On-line preconcentration for capillary electrophoresis-atomic fluorescence spectrometric determination of arsenic compounds

An on-line preconcentration method was developed for capillary electrophoresis (CE) with hydride generation-atomic fluorescence spectrometric (HG-AFS) detection of arsenite, arsenate, dimethylarsenic acid, and monomethylarsenic acid. These arsenic species were negatively charged in the sample solution with high pH. When the potential was applied to the electrophoretic capillary, the negatively charged analyte ions moved faster and stacked at the boundary of sample and CE buffer with low pH. So, high sample pH in combination with low buffer pH allowed the injection of large sample volumes (approximately 1100 nL). Comparison of the preconcentration of analyte solution, prepared with doubly deionized water and that prepared with lake or river water, indicated that preconcentration was independent on the original matrix. With injection of approximately 1100 nL sample, an enrichment factor of 37-50-fold was achieved for the four species. Detection limits for the four arsenic species ranged from 5.0 to 9.3 microg.L(-1). Precisions (RSDs, n = 5) were in the range of 4.9-6.7% for migration time, 4.7-11% for peak area, and 4.3-7.1% for peak height, respectively. The recoveries of the four species in locally collected water solution spiked with 0.1 microg.mL(-1) (as As) ranged from 83 to 109%.     

Speciation analysis of arsenic in Mya arenaria Linnaeus and Shrimp with capillary electrophoresis-inductively coupled plasma mass spectrometry

An improved sheath-flow interface used to couple capillary electrophoresis (CE) with inductively coupled plasma mass spectrometry (ICP-MS) and a microwave-assisted extraction used to extract each arsenic species in seafood were developed in this work. The improved sheath-flow interface completely avoids laminar flow in CE capillary caused by the suction from ICP-MS, makes electric supply more stable in CE, and transports analyte solution to ICP-MS easily and more efficiently. CE-ICP-MS coupled with our interface have two quantitative analysis modes: continuous sample-introduction mode and collective sample-introduction mode. The collective sample-introduction technique greatly reduced the dead volume of interface to approximately zero, obviously avoided the excessive dilution of analyte, and eventually led to a much lower detection limit and a much better electrophoretic resolution. This was demonstrated by the better symmetry and narrow peak widths (10-12 s) and much lower detection limits (0.030-0.042 μg/L) of four species of arsenic determined with collective sample-introduction mode.With the help of this improved sheath-flow interface and the microwave-assisted extraction, we have successfully separated and determined four arsenic species, As(III), As(V), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in dried Mya arenaria Linnaeus and Shrimp samples using CE-ICP-MS within 10 min with a relative standard deviation of 2-4% (peak areas, n = 6) and a recovery of 96-105%.     

Determination of arsenic species in marine samples by HPLC-ICP-MS.

Arsenic speciation analysis in marine samples was performed using high performance liquid chromatography (HPLC) with ICP-MS detection. The separation of eight arsenic species viz. arsenite (As(III)), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenate (As(V)), arsenobetaine, trimethylarsine oxide (TMAO), arsenocholine and tetramethylarsonium ion (TeMAs) was achieved on a Shiseido Capcell Pak C18 column by using an isocratic eluent (pH 3.0), in which condition As(III) and MMA were co-eluted. The entire separation was accomplished in 15 min. The detection limits for 8 arsenic species by HPLC/ICP-MS were in the range of 0.02 - 0.10 microg L(-1) based on 3sigma of blank response (n=9). The precision was calculated to be 3.1-7.3% (RSD) for all eight species. The method then successfully applied to several marine samples e.g., oyster, scallop, fish, and shrimps. For the extraction of arsenic species from seafood products, the low power microwave digestion was employed. The extraction efficiency was in the range of 52.9 - 112.3%. Total arsenic concentrations were analyzed by using the microwave acid digestion. The total arsenics in the certified reference materials (DORM-2 and TORT-2) were analyzed and agreed with the certified values. The concentrations of arsenics in marine samples were in the range 6.6 - 35.1 microg g(-1).     

