hplc question
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US><FONT face="Times New Roman">Recently I tested the R<SUB>T</SUB> of cinnamic acid standard sample by RP-HPLC C18. The column length is 150mm,200mm and 250mm respectively. The mobile phase is methanol:water:acetic acid, with the following methanol:water ratio, 72:22,72:28,72:32,72:34 and 72:88 Details are listed in the attached file.</FONT></SPAN><P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US><FONT face="Times New Roman"> <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></FONT></SPAN>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US><FONT face="Times New Roman">It is easy to understand that the R<SUB>T</SUB> varies as per the column length and the mobile ratio. But what perplex me is how to explain the fact that “ the area of the standard sample also varies as per the column length and the mobile ratio.” If that is the case, it means under different conditions the eluted amount of the standard sample varies, so how to determine the correct amount of the standard sample.</FONT></SPAN>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US><FONT face="Times New Roman"> <o:p></o:p></FONT></SPAN>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US><FONT face="Times New Roman">Any comments on this subject are welcome!</FONT></SPAN>
Different length of column have differengt number of theoretical plate.The longer of the column is ,the better of the column effect is.
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