Application of ion chromatography to the determination of water-soluble inorganic and organic ions in atmospheric aerosols

A simple, sensitive and convenient ion chromatography(IC) method was established for the simultaneous determination of twelve water-soluble inorganic anions(F -, Cl -, NO - 2, NO - 3, SO 2- 3, SO 2- 4, PO 3- 4), and fifteen water-soluble organic ions(formate, acetate, MSA, oxalate, malonate, succinate, phthalates, etc.) in atmospheric aerosols. The linear concentrations ranged from 0.005 μg/m 3 to 500 μg/m 3(r = 0.999—0.9999). The relative standard deviation(RSD) were 0.43%—2.00% and the detection limits were from 2.7 ng/m 3 to 88 ng/m 3. The proposed method was successfully applied to the simultaneous determination of those inorganic ions and organic ions in PM 2.5 of Beijing.

Simultaneous determination of fluorine and iodine in urine by ion chromatography with electrochemical pretreatment

A new method for the simultaneous determination of fluorine and iodine in urine by ion chromatography （IC） with electrochemical pretreatment has been developed. The pretreatment was performed in a novel electrochemical oxidationneutralization device （EOND）, in which iodide of the sample was oxidized to iodate and the alkaline digestion sample solution was neutralized. Under the optimized conditions, the limits of detection （LOD, S/N = 3） were 2.5 μg/L for fluoride and 20 μg/L for iodate, respectively. The recoveries were in the range of 93-102% for fluoride and 86-98% for iodate.

A novel protein refolding method integrating ion exchange chromatography with artificial molecular chaperone

Artificial molecular chaperone （AMC） and ion exchange chromatography （IEC） were integrated, thus a new refolding method, artificial molecular chaperone-ion exchange chromatography （AMC-IEC） was developed. Compared with AMC and IEC, the activity recovery of lysozyme obtained by AMC-IEC was much higher in the investigated range of initial protein concentrations, and the results show that AMC-IEC is very efficient for protein refolding at high concentrations. When the initial concentration of lysozyme is 180 mg/mL, its activity recovery obtained by AMC-IEC is still as high as 76.6%, while the activity recoveries obtained by AMC and IEC are 45.6% and 42.4%, respectively.

Determination of haloacetic acids in hospital effuent after chlorination by ion chromatography

The ion chromatography combined solid phase extraction （SPE） method was developed for the analysis of low concentration haloacetic acids （HAAs）, a class of disinfection by-products formed from chlorination of hospital wastewater. The monitored HAAs included monochloroacetic acid, monobromoacetic acid, dichloroacetic acid, dibromoacetic acid and trichloroacetic acid. The method employed a sodium hydroxide eluent at a flow rate of 0.8 ml/min, electrolytically generated gradients, and suppressed conductivity detection. To analyze the HAAs in real hospital wastewater samples, C18 pretreatment cartridge was utilized to reduce samples＇ turbidity. Preconcentration with SPE and matrix elimination with treatment cartridges were investigated and found to be able to obtain acceptable detection limits. Linearity, repeatability and detection limits of the above method were evaluated. The detection limits of monobromoacetic acid and dibromoacetic acid were 2.61 μg/L and 1.30 μg/L, respectively, and the other three acids are ranging from 0.48 to 0.82μg/L under 25-fold preconcentration. When the above optimization procedure was applied to three hospital wastewater samples with different treatment processes in Tianjin, it was found that the dichloroacetic acid was the major compound, and the growth ratios of the HAAs after disinfection by sodium hypochlorite were 91.28%, 63.61% and 79.50%, respectively.

Determination of sulfur anions by ion chromatography-postcolumn derivation and UV detection

A novel method for determination of formaldehyde sulfoxylate, sulfite, thiocyanate, and thiosulfate in foodstuffs by ion chromatography separation with postcolumn derivation and UV detection has been developed. All species are separated at Dionex IonPac AG22A and AS22A with mobile phase of a mixture of 4.5 mmol/L sodium carbonate and 0.8 mmol/L sodium bicarbonate at a flow-rate of 1.0 mL/min. The postcolunm derivation solution was 0.24% iodine in 0.2% phosphate acid and the detection wavelength was set at 288 nm. The detection limits （LOD, signal-to-noise ratio of 3） of formaldehyde sulfoxylate, sulfite, thiocyanate, and thiosulfate were 0.004, 0.006, 0.006, and 0.007 mg/L, respectively. Within-day relative standard deviations （RSD, n = 10） of formaldehyde sulfoxylate, sulflte, thiocyanate, and thiosulfate were 3.24%, 3.76%, 2.68%, and 2.07%, respectively. The recoveries of the four anions were in the range of 67.2-116.5%.

