Fast analysis of thiocyanate by ion-pair chromatography with direct conductivity detection on a monolithic column

Fast analysis of thiocyanate by ion-pair chromatography using a silica-based monolithic column and direct conductivity detection was carried out. Chromatographic separation was performed on a Chromolith Speed ROD RP-18e using tetrabutylammonium hydroxide （TBA）-phthalic acid-acetonitrile as eluent. The effects of eluent concentration, eluent pH value, column temperature and flow rate on retention time of thiocyanate were investigated. The optimized chromatographic conditions for the determination of thiocyanate were as follows： 0.25 mmol/L TBA-0.18 mmol/L phthalate-7% acetonitrile （pH 5.5） as eluent, column temperature of 30 ℃, and flow rate of 6.0 mL/min. Retention time of thiocyanate was less than 1 min under the conditions. Common anions （Cl^-, NO3 , SO42 and I^- ） did not interfere with the determination of thiocyanate. Detection limit （S/N = 3） of thiocyanate was 0.96 mg/L. Calibration graph between peak area and the concentration of thiocyanate was linear in the range of 2.0- 100.0 mg/L. Relative standard deviation （RSD） of chromatographic peak area was 1.4% （n = 5）. This method has been applied to the determination of thiocyanate in ionic liquids. Recoveries of thiocyanate after spiking were 100.5%.

Rapid and simultaneous determination of piperidinium and pyrrolidinium ionic liquid cations by ion pair chromatography coupled with direct conductivity detection

A method of ion-pair chromatography with direct conductivity detection was developed on a silicabased monolithic column for the fast and simultaneous determination of piperidinium and pyrrolidinium ionic liquid cations. The effects of the mobile phase, column temperature and flow rate on the retention of the cations were investigated. The retention rules were discussed. As an ion-pair reagent, sodium heptanesulfonate is more suitable than sodium pentanesulfonate for the separation and determination of piperidinium and pyrrolidinium cations. The increase of ion-pair reagent concentration led to the increased retention time of the cations. When acetonitrile content and mobile phase flow were increased, the retention time of the cations became shorter. The retention of piperidinium and pyrrolidinium cations is an exothermic process, and the retention of the cations conforms to the carbon number rule. The chromatographic analysis was performed using the Chromolith Speed ROD RP-18 e column, 0.5 mmol/L sodium heptanesulfonate-5% acetonitrile as the mobile phase at a flow rate of3.0 m L/min and column temperature of 30℃. Separation of N-methyl-N-ethyl piperidinium, N-methylN-propyl piperidinium, N-methyl-N-butyl piperidinium and N-methyl-N-ethyl pyrrolidinium, Nmethyl-N-propyl pyrrolidinium, N-methyl-N-butyl pyrrolidinium cations were achieved within10 min. The detection limits（S/N = 3） were between 0.19 and 3.08 mg/L. Relative standard deviations（n = 5） for peak areas were less than 1.2%. The method has been applied to the determination of piperidinium and pyrrolidinium cations in ionic liquid samples. The spiked recoveries of ionic liquid cations were between 96% and 111%. The method is accurate, reliable, rapid, and has a better practicability.

Rapid and simultaneous determination of imidazolium and pyridinium ionic liquid cations by ion-pair chromatography using a monolithic column

A method for rapid and simultaneous determination of imidazolium and pyridinium ionic liquid cations by ion-pair chromatography with ultraviolet detection was developed. Chromatographic separations were performed on a reversed-phase silica-based monolithic column using 1-heptanesulfonic acid sodium-acetonitrile as mobile phase. The effects of ion-pair reagent and acetonitrile concentration on retention of the cations were investigated. The retention times of the cations accord with carbon number rule. The method has been successfully applied to the determination of four ionic liquids synthesized by organic chemistry laboratory.

