光分析方法測定六價鉻離子的研究進(jìn)展

鄭 陽，吳一微

(湖北師范大學(xué)化學(xué)化工學(xué)院，湖北 黃石 435002)

光分析方法測定六價鉻離子的研究進(jìn)展

鄭 陽，吳一微

(湖北師范大學(xué)化學(xué)化工學(xué)院，湖北 黃石 435002)

主要從光分析的角度綜述了自2015年以來六價鉻離子的八種測試方法，詳細(xì)比較了這些檢測方法的優(yōu)缺點(diǎn)，并簡要展望了六價鉻離子測試的發(fā)展趨勢。

六價鉻離子；光分析方法；綜述

1 六價鉻離子的概述

地殼中的鉻元素和各種鉻鹽作為重要的工業(yè)原料，廣泛用于采礦、冶金、制革、紡織印染、電鍍以及木材防腐等領(lǐng)域，導(dǎo)致鉻的環(huán)境污染，進(jìn)而通過生物鏈進(jìn)入生物體內(nèi)，隨著鉻離子的毒性、遷移和生物積累研究的深入，人們逐漸意識到鉻的生物毒性與其總量和形態(tài)分布均有關(guān)[1]。無機(jī)鉻主要是以三價和六價的形式存在，一般說來鉻(VI)的毒性是鉻(III)的幾百倍[2，3]，其中，六價鉻會引起機(jī)體DNA變性，且在生物體內(nèi)以CrO42-和HCrO4-的形式穿過細(xì)胞膜，在谷胱甘肽作用下還原為鉻(III)，產(chǎn)生鉻(V)中間體及活性氧自由基(或羥基自由基)，對生物體造成嚴(yán)重而持久的危害，是公認(rèn)的有毒環(huán)境污染物[4]和致癌物[5，6]。因此，建立簡單、靈敏高效檢測實(shí)際樣品中六價鉻的方法受到越來越多分析化學(xué)家們的重視，本文主要從光分析的角度綜述比較了自2015年以來六價鉻離子的八種測試方法的優(yōu)缺點(diǎn)。

2 鉻離子的測定方法

自2015年來，用于檢測鉻(VI)的光分析方法主要包括原子吸收光譜法[7-18]、電感耦合等離子體發(fā)射光譜法[19，20]、電感耦合等離子質(zhì)譜法[21-23]、分子熒光光譜法[24-29]、X射線熒光光譜法[30-32]、拉曼散射光譜分析法[33]、紫外-可見分光光度法[34]和比色分析法[35]等，綜述如下。

從表1可知，盡管AAS方法具有選擇性好、儀器廉價、快速簡便的優(yōu)點(diǎn)，但實(shí)際樣品中六價鉻的含量較低，且存在復(fù)雜基體效應(yīng)，AAS不能直接用于檢測實(shí)際樣品中痕量六價鉻，因此，檢測前，作者都對樣品進(jìn)行了預(yù)分離富集[7,8,10,12,13]。例如：在酸性介質(zhì)中，Cr6+以HCrO4-陰離子形式存在，而Cr3+以陽離子形式存在，Rossi[7]等將N-甲基-D-葡糖胺固定在交換柱上，利用帶正電的氮原子選擇性吸附HCrO4-從而達(dá)到與Cr3+分離的目的；氧化石墨烯(GO)，由于具有單層sp2雜化碳原子的二維蜂巢平面結(jié)構(gòu)，大的比表面積，優(yōu)良的理化性能，基面和板邊眾多的吸氧官能團(tuán)等優(yōu)勢，被用作新型固相萃取材料[14,15]分離富集鉻； 引入親水基團(tuán)的GO用于鉻的分離富集時具有高吸附容量、 好的選擇性以及快速吸附動力學(xué)性質(zhì)[16,17]； 此外， 功能化納米磁性氧化石墨烯在分離富集鉻時可提高其分散性[15,18]。

2.1原子吸收光譜法

原子吸收光譜法(Atomic Absorption Spectrometry, AAS)是一種常規(guī)的單元素分析方法，常常被廣泛用于鉻的定量分析，近三年，用于鉻離子的分析檢測的原子吸收光譜法情況如表1.