Detection of Cyanide in Pollution-free Livestock Product Breeding Water by Ion Chromatography

In order to verify the accuracy of ion chromatography for cyanide detection,optimization conditions were studied,and comparison was made for the detection results of cyanide between titration and isonicotinic acid pyrazolone spectrophotometry. The results showed that ion chromatography has good linearity and reproducibility,with the recovery rate of 95%-105% and the limit of detection of 0. 001 mg/L. This method is simple,rapid,safe,selective,and suitable for the determination of cyanide in pollution-free livestock product breeding water.

Determination of toluene diisocyanate in synthetic-rubber track by ion chromatography with ultraviolet detection after alkaline suppressor

In the present work, a novel analytical method was proposed for the determination of toluene diisocyanate （TDI） in syntheticrubber track by ion chromatography （IC） coupled with an ultraviolet detector setting at 212 nm. TDI can be hydrolyzed to toluene diamine （TDA） which can be separated by cation-exchange IC easily. The optimum IC separation was performed on an IonPac CS12A column （150 mm ×4.0 mm） using 20 mmol L^-1 sodium sulfate, 10 mmol L^-1 sulfuric acid and 10% acetonitrile as eluent. It was found that a higher signal response of TDA could be obtained under alkaline condition. A suppressor was used to change the acidic eluent into alkaline one. 0.8 mol L^-1 potassium hydroxide was chosen as the optimum regeneration eluent. With the added suppressor and regenerant, signal response was magnified by about 16 times and lower limit of detection （LOD, 0.13 μg L^-1） was obtained. Within-day relative standard deviation （R.S.D.） was less than 3.6%. The recoveries of TDI spiked in synthetic-rubber track samoles were 96.4-110.6%.

Trace-Level Analysis of Hexavalent Chromium in Lake Sediment Samples Using Ion Chromatography Tandem Mass Spectrometry

The analysis of hexavalent chromium, Cr(VI), in soil and sediment samples has been predominantly carried out in materials containing elevated levels. Reliable analysis of trace-level of Cr(VI) in sediment samples remains challenging. Cr(VI) analyses with multipoint calibration and speciated isotope dilution (SID) adapted from U.S. EPA method 6800 were used to measure lower-level Cr(VI) on an ion chromatograph coupled with a tandem mass spectrometer (IC-MS/MS). Lake sediment samples were collected from various locations in Northern Ontario and Cr(VI) was extracted using both alkaline digestion and ethylene diaminetetraacetic acid (EDTA) extraction. Certified reference materials were extracted and analyzed by IC-MS/MS and UV-VIS detection. The SID-MS approach allowed for the quantification of Cr(VI) in samples with concentration levels below 0.5 μg.g-1 wet weight.

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.

Electrocatalytic Oxidation and Ion Chromatography Detection of S_2O^(2-)_3, SO^(2-)_3, I^- and SCN^- at Glassy Carbon Electrode with Functionalized Multi-Wall Carbon Nanotubes Film

In this research, a glassy carbon electrode modified with the functionalized multi-wall carbon nanotubes(MWNT-COOHs) film was used as an amperometric sensor for the determination of S_2O^(2-)_3, SO^(2-)_3, I^- and SCN^-. The electrochemical behavior of those oxidizable inorganic anions at this modified electrode was studied by means of cyclic voltammetry(CV). The experimental results indicate that the modified electrode exhibits a high electrocatalytic activity towards the oxidation of those anions with a relatively high sensitivity, a good stability and a long-life. Separated by ion chromatography(IC) with 1.25 mmol/L H_2SO_4 as an eluent, those oxidizable anions can be determined by the MWNT-COOHs modified electrode successfully. Under the optimal chromatographic conditions, the detection limits are 1.5×10^(-7) mol/L for S_2O^(2-)_3, 2.5×10^(-7) mol/L for SO^(2-)_3, 1.2×10^(-7) mol/L for I^- and 2.0×10^(-7) mol/L for SCN^-, respectively. The method was applied successfully to the determination of those anions in environmental water

