Barker 1 Extraction

D Ari L, WA Barker (1985) p-cresol formation by cell-free extracts of Clostridium difficile. Arch Microbiol 143 311-312. 

Solid-phase sorbents are also used in a technique known as matrix solid-phase dispersion (MSPD). MSPD is a patented process first reported in 1989 for conducting the simultaneous disruption and extraction of solid and semi-solid samples. The technique is rapid and requires low volumes (ca. 10 mL) of solvents. One problem that has hindered further progress in pesticide residues analysis is the high ratio of sorbent to sample, typically 0.5-2 g of sorbent per 0.5 g of sample. This limits the sample size and creates problems with representative sub-sampling. It permits complete fractionation of the sample matrix components and also the ability to elute selectively a single compound or class of compounds from the same sample. Excellent reviews of the practical and theoretical aspects of MSPD " and applications in food analysis were presented by Barker.Torres et reported the use of MSPD for the... 

In 1958 Barker (20) isolated a red, heat stable, light labile, cofactor which was required for the metabolism of glutamate in cell-extracts of Clostridium tetanomorphum. Subsequently this cofactor was crystallized. X-ray crystallography identified Barker s cofactor as the coenzyme form of Vitamin B12 (15, 21). 

Long AR, Crouch MD, Barker SA. 1991b. Multiresidue matrix solid phase dispersion (MSPD) extraction and gas chromatographic screening of nine chlorinated pesticides in catfish (Ictalurus punctatus) muscle tissue. J Assoc Off Anal Chem 74 667-670. 

Lott HM, Barker SA. 1993. Extraction and gas chromatographic screening of 14 chlorinated pesticides in crayfish (Procambarus clarkii) hepatopancreas. J AOAC International 76 663-668. 

Lynen had studied chemistry in Munich under Wieland his skill as a chemist led to the successful synthesis of a number of fatty acyl CoA derivatives which proved to be substrates in the catabolic pathway. Many of these C=0 or C=C compounds had characteristic UV absorption spectra so that enzyme reactions utilizing them could be followed spectrophotometrically. This technique was also used to identify and monitor the flavoprotein and pyridine nucleotide-dependent steps. Independent evidence for the pathway was provided by Barker, Stadtman and their colleagues using Clostridium kluyveri. Once the outline of the degradation had been proposed the individual steps of the reactions were analyzed very rapidly by Lynen, Green, and Ochoa s groups using in the main acetone-dried powders from mitochondria, which, when extracted with dilute salt solutions, contained all the enzymes of the fatty acid oxidation system. 

Barker SA, Littlefield-Chabaud MA, David C. 2001. Distribution of the hallucinogens N,N-dimethyltryptamine and 5-methoxy-N,N-dimethyltryptamine in rat brain following intraperitoneal injection application of a new solid-phase extraction LC-APCI-MS-MS-isotope dilution method. J Chromatogr B Biomed Appl 751 37. 

Another method used for nitrate determination on dried and milled herbage employs the nitrate selective electrode. One of the first published methods was that of Paul and Carlson (1968). Other anions, especially chloride, can interfere. These authors removed chloride with silver resin, but Barker ef al. (1971) omitted the resin because it tended to foul the electrode and cause excessive drift. Normally the Cl N03 ratio is so low as not to interfere, but saline precipitation from coastal plots could affect this. The method was further modified to allow storage of extracts for up to 64 h by adding a preservative of phenyl-mercuric acetate and dioxane, both very toxic (Baker and Smith, 1969). This paper mentions the need to change the electrode s membrane, filling solution and liquid ion exchanger every 2 months to minimize chloride interference. It is easy to overlook electrode maintenance between batches of nitrate analyses, and this can lead to errors and sluggish performance. 

Dry copper C-ethvlacetylacetone, 2 2 grams, is added to 0 77 gram of selenium tetrachloride in 20 e.c. of dry chloroform, the pale green precipitate which forms is shaken with ether and dilute sulphuric acid, and the ether extract evaporated until 0 6 gram of the required compound is obtained (yield, 50 per cent.). The compound crystallises from alcohol as colourless, transparent, six-sided prisms or needles, 1 Morgan, Drew and Barker, loc. cit. 

