Simultaneous determination of inorganic anions and cations in explosive residues by ion chromatography

A non-suppressed ion chromatographic method by connecting anion-exchange and cation-exchange columns directly was developed for the separation and determination of five inorganic anions (sulfate, nitrate, chloride, nitrite, and chlorate) and three cations (sodium, ammonium, and potassium) simultaneously in explosive residues. The mobile phase was composed of 3.5mM phthalic acid with 2% acetonitrile and water at flow rate of 0.2 mL/min. Under the optimal conditions, the eight inorganic ions were completely separated and detected simultaneously within 16 min. The limits of detection (S/N=3) of the anions and cations were in the range of 50-100 microg/L and 150-320 microg/L, respectively, the linear correlation coefficients were 0.9941-0.9996, and the R.S.D. of retention time and peak area were 0.10-0.29% and 5.65-8.12%, respectively. The method was applied successfully to the analysis of the explosive samples with satisfactory results.     

Simultaneous determination of mono-, di- and tributyltin in environmental samples using isotope dilution gas chromatography mass spectrometry

The development of a rapid, precise and accurate speciation method for the simultaneous determination of mono-, di- and tributyltin in environmental samples is described. The method is based on using isotope dilution gas chromatography/mass spectrometry (GC/MS) with electron ionization, a widely used technique in routine testing laboratories. A mixed spike containing (119)Sn-enriched monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT) was used for the isotope dilution of the samples. Five molecular ions were monitored for each analyte, corresponding to the (116)Sn, (117)Sn, (118)Sn, (119)Sn and (120)Sn isotopes. The detection at masses corresponding to (116)Sn and (117)Sn were used to correct for m + 1 and m + 2 contributions of (13)C from the organic groups attached to the tin atom on the (118)Sn, (119)Sn and (120)Sn masses with simple mathematical equations and the concentrations of the butyltin compounds were calculated based on the corrected (118)Sn/(119)Sn and (120)Sn/(119)Sn isotope ratios. The (119)Sn-enriched multispecies spike was applied with satisfactory results to the simultaneous determination of MBT, DBT and TBT in three certified reference materials: two sediments, PACS-2 and BCR 646, and the mussel tissue CRM 477. The method was compared with a previously published GC/inductively coupled plasma MS isotope dilution procedure, developed in our laboratory, by injecting the same samples into both instruments. Comparable analytical results in terms of precision and accuracy are demonstrated for both atomic and molecular mass spectrometric detectors. Thus, reliable quantitative organotin speciation analysis can be achieved using the more widespread and inexpensive GC/MS instrument.     

Simultaneous separation and detection of anions and cations in ion chromatography

An overview of new possibilities for the simultaneous determination of anions and cations by ion chromatography is presented. A short comparison of the characteristics of separation and detection methods for simultaneous anion–cation determinations of ions is given and applications are discussed.     

Simultaneous determination of monofluoroacetate, difluoroacetate and trifluoroacetate in environmental samples by ion chromatography

A method is reported for the sensitive, simultaneous determination of mono- (MFA), di- (DFA), and trifluoroacetates (TFA) by ion chromatography (IC). These species were separated using a Dionex AS17 anion-exchange column employed with a potassium hydroxide gradient (via a Dionex EG40 eluent generator) and suppressed conductivity detection. The fluoroacetates were successfully separated from a range of inorganic and organic species likely to be present in environmental samples, in a total analysis time of 35 min (including re-equilibration of the column). Detection limits for mono-, di- and trifluoroacetate were 21, 38 and 36 microg/l, respectively, determined using a signal-to-noise ratio of 3, and were obtained using a sample injection volume of 50 microl. Precision was less than 0.83% relative standard deviation (RSD) for replicate injections performed over a period of 30 days. The method was applied to the determination of monofluoroacetate in river water samples and also in carrot baits.     

