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Chinese Journal of Chromatography
2016, Vol. 34, No. 10
Online: 08 October 2016

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Research advance on the instrumental analysis methods of fluoride NI Chengzhu, JIANG Xinhua, LI Gang, ZHANG Jiajie, ZHANG Peimin, ZHU Yan 2016, 34 (10):  942-945.  DOI: 10.3724/SP.J.1123.2016.05035 Abstract ( 298 )   [Full Text(HTML)] () PDF (744KB) ( 132 )   The public has been paying greater attention to fluoride in the last few years, and the detection techniques of fluoride content has been updated and developed. The instrumental analysis of fluoride by ion selective electrode method, ion chromatography, reversed-high performance liquid chromatography and gas chromatography is introduced, including their advantages and disadvantages.

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Determination of carbohydrates and sugar alcohol in infant formula by ion chromatography with pulsed amperometric detection and an optimized gradient elution ZHANG Shuifeng, SHENG Huadong, JIANG Kan, PAN Xiangjie, ZHANG Hui, ZHANG Donglei, WANG Yue, CHEN Xiaozhen, ZHU Yan, ZENG Xianyuan 2016, 34 (10):  946-950.  DOI: 10.3724/SP.J.1123.2016.04021 Abstract ( 558 )   [Full Text(HTML)] () PDF (781KB) ( 110 )   A method was developed for the determination of carbohydrates and sugar alcohol related closely to metabolic diseases in infant formula, including maltitol, galactose, glucose, sucrose, fructose and lactose, by ion chromatography (IC) with pulsed amperometric detection and an optimized gradient elution. The developed method included the systematic optimizations of sample pre-treatment, column selection and gradient elution. And more attention has been paid to optimizing the gradient elution program. According to the chromatographic behavior of the targets, the total gradient elution was divided into four subprograms, including separation of the analytes with weaker retentions, separation of lactose, matrix elimination and system equilibrium, and each part was also optimized in detail. By the optimized gradient elution, both negative chromatographic phenomena of overlapping between analytes with weak retentions and tailing for lactose were eliminated well, and all of the analytes were separated completely. Both maltitol and galactose were fitted well with quadratic curve, and the others were fitted well with linear equation, with the correlation coefficients (r) greater than 0.99, in the concentration range of 0.5-100 mg/L, with the limits of detection (LODs) (S/N=3) of 0.06-0.40 mg/L. The developed method offered a helpful method for gradient elution optimization, and it had been used for the determination of the real samples. It was proved to be feasible for routine analysis.

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Determination of inorganic anions and organic acids in beer by replacement-ion chromatography with ultraviolet detection SHI Chaoou, YAO Baolong, HU Mi, CHEN Ailian 2016, 34 (10):  951-955.  DOI: 10.3724/SP.J.1123.2016.06008 Abstract ( 437 )   [Full Text(HTML)] () PDF (1038KB) ( 99 )   A new method for determination of inorganic anions and organic acids in beer was developed by replacement-ion chromatography-ultraviolet detection. Two ion replacement columns were introduced on the basis of the traditional ion chromatography. Inorganic anions and organic acids were converted into iodate salts with the same ultraviolet response, and then detected sensitively by ultraviolet detector instead of conductivity detector. The separation of the inorganic anions and organic acids was achieved on a Dionex AS11-HC anion chromatographic column with KOH as gradient eluent. The results showed that the limits of detection (S/N=3) and the limits of quantification (S/N=10) were 6.168-29.01 μg/L and 20.56-66.30 μg/L respectively; the linear relationship is good with correlation coefficients (r) greater than 0.9994. The average recoveries were between 89.0% and 117.0%, and relative standard deviations (RSDs) were all less than 1.0%, the detection results are almost the same with the results of traditional conductance. The method is simple, rapid and can realize the determination of inorganic ions and organic acids in beer using use a few standard curves.

