Liquid chromatography-inductively coupled plasma mass spectrometry.

The technique of coupling liquid chromatography to inductively plasma mass spectrometry (ICP-MS) is reviewed. A brief introduction to the ICP-MS instrument is given as well as methods to couple the two analytical instruments together. The various types of LC that have been used with ICP-MS detection are discussed and advantages over traditional methods of detection are highlighted, such as the improvements in sensitivity and selectivity. Several applications that have been described in the literature are reviewed. An outlook for the future of LC-ICP-MS, particularly with regard to elemental speciation is given.     

Simultaneous determination of arsenic species by ion chromatography-inductively coupled plasma mass spectrometry

Six arsenic species, arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine and arsenocholine, were separated by coupled column ion chromatography using carbonate and nitric acid as eluents, and were detected by inductively coupled plasma mass spectrometry. Coupling of an anion column with a cation column made the simultaneous determination of both the cationjic and the anionic arsenic species possible by ion chromatography. Extremely low detection limits, below 0.2 μg/1 (as arsenic), were obtained for all the species studied.     

Speciation of halogenides and oxyhalogens by ion chromatography-inductively coupled plasma mass spectrometry

A speciation method utilizing ion chromatography coupled with inductively coupled plasma mass spectrometry is described for simultaneous analysis of eight halogenides and oxyhalogens: chloride, chlorite, chlorate, perchlorate, bromide, bromate, iodide and iodate. The method was applied for the analysis of drinking water samples collected from water treatment plants in areas in Finland, which are known to have high bromine concentrations in ground water. Water samples collected before and after disinfection were analyzed to get information about potential species conversion as a result of purification. Chloride and chlorate were the chlorine species found in these water samples, and iodine existed as both iodate and iodide. In the case of bromine, species conversion had taken place, since total bromine concentrations were increased during disinfection but bromide concentrations were decreased. No bromate was observed in the samples. The detection limits for all the chlorine species studied were 500 μg/l, for bromine species studied 10 μg/l, for iodide 0.1 μg/l and for iodate 0.2 μg/l.     

Serum/plasma methylmercury determination by isotope dilution gas chromatography-inductively coupled plasma mass spectrometry

A method for the determination of methylmercury in plasma and serum samples was developed. The method uses isotope dilution with ¹⁹⁸Hg-labeled methylmercury, extraction into dichloromethane, back-extraction into water, aqueous-phase ethylation, purge and trap collection, thermal desorption, separation by gas chromatography, and mercury isotope specific detection by inductively coupled plasma mass spectrometry. By spiking 2 mL sample with 1.2 ng tracer, measurements in a concentration interval of (0.007–2.9) μg L⁻¹ could be performed with uncertainty amplification factors <2. A limit of quantification of 0.03 μg L⁻¹ was estimated at 10 times the standard deviation of concentrations measured in preparation blanks. Within- and between-run relative standard deviations were <10% at added concentration levels of 0.14 μg L⁻¹, 0.35 μg L⁻¹ and 2.8 μg L⁻¹, with recoveries in the range 82–110%. Application of the method to 50 plasma/serum samples yielded a median (mean; range) concentration of methylmercury of 0.081 (0.091; <0.03–0.19) μg L⁻¹. This is the first time methylmercury has been directly measured in this kind of specimen, and is therefore the first estimate of a reference range.     

Speciation of chromium in waste waters by coupled column ion chromatography-inductively coupled plasma mass spectrometry

An application of coupled column ion chromatography (IC)-inductively coupled plasma mass spectrometry (ICP-MS) is presented for speciation of chromium in waste waters. By coupling an anion column with a cation column, both the cationic Cr(III) and anionic Cr(VI) species can be analyzed with detection limits below 0.5 μg/1. The separation of the interfering ions (chloride, chlorate, perchlorate, sulphate, sulphite, sulphide, thiosulphate, carbonate, cyanide and some organic compounds) from the chromium peaks is discussed, and the use of different chromium isotopes for data acquisition is compared. Based on the results, m/z 52 was considered as an ideal isotope for speciation of chromium in waste waters by the coupled column IC-ICP-MS, because it did not suffer from polyatomic interferences and due to the high sensitivity for chromium. The analysis of the waste water samples should be performed as soon as possible after sampling according to the stability tests of the species.     

