Waters Assoc

Methods Exam. Waters Assoc. Math 1988, United Kingdom Dept, of the Environment Chem. Abstr. 108, 197583v (1988). 

Fig. 4.5. Distribution of early middle Miocene benthic molluscs and paleoposition of Japan as restored on the basis of paleomagnetism. Abbreviations w., water assoc., association (Chinzei, 1991).

Instrument Waters HPLC System (Waters Assoc. Milford, MA)... 

Plant extracts were analyzed directly and after passing through a 0 3 Waters Assoc. Sep-Pak as a clean-up procedure. 

The molar absorptivities for the two betaines and the three sulfobetaines in aqueous solution are listed in Table I. Before being used for surface tension measurements, aqueous solution of surfactants were further purified by repeated passage (12) through minicolumns (SEP-PAK Cjs Cartridge, Waters Assoc., Milford Mass.) of octadecylsilanized silica gel. The concentration of surfactant in the effluent from these columns was determined by ultraviolet absorbance, using the molar absorptivities listed in Table I. 

Altex, T.J.Baker, Bio-Rad, Merck, Pharmacia, Waters Assoc, also have a wide range of columns. 

NPRO in raw bacon 1. Extraction with water 2. Cleanup on anion-exchange resin None 12 X 0.25 in. /xBondapak C18 (Waters Assoc.) 1% Na2HP04 in water Photohydrolysis followed by detection of nitrite with Griess reagent 85-90 46... 

V-Nitroso-lV, lV -dimethyl piper-aziniumiodide in cured meats 1. Extraction with water containing sodium azide 2. Ion-pair extraction into an organic solvent None 300 X 3.9 mm (10 gm) Bondapak CN (Waters Assoc.) 10 mm camphorsulfonic acid in ethanol TEA 83 48... 

C(CH2OH)4 0.4 mole %/TA Instrument Waters Assoc., Inc. (Model 200)... 

Refractive index Analabs Applied Automation Cargille Labs., 55 Commerce Rd., Cedar Grove, N.J. 07009, U.S.A. DuPont Gow-Mac, 100 Kings Rd., Madison, N.J. 07940, U.S.A. Hewlett-Packard Laboratory Data Control Micromeritics Perkin-Elmer Siemens Tracor Varian Assoc. Waters Assoc. 

The Waters Assoc. R401 differential refractometer is based on an optical-deflection design rather than on light reflection. This permits the use of a single cell throughout the refractive-index range of 1.00-1.75. The system also has a wider dynamic range of linearity for quantitation than the Fresnel-type refractometers. 

Method. The effluent from an ion-exchange column (strong anion, pellicular Bondapak Ax-Corasil, Waters Assoc., or a similar material) is mixed in a lOO-pl chamber such that the feed-through dead volume is 50 /il. A diagram of such a set-up is shown in Fig.4.72. The... 

P. C. Rahn, M. Woodman, W. Beverung, and A. Heckendorf, Preparation liquid chromatography and its relationship in thin-layer chromatography, Waters Assoc., 1979. 

Heymann, et al (24) have used solid phase extraction techniques for the isolation of pyrazines from wines. In this analysis, it was necessary to first distill the pyrazines from the wine and then pass the distillate through a Sep-Pak C-18 cartridge (Waters Assoc.). To speed the analysis, the distillate was forced through the cartridge at a rate of 30 ml/min. 

The HPLC system consisted of a Model 600E multisolvent delivery system equipped with a heated column compartment, a Model 484 variable-wavelength detector, and a Model 745B computing integrator, all from Waters Assoc., Inc., Milford, MA. The chromatograph was equipped with a Spherisorb ODS column (10 pm particle size, 25 cm x 4.6 mm ID.). 

Figure 2,5 (a) An Arrhenius plot of log k versus I/TXK) for the dissolution rates of various silicate rocks and minerals. The data points and curves for rhyolite, basalt glass, and diabase are from Apps (1983), as is the curve labeled silicates, which Apps computed from the results of Wood and Walther (1983). Curves for the S1O2 polymorphs are based on Rimstidt and Barnes (1980). Modified from Langmuir and Mahoney (1985). Reprinted from the National Well Water Assoc. Used by permission, (b) An Arrhenius plot of log k versus 1 /T(K) for the precipitation of quartz and amorphous silica based on Rimstidt and Barnes (1980). Reprinted from Geochim. Cosmochim. Acta, 44, J.D. Rimstidt and H.L. Barnes, The kinetics of silica water reactions, 1683-99, 1980, with permission from Elsevier Science Ltd, The Boulevard. Langford Lane. Kidlington OXS 1GB, U.K. 

Figure 2. High performance liquid chromatography profile of centrifuged whole broth and mycelium extract. Column Waters Assoc. 1-125 protein analysis column (30 cm x 7.8 mm). Mobile phase 0.05 M phosphate buffer, pH 6.9. Flow rate 1.0 ml/min, Detector UV at 210 nm.

High pressure liquid chromatography (HPLC) was perforated using a series of three 60 x 0.75 cm columns two 3 x 101 2 Styragel followed by one 500 X Styragel (Waters Assoc., Milford,... 

MA.). The exclusion limit of this column system is 1.7 x 10° determined with polystyrene standards (Waters Assoc., Milford, MA). The HPLC system consists of a piston pump (mini-pump, Milton Roy Co., Hollywood, Fla.), the columns, a Rheodyne injector 7125 an R—U Differential Refractometer, and a Speedomax H recorder (Leeds and Northrop, Phila., PA), with THF as the eluant. 

The described column system is capable of separating polystyrene standards (Waters Assoc.) of 950,000 to 3,600 MW. Because of differing molecular configurations, however, a polystyrene standard curve cannot be used to accurately describe apparent molecular weights of the poly(ester-urethanes). 

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