离子液体的阴离子三氟乙酸根、硫氰酸根、四氟硼酸根和三氟甲磺酸根的离子对色谱-直接电导检测法分析

建立了同时测定离子液体的阴离子三氟乙酸根、硫氰酸根、四氟硼酸根和三氟甲磺酸根的反相离子对色谱-直接电导检测方法。采用Diamonsil C18分离柱,以离子对试剂-苹果酸-乙腈水溶液为流动相,从流动相组成和色谱柱温度两方面讨论并确定了优化的色谱条件,即以0.15 mmol/L氢氧化四丁铵-0.099 mmol/L苹果酸-20%(v/v)乙腈混合水溶液(pH 6.5)为流动相,柱温25℃。在此条件下,三氟乙酸根、硫氰酸根、四氟硼酸根和三氟甲磺酸根离子均达到基线分离,且不受其他常见阴离子氟离子、氯离子、溴离子、硝酸根、硫酸根的干扰。三氟乙酸根、硫氰酸根、四氟硼酸根和三氟甲磺酸根离子的检出限(信噪比为3)分别为0.21、0.07、0.36、0.12 mg/L。将方法应用于测定离子液体中三氟乙酸根、硫氰酸根、四氟硼酸根和三氟甲磺酸根离子,加标回收率为95.0%～104.6%。该法简便、快速、灵敏度较高,可满足离子液体样品的检测要求。

硅胶整体柱离子对色谱快速分析碘离子

建立了用硅胶整体柱和直接电导检测的离子对色谱快速分析碘离子的方法。采用Chromolith Speed ROD RP-18e色谱柱,以氢氧化四丁铵(离子对试剂)-邻苯二甲酸+乙腈(有机改进剂)为淋洗液,讨论了离子对试剂浓度、有机改进剂浓度、pH、流速和色谱柱温度对碘离子保留的影响。确定最佳色谱条件为:0.25 mmol/L氢氧化四丁铵-0.18 mmol/L邻苯二甲酸+体积分数7%乙腈(pH5.5)作为淋洗液,流速6.0 mL/min,色谱柱温30℃。在此条件下,碘离子的保留时间在0.5 min之内,其它常见阴离子(Cl-、NO3-、SO42-)及SCN-、ClO4-不干扰测定。方法的检出限为0.86 mg/L,标准曲线的线性范围为1.6～85.0 mg/L,峰面积的相对标准偏差为2.3%。将方法应用于测定地下水和果汁中的碘离子,加标回收率为98.5%～104.2%。

离子色谱-电导检测法测定不同乳制品中硫氰酸盐

建立了离子色谱-电导检测分析不同类型乳制品中硫氰酸盐(SCN-)污染物的方法,重点研究了不同形态样品如固态类(奶粉)、液态类(牛奶)、凝固态类(凝固型酸奶)和半流质态类(炼乳)等乳制品中的硫氰酸盐前处理方法,采用丙酮作为蛋白沉淀剂,有效实现了对各类样品中蛋白质的沉淀和对硫氰酸盐的提取,避免了以往采用乙腈处理样品时容易分层的弊端,方法在0～5.0mg/L浓度范围内具有良好的线性关系,相关系数r为0.9997(n=6),方法检出限(LOD)为0.15～0.5μg/g,方法回收率为95.0%～105.0%,相对标准偏差(RSD)为1.4%～5.6%(n=3)。

整体柱离子对色谱-直接电导检测法快速测定微量碘酸根

建立了整体柱离子对色谱-直接电导检测快速测定微量碘酸根的方法。采用反相硅胶整体柱,以氢氧化四丁铵(TBA)-邻苯二甲酸-水-乙腈水溶液为淋洗液,分别讨论了淋洗液、流速及柱温对碘酸根保留的影响,并确定最佳色谱条件为:以0.25 mmol/L TBA-0.18 mmol/L邻苯二甲酸-3%乙腈(pH 5.5)水溶液为淋洗液,流速4.0 mL/min,柱温30℃。在此条件下,碘酸根与其他常见阴离子(Cl-、NO3-、SO42-和I-)达到基线分离且保留时间在0.5 min之内,检出限(S/N=3)为0.36 mg/L,峰面积和保留时间的相对标准偏差(n=5)分别为0.35%和0.28%。方法应用于加碘药品中微量碘酸根的测定,加标回收率为96.4%。本方法快速、简单、准确、可靠,具有良好的实用性。

基于离子色谱/电导检测的全脂奶粉中硫氰酸盐污染物的测定及前处理方法研究

建立了氢氧根淋洗/离子色谱/电导检测分析全脂奶粉中硫氰酸盐(SCN-)污染物的分析方法,对蛋白沉淀剂、提取条件、提取液净化技术、色谱条件等作了深入研究和优化。通过对淋洗液梯度的优化,将出峰时间控制在17 min内,且不受邻近组分干扰。方法在0.02～100 mg/L范围内具有良好的线性关系,相关系数(r)为0.999 9,方法定量下限(S/N=10)为0.3μg/g,回收率为99%～102%。方法重现性好,3 d内对2.0 mg/L的标准溶液随机测试7次,其峰面积的相对标准偏差(RSD)为1.6%。