Elemental speciation by liquid chromatography-inductively coupled plasma mass spectrometry with direct injection nebulization.

A new version of the direct injection nebulizer (DIN) is used to interface liquid chromatographic (LC) separations with element-selective detection using inductively coupled plasma mass spectrometry (ICP-MS). The DIN injects all of the sample into the ICP and has a dead volume of less than 1 microliter. Charged species of arsenic and tin are separated as ion pairs on a micro-scale (1 mm i.d.), packed, reversed-phase column. Detection limits are 0.2-0.6 pg for arsenic and 8-10 pg for tin. For methanol + water eluents, the signal is highest at 25% methanol and stays within 25% of this maximum as the methanol fraction is varied from 20 to 80%. Compared with LC-ICP-MS with conventional nebulizers, the absolute detection limits and chromatographic resolution are substantially superior, and the dependence of analyte signal on solvent composition is somewhat less severe with the DIN.     

Determination of arsenic compounds in beverages by high-performance liquid chromatography-inductively coupled plasma mass spectrometry

Arsenic compounds including arsenous acid (As(III)), arsenic acid (As(V)), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) were separated by high-performance liquid chromatography (HPLC) and detected by inductively coupled plasma mass spectrometry (ICP-MS). A Hamilton PRX-100 anionic-exchange column and a pH 8.5 K₂HPO₄/KH₂PO₄ 5.0 × 10⁻³ mol L⁻¹ mobile phase were used to achieve arsenic speciation. The separation of arsenic species provided peaks of As(III) at 2.75 min, DMA at 3.33 min, MMA at 5.17 min and As(V) at 12.5 min. The detection limits, defined as three times the standard deviation of the lowest standard measurements, were found to be 0.2, 0.2, 0.3 and 0.5 ng mL⁻¹ for As(III), DMA, MMA and As(V), respectively. The relative standard deviation values for a solution containing 5.0 μg L⁻¹ of As(III), DMA, MMA and As(V) were 1.2, 2.1, 2.5 and 3.0%, respectively. This analytical procedure was applied to the speciation of arsenic compounds in drinking (soft drink, beer, juice) samples. The validation of the procedure was achieved through the analysis of arsenic compounds in water and sediment certified reference materials.     

On-line capillary supercritical fluid chromatography-inductively coupled plasma mass spectrometry for the analysis of organometallic compounds

Supercritical fluid chromatography with inductively coupled plasma-mass spectrometric detection is a new and useful technique for the analysis of organometallic compounds. An interface has been developed for coupling these techniques. The interface is compact, easy to assembel, and causes minimal disruption to either instrument. A series of organotin, organoarsenic, and organorion compounds has been used to evaluate the interface and ICPMS as a detector for SFC. The effect of analyte concentration and restrictor temperature on peak intensity has been investigated and the effect of the mobile phase on the plasma has also been studied to assess background interference from changes in the plasma.     

Measurement of arsenic species in marine sediments by high-performance liquid chromatography-inductively coupled plasma mass spectrometry

Extraction of sediments with phosphoric acid (0.5 M) and hydroxylamine hydrochloride (0.1 M) allowed the measurement of labile arsenic species while preserving the two redox states of arsenic. The forms and concentrations of arsenic species were measured using HPLC-ICP-MS. A Hamilton PRP X-100 strong anion exchange column using a 20 mM ammonium phosphate buffer (pH 6 and 9.2) was used to separate arsenic species. Recoveries of sediments spiked with As(V) were quantitative whereas for sediments spiked with As(III) recoveries of between 89 and 104% were obtained from four oxic certified reference sediments and an anoxic sediment. Application of the method to sediment samples from the marine Lake Macquarie, NSW, Australia, indicate that anoxic sediments can contain high concentrations of As(III), and two arsenosugars (sulfonate-ribose and sulfate-ribose). Extraction efficiencies for arsenic ranged between 6 and 82%. The arsenic species measured in sediments are strongly depended on the extraction procedure used. As(III) and arsenosugar concentrations in sediments that were freeze dried and oxidised were much less than in sediments that were not freeze dried and when exposure to air was keep to a minimum. Corresponding, As(V) concentrations tended to be higher in samples that were exposed to air.     