Simultaneous determination of prochlorperazine and its metabolites in human plasma using isocratic liquid chromatography tandem mass spectrometry

Oral prochlorperazine (PCZ), an antiemetic, undergoes extensive first-pass metabolism. The study developed a simultaneous analytical method for PCZ and its major metabolites, prochlorperazine sulfoxide (PCZSO), N-demethylprochlorperazine (NDPCZ) and 7-hydroxyprochlorperazine (PCZOH), in human plasma using an isocratic liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Deproteinized plasma specimens were separated using a 3 μm particle size octadecylsilyl column, and the run time was 10 min. The calibration curves were linear over the concentration ranges of 0.01-40 μg/L for PCZ, NDPCZ and PCZOH, and 0.05-80 μg/L for PCZSO. The intra- and inter-assay precisions and accuracies were within 7.0 and 99-104% and within 9.0 and 99-105%, respectively. The lower limits of quantification in human plasma were 10 ng/L for PCZ, NDPCZ and PCZOH, and 50 ng/L for PCZSO. The validated method was applied to the determination of plasma samples in 37 cancer patients receiving PCZ. Large interindividual variations were observed in plasma concentrations of PCZ, PCZSO, NDPCZ and PCZOH (relative standard deviation, 89.4, 88.7, 86.4 and 78.2%, respectively). In conclusion, this simultaneous LC-MS/MS method with acceptable analytical performance can be helpful for evaluating the pharmacokinetics of PCZ, including the determination of its metabolites in cancer patients and in clinical research.     

Simultaneous determination of inorganic cations by capillary ion chromatography with a non-suppressed contactless conductivity detector

A non-suppressed capillary ion chromatographic method with a laboratory-made packed cation-exchange column (100 mm × 0.32 mm i.d.) was developed for the separation and simultaneous determination of five common inorganic cations (sodium, ammonium, potassium, magnesium and calcium). Cation exchangers were prepared by the reaction of the hydroxyl group on the surface of diol-group bonded silica gel with 1,3-propanesultone in methanol. Simultaneous separation of these five common inorganic cations were achieved within 17 min using 1 mM methanesulfonic acid and 0.1 mM 15-crown-5 ether in methanol-water (8:2, v/v) as the eluent. The effects of organic solvents and crown ethers in the eluent on the retention of analytes were investigated. The limits of detection (S/N = 3) of the cations were in the range of 18-124 μg/l, the linear correlation coefficients were 0.9991-0.9998, and the RSD values of retention time and peak height were all smaller than 2.1%. The present analytical method was successfully applied to the rapid and direct determination of inorganic cations in samples of river water and commercial drinks, with satisfactory results.     

Simultaneous determination of malondialdehyde and ofloxacin in plasma using an isocratic high-performance liquid chromatography/fluorescence detection system

This study establishes the applicability of using high-performance liquid chromatography (HPLC) with fluorescence detection for the simultaneous determination of malondialdehyde (MDA) and ofloxacin (OFL). The MDA and OFL were separated through a reverse-phase C18 column (250 mm × 4.6 mm) at a flow rate of 1.0 mL min⁻¹ and then detected using a fluorescence detector (excitation: 532 nm; emission: 553 nm). The separation conditions were optimized by varying the concentration and pH of the phosphate buffer and the percentage of organic solvent; the optimal mobile phase was a mixture of 50 mM phosphate buffer (adjusted to pH 5.8 with potassium hydroxide) and methanol (45:55, v/v). The retention times of MDA and OFL were 3.6 and 5.9 min, respectively, with detection limits (at a signal-to-noise ratio of 3) of 0.015 and 4.0 μM, respectively. This method afforded linear responses between the MDA and OFL concentrations and the HPLC peak areas within the ranges 0.15-2.43 μM and 0.06-1.0 mM, respectively. The precisions of the determinations of MDA and OFL, measured in terms of relative standard deviations, were 1.6-5.0% and 1.9-3.6%, respectively, for intra-day assays and 1.0-4.3% and 0.3-1.8%, respectively, for inter-day assays. The average recoveries of MDA and OFL spiked in plasma were 100.4% and 98.8%, respectively. To the best of our knowledge, this paper describes the first practical analytical approach toward simultaneously monitoring the levels of MDA and OFL in plasma. The OFL-induced oxidative stress measured using this method indicated that OFL treatment did not markedly increase the level of MDA.     

