SPE-IPLC-FLD法测定助剂中的线性烷基苯磺酸盐

Determination of linear alkylbenzene sulfonates in auxiliaries by SPE-IPLC-FLD method

建立固相萃取-离子对液相色谱-荧光检测器法（SPE—IPLC—FLD），测定纺织染整助剂中的线性烷基苯磺酸盐（LAS）。样品经甲醇＋水（50＋50，体积比）超声助溶、固相萃取SAX柱净化后，以2．5mmol／L磷酸二氢四丁基铵溶液作为阳离子对试剂、乙腈梯度洗脱，经离子对反应和反相C18柱色谱分离后，得到4组峰（每组包含4个色谱峰）的独特图谱。荧光检测的激发波长为230nm，发射波长为310nm。以十二烷基苯磺酸钠为标准物，LAS的定低限为25mg／kg（S／N=10），线性范围为0．5～250mg／L，线性关系大于0．9995，方法的回收率为91．3％-97．4％，批间RSD小于6．8％。对不同类型染整助剂的实际样品检测，LAS检测结果与理论含量比较一致，阳性样品重复测试的RSD都小于4．2％，结果令人满意。

A method of solid phase extraction coupled with ion pairing liquid chromatography and fluores- cence detector （SPE-IPLC-FLD） are developed to determine linear alkylbenzene sulfonates/LAS） in dye- ing and finishing agents. The samples are dissolved in MeOH＋H20（50＋50,volume ratio） assisted by ultrasound and cleaned up in solid phase extraction （SPE） setup using SAX cartridge. The extract is first re- acted with cationic ion pairing reagent of 2.5 mmol/L tetrabutylammonium dihydrogenphosphate, and then separated on C18 column liquid chromatography with ACN as the elution solvent to obtain an exceptional chromatogram of LAS which containing four groups and each group containing four peaks. The excitation wavelength of fluorescence detector is 230 nm and emission wavelength is 310 nm. Taking sodium linear dodecylbenzene sulfonate as the reference standard material, limit of quantification （LOQ） of LAS is 25 mg/kg calculated on signal to noise of 10. The proposed method provides excellent linearity （γ〉0.999 5） at the range of 0.5--250 mg/L, good recovery with the range of 91.3%--97.4% and all relative standard deviation （RSD） less than 6.8%. The method is applied to determine LAS in different types of commercial products, with the detection results of LAS in agree with the theoretical content of LAS in the products and RSD less than 4.2% in repeatable experiments.