Studies on the Simultaneous Determination of Cr(Ⅲ)and Cr(Ⅵ)by Ion Chromatography(IC)

The research aimed to develop and validate an ion chromatography method for the simultaneous analysis of Cr(Ⅲ) and Cr(Ⅵ)from pumpkin. A new analytical method based on ion chromatography techniques was developed by the Cr(Ⅲ) pre-column derivatization and Cr(Ⅵ) post-column derivatization. The ion chromatography condition was optimized and the detection sensitivity was improved. Cr(Ⅲ) and Cr(Ⅵ) were determined by 365 and 530 nm,respectively. The temperature of water bath,the heating time for pre-column derivatization,and the flow rate of post-column derivative liquid were screened on the basis of single factor experiment,the effects of various factors were determined by the method of L16( 43) orthogonal experiment design. Considering the results of orthogonal experiments and the variation tendency of peak area under different factors,the optimum derivatization conditions were chose as follows: the flow rate of post-column derivative liquid is0. 5 m L/min,the temperature of water bath for pre-column derivatization is 100 ℃ and the heating time is 5 min. The conditions were optimized by means of orthogonal experiments under the p H of leacheate ranged from 6. 5 to 6. 8 and the I-concentration of 5 mmol/L. Under optimized derivatization conditions,the detection limits for Cr(Ⅲ) and Cr(Ⅵ) were 0. 17 and 0. 019 mg,respectively. And the average recoveries of Cr(Ⅲ) in pumpkin were in the range of 82%-85%. Results indicated that pumpkin does not contain Cr(Ⅵ) according to this ion chromatography method of simultaneously determination for Cr(Ⅲ) and Cr(Ⅵ).

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.

Screening for Plant Toxins in Honey and Herbal Beverage by Ultrahigh-Performance Liquid Chromatography-Ion Mobility-Quadrupole Time of Flight Mass Spectrometry

The standards of plant toxins were separated by a C18 column with gradient elution with 0.1% formic acid/water (V/V) and 0.1% formic acid/acetonitrile (V/V) as mobile phase and acquired by ion mobility-quadrupole time of flight mass spectrometry (IM-QTOF MS) in positive ion mode. A database of 308 plant toxins including retention time, collision cross-section (CCS) and its fragment ions was established. Honey dissolved in water or herbal beverage was extracted by acetonitrile and purified with PSA sorbent, and then acquired by ultrahigh-performance liquid chromatography IM-QTOFMS. The acquired data were processed by comparing with the database we established to confirm the target compounds. The average recoveries for samples at two levels ranged from 60.6% - 120.1%, with relative standard deviation (n = 6) less than 25%. The limit of quantitation for plant toxins ranged from 1 - 20 μg/kg. The developed screening method was used in determination of honey, herbal beverage and honey flavored tea beverage samples. The results showed that berberine was detected in one honey with 1 μg/kg and caffeine was present in some beverages with the concentration from 200 and 5500 μg/kg. This method could meet the requirement for rapid screening of plant toxins in honey and herbal beverage. It can be used for the quality control of honey and herbal beverage in enterprises or quality inspection departments. It also can be used in the rapid screening of food poisoning.

Improved method for measuring the δ15N compound-specific amino acids: Application on mesopelagic fishes in the South China Sea