Simultaneous isocratic separation of phenolic acids and flavonoids using micellar liquid chromatography

The simultaneous isocratic separation of a mixture of five phenolic acids and four flavonoids (two important groups of natural polyphenolic compounds with very different polarities) was investigated in three different RPLC modes using a hydro‐organic mobile phase, and mobile phases containing SDS at concentrations below and above the critical micellar concentration (submicellar LC and micellar LC (MLC), respectively). In the hydro‐organic mode, methanol and acetonitrile; in the submicellar mode methanol; and in the micellar mode, methanol and 1‐propanol were examined individually as organic modifiers. Regarding the other modes, MLC provided more appropriate resolutions and analysis time and was preferred for the separation of the selected compounds. Optimization of separation in MLC was performed using an interpretative approach for each alcohol. In this way, the retention of phenolic acids and flavonoids were modeled using the retention factors obtained from five different mobile phases, then the Pareto optimality method was applied to find the best compatibility between analysis time and quality of separation. The results of this study showed some promising advantages of MLC for the simultaneous separation of phenolic acids and flavonoids, including low consumption of organic solvent, good resolution, short analysis time, and no requirement of gradient elution.     

Simultaneous determination of nine trace mono- and di-chlorophenols in water by ion chromatography atmospheric pressure chemical ionization mass spectrometry

A novel analytical method was proposed for the rapidly simultaneous determination of nine mono-chlorophenols (MCPs) and di-chlorophenols (DCPs) in water samples using eluent generator ion chromatography (IC) coupled with an atmospheric pressure chemical ionization mass spectrometry (APCI-MS) in the negative mode. The IC separation was carried out on an IonPac^® AS11 analytical column (250 mm × 4.0 mm) using gradient KOH containing 15% acetonitrile as organic modifier at a constant flow rate of 1.0 mL/min. The molecular ions m/z [M − H]⁻ 127 and 161 were selected for the quantification in selected ion monitoring (SIM) mode for MCPs and DCPs, respectively. The average recoveries were between 80.6% and 92.6%. Within-day and day-to-day relative standard deviations were less than 12.1% and 13.3%, respectively. The method allowed the nine objective compounds in water samples to be determined at μg/L levels. It was confirmed that this method could be used in routine analysis.     

Extraction and determination of pyridinium ionic liquid cations in environmental water samples by using strong cation exchange solid phase extraction and ion chromatography

This paper presents a novel analytical method for the determination of pyridinium ionic liquid cations in environmental water samples by ion chromatography coupled with solid phase extraction. The water samples were purified and enriched by a sulphonic acid extraction column, and then the impurities were washed with 10 mL water – 20% (v/v) acetonitrile solution and the analytes eluted with 0.5 mol L^?1 phosphoric acid – sodium dihydrogen phosphate buffer solution – 55% methanol. The eluted analytes were determined by ion chromatography with 3.0 mmol L^?1 methane sulphonic acid – 8% acetonitrile as the mobile phase and direct conductivity detection. Three pyridinium cations were completely separated in 20 min and the retention mechanism basically conforms to the ion exchange mode. The newly developed method has been successfully applied to the analysis of pyridinium cations in spiked environmental water samples, which provided satisfactory recoveries in the range of 98.8% to 100.0% with the relative standard deviations less than 2.8%. The concentration of 0.004 to 0.01 mg L^?1 in water samples can be preconcentrated by this method. The method is accurate, reliable, simple and practical. This research provides a new reference for detecting ionic liquid cations in environmental water samples and studying the environmental risk assessment of ionic liquids.     

离子色谱法同时测定高纯试剂中痕量甲胺、二甲胺、三甲胺和6种阳离子

建立离子色谱法同时测定高纯试剂和有机溶剂中甲胺、二甲胺、三甲胺和6种阳离子的方法.对样品处理、色谱柱类型、淋洗液梯度等条件进行优化,实现了过氧化氢、乙醇、丙酮和异丙醇样品的直接进样分析.选用Metrosep C Supp 1阳离子交换柱进行梯度分离,采用微填充床阳离子抑制电导检测器检测.9种待测物质的质量浓度在5～20...     