Determination of trace-level haloacetic acids in drinking water by ion chromatography-inductively coupled plasma mass spectrometry

A new method for the determination of nine haloacetic acids (HAAs) with ion chromatography (IC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) was developed. With the very hydrophilic anion-exchange column and steep gradient of sodium hydroxide, the nine HAAs could be well separated in 15 min. After suppression with an ASRS suppressor that was introduced in between IC and ICP-MS, the background was much decreased, the interference caused by sodium ion present in eluent was removed, and the sensitivities of HAAs were greatly improved. The chlorinated and brominated HAAs could be detected as 35ClO and 79Br without interference of the matrix due to the elemental selective ICP-MS. The detection limits for mono-, di-, trichloroacetic acids were between 15.6 and 23.6 microg/l. For the other six bromine-containing HAAs, the detection limits were between 0.34 and 0.99 microg/l. With the pretreatment of OnGuard Ag cartridge to remove high concentration of chloride in sample, the developed method could be applied to the determination of HAAs in many drinking water matrices.     

Speciation analysis of arsenic compounds in edible oil by ion chromatography-inductively coupled plasma mass spectrometry

An inductively coupled plasma mass spectrometer (ICP-MS) was used as an ion chromatographic (IC) detector for the speciation analysis of arsenic in edible oil. The arsenic species studied include arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine and arsenocholine. Gradient elution using (NH(4))(2)CO(3) and methanol at pH 8.5 allowed the chromatographic separation of all species in less than 8 min. Effluents from the IC column were delivered to the nebulizer of ICP-MS for the determination of arsenic. The concentrations of arsenic species have been determined in several used and fresh vegetable oil samples. In this study, a microwave-assisted extraction method was used for the extraction of arsenic species from oil samples. The extraction efficiency was better than 92% and the recoveries from spiked samples were in the range of 90-105%. The precision between sample replicates was better than 8% for all determinations. The limits of detection were in the range of 0.008-0.024 ng mL(-1) for various arsenic species based on peak height, which corresponded to 0.08-0.24 ng g(-1) in the original oil sample. The major arsenic species in the used oil samples varied based on the food items cooked.     

反相离子对色谱-电感耦合等离子体质谱法测定化妆品中不同形态的铬

建立了反相离子对色谱(RP-IPC)与电感耦合等离子体质谱(ICP-MS)联用技术快速分离测定化妆品中Cr(III)和Cr(VI)的方法。样品经乙二胺四乙酸钠盐(EDTA)50 ℃水浴中提取后,采用XDB-C18色谱柱分离,以5%(v/v)甲醇-2.0 mmol/L四正丁基铵盐(TBA)水溶液(pH 6.0)作为流动相,流速为1.0 mL/min,进样量为100 μL。采用碰撞池技术消除ICP-MS测定时40Ar12C+、35Cl16O1H+对52Cr+的光谱学干扰。Cr(III)和Cr(VI)的分离过程在5 min内完成。样品中加标量为0.01～0.50 μg时,其回收率为82.7%～107.2%,相对标准偏差(RSD)小于5.62%。该方法操作简便、灵敏度高、重现性好,适合于化妆品中Cr(III)和Cr(VI)的同时分析。     

Speciation analysis of mercury and lead in fish samples using liquid chromatography-inductively coupled plasma mass spectrometry

