Buffer preparation

Sodium acetate-acetic acid buffer. Prepare a solution which is 0.2 M in sodium acetate and 0.8 M in acetic acid. The pH is 4.0. 

Buffer preparation requires detaiied, step-by-step caicuiations. Exampie iiiustrates the complete procedure. 

C18-0053. From Table 18-1. select the best conjugate acid-base pairs for buffer solutions at pH 3.50 and 12.60. If you were going to add HCl solution as part of the buffer preparation, what other substance should you use in each case ... 

A number of developments have increased the importance of capillary electrophoretic methods relative to pumped column methods in analysis. Interactions of analytes with the capillary wall are better understood, inspiring the development of means to minimize wall effects. Capillary electrophoresis (CE) has been standardized to the point of being useful as a routine technique. Incremental improvements in column coating techniques, buffer preparation, and injection techniques, combined with substantive advances in miniaturization and detection have potentiated rugged operation and high capacity massive parallelism in analysis. 

Exacting control of buffer preparation and the characteristics of capillaries and coatings is now recognized as key to successful electrophoretic separations.2 Repeatability of separations requires standardized surface preparation and rinse procedures. For example, capillaries can be coated with polyacrylamide using thionyl chloride surface activation. This approach was useful in DNA analysis.3 Non-aqueous buffers can be used to permit the use of thicker capillaries and higher voltages.4... 

Dissolve chloramine-T (Sigma) in 50 mM sodium phosphate, pH 7.5 (reaction buffer) at a concentration of 100 pg per 25-50 pi of buffer. Prepare fresh. 

Weigh 0.48 g of DNA grade agarose into a 150-mL beaker and add 60 mL of the buffer prepared in step 1. Heat this solution to boiling. While this solution is heating, prepare a gel-pouring tray (next step). 

Despite the obvious merit of this conventional wisdom, selectivity wild cards often prove essential, and there is real value in developing a repertoire of special weapons and tactics. Even though there is no way to predict which, if any, will produce the effect you seek, the options are limited, well defined, and the investment of resources reasonably modest. By the time you get to the point of evaluating wild cards, you will probably be sufficiently familiar with your analytical system to discern a useful result from a chromatogram without extensive secondary testing. The principal investment will be buffer preparation and the time to run the analyses. 

The transfer apparatus and the fiber pad used to hold the gel in the gel cassette should be thoroughly cleaned with detergents between use. Dirty fiber pads are a major cause of blot contamination. Also do not re-use transfer buffer, prepare fresh solution... 

Chemicals quality of deionized water and chemicals for buffer preparation and rinsing, standards for quantification and selectivity verification, test samples, correct transport and storage conditions... 

Precision studies can be planned in a full factorial matrix-type format involving multiple analysts, days, capillaries, buffer preparations, instruments, etc. Table 9 displays an example matrix for intermediate precision testing involving two analysts, two instruments, and two capillaries over a multiple day period. Typically, qualification targets for acceptable precision will be pre-defined based on method type, capability, and intent. Acceptable targets can also be mathematically determined by the method of Horwitz. ... 

Four reagents are required for performance of this reaction. The first is a 0.1% ethanolic solution ofp-nitroso-A/iA -dimethylaniline. The second is pH 9.8 Clark and Lubs buffer, prepared by adding 40.8 mL of 0.2 M sodium hydroxide (carbon dioxide-free) to 50 mL of a 0.2M aqueous solution of both boric acid and potassium chloride. The third reagent is a 0.1% solution of phenol in ethanol, and the fourth reagent is a freshly prepared 1% aqueous solution of potassium ferricyanide. 

All solutions, including AgN03, were maintained at pH 2.0 by using 0.010 M sulfate buffer prepared from H2S04 and KOH. 

Example A Dilute Buffer Prepared from a Moderately Strong Acid... 

M HC1 and 1 M NaOH for use in buffer preparation. Compositions calculated from Eq. 3-8 will usually yield buffers of pH very close to those expected. 

Introduction to fast performance liquid chromatography. Review Buffer preparation, Definitions of pH, Henderson-Hasselbalch equation, and Buffer calculations. 

Mix all the components well. Add 8 fiL of pure TEMED. Mix well and immediately pour between glass plates. Fill the space to the top of the plates. Immediately insert the comb to make sample wells in the gel. Allow the gel to polymerize (about 30 min). Remove the comb and carefully rinse the sample wells with a 1 10 dilution of Tris-glycine SDS buffer. Prepare each protein sample including the molecular weight standards as follows ... 

Ammonium persulfate solution, 1.0 g/ 10 mL of phosphate buffer (prepare fresh just before use)... 

Sephadex buffer (prepare freshly) 8Murea (ultra-pure) in 125 mMTris-HCl, pH 6 8... 

---