混合模式色谱柱离子色谱法同时测定奶粉中的碘离子和硫氰酸根

碘离子和硫氰酸根的含量是奶粉质量检测的重要项目,但由于奶粉基体复杂,色谱分析中容易产生干扰。本文使用一种带有疏水性烷基链和弱阴离子交换官能团的混合分离模式色谱柱Acclaim Mixed-Mode WAX-1,成功实现了碘离子、硫氰酸根与样品中干扰峰的基线分离,并用紫外检测器进行了检测。实验中将奶粉样品溶于水后,用乙腈沉淀蛋白,并通过OnGuard RP前处理柱除去对色谱柱有污染的有机物质。所用淋洗液为乙腈-100 mmol/L磷酸盐缓冲液(pH 6)-水（体积比为45:5:50）,紫外检测波长为226 nm。该方法对碘离子和硫氰酸根的检出限分别为4.6 μg/L和13.8 μg/L,0.2 mg/L标准溶液峰面积的相对标准偏差分别为1.2%(n=6)和1.7%(n=6)。该分析方法准确可靠,线性范围宽,检出限较低,为乳制品质量检测提供了可行方法。     

Simultaneous determination of retinol, alpha-tocopherol and beta-carotene in serum by isocratic high-performance liquid chromatography.

A simultaneous determination of retinol, alpha-tocopherol and beta-carotene in serum by high-performance liquid chromatography is described. Total analysis time is 13 min. A reversed-phase (Ultrasphere ODS, 5 microns) column is used with a mobile phase of acetonitrile-methanol-dichloromethane (70:10:20, v/v/v) and a flow-rate of 1.2 ml/min. Retinol is monitored at 325 nm, alpha-tocopherol at 292 nm and beta-carotene at 450 nm. Serum is deproteinized with ethanol containing the internal standard (alpha-tocopherol acetate), then extracted with hexane. The evaporated organic layer is reconstituted with the mobile phase and injected. The choice of the eluent is discussed, as well as the choice of an internal standard and the need for an antioxidant during the extraction step. Sixteen different eluents are compared in terms of analysis time and selectivity. The linear concentration ranges (retinol 0.016-13.7 microM, alpha-tocopherol 0.18-91.8 microM, beta-carotene 0.05-5.75 microM), within-run coefficients of variation (retinol less than 7%; alpha-tocopherol less than 8%, beta-carotene less than 7%), between-run coefficients of variation (retinol less than 13%, alpha-tocopherol less than 9%, beta-carotene less than 8%) and recoveries (retinol greater than 95%, alpha-tocopherol greater than 91%, beta-carotene greater than 80%) are suitable for clinical investigations. Serum reference values were found to be 2.47 +/- 0.61 microM (retinol), 30.5 +/- 6.8 microM (alpha-tocopherol) and 0.91 +/- 0.55 microM (beta-carotene). A significant difference (p less than 0.001) between males and females was found for retinol.     

Simultaneous separation of inorganic anions and cations by using anion-exchange and cation-exchange columns connected in tandem in ion chromatography

Inorganic anions and cations in environmental waters were determined by ion chromatography. Stationary and mobile phases were examined for the simultaneous separation of both anions and cations. Cations detection by UV detection requires a mobile phase with a UV absorbing additive, which indirectly visualizes cations as negative peaks. Simultaneous separation of anions and cations were achieved when using an eluent that consists of inorganic acid with weak basic amino acid as additives. It was convenient to separate both anions and cations by coupling anion-exchange and cation-exchange columns in tandem. The order of the separation columns connected affected the elution profiles. When the eluent comprises of multiple anions and a single cation, the anion-exchange column should be connected in the upper stream, whereas when the eluent comprises multiple cations and a single anion, the cation-exchange column should be connected in the upper stream. Use of switching valves also allowed simultaneous separation of anions and cations in a single chromatographic run. In the present work, operating conditions were optimized for the simultaneous separation of anions and cations.     

