Organic acids and inorganic anions in Bayer liquors by ion chromatography after solid-phase extraction

A method for the simultaneous separation and determination of organic acids and inorganic anions in Bayer liquors was developed by gradient ion chromatography with suppressed conductivity detection. Formate, acetate, propionate, oxalate, succinate, glutarate, fluoride, chloride and sulfate were separated and determined in 33 min. The samples were pretreated with solid-phase extraction, which has high selectivity for removing a large number of metallic ions in the Bayer liquors, and filtered with a 0.45 μm filter membrane before being injected into the ion chromatographic system. The separation of six organic acids and three inorganic anions was achieved on an IonPac AS11-HC column with KOH as the eluent, and the detection was performed by a conductivity detection mode. No interference is found in the presence of fluorate, chlorate and sulphate when organic acids are determined. The calibration graphs of peak area for all the analytes are linear over a wide range. The relative standard derivation of the peak area of analytes is less than 2.14%. Under optimum conditions the detection ranges from 0.2 to 100.0 mg/L. The average recoveries of the added standards are between 94.3% and 102.8%.

Determination of inorganic anions in ethyl acetate by in-line hollow fiber membrane extraction with ion chromatography

In this work, a novel hollow fiber membrane extractor was set up to extract inorganic anions from ethyl acetate using deionized water. Inorganic anions in slightly soluble organic solvents can be determined by the in-line hollow fiber membrane extractor coupled with ion chromatography at first time. Different aspects of the extraction procedure such as magnetic stirring speed, extraction flow rate and extraction time were optimized to achieve high extraction efficiency and good separation results. Satisfactory linear range, limits of detection and good repeatability were obtained. The procedure was applied to analyze inorganic anions in two commercial ethyl acetate samples.

Determination of Inorganic Anions and Melamine in Fertilizers by Ion Chromatography

A chromatographic analysis method for determining inorganic anions and melamine in fertilizers was established using ion chromatography(IC).The fertilizer samples were extracted by ultrasonic method with 7 g/L trichloroacetic acid solution and centrifuged.The supernatant is purified by a solid phase extraction column.Then,the anions in the solution were purified using SH-AP-1(250 mm×4.0 mm)as a separation column,and measured by a suppressed conductivity detector;the melamine in the solution was separated using SH-CC-4(200 mm×4.0 mm)as a separation column and detected by a UV detector.The results show that the mass concentration of anions had a linear relationship with its peak area within a certain range,the linear correlation coefficient r of the standard curve was greater than 0.999,the recovery rate of spiked samples was 93.4%-104.4%,and the relative standard deviation(RSD)of the measured value(n=6)was less than 4%.Thus,this method is widely suitable for detection of anions and cations in a variety of fertilizer samples.

Separation of Inorganic Anions Using Methacrylate-Based Monolithic Column Modified with Trimethylamine in Ion Chromatography Capillary System

Methacrylate-based monolithic column was prepared in fused-silica capillary (80 ′ 0.32 mm i.d.) by in situ polymerizetion reaction using glycidyl methacrylate as monomer;ethylene dimethacrylate as crosslinker;1-propanol, 1,4-butanediol, and water as porogenic solvents. The monolith matrix was modified with trimethylamine to create strong anion exchanger via ring opening reaction of epoxy groups. The morphology of the monolithic column was studied by using Scanning Electron Microscope (SEM). This column had good mechanical stability and permeability. The effects of various mobile phases for separation of inorganic anions were investigated. Iodate, bromate, nitrite, bromide, and nitrate were separated within 11 min using100 mMpotassium chloride as mobile phase and detected at 210 nm. This method showed good precision of retention time, acceptable linearity and good sensitivity. Under the optimum condition, the RSD of the retention time was in the range of 1.09%-1.75% (n = 6). The calibration curve showed linear relationships between the peak area and the concentration. The limits of detection (LOD) and the limits of quantitation (LOQ) were between 0.08-0.18 mM and 0.26-0.61 mM, respectively. This method was applied to the determination of inorganic anions in tap water and ground water samples.