A liquid chromatography-inductively coupled plasma mass spectrometric (LC-ICP-MS) method for lead and mercury speciation analysis was described. Sample containing ionic lead and mercury compounds was subjected to liquid chromatographic separation before injection into the direct injection high efficiency nebulizer (DIHEN, 170-AA). The species studied include inorganic lead (Pb(II)), trimethyl lead (trimethyl-Pb), triethyl lead (triethyl-Pb), inorganic mercury (Hg(II)), methyl mercury (methyl-Hg) and ethyl mercury (ethyl-Hg), which were well separated by reversed-phase liquid chromatography with a C18 column as the stationary phase and a pH 2.8 solution of 0.2% (v/v) 2-mercaptoethanol, 1 mg L(-1) ETDA, 174.2 mg L(-1) sodium 1-pentanesulfonate and 12% (v/v) methanol as the mobile phase. The lead and mercury species in biological tissues were quantitatively extracted, into 10 g L(-1) EDTA and 0.2% (v/v) 2-mercaptoethanol solution taken in a closed centrifuge tube and kept on water bath, using microwaves at 65 degrees C for 2 min. The spike recovery of individual lead and mercury species determined by spiking the samples with suitable concentration of lead and mercury mixture standard were between 93% and 99%. The detection limits of the species studied were in the range 0.1-0.3 microg Pb L(-1) and 0.2-0.3 microg Hg L(-1). The procedure has been applied for the speciation analysis of two reference samples namely NRCC DOLT-3 Dogfish Liver and DORM-2 Dogfish Muscle and a swordfish sample obtained locally. The sum of the concentrations of individual species has been compared with the certified values for total lead and mercury to verify the accuracy of the method. The precision between sample replicates was better than 10% with LC-DIHEN-ICP-MS method.     

离子色谱-电感耦合等离子体质谱法测定植物性样品中的碘及其形态

建立了离子色谱-电感耦合等离子体质谱联用(IC-ICP/MS)测定植物性样品中碘及其形态的方法。采用碱提取法处理样品后,应用IC-ICP/MS检测植物样品中的碘离子和碘酸根;采用高温裂解法处理样品,使样品中各种形态的碘最终均转化为碘离子,然后应用IC-ICP/MS检测碘离子,从而实现总碘的测定。碘的方法检出限为0.010 mg/kg。碱提取法和高温裂解法处理样品的碘的加标回收率分别为89.6%～97.5%和95.2%～111.2%,结果令人满意。按照所建立的方法分别考察了紫菜、海带、圆白菜、茶叶、菠菜等常见植物性样品中碘的存在形式,结果表明,紫菜中的碘以有机碘为主,而海带、圆白菜、茶叶、菠菜中的碘则以无机碘为主。     

Improved chromatographic separation of thio-arsenic compounds by reversed-phase high performance liquid chromatography-inductively coupled plasma mass spectrometry

A new group of arsenic species, thio-arsenicals, have recently been reported in several natural samples such as molluscs, algae, and urine. These compounds are the sulfur analogues of oxo-arsenicals, a large group of naturally-occurring compounds, whereby the arsinoyl (As=O) group is substituted by an arsinothioyl group (As=S). The most common separation technique for oxo-arsenicals is anion-exchange HPLC with polymer-based columns, but under these conditions the thio-arsenicals show strong retention, resulting in unacceptably long analysis times and broad peaks. We report the development of a reversed-phase HPLC method, with ICPMS detection, which allows separation of the known thio-arsenicals within 15 min with significantly improved peak shapes. The detection limit is about 0.6 microg As/L based on 10 microL injection volume. Further, we have applied the method to the identification and quantification of thio-arsenic species in two standard reference materials, BCR 710 oyster tissue and NIES 18 human urine.     

电感耦合等离子体质谱分析

简要综述了我国学者近10年来在电感耦合等离子体质谱(ICP-MS)分析领域的研究工作.在ICP-MS新进样技术和ICP-MS生物分析方法学研究方面,我国科研人员开展了开拓性的研究工作,在元素形态分析和金属组学研究方面富有特色.ICP-MS仪器/部件的设计研制尚待加强;ICP-MS成像研究和在实际生命体系的应用有待进一步强化.     

