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Chinese Journal of Chromatography
2013, Vol. 31, No. 3
Online: 28 March 2013

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Advances of molecularly imprinted polymers for solid phase extraction LI Jinhua1, WEN Yingying1,2, CHEN Lingxin1* 2013, 31 (3):  181-184.  DOI: 10.3724/SP.J.1123.2012.12029 Abstract ( 1987 )   [Full Text(HTML)] () PDF (746KB) ( 852 )   Recent advances in molecularly imprinted polymers (MIPs) as solid phase adsorbents for chromatographic sample pretreatments are summarized, including solid phase extraction, matrix solid phase dispersion extraction, solid phase microextraction, stir bar sorptive extraction and magnetic material extraction. A number of challenges and possibly effective strategies are discussed. And some perspectives of MIPs based extraction in chromatography are also proposed.

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Chromatographic evaluation of multi-mode retention behavior of thiol-ene click chemistry based β-cyclodextrin stationary phase XU Xuefeng, SHEN Aijin, GUO Zhimou*, LIANG Xinmiao 2013, 31 (3):  185-190.  DOI: 10.3724/SP.J.1123.2012.11029 Abstract ( 1660 )   [Full Text(HTML)] () PDF (1331KB) ( 614 )   A native β-cyclodextrin (β-CD) stationary phase was prepared by covalent bonding of β-CD on silica particles via thiol-ene click chemistry. The resulting β-CD bonded silica (Click TE-CD) was characterized by elemental analysis, which proved the successful immobilization of β-CD on the silica support with thiol-ene click chemistry. Click TE-CD was chromatographically evaluated with a set of flavone glycosides under hydrophilic interaction chromatography (HILIC) mode, reversed-phase chromatography (RPLC) mode and supercritical fluid chromatography (SFC) mode. The acetonitrile content dependent “U” retention curves indicated its HILIC/RPLC mixed-mode retention behavior. The difference of the separation selectivity between HILIC, RPLC and SFC was described as orthogonality by using geometric approach. The orthogonalities between HILIC/RPLC, HILIC/SFC, and RPLC/SFC reached 69.8%, 50.8% and 50.8%, respectively. The separation of Chinese traditional medicine Lignum Dalbergia Odorifera extract under HILIC, RPLC and SFC modes indicated the potential of Click TE-CD stationary phase in the analysis of complex samples. The mixed-mode HPLC properties and excellent orthogonality demonstrated its flexibility in HPLC method development and its great potential in two-dimensional liquid chromatography separation on one HPLC column by different separation modes.

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Determination of triazole fungicide and triazine herbicide residues in Chinese herbs by ultra-performance liquid chromatography-tandem mass spectrometry WANG Fei, LI Tong, MA Chen* 2013, 31 (3):  191-199.  DOI: 10.3724/SP.J.1123.2012.12019 Abstract ( 1798 )   [Full Text(HTML)] () PDF (856KB) ( 735 )   A method using QuEChERS clean-up followed by UPLC-MS/MS has been established for the quantitative determination of the residues of 10 triazole fungicides and 18 triazine herbicides in Chinese herbs including Radix Glycyrrhizae, Radix Panacis Quinquefolii, Salvia miltiorrhiza, Radix Notoginseng and Panax ginseng C. The pesticide residues were extracted from the samples by acetonitrile containing 1%(v/v) acetic acid, cleaned-up with primary secondary amine (PSA) and then analyzed using UPLC-MS/MS in multiple reaction monitoring (MRM) mode with positive electrospray ionization. The analytical column was Shim-pack XR-ODSII(75 mm×2.0 mm) and the mobile phases were water containing 0.05% (v/v) formic acid and acetonitrile in gradient elution. The limits of quantification (S/N≥10) of the 28 pesticides were 0.20-5.52 μg/kg and the limits of detection (S/N≥3) were 0.10-2.57 μg/kg. All of the pesticides had good linear responses with r≥0.999 and the average recoveries of the pesticides spiked in the Chinese herbs ranged from 70.6%-125.7% with the RSDs of 0.7%-14.2%. The results demonstrated that the method is simple, fast and sensitive to meet the requirements for the triazole fungicide and triazine herbicide residues and can be used for the analysis of the 28 pesticides in the above five Chinese herbs.