Effect of Methanol in the Wash-Solvent Bottle and the OnGuard Cartridges on the Determination of Different Anions Using Ion Chromatography

The effect of using methanol in the flush-solvent bottle of the auto-sampler of Ion Chromatograph on the determination of sulfate ions was studied using AS11-HC 2 mm analytical column. The use of 50% methanol in the flush solvent bottle results in overestimation of sulfate concentration by 18%. However, the use of 10% methanol instead of 50% did not show such error in the determination of sulfate using the same column. Furthermore, the effect of using OnGuard-RP and OnGuard-P cartridges for sample pretreatment on the determination of different anions was also studies using AS14-HC 2 mm analytical column. The results indicate that using OnGuard-RP cartridge caused the concentration of fluoride, bromide, nitrate, phosphate and sulfate ions to be underestimated, whereas the concentration of chloride ions to be overestimated. The error in the determination of fluoride, bromide, nitrate, phosphate sulfate, and chloride was found to be 40.0%, 26.0%, 22.8%, 26.8%, 18.0%, and 25.0% of the certified standard concentration, respectively. It was also found that the use of OnGuard-P cartridge resulted in underestimation of fluoride, chloride, bromide, nitrate, phosphate, and sulfate by 60.0%, 40.0%, 82.0%, 87.2%, 45.2%, and 39.0% of the certified standard concentration, respectively. These findings point out to careful corrections that should be considered in any application of ion chromatography utilizing such sample pretreatment.

Science Letters:Simultaneous determination of fluoride, chloride, sulfate, phosphate, monofluorophosphate, glycerophosphate, sorbate, and saccharin in gargles by ion chromatography

Simple, reliable and sensitive analytical methods to determine anticariogenic agents, preservatives, and artificial sweeteners contained in commercial gargles are necessary for evaluating their effectiveness, safety, and quality. An ion chroma-tography (IC) method has been described to analyze simultaneously eight anions including fluoride, chloride, sulfate, phosphate, monofluorophosphate, glycerophosphate (anticariogenic agents), sorbate (a preservative), and saccharin (an artificial sweetener) in gargles. In this IC system, we applied a mobile phased gradient elution with KOH, separation by IonPac AS18 columns, and suppressed conductivity detection. Optimized analytical conditions were further evaluated for accuracy. The relative standard deviations (RSDs) of the inter-day's retention time and peak area of all species were less than 0.938% and 8.731%, respectively, while RSDs of 5-day retention time and peak area were less than 1.265% and 8.934%, respectively. The correlation coefficients for targeted analytes ranged from 0.999 7 to 1.000 0. The spiked recoveries for the anions were 90%~102.5%. We concluded that the method can be applied for comprehensive evaluation of commercial gargles.

Analysis of trace elements in air particulate matters by non-suppressed ion chromatography

The application of non-suppressed ion chromatography for monitoring of trace elements in air particulate matter was studied in the present investigation. The results indicate that the use of microwave acid digestion method is superior in comparison with the conventional thermal acid digestion method as it leads to higher recovery, better reproducibility, lower volatility loss, better protection against environmental contamination and much less digestion time (5 minutes vs. 24 hours). The use of eluent as extractant is shown to reduce the water dip problem in the chro-matogram. The addition of chelating agent in the eluent coupled with UV detection is shown to provide satisfactory chromatographic separation and good sensitivity for the analysis of transition metals present in the air particulate matter. Using the U.S. National Bureau of Standards Reference Material 1648 Urban Particulate Matter as standard for checking, the analytical procedure is shown to give good recovery and reproducibility for the detection of the following cations and anions in air particulate matter: Fe2 Cu, Mn, Pb, Zn, Mg, Na, HN4+, Cl-, NO3- and SO42-. Field test was also performed to check the applicability of the method and the results obtained were discussed in the present paper.

