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en:buffer_solution [2013/06/09 10:10] (current)
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 +======Buffer solutions======
 +=====Good'​s buffer=====
 +
 +Good //et al.// (({{pubmed>​long:​5942950}}))reported that the Zwitterionic buffers are suitable for biological experiments.
 +
 +
 +They have the following characters.
 +  *They have physiological range of pKa(6.0 - 9.0).
 +  *The pKa values of them are not influenced by temperature and concentration of them.
 +  *Chemically stable and biologically inert.
 +  *They can be used for culture of cells, and they does not penetrate cell membrane.
 +  *They does not disturb spectroscopic analysis.
 +
 +^name^pKa(4℃)^pKa (20℃)^pKa(25℃)^pKa(37℃)^properties^
 +|[[MES]]|6.33|6.15|6.10|5.97|Autoclave with glucose causes decomposition.|
 +|[[ADA]]|6.80|6.62|6.56|6.43|This can chelate metal ions.|
 +|[[PIPES]]|6.94|6.80|6.76|6.66|This interferes Lowry analysis|
 +|[[MOPS]]|7.41|7.20|7.14|6.98|This is suitable for almost experiments.|
 +|[[HEPES]]|7.77|7.55|7.48|7.3|This is suitable for almost experiments except for Lowry analysis.|
 +|[[CHES]]|9.73|9.55|9.50|9.36|This buffers at basic pH (8.6 - 10.0). This has slight absorption at 260-280nm.|
 +
 +
 +=====Phosphate buffer=====
 +See a [[Phosphate buffer]] page.
 +
 +=====Other buffers=====
 +
 +^name^pKa(4℃)^pKa (20℃)^pKa(25℃)^pKa(37℃)^properties^
 +|[[Tricine]]|8.49|8.15|8.05|7.79|Similar to Tris. This chelates metal ions.|
 +|[[Tris-HCl buffer]]|8.75|8.30|8.08|7.82|This is suitable for many experiments. But dependence on temperature is large. Besides, primary amine of this interferes Bradford assay, immobilization of proteins and so on.|
 +|Gly-Gly|8.85|8.40|8.26|7.92|Temperature dependent.|
 +
 +======Titration curve======
 +
 +The following plot is a titration curve of Tris buffer. Notice that the pH change around pK is small.
 +
 +{{ :​buffer_titration.png}}
 +
 +<​code>​
 +#gnuplot
 +set xrange [0:​1]\\ ​
 +set xlabel "​molecular ratio of Tris to acid"​\\ ​
 +set yrange [0:​14]\\ ​
 +set ylabel "​pH"​\\ ​
 +set size 0.41\\ ​
 +pK_Tris = 8.08\\ ​
 +set label "pK = 8.08 (298K)"​ at 0.05,​9\\ ​
 +Tris(x) = pK_Tris+log(x/​(1-x))\\ ​
 +plot Tris(x),​pK_Tris
 +</​code>​
 +
 +======References======
 +
 +  *{{pubmed>​short:​5942950}}
 +  *Good, N.E. & Izawana, S.: Methods Enzymol., Part B\\ Vol. 24, p. 53 ff. (Pietro, ed.) (1972) Academic Press, New York
 +  *R.J. Beyon & J.S. Easterby: Buffer solutions The Basics,\\ (C. Howe, ed.) 1 st ed. (1996) IRL Press, Oxford
 +
 +
 +
 +======Links======
 +
 +  *[[:​緩衝液]] (JP)
 +  *[[:​zh-cn:​缓冲溶液]](zh-cn)
 +  *[[:​zh-tw:​緩衝溶液]](zh-tw)
 +
 +
 +{{tag>​Buffer preparation}}