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Simultaneous determination of sucralose, glucose, fructose and sucrose in beverage by ion-exchange chromatography with column-switching CHEN Ning, ZHANG Peimin, WU Shuchao, ZHU Yan 2016, 34 (10):  956-959.  DOI: 10.3724/SP.J.1123.2016.05018 Abstract ( 433 )   [Full Text(HTML)] () PDF (1054KB) ( 113 )   A new method of simultaneous determination of sucralose, glucose, fructose and sucrose in beverage has been established using ion-exchange chromatography coupled with column-switching and pulsed amperometric detection. A CarboPac PA10 guard column and a CarboPac PA10 analytical column, along with the mixtures of pure water and 250 mmol/L NaOH solution in different ratio acting as mobile phase in the gradient elution were used in the pulsed amperometric detection. After the separation and detection of saccharides with weak retention through elusion with 25 mmol/L NaOH, we switched the guard column to analytical column, in which sucralose can be separated through the comparatively short guard column while the four saccharides can be detected simultaneously. In this study, four saccharides had good linear relationships in 0.01-20 mg/L and the recoveries were 90.38%-102.88% (sucralose), 95.56%-102.75% (glucose), 101.66%-114.33% (fructose), 105.03%-106.49% (sucrose) with high sensitivity and good reproducibility. This method can be widely used in the determination of components with strong retention in food.

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Determination of chloride and trifluoroacetate in water- insoluble pharmaceuticals by valve switch-ion chromatography JIN Juhua, YE Mingli 2016, 34 (10):  960-963.  DOI: 10.3724/SP.J.1123.2016.07033 Abstract ( 360 )   [Full Text(HTML)] () PDF (1020KB) ( 99 )   A method was developed for the determination of chloride and trifluoroacetate in water-insoluble pharmaceuticals such as cefixime, lauroyl-indapamide, budesonide by valve switch-ion chromatography. Chromatographic separation was performed on an IonPac AS23 column, 3.5 mmol/L sodium carbonate and 1.0 mmol/L sodium bicarbonate eluents were used. The effects of the types of column and eluent, eluent concentration of inorganic anions were investigated. The linear ranges of the method for seven anions were 0.10-10.00 mg/L, and the detection limits (S/N=3) of chloride and trifluoroacetate were 0.006 mg/L and 0.06 mg/L respectively. The recoveries of inorganic anions spiked in cefixime were between 90% and 94%. The method was successfully used in the determination of inorganic anions in real samples.

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Determination of β-glycerophosphate and L-malate in glycerol phosphate preparations by ion chromatography LIU Yuxiu, YU Hongwei 2016, 34 (10):  964-967.  DOI: 10.3724/SP.J.1123.2016.05020 Abstract ( 401 )   [Full Text(HTML)] () PDF (751KB) ( 97 )   An analytical method for the determination of β-glycerophosphate and L-malate in glycerol phosphate preparations was established by ion chromatography with isocratic elution. α -Glycerol phosphate was completely separated from β-glycerol phosphate in the glycerol phosphate preparations. A Metrosep A Supp7 column (250 mm×4.0 mm, 5 μm) was used for separation with the eluent of 3.6 mmol/L Na2CO3 at a flow rate of 0.7 mL/min. The column temperature was 35℃. With this method, good accuracy and precision were obtained. The recoveries of the method ranged from 90.73% to 106.27%. The method is simple, rapid, sensitive, and suitable for the determination of β-glycerophosphate and L-malate in glycerol phosphate preparations.

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Rapid determination of seven inorganic anions by high pressure ion chromatography in drinking water SONG Xiaowei, GAO Lihong, SHI Yali, CAI Yaqi, LI Renyong 2016, 34 (10):  968-971.  DOI: 10.3724/SP.J.1123.2016.06024 Abstract ( 518 )   [Full Text(HTML)] () PDF (770KB) ( 121 )   A new method was developed for the determination of inorganic anions in drinking water by high pressure ion chromatography (HPIC). Water samples were analyzed directly after filtered by 0.22 μm nylon membrane. Seven anions (F-, Cl-, Br-, NO2-, NO3-, SO42- and PO43-) were separated well in 5 min by Dionex Integrion HPIC and AS22-Fast-4 μm anion exchange column. In this study, 4.5 mmol/L sodium carbonate and 1.4 mmol/L sodium bicarbonate were used as the mobile phases with the flow rate of 2 mL/min. The limits of detection of the analytes (S/N=3) ranged from 0.007 to 0.07 mg/L, and they all had good linear relationships (r≥0.999) in a wide range with good relative standard deviations (RSDs≤0.48%, n=8). The recoveries of the seven anions in drinking water ranged in 91.4%-109.7% with RSDs of 0.30%-0.45% (n=5). The developed method was applied to analyze the drinking water samples from seven tap waterworks. The results showed that six anions were detected in these samples, and Cl-, NO3- and SO42- were the predominant anions. The method is simple, rapid, accurate, reliable, and suitable for the rapid determination of common anions in water samples.

