phase, e.g., chloroform, as it is formed. The reaction is monitored by addition of a water-soluble cationic dye, dimidium bromide (2), and a water-soluble anionic dye, disulfine blue (3). The cationic dye forms an extractable... 

Ealy [ 75 ] also used conversion to alkyl mercury iodides for the gas chromatographic determination of organomercury compounds in benzene extracts of water. The iodides were then determined by gas chromatograph of the benzene extract on a glass column packed with 5% of cyclohexane-succinate on Anakron ABS (70-80 mesh) and operated at 200 °C with nitrogen (56 ml min-1) as carrier gas and electron capture detection. Good separation of chromatographic peaks was obtained for the mercury compounds as either chlorides, bromides, or iodides. The extraction recoveries were monitored by the use of alkylmer-cury compounds labelled with 203 Hg. 

Fig. 4. — Monitoring of the Multiple Molecular Forms of Tomato Pectinesterase by Starch-gel Electrophoresis.98 [ENZ, detection of pectinesterase activity by paper print with pectin and Bromothymol Blue PROT, protein staining with nigrosin O, origin. Key A, 1 crude tomato extract after ammonium sulfate salting-out, and dialysis 2 pectinesterase fraction from column of DEAE-Sephadex A-50 3 and 4 pectinesterase fractions from column of Sephadex G-75. B, Two parts of the same gel after horizontal slicing 1, 500 fig of the isolated form of pectinesterase from a column of CM-Seph-adex C-50 with 175 mM phosphate-sodium chloride buffer 2, active fraction at 150 mM buffer 4 and 5, 250 fig and 1 mg of the isolated form of pectinesterase, respectively.]...

Methanolic MeONa (3M, 0.12 ml) is added to the V-benzylquininium or quinidinium chloride (0.162 g, 0.36 mmol) in dry THF (2 ml) at room temperature. The mixture is stirred at room temperature for 10 min and the Meldrum s acid derivative (0.3 mmol) in dry PhMe (13 ml) is added at -50°C. The course of the reaction is monitored by GLC. On completion, the mixture is stirred for a further 15 min at -50°C and aqueous itric acid (3%, 30 ml) is added. The aqueous phase is separated, and extracted with Et20 (3 x 20 ml). The combined extracts are washed with brine (20 ml) and dried (Na2S04). Evaporation of the Et20 under reduced pressure gives the monomethyl malonic ester. 

B. Mono(2,6-dimethoxybenzoyl)tartaric acid. In a 250-mL, three-necked, round-bottomed flask, equipped with a nitrogen inlet, a reflux condenser and a magnetic stirring bar are placed 6.1 g (18.5 mmol) of dibenzyl tartrate, 100 mL of dry dichloromethane, 4 mL (28.8 mmol) of triethylamine and 50 mg (0.4 mmol) of 4-(dimethylamino)pyridine. The stirred mixture is cooled to 0°C 3.65 g (18.2 mmol) of 2,6-dimethoxybenozyl chloride (Note 3) is added portion-wise over 1 hr. The reaction mixture is then warmed to room temperature and refluxed for 12 to 18 hr (the reaction is easily monitored by TLC). The reaction mixture is then allowed to cool down to room temperature and poured in 100 mL of water, The aqueous phase is extracted with 2 x 75 mL of dichloromethane. The organic phases are combined, dried over odium sulfate, filtered and concentrated to give a viscous oil. This is purified by... 

Freshly prepared NaBH4-alumina (1.13 g, 3.0 mmol of NaBH4) is thoroughly mixed with neat acetophenone Id (0.36 g, 3.0 mmol) in a test tube and placed in an alumina bath inside the microwave oven and irradiated (30 s). Upon completion of the reaction, monitored on TLC (hexane-EtOAc, 8 2, v/v), the product is extracted into ethylene chloride (2x15 mL). Removal of solvent under reduced pressure essentially provides pure sec-phene thy 1 alcohol 2d in 87% yield. No side product formation is observed in any of the reactions investigated and no reaction takes place in the absence of alumina. 

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