Trace analysis of anions in organic matrices by ion chromatography coupled with a novel reversed-phase column for on-line sample pretreatment

An ion chromatography（IC） system coupled with on-line column-switching technique was used to determine anions ofμg/g levels in organic chemicals of analytical reagent grade.A novel polystyrene-divinylbenzene-carbon nanotube（PS-DVB-CNT） stationary phase was utilized for matrix elimination.A calibration study was conducted by preparing and analyzing eight concentrations（between 10 and 5000μg/L） of eight standards in deionized water.The linearity was between 0.9978 and 1.And the detection limits ranged from 1.54μg/L to 10.02μg/L.A spiking study was performed on two representative organic chemicals.The recoveries were between 84.3%and 119.6%.

Trace Analysis of Anions in Perfluorodecalin by Green Liquid-Liquid Extraction Combined with Ion Chromatography

Perfluoronaphthenes,with inert chemical and biological properties and ability to dissolve large amounts of oxygen,have received the most attention in medical applications.However,the excessive anion contained may cause some side effects.Herein,liquid-liquid extraction technique with shaking and ultrasonic extraction was used for the trace analysis of five anions(F^(-),Cl^(-),NO_(3)^(-),PO_(4)^(3-),SO_(4)^(2-))in perfluorodecalin using water as green extractant.The optimum pretreatment technology and ion chromatography detection conditions were established.Good linearity was observed in each concentration range,and the linear correlation coefficient(R^(2))was better than 0.997.The limits of detection(S/N=3)of five anions from perfluorodecalin were 3.2,5.5,14.2,23.2 and 29.5μg/L,respectively.The established method with high sensitivity and accuracy has been successfully appliedfor the determination of five anions in three perfluorodecalin products,which provides a basis for further development of green detection and quality standard formulation in perfluorodecalin and other fluorocarbon solvents.

Determination of common anions in oxalate by ion chromatography coupled with UV photolysis pretreatment

A new and simple method was developed to determine anions in oxalate of analytical reagent grade. After UV photolysis with optimal 1% H2O2 in 10,000 mg/L oxalate in the fabricated photoreactor, sample was directly injected into IC system. Satisfactory linearity, detections limits, good repeatability and spiked recovery were obtained. The method was successfully applied to determine anions in two commercial oxalate samples.

双通道离子色谱法测定陶质文物表面结晶盐中有机酸根和无机阴阳离子

对双通道离子色谱同时测定陶质文物表面结晶盐中的CH_(3)COO^(-)、HCOO^(-)、F^(-)、Cl^(-)、SO_(4)^(2-)、NO_(3)^(-)等9种阴离子和Li^(+)、Na^(+)、K^(+)等6种阳离子的测定方法进行优选。通过优化色谱条件,确定采用Metrosep A Supp7色谱柱为阴离子分析柱,3 mmol/L碳酸钠为阴离子淋洗液,流速为0.7 mL/min;Metrosep C4型色谱柱为阳离子分析柱,0.8 mmol/L吡啶二羧酸-1.6 mmol/L硝酸为阳离子淋洗液,流速为0.7 mL/min。在此方法下,净化后的滤液一次进样,电导检测器检测,各离子峰形好,分离时间适中,分离效果很好。各离子的标准曲线相关系数R>0.999,具有良好的线性关系,检出限在0.005~0.05 mg/L之间,加标回收率在96%~106%之间,相对标准偏差为0.1%~4%(n=5)。结果表明,瓦当表面结晶盐中主要含有Ca^(2+)、Na^(+)、CH_(3)COO^(-)、Cl^(-)、SO_(4)^(2-)、NO_(3)^(-)。该方法简单快速、准确度高,可有效分离文物表面结晶盐中的常见有机酸根离子和无机阴阳离子。