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Determination of ammonia, hydrazine and ethanol amine in air by ion chromatography WANG Zhen, JIANG Zhenbang, LI Renyong 2016, 34 (10):  972-975.  DOI: 10.3724/SP.J.1123.2016.06031 Abstract ( 648 )   [Full Text(HTML)] () PDF (748KB) ( 128 )   A method was developed for simultaneous determination of ammonia, hydrazine and ethanol amine in air by suppressed conductivity ion chromatography (IC). The method was applied to evaluate the safety of workplace air. The ammonia, hydrazine and ethanol amine were absorbed with methyl sulfonic acid (MSA) aqueous solution as absorbing solution. The water-insoluble particles were removed by 0.22 μm filter membranes. The separation was performed on ThermoFisher IonPac CS19 carboxylic acid type cation exchange chromatographic column (250 mm×4 mm) and CG19 guard column (50 mm×4 mm). MSA was generated as mobile phase by eluent generator, and isocratically eluted. Suppressed conductance has been selected as the principle for detection of the three compounds simultaneously. The results showed that the precisions of ammonia, hydrazine and ethanol amine were between 0.98% and 1.6%, and the limits of detection (LODs) of ammonium, hydrazine and ethanol amine were 0.003, 0.011 and 0.016 mg/L, respectively. It is a simple, quick and accurate method without any complex pretreatment such as derivatization. The separation of ammonium, hydrazine and ethanol amine can be completed in 15 min. The method can shorten the detection time and improve work efficiency. It has a high practical application value.

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Determination of trace impurities of iron and ferric oxide in high purity microsilica by ion chromatography LUO Jin, ZHENG Hongguo, LI Renyong, ZHAO Haineng, LI Chao, ZHAO Jiong, LI Chunlin 2016, 34 (10):  976-981.  DOI: 10.3724/SP.J.1123.2016.06047 Abstract ( 535 )   [Full Text(HTML)] () PDF (807KB) ( 135 )   A method for detecting trace impurities of iron and ferric oxide in high purity microsilica was established by ion chromatography with post column derivatization plus UV detection. The separation of ferric and ferrous was achieved on Thermo Scientific DionexTM IonPacTM CS5A column containing anion and cation exchange functional groups with 2,6-pyridinedicarboxylic acid (PDCA) solution elution. The target compounds were derivatized with 4-(2-pyridylazo)resorcinol (PAR) and detected at 530 nm. The limits of detection for ferrous and ferric were 0.013 mg/kg and 0.006 mg/kg respectively. Both of the linear correlation coefficients for ferrous and ferric were better than 0.999. The recoveries of ferrous and ferric were 79%-90% and 92%-105% respectively. The method provides high sensitivity, high accuracy and high selectivity for the detection of ferrous and ferric in microsilica, which would be used for monitoring the different sources of iron in microsilica industry.

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Determination of hexafluorosilicic acid in the wasted hydrofluoric acid in the etching bath solution with ion chromatography HUO Shixin, LUO Quanqian, CAO Lin 2016, 34 (10):  982-985.  DOI: 10.3724/SP.J.1123.2016.05021 Abstract ( 473 )   [Full Text(HTML)] () PDF (1020KB) ( 105 )   A new method for the determination of the hexafluorosilicic acid in the wasted hydrofluoric acid by ion chromatography (IC) with UV-Vis (ultraviolet-visible) detector after post column reaction was investigated. The wasted hydrofluoric acid was produced in the silicon etching bath. The separation was achieved on a Metrosep A Supp 7 column with 3.2 mmol/L sodium carbonate and 1.0 mmol/L sodium bicarbonate at a flow rate of 0.7 mL/min. In this thesis, the derivatization reaction temperature, reagent adding rate and the UV detector wavelength were studied. The other mineral acids in the etching bath, such as hydrofluoric acid, chloric acid, nitric acid, phosphoric acid, acetic acid and sulfuric acid also could be determined in the same time by the suppressed conductivity detection. The method showed that hexafluorosilicic acid had good linearities in the range of 2.4-120 mg/L. The average recovery of the hexafluorosilicic acid in the real sample was 97.2%. The limit of quantification of hexafluorosilicic acid was 0.24 mg/L. The method is accurate, fast and suitable for the determination of hexafluorosilicic acid in the etching bath solution.