Fast determination of arsenosugars in algal extracts by narrow bore high-performance liquid chromatography-inductively coupled plasma mass spectrometry

The potential of narrow bore high-performance liquid chromatography (HPLC) with detection by inductively coupled plasma mass spectrometry (ICP-MS) for fast determination of arsenosugars in algal extracts was explored. The retention behavior of four naturally occurring dimethylarsinoylribosides on an anion-exchange microbore column was investigated, with the mobile phase flow rate ranging from 60 to 200μLmin(-1). A low sample consumption system consisting of a micronebulizer and a low inner volume cyclonic spray chamber was used as the interface between the micro-column and the ICP mass spectrometer. Both the high efficiency nebulizer, HEN, and the PFA micronebulizer were tested, with the former providing 20-50% greater sensitivity than PFA (depending on the liquid flow rate), but comparable limits of detection and slightly lower chromatographic resolution. With the setup employed and under the optimal conditions, a satisfactory separation of the arsenosugars was achieved in less than 5min. The instrumental limit of detection was 0.20μgAsL(-1) and the precision was better than 3% (RSD%, n=5). The accuracy of the determination was verified by the analysis of a reference algal extract, obtaining values in good agreement with the reference ones.     

高效液相色谱-电感耦合等离子体质谱测定血浆中铂类抗癌药物

建立了高效液相色谱-电感耦合等离子体质谱快速测定血浆中顺铂、卡铂、奥沙利铂的方法。实验表明顺铂和奥沙利铂在纯水和血浆中不稳定,奥沙利铂在0.9%的NaCl中不稳定,因此采集的样品需尽快分析。提出了可通过测定顺铂、奥沙利铂色谱保留时间和卡铂的标准曲线来间接测定血浆中不稳定的顺铂和奥沙利铂含量的简化方法。方法检出限以铂计为0.04 ng/mL,顺铂、卡铂、奥沙利铂线性回归曲线的回归系数r均大于0.9995。方法的加标回收率在84%～102%之间,相对标准偏差在0.9%～6.4%之间。     

Speciation of butyltin compounds in environmental and biological samples using headspace single drop microextraction coupled with gas chromatography-inductively coupled plasma mass spectrometry

A method based on headspace single drop microextraction (HS-SDME) in combination with gas chromatography-inductively coupled plasma mass spectrometry (GC-ICP-MS) was proposed for the speciation analysis of butyltin compounds in environmental and biological samples. The sodium tetraethylborate (NaBEt4) and sodium tetrahydroborate (NaBH4) were used as the derivatizing reagent for in situ derivatization of the butyltins. For the two derivatizations, the HS-SDME parameters such as organic solvent, drop volume, sample pH, stirring rate, temperature, extraction time and the ionic strength were examined systematically. The analytical performance including the linearity ranges, limits of detection (LODs) and reproducibilities of the two derivatizations were compared under the respective optimized conditions. Derivatization with NaBEt(4) proved to be more sensitive and robust than that with NaBH4, leading to the LODs of 1.4 ng/L for MBT, 1.8 ng/L for DBT and 0.8 ng/L for TBT. The reproducibilities, expressed as relative standard deviations (RSDs), were in the range of 1.1-5.3% (c=1 microg/L, n=3). With tripropyltin (TPrT) as internal standard, HS-SDME-GC-ICP-MS with NaBEt(4) derivatization was applied for the speciation analysis of butyltins in real seawater and shellfish samples. The butyltins found in the real-world samples are 31ng/L MBT, 79 ng/L DBT and 32 ng/L TBT for seawater, and 11.6-30.4 ng/g MBT, 11.8-8.9 ng/g DBT and 12.8-52.6 ng/g TBT for different shellfish samples. For validation, the developed method was also employed for the speciation analysis of butyltins in certified reference material (CRM) of PACS-2 sediment, and the determined values are in a good agreement with the certified values. The developed method is simple, rapid, sensitive, and cost-effective and provides an attractive alternative for butyltins speciation in biological and environmental samples with complex matrix.