Separation of arsenic species by capillary electrophoresis with sample-stacking techniques

A simple capillary zone electrophoresis procedure was developed for the separation of arsenic species (AsO(2)(2-), AsO(4)(2-), and dimethylarsinic acid, DMA). Both counter-electroosmotic and co-electroosmotic (EOF) modes were investigated for the separation of arsenic species with direct UV detection at 185 nm using 20 mmol L(-1) sodium phosphate as the electrolyte. The separation selectivity mainly depends on the separation modes and electrolyte pH. Inorganic anions (Cl(-), NO(2)(-), NO(3)(-) and SO(4)(2-)) presented in real samples did not interfere with arsenic speciation in either separation mode. To improve the detection limits, sample-stacking techniques, including large-volume sample stacking (LVSS) and field-amplified sample injection (FASI), were investigated for the preconcentration of As species in co-CZE mode. Less than 1 micromol L(-1) of detection limits for As species were achieved using FASI. The proposed method was demonstrated for the separation and detection of As species in water.     

Speciation of arsenic compounds in fish and oyster tissues by capillary electrophoresis-inductively coupled plasma-mass spectrometry

A capillary electrophoresis-inductively coupled plasma-mass spectrometric (CE-ICP-MS) method for the speciation of six arsenic compounds, namely arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid, dimethylarsinic acid, arsenobetaine and arsenocholine is described. The separation has been achieved on a 70 cm length x 75 microm ID fused-silica capillary. The electrophoretic buffer used was 15 mM Tris (pH 9.0) containing 15 mM sodium dodecyl sulfate (SDS), while the applied voltage was set at +22 kV. The arsenic species in biological tissues were extracted into 80% v/v methanol-water mixture, put in a closed centrifuge tube and kept in a water bath, using microwaves at 80 degrees C for 3 min. The extraction efficiencies of individual arsenic species added to the sample at 0.5 microg As/g level were between 96% and 107%, except for As(III), for which it was 89% and 77% for oyster and fish samples, respectively. The detection limits of the species studied were in the range 0.3-0.5 ng As/mL. The procedure has been applied for the speciation analysis of two reference materials, namely dogfish muscle tissue (NRCC DORM-2) and oyster tissue (NIST SRM 1566a), and two real-world samples.     

Quantification of phosphorus in DNA using capillary electrophoresis hyphenated with inductively coupled plasma mass spectrometry

We have analyzed phosphorus in an enzymatically digested DNA molecule using capillary electrophoresis (CE) hyphenated with inductively coupled plasma mass spectrometry (ICP-MS). The DNA concentration was quantified by the phosphorus value obtained in the CE-ICP-MS analysis. The CE-ICP-MS measurement, for which the interface device AIF-01 equipped three layered nebulizer was adopted, was achieved with limited μL/min nebulizing without loss of sample in the vaporizing chamber. The samples of nucleotides and free phosphate were separated well in the CE-ICP-MS measurement, and the calibration curve (0.1-10μg/mL) of the phosphorus showed a linear (R(2)=0.999) increase in intensity. After digestion of the 100-bp double-strand DNA sample to deoxyribonucleotide-5'-monophosphates (dNMPs) by phosphodiesterase-I, phosphorus was detected by CE-ICP-MS without further purification steps. In this study, we applied two calculation schemes of DNA analysis using a dNMP concentration obtained from CE-ICP-MS. Comparative CE-ICP-MS analysis with DNA digested to dNMPs showed that the assay gave an equal value obtained from the total DNA quantification using fluorescence detection. The detection limits of the DNA sample obtained from these species and phosphorus in nucleotides using CE-ICP-MS were 3.1-26ng/mL. These LOD values were equal to the conventional fluorescence determination of DNA.     

