Abstract: <SPAN lang=EN-US>Microcontents of Cl</SPAN><SPAN lang=EN-US><SUP>-</SUP> and SO</SPAN><SPAN lang=EN-US><SUP>2-</SUP></SPAN><?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" /><st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="True" SourceValue="4" UnitName="in"><SPAN lang=EN-US><SUB>4</SUB> in</SPAN></st1:chmetcnv><SPAN lang=EN-US> boric acid were determined by photoelectricity turbidimetry with acid as medium.The effects of stabilizer selection,acidity of solution,dosage of precipitant,heating time and temperature as well as measuring time on the turbidity of solution were studied.The optimum experiment parameters were confirmed,which simplified the operation process.In the measurements to determine SO<SPAN lang=EN-US><SUP>2-</SUP></SPAN><st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="True" SourceValue="4" UnitName="in"><SPAN lang=EN-US><SUB>4</SUB></SPAN></st1:chmetcnv></SPAN><st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="True" SourceValue="4" UnitName="in"><SPAN lang=EN-US> in</SPAN></st1:chmetcnv><SPAN lang=EN-US> boric acid,stabilizer was glycerine-ethanol (1</SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman"">∶</SPAN><SPAN lang=EN-US>4 by volume ratio),precipitant was acidic BaCl</SPAN><SPAN lang=EN-US><SUB>2</SUB> solution.The solution was shaken manually to mix well and heated,as a result,the adding sequence of reagents had no effects on results.The detection limit was 0.10 mg/L,relative standard deviation (RSD) was less than 0.03%,recovery rate was 98.85%~103.00%,and measuring time lasted over 40 min.SO<SPAN lang=EN-US><SUP>2-</SUP></SPAN><st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="True" SourceValue="4" UnitName="in"><SPAN lang=EN-US><SUB>4</SUB></SPAN></st1:chmetcnv></SPAN><SPAN lang=EN-US> concentration in the range of 0.33~</SPAN><SPAN lang=EN-US>0.83 mg/L </SPAN><SPAN lang=EN-US>showed a linear relationship with turbidity.In the measurements of chlorine,the stabilizer was glycerine,measuring time held in 40 min,detection limit was 0.03 mg/L,RSD was less than 0.04%,and recovery rate was 102.2%~106.5%.Cl</SPAN><SPAN lang=EN-US><SUP>-</SUP> concentration in the range of 0.10~0.25 mg/L showed a linear relationship with turbidity.Photoelectricity turbidimetry improved the precision and accuracy of the measurements.The method of turbidimetry to determine Cl</SPAN><SPAN lang=EN-US><SUP>-</SUP> and SO<SPAN lang=EN-US><SUP>2-</SUP></SPAN><st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="True" SourceValue="4" UnitName="in"><SPAN lang=EN-US><SUB>4</SUB></SPAN></st1:chmetcnv></SPAN><st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="True" SourceValue="4" UnitName="in"><SPAN lang=EN-US> in</SPAN></st1:chmetcnv><SPAN lang=EN-US> boric acid is simple,reliable,innocuous,and applicable in practice.<BR></SPAN>