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Determination of nine β-agonist residues in pig tissues by liquid chromatography-tandem mass spectrometry combining with library search CAI Qinren1*, WU Jieshan1, QIAN Zhenjie1, PENG Yufen1, CAI Jie1, DU Zhifeng2 2013, 31 (3):  200-205.  DOI: 10.3724/SP.J.1123.2012.11004 Abstract ( 1465 )   [Full Text(HTML)] () PDF (817KB) ( 810 )   : A new method has been developed using a hybrid triple-quadrupole linear ion trap (QTrap) mass spectrometer for the fast detection and identification of nine β-agonists, clenbuterol, salbutamol, ractopamine, ritodrine, terbutaline, isoxsuprine, tulobuterol, cimaterol and bambuterol, in one single liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The homogenized tissue samples were purified with liquid-liquid extraction after enzymatic hydrolysis by β-glucuronidase/aryl sulfatase. After gradient elution separation on C18 LC column using acetonitrile and formic acid aqueous solution as the mobile phases, a multiple reaction monitoring (MRM) scan as survey scan and an enhanced product ion (EPI) scan as dependent scan were performed in an information dependent acquisition (IDA) experiment. Finally, the identification of the drugs was carried out by library search with a newly developed MS/MS library based on EPI spectra at three different collision energies in positive mode. The analytical method in the present study was well validated and good results were obtained with respect to precision, repeatability and spiked recovery. The limits of detection of residues were 0.1-0.2 μg/kg for β-agonists, and with a linear range from 0.1 to 50.0 μg/L. Three concentration levels of 0.5, 1.0 and 5.0 μg/kg were spiked in pig tissues, and the overall recoveries were between 72.0% and 95.1% with the relative standard deviations (RSDs) between 3.1% and 12.1%. The real sample test showed that this method could be used for sensitive and accurate determination of β-agonist residues in pig tissues.

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Determination of metabolite residues of nitrofuran antibiotics in aquatic products by liquid chromatography-tandem mass spectrometry 2013, 31 (3):  206-210.  DOI: 10.3724/SP.J.1123.2012.11010 Abstract ( 2123 )   [Full Text(HTML)] () PDF (773KB) ( 667 )   A method was developed for simultaneous qualitative and quantitative analysis of five metabolites of nitrofuran antibiotics, including 3-amino-2-oxazolidinone (AOZ), 5-morpholino-methyl-3-amino-2-oxazolidinone (AMOZ), semicarbazide (SEM), 1-aminohydantoin (AHD) and 3,5-dinitrosalicylic acid hydrazide (DNSH) in aquatic products by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were hydrolyzed with HCl, and derivatized with 2-nitrobenzaldehyde at 37 ℃ for 16 hours. The derivative solutions were adjusted to pH 7.0-7.5, and the analytes were extracted by ethyl acetate. The separation was based on Thermo Aquasil C18 column (150 mm×4.6 mm, 3.0 μm). The analytes were detected by tandem mass spectrometry with electrospray ionization source with multiple reaction monitoring (MRM) mode. The developed method showed good linear correlation between the peak area ratios of the analyte and the internal standard and the concentration of the analyte with the correlation coefficients all above 0.99 over the dynamic range of 0.5-10 μg/kg. The limits of quantitation (LOQs) of AOZ, AMOZ, SEM, AHD and DNSH were 0.5 μg/kg. The average recoveries of all the compounds at four spiked levels of 0.5, 1.0, 2.0 and 4.0 μg/kg ranged from 81.3% to 100.5% with the RSDs between 3.4% and 10.0% (n=6). The method is proved to be fast and effective for simultaneous qualitative and quantitative analysis of the metabolites of the nitrofuran antibiotics in aquatic products.