Gamer, R. C., Barker, J., Flavell, C., Gamer, J. V., Whattam, M., Young, G. C., Cussans, N., Jezequel, S., and Leong, D. (2000). A validation study comparing accelerator, M. S., and liquid scintillation counting for analysis of 14C-labelled chugs in plasma, urine and faecal extracts. J. Pharm. Biomed. Anal. 24 197-209. 

Gamer RC, Barker J, Flavell C et al. (2000) A validation study comparing accelerator MS and liquid scintillation counting for analysis of 14C-labelled drugs in plasma, urine and faecal extracts. J Pharm Biomed Anal 24 197-209 Hayakawa H, Fukushima Y, Kato H et al. (2003) Metabolism and disposition of novel des-fluoro quinolone garenoxacin in experimental animals and an interspecies scaling of pharmacokinetic parameters. Drug Metab Dispos 31 1409-1418... 

Wastewater Treating. Barker we discussed the importance of bringing environmental experts into the project early. Wastewater treating can be part of the battery limits process area in the case of phenol extraction from coal gasification gas liquor, but this is an exception. 

Extracts of whole ripe and unripe berries, seed, pulp, root, leaf, and stem produce erythrocyte agglutination and leukocyte mitosis (Fames et al., 1964). A glycoprotein known as pokeweed mitogen is responsible for leukocyte mitosis, and in pokeweed poisonings, plasmacytosis variable in onset and lasting 2 mo or longer is seen (Barker et al., 1966 Roberge et al., 1986). 

Long, A.R. Hsieh, L.C. Malbrough, M.S. Short, C.R. Barker, S.A. A multiresidue method for the isolation and liquid chromatographic determination of seven sulfonamides in infant formula. J.Liq.Chromatogr., 1989, 12, 1601-1612 [extracted sulfadiazine, sulfadimethoxine, sulfamerazine, sulfamethazine, sulfathiazole, sulfisoxazole column temp 45 SPE]... 

Matrix solid phase dispersion (MSPD) is an effective sample preparation technique that combines extraction and purification in one step. Barker et al. defined MSPD procedures as those that use dispersing sorbents with chemical modification of the silica surface (e.g.. Cl8, C8). Samples are blended and dispersed on particles (diameters of 40-100 p.m) using a glass or agate mortar and pestle (Pig. 4.3). The use of ceramic or clay mortars and pestles can result in loss of analytes. A disadvantage of the method is the traditionally high sorbent sample ratios... 

The fermentative bacteria, Lactobacillus leichmannii probably possess the most simple of all ribonucleotide reductases, but the protein does require the most complex coenzyme known, 5 -deoxyadenosylcobalamin (Fig. 1). This corrinoid coenzyme catalyzes but few enzymatic reactions, usually involving an intramolecular 1,2-hydrogen shift as found in the common methylmalonylCoA succinylCoA isomerase reaction. Participation in deoxyribonucleotide formation, where hydrogen transfer occurs intermolecularly (Eq. I), was first implicated by the nutritional requirement of lactobacilli for vitamin B12 during DNA synthesis, and was verified in cell-free extracts by Blakley and H. A. Barker in 1964 The reaction has been studied in great detail in the laboratories of Beck Blakley and Hogenkamp ... 

Barker (1978) advocated plotting mineral compositions on an AFM diagram in addition to rock compositions to assess mineralogical control of magmatic processes. However, this approach can only be semiquantitadve since the lever rule.(see below), which works well in bivariate plots, cannot be applied because of the disparate proportions of the compositions before projection. Thus AFM diagrams cannot be used in petrogenetic studies to extract quantitative information about... 

Kumarasamy, Y., L. Nahar, M. Byres, A. Delazar, and S.D. Barker. 2005. The assessment of biological activities associated with the major constituents of the methanol extract of wUd carrot (Daucus carota L.) seeds.). Herb. Pharmacother. 5(l) 61-72. 

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