CZE for the speciation of arsenic in aqueous soil extracts

We developed two separation methods using CZE with UV detection for the determination of the most common inorganic and methylated arsenic species and some phenylarsenic compounds. Based on the separation method for anions using hydrodynamic sample injection the detection limits were 0.52, 0.25, 0.27, 0.12, 0.37, 0.6, 0.6, 1.2 and 1.0 mg As/L for phenylarsine oxide (PAO), p-aminophenylarsonic acid (p-APAA), o-aminophenylarsonic (o-APAA), phenylarsonic acid (PAA), 4-hydroxy-3-nitrobenzenearsonic acid (roxarsone), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenite or arsenious acid (As(III)) and arsenate (As(V)), respectively. These detection limits were improved by large-volume sample stacking with polarity switching to 32, 28, 14, 42, 22, 27, 26 and 27 microg As/L for p-APAA, o-APAA, PAA, roxarsone, MMA, DMA, As(III) and As(V), respectively. We have applied both methods to the analysis of the arsenic species distribution in aqueous soil extracts. The identification of the arsenic species was validated by means of both standard addition and comparison with standard UV spectra. The comparison of the arsenic species concentrations in the extracts determined by CZE with the total arsenic concentrations measured by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) indicated that CZE is suited for the speciation of arsenic in environmental samples with a high arsenic content. The extraction yield of phenylarsenic compounds from soil was derived from the arsenic concentrations of the aqueous soil extracts and the total arsenic content of the soil determined by ICP-AES after microwave digestion. We found that 6-32% of the total amount of arsenic in the soil was extractable by a one-step extraction with water in dependence on the type of arsenic species.     

毛细管电泳-电感耦合等离子体质谱法测定藻类中6种不同形态的砷化合物

建立了一种利用毛细管电泳与电感耦合等离子体质谱联用技术(CE-ICP-MS)分析检测6种不同形态砷化合物的方法。详细研究了缓冲溶液的种类、pH值和浓度,分离电压以及进样时间等因素对6种砷化合物的分离度、灵敏度和重现性等的影响。结果表明,在最佳条件下,三价砷(As3+)、一甲基砷(MMA)、二甲基砷(DMA)、五价砷(As5+)、砷胆碱(AsC)和砷甜菜碱(AsB)6种化合物在25 min内得到完全分离。6次平行测定中,6种砷化合物峰面积的相对标准偏差(RSD)为3%～5%,检出限(以As计)(3倍信噪比)为0.08～0.12 μg/L。应用该方法成功地对海带中6种砷化合物进行了分析,回收率为90%～103%。该方法具有耗时短、灵敏度高、样品消耗量少、稳定性好等优点,可用于藻类样品中不同形态砷化合物的分析。     

Simultaneous determination of arsenic species and chromium(VI) by high-performance liquid chromatography-inductively coupled plasma-mass spectrometry

The simultaneous determination of As(III), As(V), monomethylarsenic acid (MMA), dimethylarsinic acid (DMA) and Cr(VI) in fresh water has been carried out by coupling an anion-exchange column to an inductively coupled plasma-mass spectrometer. Optimisation of chromatographic conditions led to baseline separation of signals from the five species in approximately 9 min using gradient elution. Detection limits were 0.02-0.05 microg As l(-1) and 5.5 microg Cr l(-1). Repeatability was 2-3% for arsenic species and higher, i.e., 8%, for Cr(VI) due to the higher background for this species. Arsenic species and hexavalent chromium stability in surface water samples was evaluated, and storage conditions were set to 1 day at 4 degrees C in polyethylene flasks (without acidification) in order to avoid As(III)-As(V) conversions. The method was applied to the analysis of surface water.     

On-line hyphenation of capillary electrophoresis with flame-heated furnace atomic absorption spectrometry for trace mercury speciation

Capillary electrophoresis (CE) was directly interfaced to flame-heated furnace atomic absorption spectrometry (FHF-AAS) via a laboratory-made thermospray interface for nanoliter trace element speciation. The CE-FHF-AAS interface integrated the superiorities of stable CE separation, complete sample introduction, and continuous vaporization for AAS detection without the need of extra external heat sources and any post-column derivation steps. To demonstrate the usefulness of the developed hybrid technique for speciation analysis, three environmentally significant and toxic forms of methylmercury (MeHg), phenylmercury (PhHg), and inorganic mercury (Hg(II)) were taken as model analytes. Baseline separation of the three mercury species was achieved by CE in a 60 cm long x 75 microm inner diameter fused-silica capillary at 20 kV and using a mixture of 100 mM boric acid and 10% v/v methanol (pH 8.30) as running electrolyte. The precision (relative standard deviation, RSD, n = 7) of migration time, peak area and peak height for the mercury species at 500 microg x L(-1) (as Hg) level were in the range of 0.9-1.2%, 1.5-1.9%, and 1.4-2.0%, respectively. The detection limit (S/N = 3) of three mercury species was 3.0 +/- 0.15 pg (as Hg), corresponding to 50.8 +/- 2.4 microg x L(-1) (as Hg) for 60 nL sample injection, which was almost independent on specific mercury species. The developed hybrid technique was successfully applied to the speciation analysis of mercury in a certified reference material (DORM-2, dogfish muscle).     

