新型搅拌棒吸附萃取技术进展
崔姣妍 张琼瑶
摘 ?????要:搅拌棒吸附萃取SBSE是一种新型微型化的样品前处理技术,普遍应用于痕量有机物的富集。其具有有机溶剂用量小、不需进一步蒸发浓缩、减少了对环境的污染的优点。由于其涂层材料的局限性,为扩大SBSE技术的应用范围。近年来,人们都在开发新型SBSE极性涂层材料。阐述了新型搅拌棒涂层的种类、制备进展。
关 ?键 ?词:SBSE;合成;涂层材料
中图分类号:O652.6 ??????文献标识码: A ??????文章编号: 1671-0460(2019)01-0111-04
Abstract: ?Stir bar sorptive extraction SBSE is a new type of miniaturized sample pretreatment technology, which is widely used in the enrichment of trace organics. It has the advantages of small using amount of organic solvent, no need of further evaporation, and less pollution to the environment. Due to the limitations of its coating materials, the application of SBSE technology is restricted. In recent years, new types of SBSE polar coating materials have been developed. In this paper, types, preparation methods and application of new stir bar coating material were reviewed.
Key words: SBSE; synthesis; coating material
传统的样品前处理方法存在操作繁琐,且多为手工操作,所需分析时间较长,同时消耗较多的有机溶剂等缺点。用于液体样品分析的传统液液萃取(LLE)进一步被耗时较少的固相萃取(SPE)所取代,萃取效率增加,简化样品操作,减少样品和有机溶剂的使用量,使分析装置小型化,并消除复杂基质的干扰成为样品预处理的目的。如今,发展的新型吸附萃取技术(SPME),搅拌棒吸附萃取(SBSE)或填充吸附剂微萃取技术和新型溶剂萃取技术等[1-4]。
1 ?搅拌棒吸附萃取技术
搅拌棒吸附萃取SBSE是一项新型微型化的样品前处理技术,由固相微萃取技术演化发展而来,在其表面涂布不同材料以获得更好的富集因子,提供更好的吸附相和更高的表面积,具有更大的萃取能力。传统的SBSE是一种将聚二甲基硅氧烷(PDMS)吸附剂涂覆在磁力搅拌棒的外层上,将其放置在液体样品中吸附有机化合物,然后进行解吸。
首先是溶剂解吸,将搅拌棒置于溶液中以解吸分析物成分,产生浓缩物。第二个是热解吸,需使用专门的热脱附仪(TDU)进行脱附,然后进入检测系统进行测量分析,这是气相色谱常用的[4-6]。可根据被测样品的性质选择解析的方式。其他方面,搅拌棒吸附萃取有许多因素的控制,例如搅动速率,温度影响,样品体积等。因此,在实验中必须优化适合的萃取条件。1998年Erik Baltussen首次提出搅拌棒萃取,在含有疏水性吸附剂的磁力搅拌棒上萃取50种化合物。利用自动吸附萃取 -热解吸-气体色谱-质谱分析:测定水样中的酚类化合物[7]。T?lgyessy, SNagyov, M,使用PDMS搅拌棒吸附萃(SBSE)与热脱附-气相色谱-三重串联四极杆串联质谱(TD-GC-QqQMS/ MS)用于测定水中短链氯化石蜡(SCCPs),由于短链氯化石蜡的非极性,使PDMS搅拌棒吸附萃取回收率较高[8]。虽然SBSE有很多的优点包括操作简单,预浓缩因子高等。但是随着发展,人们发现SBSE的主要的缺点是商业数量的减少,仅限于聚二甲基硅氧烷,PDMS是一个非极性材料,根据相似相溶原理,它不适用于萃取极性化合物,尤其是具有log Kow值低于3的化合物。当使用PDMS搅拌棒涂布时,极性化合物的回收率差。为了克服这个限制,制备合適的SBSE极性涂层材料至关重要。现今,烷基-二醇-二氧化硅材料(RAM),聚氨酯,PDMS /聚吡咯和PDMS/β-环糊精的开发,扩展了SBSE对极性溶质的适用性[9]