Compound-specific stable isotope analysis of individual amino acids(CSIA-AA)has been widely used in ecological and biogeochemical studies.It has been proven to be powerful in tracing the diet sources and trophic interactions.However,assessing the N sources of mesopelagic fishes has been inconclusive because the mesopelagic fishes’unique domain(water depth ranged from 0 to 1000 m)and unresolved nitrogen isotopes of various forms.This study proposes a new method for coupling instruments(ion chromatography and PreconIRMS)and chemical method of oxidation-reduction of amino acids,and also combinedδ15N of AAs withδ13C of fatty acids(FAs)to analyze the trophic interactions of mesopelagic fishes in the South China Sea(SCS).AAs were isolated by ion chromatography with high peak resolution and collected by an automated fraction collector.The chemical method then converted the AAs into N2 O with a robust oxidation yields and suitable molar ratio of NH2 OH to.Finally,theδ15N of AAs at 20 nmol were measured with a reasonable precision(<0.6‰).With this method,this study report the first batch high precisionδ15N of AAs andδ13C of FAs of mesopelagic fishes collected from SCS.Diaphus luetkeni,Chauliodus minimus and Bathygadus antrodes showed similarδ13C values of 20:4 n-6(~-28‰),while Argyropelecus affinis and Stomias had similar values(~-32‰).These results reflect that mesopelagic fishes had complex diet sources.An increase of 4‰inδ15N of glutamic acid(Glu)was found between piscivorous and planktivorous fishes,which might suggest a trophic discrimination factor of mesopelagic fishes in the SCS.This study usedδ13C of 20:4 n-6 to reveal the diet sources of mesopelagic fishes andδ15N of Glu to clarify trophic level between piscivorous and planktivorous fishes.Thus,this combinative method could therefore ultimately be applied in a variety of deep-sea ecosystem.

Separation of Aromatic Carboxylic Acids in IC and the Study on the Relationship Between Retention Behavior and Electrostatic Potential

A method has been developed for separation of 20 kinds of aromatic carboxylic acid using anion-exchange chromatography. A Dionex IonPac AS9-HC guard column （250mm×2mm） was used with a 9mmol/L sodium carbonate solution containing 50% （v/v） acetonitrile as eluent. A set of retention time data has been obtained using a conductivity detector DS6. Furthermore, geometrical optimization and electrostatic potential calculation of 20 kinds of aromatic carboxylic acid have been performed at the HF/6-31G＊ level of theory. A number of statistically-based parameters derived from molecular surface electrostatic potential have been obtained. Linear relationship between retention time and structural parameters has been established by multiple regression method. The result shows that parameters derived from electrostatic potential Vs ＋, Vs -, П together with the dipole moment μ can be well used to express the quantitative structure-retention time of this kind of aromatic carboxylic acid. Good predictive capability has also been demonstrated. The result has provided a framework which further proves the general applicability of this electrostatic potential parameter set to a great extent,and with which the ion chromatographic adsorption mechanism can be investigated.

Elution Behaviour of Monocarboxylic Acids on a Cation-exchange Resin Column

The retention mechanism of monocarboxylic acids on a cation-exchange resin column was investigated. It was assumed that both Donnan membrane equilibrium and adsorption equilibrium were involved in the chromatographic process. On the basis of the proposed mechanism, an equation was derived for correlating distribution coefficient, Kd, dissociation constant, Aa, and adsorption equilibrium constant, K, of the analyzed acid. By this approach, retention data for some aliphatic acids under different operating conditions were predicted. Results are reasonably in agreement with experiment.

Determination of components in traditional Chinese medicines associated with promoting or inhibiting urinary stone formation

Objective:To measure oxalate,calcium,and sodium contents of traditional Chinese medicines(TCMs)that are commonly used to prevent and dissolve urinary stones to exclude the possibility that long-term use of such medicines promotes stone formation.The second objective was to measure citrate,potassium,and magnesium contents in the same medicines to provide possible clues about the mechanisms of prevention and dissolution of urinary stones by TCMs.Methods:Ten of the most commonly-used TCMs for preventing and dissolving urinary stones were chosen and subjected to ion chromatography(IC)to measure water-soluble and total oxalate and citrate contents.Inductively coupled plasma atomic emission spectrometry(ICPAES)was used to measure calcium,potassium,magnesium,and sodium contents in a water extract and in digestion liquid.Results:Average contents of water-soluble oxalate,calcium,and sodium in the water extract were 41.92,84.32,and 22.82 mg/100 g,respectively,far below the normal dietary intake of adults in China.The average contents of citrate and magnesium in water extracts were 268.99 and 66.65 mg/100 g,respectively,below the recommended intake for adults.These ion contents are therefore insufficient to inhibit the formation of urinary stones.The average content of potassium in the water extract was 867.71 mg/100 g,which was relatively abundant,so taking the prescription used in this experimental protocol can increase the body’s potassium content to some extent.Conclusions:Long-term use of TCMs would not increase the risk of urinary stone formation.The potassium content in TCMs is high,which is one possible reason for the prevention of urinary stones by TCMs.