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Determination of perchlorates in tea by ion chromatography- tandem mass spectrometry LIU Xiaofang, FANG Congrong, LIU Hui, LI Renyong, YAN Chao 2016, 34 (10):  986-988.  DOI: 10.3724/SP.J.1123.2016.06015 Abstract ( 593 )   [Full Text(HTML)] () PDF (744KB) ( 132 )   A rapid ion chromatography-tandem mass spectrometry(IC-MS/MS) method was developed for the determination of perchlorates in tea. The chromatographic analysis was performed on Dionex 5000+, using high capacity and hydroxide selective column IonPac AS20 (2 mm). Perchlorates were separated by isocratic elution with 70 mmol/L KOH eluent generated from on-line eluent generation cartridge. TSQ QuantivaTM, as a detector, scanned samples and monitored multi ion pairs simultaneously for confirmation and quantification, in the mode of negative ESI and multiple reaction monitoring (MRM). The results displayed good linearity in the range of 0.02-10.0 μg/L, with correlation coefficient (r) of 0.9991. The relative standard deviations (RSDs) were 2.67% (n=5). The limits of quantification of the method were 2 μg/kg. The average recoveries of perchlorates in the five kinds of tea ranged from 87.3% to 112.2%. The results showed that the method is fast, simple, selective, sensitive and suitable for the determination of perchlorates in various complex matrix samples such as tea.

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Determination of perchlorate in wine by ion chromatography LI You, YU Hongwei, WANG Fei 2016, 34 (10):  989-991.  DOI: 10.3724/SP.J.1123.2016.05032 Abstract ( 662 )   [Full Text(HTML)] () PDF (886KB) ( 84 )   An ion chromatographic method was developed for the determination of perchlorate in wine. The content of perchlorate in four kinds of wine was determined. Metrosep A Supp5 column (150 mm×4.0 mm) was used for the separation with the eluent of 1.0 mmol/L Na2CO3-acetone (85 : 15, v/v) at the flow rate of 0.8 mL/min, and the column temperature was 40℃. Perchlorate had good linearity in the range of 0.1-10.0 mg/L. The recoveries of the method were more than 86.0%, and the relative standard deviations were less than 2.6%. The method is simple and rapid, and can be used for the determination of perchlorate in wine.

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Optimization of the extraction method for high performance liquid chromatography analysis of trace di(2-ethylhexyl)phthalate in drinking water by response surface methodology and the migration regularity WU Fei, LÜ Xiaodan, TANG Junjie, CHEN Qixian, PENG Xuetang, CHEN Qidan 2016, 34 (10):  992-997.  DOI: 10.3724/SP.J.1123.2016.06048 Abstract ( 490 )   [Full Text(HTML)] () PDF (1044KB) ( 82 )   A simple and rapid method for the determination of trace di(2-ethylhexyl)phthalate (DEHP) in drinking water was developed and the migration regularity was studied. In this work, the migration of DEHP from plastic bottle products of supermarket was studied by high performance liquid chromatography coupled with ultraviolet detection (HPLC-UV), and the extraction conditions were optimized by response surface methodology (RSM). With the effect of NaCl, DEHP in drinking water sample was extracted in n-hexane by vortex, dried and concentrated by N2, and then dissolved by methanol. The filtrate was injected into an HPLC-UV system for the analysis. The optimized extraction conditions were NaCl of 16 g/L, the vortex time of 90 s and the volume of n-hexane of 5.28 mL. Under the optimized conditions, the experimental value and the predicted value of the recoveries of DEHP were 92.97% and 92.91%, respectively, and the difference was only 0.063%. The limit of detection was 0.006 mg/L, the linear range was 0.01-15 mg/L (R=0.9996), and the relative standard deviation (RSD) was 0.015%-2.45%. In addition, the real water sample in plastic bottles from local supermarket was determined by the method and the migration regularity of trace DEHP in drinking water from plastic container under different temperature and time conditions was studied. The results showed that the application of RSM in the selection of optimal conditions for trace analysis is feasible, low-cost and eco-friendly.