表1 原子吸收光譜法檢測鉻離子的情況

2.2電感耦合等離子體原子發(fā)射光譜法

電感耦合等離子體原子發(fā)射光譜法(Inductively Coupled Plasma-Optical Emission Spectrometer, ICP-OES)是一種多元素同時測定的方法，也常被用于六價鉻的測定。Vu等[19]利用GO有效吸附重金屬離子的優(yōu)越性能，設(shè)計(jì)合成了一種外包海藻酸鈉分子的磁性氧化石墨烯納米粒子，采用這種高性能的綠色化學(xué)吸附劑，成功檢測了廢水中的鉻(VI)，該方法具有快速吸附磁分離的優(yōu)點(diǎn)，且適用于高鹽含量的工業(yè)廢水中無機(jī)鉻的分析。Weibel等[20]探討了不同樣品基體對富鉻土壤、水泥、煤灰、粉塵中萃取鉻(VI)可能產(chǎn)生的影響。電感耦合等離子體原子發(fā)射光譜法雖然精密度好，線性動態(tài)范圍寬，基體干擾少，但運(yùn)行費(fèi)用較高。

2.3電感耦合等離子體質(zhì)譜法

電感耦合等離子體質(zhì)譜法(Inductively Coupled Plasma-Mass Spectrometry,ICP-MS)是一種多元素同時測定的質(zhì)譜型分析技術(shù)之一，多被用作同位素檢測和痕量元素形態(tài)分析。將其與高效液相色譜(HPLC)聯(lián)用，分離鉻(VI)和鉻(III)后檢出，是目前分析檢測痕量鉻(VI)的靈敏方法。Jia等[21]利用有機(jī)共聚物在線固相萃取、液相色譜分離鉻(VI)和鉻(III)，ICP-MS檢測奶制品、面粉、貝類、果汁沖劑中的鉻(VI)，方法檢出限6.8 ngL-1；ICP-MS測定前利用離子交換色譜法分離鉻(VI)和鉻(III)[22]；Leese等[23]建立了ICP-MS測定工廠工人的呼吸冷凝液和飲用水中鉻(VI)含量的新方法。

與傳統(tǒng)無機(jī)分析技術(shù)相比，ICP-MS具有高靈敏度、低檢測限，進(jìn)樣少、分析速度快、分析精密度和準(zhǔn)確度高的優(yōu)點(diǎn)，常用于超痕量重金屬離子的檢測，但儀器昂貴，運(yùn)行成本高。

2.4分子熒光光譜法

分子熒光光譜法(Molecular fluorescence spectrometry, MFS)也叫熒光分光光度法，是借助熒光染料或發(fā)熒光的物質(zhì)產(chǎn)生反映該物質(zhì)特性的一種熒光光譜分析技術(shù)。同為分子光譜法，相比于紫外可見分光光度法(UV-vis)，MFS最大的優(yōu)點(diǎn)就是靈敏度高和選擇性好，對微量物質(zhì)的檢測可達(dá)到10-10數(shù)量級，比UV-vis靈敏了2～3個數(shù)量級。近三年，運(yùn)用分子熒光光譜法檢測鉻離子的方法如表2.

表2 分子熒光光譜法檢測鉻離子的情況

從表2中可見，對于本身不發(fā)熒光的鉻(VI)離子而言，合適的熒光探針是測定鉻(VI)的關(guān)鍵因素，檢測機(jī)理主要基于以下兩方面：利用鉻(VI)對熒光探針的猝滅作用[24-28]，或利用鉻(VI)與有機(jī)試劑的螯合作用形成熒光物質(zhì)[29]。

2.5X射線熒光光譜法

X射線熒光光譜法(X-ray fluorescence spectrometry, XRF)基于核內(nèi)層電子躍遷建立起來的元素分析方法。Figueiredo等[30]利用XRF對藥品和營養(yǎng)劑中鉻(VI)的檢測的可行性進(jìn)行了研究，實(shí)驗(yàn)證明該方法符合歐洲藥典規(guī)定的驗(yàn)證要求。其中全反射X射線熒光光譜法(Total reflection X-ray fluorescence spectrometry, TXRF)不僅具有背景低、信噪比高的特點(diǎn)，而且光線入射角和反射角可小到基體效應(yīng)忽略不計(jì)，這也就為XRF超痕量分析開創(chuàng)了一個美好前景。Bahadir等[31]基于液液分散微萃取和TRXF，成功檢測了水溶液中的鉻(VI)；Romero等[32]利用高彈性的石墨烯膜預(yù)濃縮富鹽溶液中的鉻(VI)，結(jié)合TRXF檢測，方法靈敏、選擇性好，檢出限為0.08 μg L-1.