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Simultaneous determination of four trace aconitum alkaloids in urine using ultra performance liquid chromatography-mass spectrometry ZHANG Panpan1,5, ZHANG Fucheng2, WANG Zhaohong3, JIANG Ye1,5*, LU Yongjiang4 2013, 31 (3):  211-217.  DOI: 10.3724/SP.J.1123.2012.10018 Abstract ( 1353 )   [Full Text(HTML)] () PDF (895KB) ( 375 )   A rapid, specific and sensitive ultra performance liquid chromatography-mass spectrometry (UPLC-MS/MS) method was developed for the simultaneous determination of four trace alkaloids, including aconitine (AC), hypaconitine (HA), mesaconitine (MA) and yunaconitine (YA) in human urine samples. UPLC-MS-MS system coupled with an electrospray ionization (ESI) source was performed in multiple reaction monitoring (MRM) mode. The sample preparation was performed with hollow fiber microextraction (HF-LPME) prior to the analysis. The enrichment factors of the four alkaloids were 102-301. The separation was applied on a Waters ACQUITY UPLC BEH C18 column (50 mm×2.1 mm, 1.7 μm) with a gradient elution of acetonitrile and 10 mmol/L NH4HCO3 as mobile phase. The retention times were less than 3 min. This method significantly improved the detection sensitivity, and the limits of quantitation were from 0.01 to 0.1 ng/L. The calibration curves were linear over the ranges of 0.01-10 ng/L for AC, MA and YA, 0.1-100 ng/L for HA in human urine samples, and the correlation coefficients were 0.9981, 0.9984, 0.9995 and 0.9986, respectively. The method was proved to be rapid and sensitive for aconitum alkaloid analysis in urine samples.

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Determination of ten pesticides of pyrazoles and pyrroles in tea by accelerated solvent extraction coupled with gas chromatography-tandem mass spectrometry 2013, 31 (3):  218-222.  DOI: 10.3724/SP.J.1123.2012.10003 Abstract ( 1508 )   [Full Text(HTML)] () PDF (1008KB) ( 588 )   An effective method was developed and applied to determine the residues of ten pesticides of pyrazoles and pyrroles in tea by accelerated solvent extraction coupled with gas chromatography-tandem mass spectrometry (ASE-GC-MS/MS). The samples were extracted with ethyl acetate-hexane(1:1, v/v) for 5 min at 1.03×107 Pa and 100 ℃ for one cycle. Then, they were purified by Envi-Carb/PSA column, and eluted by ethyl acetate-hexane (1:1, v/v). The analytes were determined by GC-MS/MS and quantified by external standard method. The limits of quantification were 0.003 mg/kg for fenpyroximate, 0.001 mg/kg for fipronil-sulfide, 0.002 mg/kg for fipronil, 0.005 mg/kg for fipronil-sulfone, 0.002 mg/kg for chlorfenapyr, 0.006 mg/kg for flusilazole, 0.001 mg/kg for difenzoquat, 0.001 mg/kg for pyraflufen-ethyl, 0.0003 mg/kg for tebufenpyrad and 0.005 mg/kg for tolfenpyrad. The results show that the proposed method is sensitive and accurate for the determination of the ten pesticide residues.