气相色谱-离子迁移谱技术在茶叶领域应用的研究进展

茶叶是中国传统农业中重要的经济作物,具有悠久的历史和丰富的文化内涵,其在产地、贮藏时间、加工方式等方面的不同,决定了茶叶的品质、营养价值和市场定位。挥发性有机化合物(VOCs)是表征不同茶叶间差异性的重要指标。气相色谱-离子迁移谱(GC-IMS)技术作为一种新发展起来的无损检测技术,可在常压条件下实现对样品中VOCs的分析,用于表征样品间的差异。搜集了目前已有的文献资料,综述了GC-IMS技术在茶叶种类区分、等级鉴定、产地溯源、贮藏时间判定、加工过程中品质控制等方面的研究现状,分析存在的问题,并对GC-IMS技术在茶叶领域的应用前景进行了展望,以期为茶叶的风味研究、加工工艺优化、品质分析和质量监测提供参考。

冷凝收集-离子色谱法测定呼出气中的有机酸和阴离子

建立了一种非侵入式冷凝收集-离子色谱方法测定人体呼出气中乳酸、甲酸、乙酸、丙酮酸、Cl^(-)、NO_(2)^(-)、NO_(3)^(-)、SO_(4)^(2-)。搭建自制呼出气冷凝装置,该装置包括吹气口、与吹气口相连的单向阀和流量计、置于半导体冷凝装置中的冷阱以及一次性冷凝收集管。通过呼出气冷凝装置对人体呼出气进行收集,利用离子色谱对冷凝液(EBC)中有机酸和阴离子的含量进行检测。优化采集冷阱温度和采集流量,得到冷阱最佳冷凝温度为-15℃,呼气流量为15 L/min。采用1.5 mmol/L碳酸钠和3 mmol/L碳酸氢钠混合溶液作为流动相,泵流速为0.8 mL/min,分析柱为IC-SA3(250 mm×4.0 mm),柱温为45℃。8种有机酸和阴离子的线性范围均为0.1~10.0 mg/L,相关系数均≥0.9993。在进样量为100μL时,方法的检出限为0.0017~0.0150 mg/L(S/N=3),定量限为0.0057~0.0500 mg/L(S/N=10)。方法的日内和日间精密度均≤7.50%(n=5)。采用该方法对5位健康受试者呼出气中的有机酸和阴离子进行检测,得到8种有机酸和阴离子的含量为0.18~42.3 ng/L。在10 km的长跑运动过程中,除了一位受试者代谢异常,其余受试者呼出气中的有机酸和阴离子含量总体变化趋势为先增加后减小。本方法采样过程简单,精密度好,且没有副作用,受试者不会产生任何明显不适或风险,可为日后人体代谢物的研究提供实验思路和理论依据。

离子交换色谱-串联质谱法快速测定茶叶中氯酸盐和高氯酸盐

目前,氯酸盐和高氯酸盐作为新型持久性环境污染物受到了广泛关注。茶树在我国有大面积种植,而在受高氯酸盐污染的土壤中,其含有的氯酸盐和高氯酸盐可在茶树中富集,鉴于氯酸盐和高氯酸盐对人体具有的潜在健康风险,因此亟需建立一种茶叶中氯酸盐和高氯酸盐残留量的快速检测方法。本文建立了茶叶中氯酸盐和高氯酸盐残留量的离子交换色谱-串联质谱检测方法。本研究优选Oasis PRiME HLB SPE柱对样品提取液进行净化,使用AceChrom Hybri-A(150 mm×21 mm,50μm)作为离子交换色谱柱,以100 mmol/L乙酸铵-乙腈(40∶60,v/v)作为流动相,在电喷雾负离子和MRM模式下,对目标物实现快速、准确的定性分析,并采用内标法定量。研究结果表明:当氯酸盐与高氯酸盐分别在200~200μg/L和100~100μg/L范围内时,方法的线性关系良好(r2>09990);在低、中、高3个加标水平下,氯酸盐和高氯酸盐平均回收率为8854%~9725%,方法的检出限分别为120μg/kg和80μg/kg,方法的定量限分别为400μg/kg和266μg/kg。该方法简单、快速、灵敏、准确,能够满足大批量茶叶样品中氯酸盐和高氯酸盐的快速筛查与定量分析。