2.6拉曼光譜分析法

拉曼光譜 (Raman spectra)是一種散射光譜分析方法，表面增強(qiáng)拉曼散射光譜(Surface Enhanced Raman Scattering, SERS)是對吸附在膠質(zhì)金屬微球表面的粒子進(jìn)行分析的表面光譜技術(shù)。在SERS技術(shù)中，基底開發(fā)制備是關(guān)鍵，金屬基底等離子體共振造成拉曼光譜信號可增強(qiáng)至3～6個數(shù)量級，靈敏度大大提高。Lv等[33]研究了涂覆有2～6 nm TiO2的Fe3O4@Au粒子光催化-SERS檢測鉻(VI)，該方法為現(xiàn)場的快速分析鉻(VI)提供了新的策略。拉曼光譜分析法具有靈敏度高、響應(yīng)快及能分析待測物結(jié)構(gòu)指紋信息等優(yōu)點(diǎn)，吸引了越來越多的科研人員致力于這方面的研究。

2.7紫外-可見分光光度法

紫外-可見分光光度法(UV-vis Spectrophotometry)是基于物質(zhì)分子對200-760 nm光譜區(qū)內(nèi)光輻射吸收特性，建立的對物質(zhì)定性、定量和結(jié)構(gòu)分析的方法。Sereshti等[34]利用3-氨丙基三乙氧基硅修飾的熱還原石墨烯萃取環(huán)境水中的鉻(VI)，與二苯碳酰二肼形成鉻(VI)的絡(luò)合物，最大吸收波長為540 nm，該方法成功用于檢測自來水、河流、污水和地下水中的痕量鉻(VI)。紫外-可見分光光度法儀器設(shè)備便宜、操作簡便快速，但檢測鉻(VI)的靈敏度度不高，因此需要結(jié)合一些分離富集技術(shù)。

2.8比色分析法

比色分析法是基于鉻(VI)的顏色深淺與離子濃度存在的線性關(guān)系而建立起來的半定量分析方法。Guo等[35]開發(fā)出了一種靈敏檢測鉻(VI)的紙基比色傳感技術(shù)，將牛血清白蛋白修飾的金納米粒子截獲在硅烷化二氧化鈦修飾的濾紙上，紙基上的納米金與鉻(VI)反應(yīng)逐漸浸出，出現(xiàn)明顯顏色變化從而達(dá)到可視化分析檢測鉻(VI)的目的。雖然那些基于大型設(shè)備的方法(如ICP-MS、AAS、XRF等)通常具有優(yōu)越的精度和穩(wěn)定性，但它們不適合實(shí)時現(xiàn)場監(jiān)測。基于金屬納米粒子的比色法不需要復(fù)雜的儀器和信號識別，僅通過肉眼識別顏色變化來半定量分析，引起了越來越多的關(guān)注。

3 結(jié)語與展望

近年來，隨著電鍍、制革、冶金等工業(yè)發(fā)展，鉻(VI)對環(huán)境的污染和人體健康的危害越來越受到人們的廣泛關(guān)注，鉻(VI)的鑒定分離分析研究一直在進(jìn)行。本綜述針對“光分析方法用于鉻(VI)檢測分析”詳細(xì)總結(jié)了火焰原子吸收光譜法、電感耦合等離子體發(fā)射法、電感耦合等離子體質(zhì)譜法、分子熒光光譜法、X射線熒光光譜法、拉曼光譜分析法、紫外可見分光光度法、比色分析法這8種光分析方法近三年用于鉻(VI)研究的發(fā)展近況。八種分析方法中僅比色分析實(shí)現(xiàn)了簡便快速，低成本的實(shí)時現(xiàn)場檢測鉻(VI)，但靈敏度低；其他大型儀器設(shè)備如ICP-MS雖然儀器設(shè)備昂貴，操作運(yùn)行成本高，但檢出限低、靈敏度高、線性范圍寬，不僅適用于生物醫(yī)藥、生活用水、食品等實(shí)際樣品中超痕量鉻(VI)的定性定量檢測，還適用于細(xì)胞、腫瘤組織和體液中超痕量的鉻(VI)的檢測；具有靈敏度高、選擇性好的分子熒光光譜法也倍受關(guān)注，但必須找到特定的熒光探針或者是能與鉻(VI)形成螯合物的有機(jī)試劑。這些都是鉻(VI)測定的未來發(fā)展研究方向。

[1]Rosales R M, Faz A, Gómez-Garrido M, et al. Geochemical speciation of chromium related to sediments properties in the riverbed contaminated by tannery effluents [J]. J Soil Sediment, 2016: 1～12.

[2]Gill T, Singh S K, Kumar P A. Treatment of Heavy Metals Contaminated industrial waste water by Functionalized Polymers [J]. Int J Adv Research, 2015, (3): 178～181.

[3]Hokkanen S, Bhatnagar A, Repo E, et al. Calcium hydroxyapatite microfibrillated cellulose composite as a potential adsorbent for the removal of Cr(VI) from aqueous solution [J]. Chem Eng J, 2016, 283: 445～452.