The potential of inductively coupled plasma-mass spectrometric detection for capillary electrophoretic analysis of pesticides

In this work, the potential of inductively coupled plasma-mass spectrometry (ICP-MS) coupled to capillary electrophoresis (CE) to determine organophosphorus pesticides (OPPs) is demonstrated. Element specific detection of (31)P with ICP-MS is performed for the detection of OPPs. Three common OPPs, including glyphosate, glufosinate, and aminomethylphosphonic acid (AMPA), were analyzed by CE-ICP-MS to demonstrate its applicability for the analysis of OPPs. The advantages of using ICP-MS with respect to other common detectors, such as flame photometric detection (FPD), for CE analysis of OPPs are shown. Additionally, different CE separation conditions were studied to achieve complete baseline separation of the pesticide compounds in short migration times. Two CE buffer systems were evaluated for the separation of OPPs using ICP-MS detection. A buffer solution containing 40 mmol.L(-1) ammonium acetate at pH 9.0 and an applied voltage of +20 kV were finally selected leading to a separation time of 10.0 min. Both migration time and area relative standard deviations (%RSD) were evaluated and their respective values were in the intervals of 1.1-3.3% and 2.7-5.3%. Detection limits obtained with the CE-ICP-MS system were in the range of 0.11-0.19 mg.L(-1) (as compound) yielding an enhancement of 130- to 230-fold with respect to FPD. The proposed methodology was finally applied for the determination of the OPPs mentioned above in natural river water samples.     

Speciation of arsenic by ion chromatography inductively coupled plasma mass spectrometry using ammonium eluents

A method based on ion chromatography (IC) and inductively coupled plasma MS (ICP-MS) was developed for the speciation of arsenic in water and soil extracts. An anion-exchange column (G3154A/101) was used to separate As(III), As(V), dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA) with excellent resolution. Various ammonium salts, including NH4H2PO4, (NH4)2HPO4, (NH4)2CO3, and NH4HCO3, were examined as eluents to reduce matrix interference from chloride and to solve clogging problems. The best arsenic speciation was obtained within 9 min with excellent resolution and without interference from high chloride concentrations using an eluent containing 7.5 mM (NH4)2HPO4 at pH 7.9. The detection limits for the target arsenic species ranged from 0.1 to 0.4 microg/L with direct injection of sample without matrix elimination. The proposed method was effectively demonstrated by determining arsenic species in contaminated waters and soils of Bangladesh.     

Sensitive determination of phenylarsenic compounds based on a dual preconcentration method with capillary electrophoresis/UV detection

A novel method based on off-line hollow fiber based liquid liquid liquid microextraction (HF-LLLME) combined with on-column anion selective exhaustive injection (ASEI)-capillary electrophoresis/ultraviolet (CE/UV) detection was proposed for the speciation of five phenylarsenic compounds including phenylarsonic acid (PAA), 4-aminophenylarsonic acid (4-APAA), 4-hydroxyphenylarsonic acid (4-HPAA), 4-nitrophenylarsonic acid (4-NPAA) and 3-nitro-4-hydroxyphenylarsonic acid (NHPAA) in this paper. In HF-LLLME, the target analytes were extracted from 5 mL aqueous samples (donor solution pH 2.15) through a thin phase of tributyl phosphate (TBP) inside the pores of a polypropylene hollow fiber and finally into an 18 μL 0.8 mmol/L Tris acceptor solution inside the lumen of the hollow fiber. Following HF-LLLME, the acceptor solutions were directly analyzed by ASEI-CE/UV. For ASEI, a large plug of water (91% length of total capillary) was introduced into the separation capillary before sample injection in order to prolong the sample injection time, and thus enhance the stacking efficiency. Under the optimized ASEI conditions, up to 236-fold of enrichment factor (EF) was obtained for the ASEI-CE/UV determination of target phenylarsenic compounds. By combining HF-LLLME with ASEI-CE/UV, EFs ranging from 155 to 1780-fold were achieved and the limits of detection (LODs) (at a signal-to-noise ratio of 3) were in the range of 0.68-6.90 μg/L for five phenylarsenic compounds; the relative standard deviations (RSDs) of corrected peak area were 5.6-11.8%. The proposed HF-LLLME-ASEI-CE/UV method was applied for the determination of five target phenylarsenic compounds in pig feed from a local pig farm, and storage pig litter, soil in agricultural field and lake water collected near this pig farm, the recoveries for the spiked samples were in the range of 85.7-104.5%, 66.7-96.2%, 28.9-46.9% and 86.9-107.8% for pig feed, pig litter, soil and lake water, respectively.     