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Determination of volatile N-nitrosamine compounds in salted aquatic products by gas chromatography-mass spectrometry ZHAO Hua1, WANG Xiuyuan2*, WANG Pingya1, ZHOU Yong1, XUE Chaobo1, JIANG Lingbo1 2013, 31 (3):  223-227.  DOI: 10.3724/SP.J.1123.2012.10020 Abstract ( 1756 )   [Full Text(HTML)] () PDF (795KB) ( 624 )   An analytical method was developed for the determination of the extraction of volatile N-nitrosamine compounds including N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosodipropylamine (NDPA), N-nitrosodibutylamine (NDBA), N-nitrosopiperidine (NPIP), and N-nitrosopyrrolidine (NPYR) from salted aquatic products by gas chromatography-mass spectrometry (GC-MS). In this experiment, the separation and detection conditions were optimized for different extraction methods, solid-phase extraction columns, and chromatographic columns. The results showed that the linear correlation coefficients (R2) were higher than 0.9998 within 10-1000 μg/L, and the reproducibilities were good with the relative standard deviations (RSD) less than 8%. The recoveries were 79%-105%. It is noted that this method for the determination of volatile N-nitrosamine compounds in salted aquatic products was much more sensitivity and with a lower detection limits (0.05 μg/kg except NDPA) than the previously reported methods. This proposed method is rapid and convenient for the determination, and easy for the operation. It is appropriate for the determination of volatile N-nitrosamine compounds in various salted aquatic products.

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Rapid determination of 129 pesticide residues in vegetables and fruits by gas chromatography-triple quadrupole mass spectrometry Zhi-Ling MA Shu-Ning ZHENG 2013, 31 (3):  228-239.  DOI: 10.3724/SP.J.1123.2012.10029 Abstract ( 1504 )   [Full Text(HTML)] () PDF (895KB) ( 520 )   An analytical method for the simultaneous determination of 129 pesticides in vegetables and fruits was established based on optimized QuEChERS with gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS). The samples were extracted with acetonitrile (containing 1% (v/v) acetic acid), then the extracts were determined by GC-MS/MS in multi-reaction monitoring (MRM) mode after being cleaned up with mixed solid-phase dispersion, and the external standard method was applied to quantify the pesticides. The results showed that all the 129 pesticides had good linearity in certain ranges with the correlation coefficients (r2) higher than 0.98. The average recoveries of the most of 129 pesticides in different matrices were in the range of 66.2%-124.7% at the spiked level of 10 μg/kg, with relative standard deviations (RSDs)of 0.9%-24.4%. The limits of quantification (LOQs) of the method were 0.03-16.7 μg/kg. The results demonstrated that the developed method is simple, rapid, sensitive and high efficient for screening multiple pesticide residues in vegetables and fruits.

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Rapid determination of fatty acids in Ranunculus ternatus Thunb. by microwave-ultrasonic synergistic one-step extraction-derivatization and gas chromatography-mass spectrometry ZHAN Hanying, LIU Ruilin, WANG Dejin, YUAN Jing, XU Shengjie, ZHANG Zhiqi* 2013, 31 (3):  240-248.  DOI: 10.3724/SP.J.1123.2012.10031 Abstract ( 1439 )   [Full Text(HTML)] () PDF (2992KB) ( 433 )   A rapid and simple microwave-ultrasonic synergistic one-step extraction-derivatization (MUED) method and gas chromatography-mass spectrometry was established for the determination of low content fatty acids (FAs) profile in Ranunculus ternatus Thunb. The critical experimental parameters for MUED method were optimized with response surface methodology by taking the chromatographic peak areas of total FAs as a major response index. The best technological parameters were determined as 5.0 g of Ranunculus ternatus Thunb. powder, 50.0 mL of n-hexane, 500 W of microwave power, 50 ℃ of reaction temperature, 0.30 g of catalyst (KOH), 4.0 mL of derivatization reagent (methanol) and the time of extraction-derivatization of 8 min. The contents of individual FAs were quantified by internal standard method. The results showed that the chromatographic peak areas of the total FAs and the total unsaturated FAs contents obtained with MUED were (3.327±0.023)×107 (n=3) and (13.59±0.30) mg/g (n=3) respectively. They were markedly higher than those obtained by the conventional method which were (2.410±0.036)×107 (n=3) and (12.05±0.34) mg/g (n=3) respectively. The MUED method simplified the complicated sample handling steps, shortened the sample preparation time, reduced the cost of analysis, and improved the extraction and derivatization efficiency of the lipids, especially weakened the oxidization and decomposition of the unsaturated FAs. The simplicity, speed and practicability suggest the proposed method has significant potential for the determination of low content FAs in herbal medicines.