离子色谱法测定玉溪北城“涩水”中4种无机阴离子

为了研究玉溪市北城“涩水”中无机阴离子的含量是否符合《生活饮用水卫生标准》中的限值,采用离子色谱法测定了玉溪北城“涩水”中F^(-)、Cl^(-)、NO_(3)^(-)、SO_(4)^(2-)的含量。结果表明,玉溪北城“涩水”中1月、2月、3月和4月的F^(-)、Cl^(-)、NO_(3)^(-)、SO_(4)^(2-)四种无机阴离子含量低于《生活饮用水卫生标准》中的限值。该方法标准曲线相关系数在0.9990以上,样品加标回收率在93.73%~109.20%之间,检出的数据准确可靠。结果为进一步探究“涩水”的水源保护和商用价值开发提供了数据支撑。

超高效液相色谱-四极杆-飞行时间质谱法鉴定黄大茶化学成分

黄大茶是中国特有的茶叶品种,具有降脂、降糖、改善代谢综合征的保健功效,但由于缺乏对黄大茶化学成分的研究,其功效性物质基础尚未被完全揭示。本研究以超高效液相色谱-四极杆-飞行时间质谱(UPLC-Q TOF/MS)作为检测工具,结合中性丢失和特征碎片离子等信息,对黄大茶的主要化学成分进行筛查和分析。选取Waters ACQUITY UPLC BEH C18色谱柱(100 mm×21 mm,17μm)进行分离,以01%甲酸水和乙腈作为流动相进行梯度洗脱,流速02 mL/min,进样量2μL,柱温35℃。在电喷雾电离(ESI)正/负离子模式下,利用全信息串联质谱(MSE)技术采集黄大茶样品溶液的质谱信息。通过查阅文献构建茶叶化学成分数据库,主要包括化学名称、分子式、结构式、准分子离子、碎片离子等信息,对自建数据库中的化学成分按照骨架结构进行归类;基于UPLC-Q TOF/MS测定结果,利用对照品对主要类别化合物的质谱裂解规律进行梳理,并总结其特征碎片离子和中性丢失特征;结合化合物的保留时间、准分子离子、碎片离子等信息对化合物结构进行表征。本研究共从黄大茶中鉴定出87个化学成分,包括10个儿茶素类、32个黄酮类、16个酚酸类、12个鞣质类、6个茶黄素类以及11个其他类别化合物,其中14个成分经对照品予以验证。该方法能够全面阐明黄大茶的主要化学成分,为黄大茶功效性成分发现、品质评价提供科学依据和数据支撑。

基于GC-IMS技术的不同产地青钱柳茶挥发性成分表征及分析

目的:研究不同产地青钱柳茶挥发性气味物质差异。方法:以湖南常德、湖南张家界、湖南邵阳、江西修水、贵州黔东南、湖北恩施的青钱柳茶为研究对象,采用气相色谱—离子迁移谱联用(GC-IMS)技术并结合偏最小二乘判别分析(PLS-DA),探讨不同产地青钱柳茶中特征差异挥发性物质及其相似度。结果:不同产地青钱柳茶共检测出120种挥发性有机物,包括部分物质的单体及其多聚体,分别为醛类34种、烯烃类21种、醇类19种、酮类16种、酯类10种、羧酸类8种、呋喃类5种、吡嗪类4种、醚类2种及苯系物1种。其中γ-松油烯、苯乙烯、4-甲基-1-戊醇、正辛醛为主要特征差异挥发性物质。结论:不同产地间青钱柳茶挥发性有机物质均存在一定差异(P<0.05),GC-IMS技术可有效实现青钱柳茶的产地鉴别和质量控制。