毛细管电泳-电感耦合等离子体质谱联用测定海藻中铅形态化合物

建立了毛细管电泳( CE)与电感耦合等离子体质谱( ICP-MS)联用技术测定铅离子( PbⅡ)、三甲基铅(TML)和三乙基铅(TEL)3种不同形态铅化合物的方法,以及海藻中不同形态铅化合物的提取技术,实现了海藻中3种铅形态化合物的定性定量分析。结果表明：以70 mmol/L H3BO3-17.5 mmol/L Na2B4O7(pH 8.90)为缓冲溶液,在最佳CE-ICP-MS条件下3种铅化合物20 min内可实现有效分离,重现性较好,迁移时间RSD﹤4%,峰面积的RSD﹤5%;在10~200μg/L 范围内3种铅化合物线性较好,相关系数大于0.90; PbⅡ、TML和TEL的CE-ICP-MS检出限(3S/N,以Pb计)分别为0.091,0.023和0.030μg/L;采用分步提取海藻中Pb元素,提取率高达80%以上,以藻体为基底 PbⅡ, TML 和 TEL 回收率分别为103.6%,95.7%和90.6%;通过检测紫菜和海带中铅含量,结果显示藻体内Pb主要以PbⅡ形式存在。本方法具有简单、高效、样品消耗量少等优点,可为海藻及其它海产品的质量控制提供技术支撑。     

Capabilities of microbore columns coupled to inductively coupled plasma mass spectrometry in speciation of arsenic and selenium

The performance of microHPLC-microconcentric nebulizer-inductively coupled plasma-mass spectrometry (ICP-MS) coupling for the simultaneous determination of As(III), As(V), monomethylarsenic acid (MMA), dimethylarsinic acid (DMA), selenite (SeIV) and selenate (SeVI) in water was evaluated. The accurate reduction of the off-column dead volume, specially the capillary of the micronebulizer, as well as the optimization of chromatographic conditions led to the claimed advantages expected for microbore columns: a significant diminution of sample and solvent consumption without sacrificing sensitivity and the overall resolution in faster analysis time (less than 5 min). Detection limits are in the range 0.03-0.04 microg L(-1) for arsenic species and 0.35 microg L(-1) for selenium species. The developed method was validated by analysing different spiked environmental water samples. Linearity, tested up to 50 microg L(-1), showed correlation coefficients above 0.999 and no matrix effect for high saline water samples. Good accuracy and repeatability was obtained for spiked influent and effluent water treatment plant.     

Optimization of HPLC-ICP-AES for the determination of arsenic species

High performance liquid chromatography coupled to ICP-AES detection provides a rapid, reliable and sensitive method for arsenic speciation. The separation of As(III), As(V), DMA and MMA was achieved with ion exchange chromatography coupled to an axially-viewed sequential ICP-AES. After optimization of the chromatographic parameters (pH and concentration of the mobile phase), a careful study of the interface was conducted. Five nebulizers associated to three spray chambers were tested. Response of the ICP to each arsenic species was strongly affected by the selection of the nebulizer and spray chamber, however similar responses were obtained for each arsenic species. Best signal-to-noise ratios were obtained by using a microconcentric nebulizer and a cyclone spray chamber and did not affect the chromatographic resolution. Detection limits better than 10 microg L(-1) were obtained for As(III), DMA, MMA and 20 microg L(-1) for As(V), which is a significant improvement over previously published results.     