Simultaneous determination of silicate and phosphate in environmental waters using pre-column derivatization ion-pair liquid chromatography

A highly sensitive HPLC method for the simultaneous determination of soluble silicate and phosphate in environmental waters was developed, using ion-pair liquid chromatography preceded by the formation of their yellow α-heteropolymolybdates. The moderate-pH mobile phase enabled to use a highly efficient reversed-phase silica column. The pre-column coloring reactions at moderate-pH were reproducible for both silicate and phosphate in all quantification ranges with R.S.D.s less than 2% and 5%, respectively. The linear calibration lines between concentrations (mg-SiO₂/L and mg-PO₄/L) and peak area intensities were obtained for silicate and phosphate both with acceptable determination coefficients (r²) of 0.9999. The limits of determination for both analytes were 0.007 mg-SiO₂/L and 0.003 mg-PO₄/L, which were calculated theoretically using 10σ/slope. The four-digit dynamic ranges were obtained for 0.007-10 mg-SiO₂/L and 0.003-20 mg-PO₄/L. The developed method was applied for the analysis of tap water, river water, coastal seawater, well water, hot-spring water, commercial mineral water, and laboratory water. The results were very reasonable and acceptable from the environmental viewpoints, which were well correlated with those confirmed by the molybdenum-blue spectrophotometry.     

离子色谱法同时测定大气降水中7种阴离子

建立离子色谱法同时测定大气降水中F^-,Cl^-,NO2^-,Br-,NO3^-,SO4^2-和PO43^-7种阴离子的分析方法。选用IonPac■AS19型色谱柱(4 mm×250 mm),以KOH梯度淋洗,用抑制电导检测器进行测定。7种阴离子在各自的质量浓度范围内与色谱峰面积成良好的线性关系,相关系数均不小于0.997,方法检出限为0.002~0.004 mg/L。测定结果的相对标准偏差为0.80%~3.38%(n=6),样品加标回收率为75.0%~98.7%。该方法简便、快速,灵敏度高,适用于大气降水中F^-,Cl^-,NO2^-,Br^-,NO3^-,SO4^2-和PO43^-7种阴离子的同时测定。     

Simultaneous determination of cations, zwitterions and neutral compounds using mixed-mode reversed-phase and cation-exchange high-performance liquid chromatography

A novel mixed-mode reversed-phase and cation-exchange high-performance liquid chromatography (HPLC) method is described to simultaneously determine four related impurities of cations, zwitterions and neutral compounds in developmental Drug A. The commercial column is Primesep 200 containing hydrophobic alkyl chains with embedded acidic groups in H(+) form on a silica support. The mobile phase variables of acid additives, contents of acetonitrile and concentrations of potassium chloride have been thoroughly investigated to optimize the separation. The retention factors as a function of the concentrations of potassium chloride and the percentages of acetonitrile in the mobile phases are investigated to get an insight into the retention and separation mechanisms of each related impurity and Drug A. Furthermore, the elution orders of the related impurities and Drug A in an ion-pair chromatography (IPC) are compared to those in the mixed-mode HPLC to further understand the chromatographic retention behaviors of each related impurity and Drug A. The study found that the positively charged Degradant 1, Degradant 2 and Drug A were retained by both ion-exchange and reversed-phase partitioning mechanisms. RI2, a small ionic compound, was primarily retained by ion-exchange. RI4, a neutral compound, was retained through reversed-phase partitioning without ion-exchange. Moreover, the method performance characteristics of selectivity, sensitivity and accuracy have been demonstrated to be suitable to determine the related impurities in the capsules of Drug A.     

Automatic simultaneous determination of anions and cations in atmospheric aerosols by ion chromatography

The application of an automatic quadruple ion chromatography system for the simultaneous determination of inorganic and organic anions, and inorganic cations in atmospheric aerosol extracts using a total volume of 5 ml is described. The automation of the analysis via a single loading system and analysis by anion isocratic, anion gradient (with and without preconcentration) and cation gradient methods with chemical suppression and conductometric detection is presented. Comparison of anion results obtained by the respective methods is shown.