Separation and Detection of Lanthanide Ions with Nitrilotri (methylenephosphonic) Acid as Complexing Agent and Eluent by IPC

A mixture containing eleven lanthanide ions was separated and detected on an anion exchange co lumn by ion chromatography with indirect photometry detection (IPC).An aqueous solution of 1.5×10 -2 mol/L nitrilotri(methylenephosphonic) acid and 2.5×10 -3 mol/L tiron was used as the eluent in which the former served as complexing agent and eluent,the latter played as color reagent and eluent.The effects of acidity,concentration and composition of eluent on the retention behavior of the analytes and detection sensitivity are discussed.

Separation and purification of Yb_(2)O_(3) by ion exchange chromatography and preparation of ultra-high purity Yb_(2)O_(3)

Ultra-high purity Yb_(2)O_(3) is the critical material of many high-tech materials such as laser glass and fiber,in which impurities seriously affect the laser color quality,intensity and power.In order to reduce the influence of impurities on the properties of laser materials,the purification process of Yb_(2)O_(3) was studied by comparing two kinds of resins(RT-1 and RS-1)using improved ion-exchange chromatography(IEC)method.In this study,through the synergistic improvement of resin structure and eluting system,the environmental pollution caused by ammonia water in the traditional IEC method was reduced,and the requirements of high temperature and pressure were cut.The ion exchange behavior and impurity removal mechanism in the resin column during the loading and eluting process were compared and analyzed.The experimental results show that RS-1 resin is all superior to RT-1resin in elements selectivity,ion exchange capacity and impurities removal rate.After separation and purification by IEC with RS-1 resin,the total removal rate of rare earth impurities was 77.59%and that of non-rare earth impurities was 95.86%when Yb recovery was more than 70%,both higher than that of RT-1 resin(73.26%and 83.18%).This indicates that the improved IEC method is very effective in separating and removing different metal impurities from Yb_(2)O_(3).The pilot test results of IEC method separating and purifying Yb_(2)O_(3) with RS-1 resin show that the purity of Yb_(2)O_(3) can be increased from 99.9929%to 99.9997%by IEC method.It has exhibited huge potential of preparing ultra-high purity Yb_(2)O_(3),especially the deep removal of non-rare earth impurities.

同时测定无机离子的改良离子色谱法在河水和废水质量监控中的应用(英文)

In this study,our recent work on advanced ion chromatographic methods for the simultaneous determination of inorganic ionic species such as common anions(SO2-4,Cl-and NO-3) and cations(Na+,NH+4,K+,Mg2+,and Ca2+),nutrients(phosphate and silicate) and hydrogen ion/alkalinity are summarized first.Then,the applications using these methods for monitoring environmental water quality are also presented.For the determination of common anions and cations with nutrients,the separation was successfully performed by a polymethacrylate-based weakly acidic cation-exchange column of TSKgel Super IC-A/C(Tosoh,150 mm×6.0 mm i.d.) and a mixture solution of 100 mmol/L ascorbic acid and 4 mmol/L 18-crown-6 as acidic eluent with dual detection of conductivity and spectrophotometry.For the determination of hydrogen ion/alkalinity,the separation was conducted by TSKgel ODS-100Z column(Tosoh,150 mm×4.5 mm i.d.) modified with lithium dodecylsulfate and an eluent of 40 mmol/L LiCl/0.1 mmol/L lithium dodecylsulfate/0.05 mmol/L H2SO4 with conductivity detector.The differences of ion concentration between untreated and treated wastewater showed the variation of ionic species during biological treatment process in a sewage treatment plant.Occurrence and distribution of water-quality conditions were related to the bioavailability and human activity in watershed.From these results,our advanced ion chromatographic methods have contributed significantly for water quality monitoring of environmental waters.