Negative ion chemical ionization GC/MS-MS analysis of dialkylphosphate metabolites of organophosphate pesticides in urine of non-occupationally exposed subjects

Low level exposure to organophosphate (OP) pesticides can be determined by the measurement of dialkylphosphate (DAP) metabolites in urine. An analytical method is presented here which can measure the metabolites dimethyl phosphate (DMP), diethyl phosphate (DEP), dimethyl thiophosphate (DMTP), dimethyl dithiophosphate (DMDTP), diethyl thiophosphate (DETP), and diethyl dithiophosphate (DEDTP) at low levels. This was achieved by lyophilization of the urine, derivatization with pentafluorobenzyl bromide (PFBBr) and quantification by negative ion chemical ionization GC/MS-MS. The detection limits for the metabolites were 0.5 microg L(-1) DMP, 0.1 microg L(-1) DEP, 0.1 microg L(-1) DMTP, 0.04 microg L(-1) DMDTP, 0.04 microg L(-1) DETP and 0.02 microg L(-1) DEDTP. The RSD for the analytical method was 4-14% for the six metabolites. The method was used to monitor a group of non-occupationally exposed individuals in Sydney, Australia. The metabolites DMP, DEP, DMTP, DMDTP, DETP and DEDTP occurred in 73, 77, 96, 48, 100 and 2% of the samples with median values of 13, 3, 12, <1, 1 and 1 microg L(-1) respectively. The method is simple to use, sensitive and suitable for routine analysis of non-occupational exposure levels. These detection limits are between one and two orders of magnitude lower than those previously reported in the literature.     

高效液相色谱-串联质谱法测定葡萄中的吡效隆和赤霉素

采用高效液相色谱-串联质谱法（HPLC-MS/MS）建立了葡萄果实中吡效隆（CPPU）和赤霉素（GA3）两种植物生长调节剂残留量的定性定量分析方法。样品用0.5%甲酸水溶液和乙腈（体积比4:1）混合溶剂提取,经Strata-X固相萃取净化,使用Agilent SB-C18 色谱柱（50mm×2.1mm,1.8μm）,以0.5%甲酸水溶液-乙腈为流动相,流量0.3mL/min,采用电喷雾离子化源（ESI）多反应监测（MRM）模式下HPLC-MS/MS检测。在最佳检测条件下,得到吡效隆和赤霉素在2.0～100.0μg/L检测范围内线性关系良好,相关系数大于0.999;检出限(LOD)分别为0.3μg/L、0.5μg/L,定量限(LOQ)分别为1.0μg/L、2.0μg/L,回收率和精密度均能达到要求,表明该法准确,可用于葡萄中吡效隆和赤霉素残留量测定。     

Determination of phosphate in seawater by CZE with on-line transient ITP

We developed CZE with indirect UV detection for the determination of phosphate in seawater using transient ITP as an on-line concentration procedure. The following optimum conditions were established: BGE, 5 mM 2,6-pyridinedicarboxylic acid (PDC) containing 0.01% hydroxypropylmethylcellulose (HPMC) adjusted to pH 3.5; detection wavelength, 200 nm; vacuum injection period of sample, 3 s (45 nL); terminating ion solution, 500 mM MES adjusted to pH 4.0; vacuum injection period of the terminating ion solution, 30 s (450 nL); applied voltage, 30 kV with the sample inlet side as the cathode. The LOD for phosphate was 16 microg/L (PO(3-)(4) -P) at S/N of 3. The respective values of the RSD of the peak area, peak height, and migration time for phosphate were 2.6, 2.3, and 0.34%. The proposed method was applied to the determination of phosphate in a seawater certified reference material for nutrients, MOOS-1, distributed by the National Research Council of Canada (NRC). The results were very similar to certified values. The method was also applied to the determination of phosphate in coastal seawaters. The results agreed with those obtained using a conventional spectrophotometric method.     

裂解气中NO,AsH_3,COS等杂质的色/质联用测定研究

 以气相色谱 /质谱 (GC/MS)的选择离子监测 (SIM )测定方式对裂解气中的一氧化氮、砷化氢、羰基硫、硫醚、硫醇等杂质进行了测定。针对一氧化碳、二氧化碳、乙烷、乙烯及氮气对一氧化氮测定的干扰 ,分别采取色谱分离和扣除响应的方法对其予以排除。考察了裂解工艺气物流对所选择离子的测定的干扰情况。对实际工艺气中的上述杂质进行了测定 ,结果一氧化氮的检出限为 10 0nL/L。