[4]Najafabadi H H, Irani M, Rad L R, et al. Removal of Cu2+, Pb2+and Cr6+from aqueous solutions using a chitosan/graphene oxide composite nanofibrous adsorbent [J]. RSC Adv, 2015, (5): 16532～16539.

[5]Erdem E, Güng rm H, K ln arslan R. The investigation of some properties of cement and removal of water soluble toxic chromium (VI) ion in cement by means of different reducing agents [J]. Constr Build Mater, 2016, 124: 626～630.

[6]Markiewicz B, Komorowicz I, Bara kiewicz D. Accurate quantification of total chromium and its speciation form Cr (VI) in water by ICP-DRC-IDMS and HPLC/ICP-DRC-IDMS [J]. Talanta, 2016, 152: 489～497.

[7]Rossi E, Errea M I, de Cortalezzi M M F, et al. Selective determination of Cr(VI) by on-line solid phase extraction FI-SPE-FAAS using an ion exchanger resin as sorbent: An improvement treatment of the analytical signal [J]. Microchem J, 2017, 130: 88～92.

[8]Shirkhanloo H, Khaligh A, Golbabaei F, et al. On-line micro column preconcentration system based on amino bimodal mesoporous silica nanoparticles as a novel adsorbent for removal and speciation of chromium (III, VI) in environmental samples [J]. Iran J Environ Healt, 2015, 13: 1.

[9]Silva A S, Brandao G C, Matos G D, et al. Direct determination of chromium in infant formulas employing high-resolution continuum source electrothermal atomic absorption spectrometry and solid sample analysis [J]. Talanta, 2015, 144: 39～43.

[10]Shirkhanloo H, Ghazaghi M, Mousavi H Z. Chromium speciation in human blood samples based on acetyl cysteine by dispersive liquid-liquid biomicroextraction and in-vitro evaluation of acetyl cysteine/cysteine for decreasing of hexavalent chromium concentration [J]. J Pharmaceut Biomed, 2016, 118: 1～8

[11]Borges A R, Fran,cois L L, Becker E M, et al. Method development for the determination of chromium and thallium in fertilizer samples using graphite furnace atomic absorption spectrometry and direct solid sample analysis [J]. Microchem J, 2015, 119: 169～175.

[12]V Islam A, Ahmad H, Zaidi N, et al. A graphene oxide decorated with triethylenetetramine-modified magnetite for separation of chromium species prior to their sequential speciation and determination via FAAS [J]. Microchim Acta, 2016, 183: 289～296.

[13]Yilmaz E, Soylak M. Ultrasound assisted-deep eutectic solvent based on emulsification liquid phase microextraction combined with microsample injection flame atomic absorption spectrometry for valence speciation of chromium (III/VI) in environmental samples [J]. Talanta, 2016, 160: 680～685.

[14]Hu B, He M, Chen B. Nanometer-sized materials for solid-phase extraction of trace elements [J]. Anal Bioanal Chem, 2015, 407: 2685～2710.

[15]Sitko R, Zawisza B, Malicka E. Graphene as a new sorbent in analytical chemistry [J]. Trace-Trend Anal Chem, 2013, 51: 33～43.

[16]Islam A, Ahmad H, Zaidi N, et al. Graphene oxide sheets immobilized polystyrene for column preconcentration and sensitive determination of lead by flame atomic absorption spectrometry [J]. ACS Appl Mater Inter, 2014, (6): 13257～13265.

[17]Sayar O, Mehrani K, Hoseinzadeh F, et al. Comparison of the performance of different modified graphene oxide nanosheets for the extraction of Pb(II) and Cd(II) from natural samples [J]. Microchim Acta, 2014, 181: 313～320.

[18] Li J, Zhang S, Chen C, et al. Removal of Cu(II) and fulvic acid by graphene oxide nanosheets decorated with Fe3O4 nanoparticles [J]. ACS Appl Mater Inter, 2012, (4): 4991～5000.

[19] Vu H C, Dwivedi A D, Le T T, et al. Magnetite graphene oxide encapsulated in alginate beads for enhanced adsorption of Cr(VI) and As(V) from aqueous solutions: Role of crosslinking metal cations in pH control [J]. Chem Eng J, 2017, 307: 220～229.

[20]Weibel G, Waber H N, Eggenberger U, et al. Influence of sample matrix on the alkaline extraction of Cr(VI) in soils and industrial materials [J]. Environ Earth Sci, 2016, 75: 1～14.

[21]Jia X, Gong D, Xu B, et al. Development of a novel, fast, sensitive method for chromium speciation in wastewater based on an organic polymer as solid phase extraction material combined with HPLC-ICP-MS [J]. Talanta, 2016, 147: 155～161.