离子色谱-电导法同时测定奶粉中碘离子和硫氰酸根离子

采用离子色谱法建立了奶粉中微量碘离子和硫氰酸根离子同时定量分析的方法。样品采用乙酸冷藏法沉淀蛋白,超声波提取,上清液以On Guard RP小柱净化除杂。以高亲水阴离子交换色谱柱IonPac AS16柱为分析柱,KOH溶液梯度淋洗,电导检测器同时测定奶粉中微量碘离子和硫氰酸根离子,以外标法进行定量分析。结果表明,碘离子和硫氰酸根离子在5.0~200.0μg/L范围内线性关系良好,相关系数r>0.999,检出限分别为0.12mg/kg和0.09mg/kg,回收率、精密度良好。该方法操作简便,专属性强,线性良好,可以用于奶粉中碘离子和硫氰酸根离子的含量检测。

反相硅胶整体柱离子色谱法快速分析BrO_3^-

研究了基于反相硅胶整体柱的离子色谱快速分析BrO3-的方法。以氢氧化四丁铵(TBA)为流动相动态修饰反相硅胶整体柱,采用直接电导检测,在普通高效液相色谱仪上实现了BrO3-和常见阴离子的快速分析。实验考察并讨论了流动相、色谱柱温度和流速对所测阴离子保留和分离的影响。确定分离测定BrO 3-的最佳色谱条件是:以0.75 mmol/L TBA-0.5 mmol/L邻苯二甲酸(pH6.0)为淋洗液,流速3.0 mL/min,柱温30℃。在此条件下,BrO 3-与Cl-、Br-、NO 3-、ClO3-、SO42-、I-7种阴离子在2.2 min内即可分离。BrO 3-的保留时间为36 s,检出限为2.94 mg/L,保留时间和峰面积的相对标准偏差(n=5)分别为0.2%和0.4%。将此方法用于地下水样品的分析,BrO 3-的加标回收率为98.7%。本方法快速、简单和方便。

血清中硫氰酸盐含量的离子色谱电导法测定及其在太原市健康人群中的参考范围研究

目的本研究建立血清中硫氰酸盐的离子色谱-电导检测方法并确定太原地区健康人群血清中硫氰酸盐的正常参考值范围。方法本研究采集太原地区某高校119例志愿者(男性44人,女性75人)的血清,经乙腈沉淀蛋白、液液萃取后过Dionex OnGuard II RP 1cc Cartridge小柱,利用离子色谱电导检测方法检测其血清中硫氰酸盐的含量。结果血清样品中硫氰酸盐在125ng/mL到5000ng/mL之间线性关系良好,相关系数R2为0.9999,最低检出限为20ng/mL,最低定量下限为64.1ng/mL,日间和日内精密度均小于10%。44例健康男性血清中硫氰酸盐含量为374.8±209.6ng/mL,范围为64.1ng/mL-943.4ng/mL,75例健康女性血清中硫氰酸盐含量为395.8±145.9ng/mL,范围为109.7ng/mL-807.5ng/mL,性别无统计学差异。结论离子色谱-电导检测法可用于检测血清中硫氰酸盐含量。该方法操作简便,回收率高、专属性强、灵敏度高、准确度高,可满足正常人群及中毒人群的体内硫氰酸盐的定性、定量检测。太原地区健康人群的参考值范围为64.1ng/mL-943.4ng/mL,95%参考值上限为669.5ng/mL。

离子色谱-电导法检测液体乳中的硫氰酸根

建立用离子色谱-电导检测法测定液体乳中硫氰酸根的分析方法。试样用乙腈沉降蛋白,上清液用水稀释后,依次过0.22μm微孔滤膜、Dionex OnGuard II RP小柱处理后进样检测,选用IonPac AS19阴离子交换分离柱,在线产生50~70 mmol/L KOH淋洗液梯度洗脱,流速1.0 mL/min,以抑制型电导检测器检测。结果表明:硫氰酸根在0.0~1.0μg/mL质量浓度范围内线性良好,相关系数r为0.999 9,方法检出限为0.069μg/g;在0.1, 0.2和0.6μg/mL这3个添加质量浓度水平下,平均回收率为93.55%~98.06%。该方法线性范围广,准确性和精密度良好,操作简便,适用于液体乳中硫氰酸根检测。