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Determination of four alkaloids in Compound Kushen Injection by high performance liquid chromatography with ionic liquid as mobile phase additive QI Liang, ZHANG Jing, ZHANG Zhiqi* 2013, 31 (3):  249-253.  DOI: 10.3724/SP.J.1123.2012.10039 Abstract ( 1559 )   [Full Text(HTML)] () PDF (784KB) ( 647 )   In order to improve the resolution and peak shape, 1-butyl-3-methylimidazolium tetrafluoroborate (［BMIM］BF4) was used as mobile phase additive to develop an HPLC method for the determination of four main alkaloids in Compound Kushen Injection. An Agilent TC-C18 column was used with the mobile phase of methanol-0.1% phosphoric acid solution (containing 2.2×10-4mol/L ［BMIM］BF4) (5:95, v/v), flow rate of 1.0 mL/min, column temperature of 30 ℃, and injection volume of 20 μL, detected at 205 nm. The calibration curves of matrine, sophoridine, oxymatrine and oxysophocarpine were in good linearity over the ranges of 25.8-155.0 mg/L, 40.0-240.0 mg/L, 21.7-130.0 mg/L and 37.5-225.0 mg/L, respectively, with correlation coefficients above 0.9990. The mean recoveries (n=9) were between 96.2% and 98.9%. Ionic liquid, ［BMIM］BF4, can obviously improve the resolution and peak shape. The method is simple, rapid, and reliable, and can be used for the determination of alkaloids in Sophora flavescens Ait in Compound Kushen Injection.

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Simultaneous determination of the migrations of bisphenol A and phenol in polycarbonate bottles based on subcritical water extraction and high performance liquid chromatography BAI Weiwei, LIU Shuhui*, CAO Jiangping, FAN Yingying, XIE Qilong 2013, 31 (3):  254-259.  DOI: 10.3724/SP.J.1123.2012.10033 Abstract ( 1357 )   [Full Text(HTML)] () PDF (806KB) ( 552 )   A new method was established for the simultaneous determination of the migration amounts of bisphenol A (BPA) and phenol from polycarbonate (PC) bottles based on subcritical water extraction (SWE) and high performance liquid chromatography. The optimum extraction conditions included an extraction temperature of 120 ℃, a pressure of 6.89 MPa (1000 psi), a static extraction time of 1 h and one cycle. Under the conditions, the migration amounts of the BPA ranged from 6.81 to 11.16 μg/g in 11 samples. Phenol was not detectable in 5 samples, and in other ones the migration amounts of phenol varied in the range of 3.25-6.08 μg/g. The traditional soaking extraction experiments showed that PC was subjected to weak hydrolysis after long-time leaching. The BPA and phenol were separated in 8 min. Good linearities were obtained in the range of 0.05-20 mg/L for BPA and 0.02-20 mg/L for phenol (r＞0.9997). The limits of detection were 7.6 μg/L for BPA and 2.0 μg/L for phenol. Intra-day and inter-day repeatabilities (expressed as RSD) were less than 5.21% and 11.63%, respectively. Compared with traditional water soaking extraction, the extraction efficiencies increased 49-106 times using this developed SWE method. The procedure is simple, rapid and environment friendly, and can be utilized to determine the migration amounts of BPA and phenol in PC bottles.

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Purification and identification of microcystin-RR ZHANG Yonglu, HUANG Xianing, XIAO Wenqing, ZHONG Qing, GU Kangding* 2013, 31 (3):  260-263.  DOI: 10.3724/SP.J.1123.2012.11005 Abstract ( 1251 )   [Full Text(HTML)] () PDF (768KB) ( 379 )   An effective method based on the combination of solid phase extraction and gel chromatography to extract and purify microcystin-RR (MC-RR) from natural cyanobacteria bloom was developed. Thirty five gram natural cyanobacterial bloom scum was extracted with 70% aqueous methanol. After the methanol in the crude extract was removed by a rotary evaporator, the solid phase extraction was used for preliminary purification and concentration. And then 7.5 mL eluent was concentrated to 2 mL and loaded onto a Sephadex LH-20 gel chromatographic column for further purification. The eluate was collected by tubes and detected at 238 nm. The elution curve was plotted by tube numbers as X-axis and the absorbance at 238 nm as Y-axis. The purity and the spectral characteristics of the final extract were identified with high performance liquid chromatograph (HPLC) and spectrophotometer, respectively. A total of 3.65 mg of MC-RR with a final yield of 74.1% was obtained, and the purity was more than 90% with characteristic UV absorption spectra at 238 nm.