2 ??搅拌棒涂层合成方法
到目前为止,大部分人都在开发新型SBSE极性涂层材料和合成策略。首先是溶胶-凝胶技术,用β-环糊精修饰PDMS的新型材料来吸附水样中的雌激素和双酚A [10]或基于用聚乙烯醇提取蜂蜜中的有机磷农药[11]等。Cong Hu, Man He利用金属有机骨架(MOFs,Al-MIL-53-NH2)通过水热合成方法和溶胶 - 凝胶技术制备新型聚二甲基硅氧烷/金属有机骨架(PDMS / MOFs)涂覆的搅拌棒。制备搅拌棒的结果重现性良好[12]。但是,溶胶 - 凝胶过程较其他合成技术复杂。第二种方法是开发整体材料, Núria Gilart a, P.A.G. Cormack基于聚乙二醇聚甲基丙烯酸酯-共-季戊四醇三丙烯酸酯的新型极性整体材料(聚(PEGMA-co-PETRA))首先被合成[13]。其他包括乙烯基邻苯二甲酰亚胺(VPA)和N,N'-亚甲基双丙烯酰胺(MBAA)确定牛奶和蜂蜜中的苯并咪唑[14],或乙烯基吡咯烷酮(VPD)和二乙烯基苯(DVB)能够有效提取环境水域的PPCPs [15]。Linna You, Man He利用一点法合成沸石咪唑酯框架整体式涂层的搅拌棒,从果实样品中提取植物激素进行高效液相色谱 - 紫外检测[16]。第三,分子印迹聚合技术,模板分子通常为待测物或待测物的同系物,将其先和功能单体之间以非共价键(或共价键)相互作用进行预组装,产生高度交联的三维网状聚合物,然后再发生聚合反应,随后去除印记分子留下的具有与模板的大小,形状和化学官能团互补的空腔[17]。Yun Lei, Guanhong Xu使用多巴胺作为模板的分子印迹聚合物涂覆搅拌棒(MIP-SB)。发现 MIP-SB的吸附能力几乎是非印迹搅拌棒的4倍。建立尿液样品中多巴胺的分析方法,用HPLC-荧光检测器进行MIP-SB吸附萃取。与酶联免疫吸附试验相比,该方法简单,灵敏性好[18]。Zhu等人制备了MIP-SB用于测定奶粉中的三聚氰胺。将目标化合物作为模板,印迹层被化学锚定在磁性搅拌棒表面,其开始用3-(三甲氧基甲硅烷基)丙基甲基丙烯酸酯衍生化。所获得的涂层(?4.5μm)均匀,结构紧凑,由许多互相连接的小球组成。该搅拌棒涂层与NIP相比,MIP-SB的吸附容量高3.6倍[19]。
3 ??搅拌棒的涂层材料
搅拌棒涂层可分为以下几大类,分别为金属有机框架,碳基材料,复合材料等[20]。一,金属有机框架,是一类由金属中心和有机配体经过自我组装形成的具有可调节孔径材料。金属离子在骨架中起到了两个作用:一个是作为结点提供骨架的中枢 ;另一个是在中枢中形成分支 ,从而增强了MOFs的物理性质(如多孔性和手性)[21]。肖[22]等人开发了一个基于PDMS/MIL-101-Cr-NH2的SBSE与GC-FPD耦合的新方法对东湖和池塘水样中OPPs的测定。提出的方法得到好的富集因子(110~151)和回收89.3%~115%和80.0%~113%。金属有机框架孔结构高度有序 ,具有比表面积大、孔隙率高、孔径可调、化学可修饰性及结构组成、多样性孔表面的官能团和表面势能可控制等诸多优点。通过选择合适的金属离子和有机配体, 并在材料的孔内和表面进行修饰, 嫁接功能多样化的有机官能团, 设计出与目标物亲和力强、选择性好MOFs 材料[23-25]。二,碳基材料。需要用不同基团或有机分子对其表面进行修饰。活性炭,石墨烯,碳纳米材料具有较大的吸附表面积 - 体积比和高亲和力,良好的物理和化学稳定性以及低成本[26] 。Talebianpoor用制成ZnS装载在活性炭上的纳米粒子涂层的搅拌棒进行预浓缩微量水平的氨基甲酸酯杀虫剂的分析[27]。Jun Peng, Dong hao Liu将分子印迹聚合物和磁性碳纳米管结合。利用两种单体来增强选择性分子印迹聚合物,测定环境中的水质中微量头孢克洛和头孢氨苄[26]。三,复合材料,复合材料是指由两种或两种以上不同性质的材料通过物理或化学方法组成的性能优于单一组分的材料。在一研究中,一种基于蒙脱土(MMT)掺入聚苯胺 - 聚酰胺(PANI-PA)杂化物的新型纳米复合材料,通过在MMT-PA混合物中发生聚苯胺的氧化聚合反应,溶剂交换法获得搅拌棒薄层基材[28]。YunLei,ManHe采用溶胶-凝胶法制备了一种新型聚苯胺/α-环糊精复??合涂层搅拌棒,用于分析环境水体中痕量多氯联苯(PCBs)。该方法成功应用于长江水和东湖水中7种目标多氯联苯的测定,河水样本加标回收率分别为73.0%~120%,82.7%~121%[29]。
