请问各位缓冲盐溶液里面加入有机相后再测pH值还有意义吗????4.5.1 Mobile-Phase pH. Practical Considerations The pH specified in analytical methods for pharmaceutical analysis should be that of the aqueous solvent. Note that the addition of organic modifier to aqueous buffer generally results in a shift in mobile-phase pH.The pKa of the solute is also subject to variation and is dependent on the type and concen- tration of the organic modifier in the eluent. Practical Recommendations The pH of the aqueous portion of the mobile phase must be accurately controlled with a calibrated pH meter.That is, the desired pH of the aqueous portion of the mobile phase must be within the calibrated pH range. The calibration standards should be close in ionic strength and temperature of the buffer solutions that will be measured.Typical standards include pH 1, pH 2, pH 4, pH 7, and pH 10. Some pH meters allow a three-point calibration curve, and others allow for a two point calibration curve. In any event, the appropriate criteria for the slope of the cal- ibration curve should be met and recorded in a log book and/or notebook and should be calibrated each time prior to use.The pH of the buffer should be con- trolled within ±0.1 pH units. Additionally, buffers can be made by weighing a known amount of salt of the acid or base to make the buffer and adding, if nec- essary, a known volume of acid or base to generate the desired pH. Once this is performed, the pH of the aqueous portion of the mobile phase can be measured as an additional precautionary measure. 出处：HPLC for Pharmaceutical Scientist 158-159pp 国外的科学家才是真正的大神查看更多
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