Technical Notes

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Determination of seven strobilurin fungicide residues in Chinese herbs by liquid chromatography-tandem mass spectrometry coupled with solid phase extraction ZHANG Yule1, HUANG Chaoqun2, ZHU Xiaoyu2*, CHEN Xiaomei1,2, MO Weimin1 2013, 31 (3):  264-269.  DOI: 10.3724/SP.J.1123.2012.10021 Abstract ( 1721 )   [Full Text(HTML)] () PDF (812KB) ( 624 )   An LC-MS/MS method was developed for the simultaneously determination of seven strobilurin fungicide residues in Chinese herbs. The strobilurin fungicides include Z-metominostrobin, kresoxim-methyl, dimoxystrobin, picoxystrobin, pyraclostrobin, azoxystrobin and trifloxystrobin. The sample was extracted with ethyl acetate and cleaned-up by an amino SPE column. The seven strobilurin fungicide residues were separated on a C18 column with gradient elution of 1.0‰ formic acid and methanol as mobile phases, and detected by ESI-MS in positive ion and selective reaction monitoring （SRM） mode. External standard method was used to the quantification with good linear relationships （r≥0.996）. The LOQs were 2 μg/kg for dimoxystrobin, picoxystrobin and trifloxystrobin, 4 μg/kg for pyraclostrobin and azoxystrobin, 10 μg/kg for Z-metominostrobin and kresoxim-methyl. The recoveries were from 60.4% to 110% with the RSDs between 1.2% and 17%. The developed method is suitable for the determination and confirmation of the seven strobilurin fungicide residues in the three of Eight Zhes （Ophiopogon japonicus （Thunb.）, Scrophularia ningpoensis Hemsl. and Corydalis yanhusuo W T Wang）.

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Determination of thyroid hormones in milk by high performance liquid chromatography-tandem mass spectrometry WANG Zongyi1, YANG Dingzhong2, JI Mengyao1, JIA Changxi1*, HUANG Manqing1 2013, 31 (3):  270-274.  DOI: 10.3724/SP.J.1123.2012.10038 Abstract ( 1382 )   [Full Text(HTML)] () PDF (775KB) ( 432 )   A method of high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for the determination of thyroid hormones in milk including 3,3′,5,5′-tetraiodothyronine (T4), 3,3′,5-triiodothyronine (T3) and 3,3′,5′-triiodothyronine (rT3). The sample was extracted with acetonitrile and centrifuged, then the up layer was alkalized with concentrated ammonia water and cleaned up with a Cleanert PAX cartridge. The chromatographic separation was carried out on a Zorbax Eclipse XDB-C18 column (150 mm×2.1 mm, 3.5 μm) with the mobile phase of 37% water containing 0.1% (v/v) acetic acid and 63% of methanol with an isocratic elution mode at a flow rate of 0.3 mL/min. The mass spectrometry detection was performed in positive electrospray ionization and monitored using multiple reaction monitoring (MRM) mode (m/z 652.0/605.5 and 652.0/478.6 for T3 and rT3; m/z 777.7/731.7 and 777.7/604.9 for T4; m/z 784.0/737.9 and 784.0/639.4 for T4-13C6). The analytes were identified by their retention times and relative abundance ratios of the characteristic product ions, and quantified by internal standard method. The method was linear with the correlation coefficients (r2) greater than 0.998 in the concentration ranges investigated. The limits of detection (LODs) were not more than 0.03 ng/g, and the limits of quantification (LOQ) were not more than 0.1 ng/g for the analytes. The recoveries were 80.61%-101.7% with the relative standard deviations (RSDs) of 1.48%-9.70%. The results of five real milk samples showed that the contents of T3 were 0.59-1.30 ng/g with the RSDs of 2.06%-7.70%, and T4 and rT3 weren’t found. The method presents many merits including simple sample pretreatment, high sensitivity, good reproducibility and unequivocal confirmation and quantification for the analytes. It could be used to monitor the levels of thyroid hormones in the milk for safety quality evaluation.