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Determination of nine N-nitrosamines in animal derived foods by dispersive solid-phase extraction-gas chromatography-tandem mass spectrometry ZHAO Bo, DENG Meilin, YANG Xiaoshan, DUAN Yunpeng, WU Xiaoqin, TU Dawei 2016, 34 (10):  998-1004.  DOI: 10.3724/SP.J.1123.2016.07012 Abstract ( 416 )   [Full Text(HTML)] () PDF (1064KB) ( 150 )   A method has been developed and validated for the determination of nine N-nitrosamines in animal derived food using dispersive solid-phase extraction (dSPE) coupled with isotope dilution-gas chromatography-tandem mass spectrometry (GC-MS/MS). The samples were extracted by acetonitrile. The extracts were purified using mixed adsorbent by dSPE and then concentrated. The analytes were separated on a DB-WAX polar capillary column, and ionized by EI source. The data were collected by multiple reaction monitoring (MRM) mode, followed by qualitative screening and quantitative analysis. The correlation coefficients of linear calibration curves were over 0.99 in the corresponding linear ranges. Four kinds of typical animal derived foods were spiked at three levels. The average recoveries of the nine N-nitrosamines ranged from 62.5% to 118% with RSDs of 2.11%-25.6%. The limits of detection (LODs, S/N=3) were 0.02-0.31 μg/kg. The method is of low cost, sensitive, reliable, and suitable for the determination of nine N-nitrosamines in animal derived foods.

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Determination of lambda-cyhalothrin in apples and soil by gas chromatography CHEN Jiaojiao, ZHANG Jing, WU Sizhuo, ZHANG Guanglong, ZHANG Kankan, HU Deyu 2016, 34 (10):  1005-1010.  DOI: 10.3724/SP.J.1123.2016.05026 Abstract ( 458 )   [Full Text(HTML)] () PDF (793KB) ( 127 )   A modified QuEChERS-gas chromatography method was developed to determine the residues of lambda-cyhalothrin in apples and soil. Moreover, the matrix effects in apples and soil were investigated and evaluated. The apple and soil samples were extracted with acetonitrile and purified by graphitized carbon black (GCB). The linearity of lambda-cyhalothrin was good in the range of 0.05-10 mg/L with correlation coefficients (R2) more than 0.999. The limits of detection and limits of quantification were 0.12-0.15 μg/kg and 0.38-0.50 μg/kg, respectively. With the matrix-matched calibration, the recoveries were 88.29%-97.65% and 80.70%-98.69% in soil and apples, respectively, which were in the acceptable range. Matrix enhancement effects were observed in the apple and soil samples. The established method can be applied on the residual analysis of lambda-cyhalothrin in actual apple and soil samples. The matrix-matched calibration solution can efficiently compensate the matrix effects of the lambda-cyhalothrin in gas chromatography-electron capture detector (GC-ECD) analysis.

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Determination of three flavonoids in loquat leaves from different producing areas by high performance liquid chromatography ZHU Shita, ZHOU Qiaoling, JIN Ping, XIAO Yao 2016, 34 (10):  1011-1014.  DOI: 10.3724/SP.J.1123.2016.07022 Abstract ( 383 )   [Full Text(HTML)] () PDF (754KB) ( 118 )   A method for simultaneous determination of three flavonoids in loquat leaves was established by high performance liquid chromatography (HPLC), and the variations of contents of rutin, quercetin and kaempferol in loquat leaves from different producing areas were investigated. Powder of loquat leaves was extracted with methanol under ultrasonic extraction, then the lipid substances were recovered with hydrochloric acid before analyzed. A Diamonsil C18 column (250 mm×4.6 mm, 5 μm) was used. The mobile phases consisted of 0.4% (v/v) phosphoric acid and acetonitrile as gradient elution. The contents of rutin, quercetin and kaempferol in eight loquat leaf samples collected from seven producing areas were determined. Three flavonoids all showed good linear relationships in external standard method. The spiked recoveries of rutin, quercetin and kaempferol were 96.33%, 95.81% and 95.80%, with RSDs of 6.48%, 0.90% and 3.02%, respectively. The method can be applied in a rapid and easy way with high resolution and good repeatability. The contents of the three flavonoids in loquat leaves showed significant differences among producing areas, especially rutin. Kaempferol had been detected in all samples with a relative stable content. Kaempferol may be selected as an active ingredient for quality control of loquat leaf medicinal materials.