Water quality HPLC grade

The checkers purchased [(COD)RuCl2]n from Fluka (purum quality), BINAP from Aldrich (97 %), and toluene (HPLC grade) and triethylamine (reagent grade) from Fisher Scientific the latter was distilled from CaH2 under Ar prior to use. The submitters dried toluene and triethylamine over 4 A molecular sieves. Karl-Fischer titration indicated <200 pg/mL water. 

Materials. Aldicarb standards were obtained from the United States Environmental Protection Agency (USEPA), Quality Assurance Section and from Union Carbide Corporation. Crystalline samples of carbofuran and 3-hydroxycarbofuran were supplied by the Agricultural Chemical Group of FMC Corporation. Reference standards of methomyl (99% pure) and oxamyl (99% pure) were obtained from USEPA. HPLC grade methanol was purchased from Burdick and Jackson, Inc. Methylene chloride used for bulk extractions of the carbamate pesticides in solution was recovered, distilled and reused. Analytical reagent grade chemicals and solvents were used in all experiments. Doubly distilled deionized water was used for solution rate studies. Deionized distilled water (DDW) was used for dilutions in reactive ion exchange experim ts., , ... 

Methanol, acetonitrile, TFA are HPLC grade. Water is Ultrapure (MilliQ or of HPLC quality). A proposed system for elution, solution A acidified water (0.05% TFA) and solution B acetonitrile in acidified water. 

Docetaxel and paclitaxel were obtained from Hande Tech Development Co. (Houston TX, USA) with a purity of 99%. Methanol and acetonitrile were used in HPLC grade quality from Fisher Scientific (Houston TX, USA). Organic solvents have been filtered using 0.2 xM nylon membrane filters from Whatman (Maidstone UK) with a diameter of 47 mm. Milli-Q deionised water was used in this study. All water based mobile phases were filtered using 0.22 pM GP Express plus membranes from Millipore (Bedford, USA). Formic acid (95 % or higher) from Sigma (St. Louis USA) was used. 

Hyperforin (containing traces of adhyperforin) was obtained form Dr. W. Schwabe Pharmaceuticals (Karlsruhe, Germany). Methanol and acetonitrile were purchased from Caledon (Georgetown, ON, Canada) in HPLC-grade quality. Purified water from a Milli-Q water purification system (Millipore, Bedford, MA) was used. All other solvents and reagents (Tris buffer, ascorbic acid, formic acid and ammonium formate) were obtained from Sigma-Aldrich (Missisauga, ON, Canada). 

Simvastatin and lovastatin (internal standard) were obtained from U.S.P. Both hydrolyzed compounds (simvastatin acid and lovastatin acid) were obtained from Bristol-Myers Squibb Pharmaceutical Research Institute. Acetonitrile (in HPLC grade quality) as well as formic acid (88 %) were ordered from VWR Scientific (Piscataway NJ USA). In addition to that, glacial acetic acid and sodium acetate trihydrate (both ACS grade) were purchased from Baker JT (Phillipsburg NJ USA). Purified water from a Milli-Q water purification system (Millipore Bedford MA USA) was used. Blank plasma was obtained form Bioreclamation (Meadow E, NY USA). 

The benzene used was Analytical Reagent Grade from Mallinckrodt Chemical Company, distilled through a 25-plate bubble-cap column and stored in vapor contact with desiccant prior to use. High-quality 1-hexadecylpyridinium chloride (CPC) from Hexcel Corporation was used without further purification. Sodium dodecylsulfate (SDS) was HPLC-grade chemical from Fisher Scientific Company, purified by recrystallization from an ethanol-water mixture. 

The mobile phase may be contaminated with something that is present at very low levels and slowly accumulates on the column. Check the quality of the solvents The use of HPLC-grade solvents is highly recommended. Water can easily be contaminated. Water that is deionized using an ion-exdiange process should be treated subsequently with activated charcoal to remove small amounts of the ion-exchange resin, which otherwise would accumulate on a reversed-phase column and cause retention-time drift for compounds that can interact with the resin. Other column contamination mechanisms are discussed in more detail below. 

High performance liquid chromatography (HPLC)-grade water (Honeywell Burdick and Jackson [Morristown, NJ] or other high quality liquid chromatography-mass spectrometry [LC/MS]-grade water). 

Matrix solution 10 g/1 sinapinic acid (puriss. p.a. Sigma) in 60% acetonitrile (HPLC grade), 0.2% trifluoroacetic acid, 39.8% water (v/v). It is not necessary to use the ultrapure quality of sinapinic acid. The matrix solution should be prepared weekly and stored in the dark. 

The solvents used, acetonitrile, ethanol, 2-propanol, 1-propanol, 2-butanoI, ethyl acetate, toluene, acetone and hexane, were of pro-analysis grade. All the solvents were purchased from Merck (Darmstadt, Germany), except ethanol (99.5 %), Miich was obtained from Kemetyl (Haninge, Sweden). MilliQ-water was obtained from a purification system (Millipore). Nitrogen, (99.996 % by volume) was from AGA, (Stockholm, Sweden). Methanol of HPLC quality (Merck) was used as a mobile phase. Isolute sorbent (pelletized diatomaceous earth. International Sorbent Technology, Great Britain) was used as adsorbent in the initial studies. 

Most of the applications are performed under typical reversed-phase HPLC conditions. Nondeuterated solvents such as MeOH or MeCN are used. Great care in selecting the appropriate solvent grades is important since most solvents contain small impurities such as stabilizing chemicals, which will not be detected in UV but will cause interferences in the LC/ NMR spectra. Water is usually replaced by D2O, which is a relatively cheap deuterated solvent, and gives better quality spectra. 

Grades and purities There are two main grades of MTBE (1) the usual commercial purity, which is 98 to 99 wt %, and (2) a special quality with 99.95% MTBE, marketed under the trade name Driveron S. Other grades are HPLC and anhydrous. Impurities are usually water, hydrocarbons (C5, Cg, and diisobutenes), and alcohols (methanol and tert-butanol) (Elvers et al., 1990). 

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