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Determination of 17 amino acids in fish eggs by ultra performance liquid chromatography coupled with precolumn derivatization SUN Yanchun1,2, XU Xianzhu1*, XU Yanling1, TAN Zhijun3, MOU Zhenbo2, DU Ningning2 2013, 31 (3):  275-280.  DOI: 10.3724/SP.J.1123.2012.11011 Abstract ( 1557 )   [Full Text(HTML)] () PDF (799KB) ( 537 )   A rapid quantitative method of ultra performance liquid chromatography (UPLC) has been developed for the analysis of 17 amino acids in fish eggs from Acipenser schrenckii, Huso dauricus and Acipenser ruthenus. The analytes were hydrolyzed with 6.0 mol/L HCl. The extraction solution was concentrated under low pressure and neutralized with NaOH solution before derivatization with 6-aminoquinolyl-N-hydroxy-succinimidyl carbamate (AQC) as derivatization agent in borate buffer solution (pH 8.8). Gradient UPLC separation was performed on a C18 column (BEH C18, 100 mm×2.1 mm, 1.7 μm) with 30 mmol/L ammonium acetate (pH 3.5 adjusted with formic acid) and acetonitrile (containing 0.15%(v/v) formic acid and 30 mmol/L ammonium acetate) as the mobile phases at a flow rate of 0.7 mL/min. The detection was carried out with a photo-diode array (PDA) detector and the wavelength was set at 260 nm. The linear ranges were from 5.0 to 1000 μmol/L with the correlation coefficients (r2) ≥ 0.9950. The method was validated by the analysis of seven replicates. The 17 amino acid standards were spiked in fish eggs at three levels of 100, 500 and 750 μmol/L, and the average recoveries were 75.4%-107.3% with the relative standard deviations of 2.19%-12.3%. The limits of detection (LOD) for the analytes were from 0.94 μmol/L to 4.04 μmol/L. The method was successfully applied to the analysis of the 17 amino acids in fish eggs from Acipenser schrenckii, Huso dauricus and Acipenser ruthenus. The method is simple, rapid, precise and reliable.

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Determination of iodide, thiocyanate and perchlorate ions in environmental water by two-dimensional ion chromatography LIN Li1,3*, WANG Haibo2, SHI Yali2 2013, 31 (3):  281-285.  DOI: 10.3724/SP.J.1123.2012.10034 Abstract ( 1485 )   [Full Text(HTML)] () PDF (981KB) ( 499 )   A procedure for the determination of iodide, thiocyanate and perchlorate ions in environmental water by two-dimensional ion chromatography has been developed. At first the iodide, thiocyanate and perchlorate ions were separated from interfering ions by a column (IonPac AS16, 250 mm×4 mm). The iodide ion, thiocyanate and perchlorate ions were then enriched with an enrichment column (MAC-200, 80 mm×0.75 mm). In the 2nd-dimensional chromatography, iodide thiocyanate and perchlorate ions were separated and quantified by a capillary column (IonPac AS20 Capillary, 250 mm×0.4 mm). The linear ranges were 0.05-100 μg/L with correlation coefficients of 0.9999, and the detection limits were 0.02-0.05 μg/L. The spiked recoveries of iodide, thiocyanate and perchlorate ions were in the range of 85.1% to 100.1%. The relative standard deviations of the recoveries were 1.7% to 4.9%.