[22]Vacchina V, de la Calle I, Séby F. Cr(VI) speciation in foods by HPLC-ICP-MS: investigation of Cr(VI)/food interactions by size exclusion and Cr(VI) determination and stability by ion-exchange on-line separations [J]. Anal Bioanal Chem, 2015, 407: 3831～3839.

[23]Leese E, Morton J, Gardiner P H E, et al. Development of a method for the simultaneous detection of Cr(III) and Cr(VI) in exhaled breath condensate samples using μLC-ICP-MS [J]. J Anal Atom Spectrom, 2016, 31: 924～933.

[24]Huang S, Qiu H, Zhu F, et al. Graphene quantum dots as on-off-on fluorescent probes for chromium (VI) and ascorbic acid [J]. Microchim Acta, 2015, 182: 1723～1731.

[25]Song X, Sun H, Yang S, et al. Synthesis of photoluminescent o-phenylenediamine-m-phenylenediamine copolymer nanospheres: An effective fluorescent sensing platform for selective and sensitive detection of chromium (VI) ion [J]. J Lumin, 2016, 169: 186～190.

[26]Cui M, Song G, Wang C, et al. Synthesis of cysteine-functionalized water-soluble luminescent copper nanoclusters and their application to the determination of chromium (VI) [J]. Microchim Acta, 2015, 182: 1371～1377.

[27]Rong M, Lin L, Song X, et al. Fluorescence sensing of chromium (VI) and ascorbic acid using graphitic carbon nitride nanosheets as a fluorescent “switch” [J]. Biosens Bioelectron, 2015, 68: 210～217.

[28]Campos B B, Algarra M, Alonso B, et al. Fluorescent sensor for Cr(VI) based in functionalized silicon quantum dots with dendrimers [J]. Talanta, 2015, 144: 862～867.

[29]Zhang Z, Sha C, Liu A, et al. Highly selective detection of Cr(VI) in water matrix by a simple 1, 8-naphthalimide-based turn-on fluorescent sensor [J]. J Fluoresc, 2015, 25: 335～340.

[30]Figueiredo A, Fernandes T, Costa I M, et al. Feasibility of wavelength dispersive X-ray fluorescence spectrometry for the determination of metal impurities in pharmaceutical products and dietary supplements in view of regulatory guidelines [J]. J Pharmaceut Biomed, 2016, 122: 52～58.

[31]Bahadir Z, Bulut V N, Hidalgo M, et al. Cr speciation in water samples by dispersive liquid-liquid microextraction combined with total reflection X-ray fluorescence spectrometry [J]. Spectrochim Acta A B, 2016, 115: 46～51.

[32]Romero V, Costas-Mora I, Lavilla I, et al. Graphene membranes as novel preconcentration platforms for chromium speciation by total reflection X-ray fluorescence [J]. RSC Adv, 2016, (6): 669～676.

[33]Lv B, Sun Z, Zhang J, et al. Multifunctional satellite Fe3O4-Au@TiO2nano-structure for SERS detection and photo-reduction of Cr(VI) [J]. Colloid Surface A, 2016, 513: 234～240.

[34]Sereshti H, Farahani M V, Baghdadi M. Trace determination of chromium (VI) in environmental water samples using innovative thermally reduced graphene (TRG) modified SiO2 adsorbent for solid phase extraction and UV-vis spectrophotometry [J]. Talanta, 2016, 146: 662～669.

[35]Guo J, Huo D, Yang M, et al. Colorimetric detection of Cr(VI) based on the leaching of gold nanoparticles using a paper-based sensor [J]. Talanta, 2016, 161: 819～825.

Abstract: Eight kinds of optical analytical methods employed in detecting chromium (VI) ion were reviewed since 2015 years. The advantages and disadvantages of these methods were compared in detail, and the developing prospection of optical methods used to determine chromium ion is also proposed.

Keywords: chromium (VI) ion; optical analysis method; review

Progressofopticalanalyticalmethodsemployedindetectingchromium(VI)ion

ZHENG Yang, WU Yi-wei

(Department of Chemistry and Chemical Engineering, Hubei Normal University, Huangshi 435002)

O657.3

A

2096-3149(2017)03- 0047-06

10.3969/j.issn.2096-3149.2017.03.009

2017—07—03

湖北省教育廳重點(diǎn)基金(No.D20130501)

鄭陽(1991— )，女，湖北荊門人，碩士生，研究方向?yàn)榉蛛x分析技術(shù).

吳一微(1971— )，女，湖北武穴人，教授.