离子色谱法测定茶叶中9种有机酸和3种阴离子的含量及基于多元统计分析的不同品种茶叶的区分

取0.25 g茶叶样品,加入50 mL水,于35℃超声提取30 min,静置5 min,取上清液过0.22μm亲水性聚醚砜注射过滤器,滤液用离子色谱仪分析。以Dionex IonPac AS11-HC色谱柱作分析柱,氢氧化钾溶液梯度洗脱分离样品溶液中的9种有机酸和3种阴离子,抑制型电导检测器测定。以聚类分析法区分不同种类茶叶样品,主成分分析法确定影响茶叶种间差异的关键因子。结果显示,12种目标物的质量浓度均在一定范围内和峰面积呈线性关系,检出限(3S/N)为0.35~2.31 mg·kg^(-1);按照标准加入法进行回收试验,回收率为89.8%~109%,测定值的相对标准偏差(n=6)不大于6.0%。方法应用于31批不同品种茶叶样品的分析,富马酸、柠檬酸、乙酸和PO43-检出量较高;聚类分析将31批样品分为4类,其中红茶、普洱茶单独聚为一类;主成分分析提取出的对茶叶种间差异贡献度最大的是阴离子PO43-,有机酸苹果酸次之。

离子色谱法测定茶叶中多种有机酸和无机阴离子的研究

采用离子色谱分析方法同时测定了茶叶中奎尼酸、乳酸、乙酸、丙酮酸、酒石酸、草酸、富马酸、柠檬酸、水杨酸和F-、Cl^(-)、Br^(-)、NO_(2)^(-)、NO_(3)^(-)、SO_(4)^(2-)、PO_(4)^(3-)的含量。茶样经沸水浴浸提30 min后,采用Dionex IonPac TM AS11-HC分析柱和Dionex IonPac TM AG11-HC保护柱,柱温为30℃,采用KOH淋洗液梯度洗脱,流速为0.85 mL·min^(-1),抑制电流为116 mA,电导检测器检测,池温为35℃。离子色谱分析方法学考察结果表明,各有机酸和无机阴离子的线性相关系数均达到0.999以上,该方法的精密度、重复性、准确性良好,茶样提取液在24 h内稳定。结果表明,所测茶样中含量较高的有机酸主要有奎尼酸、草酸、酒石酸,含量较高的无机阴离子主要有PO43-、SO_(4)2-、Cl-,该研究可促进对茶叶产品的质量控制,为茶叶中有机酸组分检测方法标准和无机阴离子限量标准的制定提供参考。

离子色谱法测定种植土壤中8种水溶性阴离子

对土壤中水溶性阴离子进行测定,可监测土壤盐渍化的类型和程度,为改良、治理及科学施肥提供参考。土壤样品经风干研磨过0.15 mm筛,以去离子水萃取、0.22μm微孔滤膜过滤,用碳酸钠和碳酸氢钠溶液等度洗脱,离子色谱仪同时测定土壤萃取液中F^(-)、BrO_(3)^(-)、Cl^(-)、NO_(2)^(-)、Br^(-)、NO_(3)^(-)、PO_(4)^(3-)、SO_(4)^(2-)等8种水溶性阴离子含量。结果表明:8种阴离子在0.2~10.0 mg/L曲线线性关系良好,相关系数大于0.999;土壤样品阴离子检出限为0.6~7.0 mg/kg;进行3浓度水平加标实验,回收率为65.6%~120%,相对标准偏差为0~8.9%,表明方法具有较高的精密度和准确度。方法用于蔬菜种植基地、农田、绿化带土壤及养殖塘泥检测,结果显示,样品中检出F^(-)、Cl^(-)、NO_(2)^(-)、Br^(-)、NO_(3)^(-)、PO_(4)^(3-)和SO_(4)^(2-),浓度为5.0~1 090.6 mg/kg,均未检出BrO_(3)^(-)。各类型土壤阴离子浓度差异较大,蔬菜种植基地土壤中含有较高的Cl^(-)、NO_(3)^(-)或SO_(4)^(2-),可能与长期施用特定类型的化肥有关,农田土壤和塘泥长时间处于水中,水溶性阴离子已充分溶解,各阴离子含量较低;绿化带土壤未充分开垦,阴离子浓度接近于该类型土壤本底值。