4 ?SBSE的新进展
4.1 ?新涂层材料
如今,已经将纳米材料和MOFS材料结合,纳米金属-有机框架材料因具有纳米尺寸,既拥有传统块状MOFS的性质,也具备特殊的物理、化学特性,表现出更为优异的性能。金属纳米粒子涉及各种不同的无机纳米粒子,具有比表面积大,吸附容量大,低温改性等独特性能。目前,金属纳米材料包括Fe3O4,TiO2,Al2O3,ZrO2,MnO和CeO2,用于功能涂层材料的改性[30, 31]。磁性纳米材料提取分析物通常基于疏水性相互作用,静电吸引和共价键形成。其适用于提取和富集大量的目标分析物,因为它们可以提供高比表面积,容易表面修饰和强磁性[32]。Lin等人[33]制备水稳定的Fe3O4 @ MOF-5复合材料,然后利用其磁性作为SBSE涂层粘附在Nd-Fe-B永磁体上。他们将基于MOF-5的SBSE与GC-MS联用以检测鱼样品中的多氯联苯,得出结论比较满意(94.3%~97.5%)。 在他们的另一项工作中,他们使用修饰了MOF-5捕获适体,目的是提高鱼类样品多氯联苯对这种SBSE涂层的选择性,提供了大量的富集因子(50~100)[34]。Irene Aparicio , Julia Martín,等人首次利用SBSE成功提取一大批极性和非极性污染物,发现 EG-硅氧烷涂层允许同时提取两者极性和非极性污染物。乙烯乙二醇改性硅酮的涂层材料对极性和非极性化合物中的酸性样本萃取回收率高。该方法已成功地用于自来水和地表水样品的应用,良好的线性范围,准确度,获得所有48个目标化合物[35] 。考虑到有些材料的搅拌棒制作可能复杂耗时,搅拌棒易萃取而不易解析的情况。Jackeline Stoskia,b, Natalicio F. Leite等人第一次將树脂作为搅拌棒涂层而不需要任何附加的吸附剂相的附着,从而提供简单的和低成本的方法,使得该材料适合于解吸分析物[36]。Inés Racamonde, 用聚二甲基硅氧烷(PDMS),聚丙烯(PP)和聚醚砜(PES)吸附剂萃取,然后用液相色谱串联质谱(LC-MS / MS)同时测定水中17种苯并二氮类(BZPs)和相关药物(唑吡坦)。发现PP可能成为用于提取碱性分析物的PDMS或PES的良好替代物[37]。
4.2 ?新方法
为解决大样本的待测物,试验人员采用多个搅拌棒的萃取方法。Li Feng,Sheng jun Zhang用搅拌棒吸附萃取法热脱附气相色谱检测大量水样中有机氯农药,为解决长时间萃取和小样本量问题,他们选择多个搅拌棒萃取较大容量的水样,同时得到良好的线性关系[38]。Xiao bing Pang, Alastair C. Lewis用PDMS搅拌棒吸附萃取技术与化学衍生气相色谱 - 质谱联用技术分析雨水中生物羰基化合物。从水样中可以提取和分析29种羰基化合物,采用SBSE技术对雨水中的羰基进行了分析,20个羰基化合物的提取效率均在85%以上[39]。对于热解析萃取吸附的检测物时无法将搅拌棒解吸成分流/GC不分流进样,增加了一个额外的步骤即在合适的有机溶剂中解吸提取的分析物。针对这个问Mohammad T. Jafari, Mohammad R. Rezayat论述了离子迁移谱联用搅拌棒吸附萃取注射口的设计与构建。由黄铜合金制成的不同的热解吸单元TDU,结果显示注射口可用于直接分析任何吸附剂载体提取的样品,无需进一步制备样品[40]。同时,Madelien Wooding, Egmont R. Rohwer比较了在气相色谱入口用专用热解吸器或热解吸附的一次性吸附取样器与常规搅拌棒吸附萃取 - 热解吸附法测定水中微量污染物,他们均用PDMS搅拌棒吸附萃取非极性化合物,得到较好的提取效率[41]。因此,在仪器分析之前,引入热脱附单元,消除了有机溶剂中搅拌棒的重构步骤,有助于使用气相色谱在线自动化萃取方法。
5 ?结束语
SBSE作為一种新型样品前处理的技术。与其他的固相萃取、固相微萃取与液液萃取等方法比较,具有有机溶剂用量小、不需进一步蒸发浓缩、减少了对环境的污染、节约了大量提取时间的优点。但是由于其在商品化涂层材料种类少、价格高,一般在涂层材料对样品中目标检测物的选择性差等方面存在的问题,因此,SBSE技术的发展主要集中在涂层材料。
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