Chinese Journal of Chromatography

Trypsin immobilization on silica beads modified by squamous polymer for ultra fast and highly efficient proteome digestion

SONG Zifeng1,2, ZHANG Qinglin2, ZHANG Yangjun2*, QIN Weijie2*, QIAN Xiaohong2

2012, 30 (06): 549-554. DOI: 10.3724/SP.J.1123.2012.02006

Abstract ( 1970 ) [Full Text(HTML)] ()

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Currently, the shotgun based strategy has been widely applied in proteomic research. In this strategy, protein identification relied on the identification of the corresponding proteolytic peptides. Therefore, rapid and efficient protein digestion is crucial for accurate protein identification and characterization. Even though traditional free protein digestion in solution has been widely adopted, it had a few inherent disadvantages including long incubation time, incomplete digestion and non-reusability of the protease. In this work, we developed a new type of trypsin immobilized on squamous polymer modified silica bead (SPMSB) for ultra fast and highly efficient protein digestion. The squamous polymer coated silica beads were prepared by surface initiated atom transfer radical polymerization (SI-ATRP), which leaded to surface confined growth of non-crosslinked polymer chains on the surface of the silica beads for trypsin immobilization. The digestion efficiency of the obtained SPMSB-trypsin was evaluated using both standard proteins and complex protein extracts obtained from E. coli. Highly efficient digestion was achieved in only 1-2 min digestion. Furthermore, the SPMSB-Trypsin exhibited both good stability and excellent recovery, therefore can be applied in proteomic research in the future.

Simultaneous determination of flonicamid and its metabolites in cucumbers and apples by liquid chromatography-tandem mass spectrometry

CHEN Guo, SUN Yami, YANG Ting, WU Yinliang*

2012, 30 (06): 555-559. DOI: 10.3724/SP.J.1123.2012.01034

Abstract ( 2332 ) [Full Text(HTML)] ()

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A method was developed for the simultaneous determination of flonicamid and its metabolite ［N-(4-trifluoromethylnicotinoyl)glycine (TFNG), 4-trifluoromethylnicotinic acid (TFNA) and 4-trifluoromethylnicotinamide (TFNA-AM)］ in cucumbers and apples by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with liquid-liquid extraction. The sample was extracted twice with phosphate buffer solution (pH 7.0), and the extract was adjusted to pH 1.5-2.0, then an aliquot of the extract (3 mL) was extracted with ethyl acetate. The final extract was dried under nitrogen and the residue was dissolved in 0.1% formic acid in water/methanol (80/20, v/v). The sample was analyzed by LC-MS/MS and quantified with the external standard calibration curve method. The detection limits of flonicamid, TFNG, TFNA and TFNA-AM were 0.17, 0.20, 0.35 and 0.60 μg/kg, respectively. The average recoveries of flonicamid and its metabolites in cucumbers and apples were 82.9%-104.1%. In the intra-assay, the relative standard deviations were 3.6%-6.9% at the spiked levels of 5.0-2000 μg/kg. There were good linear correlations (the calibration coefficients were above 0.998) between the peak areas and the concentrations of flonicamid and its metabolites in the range of 0.5-200 μg/L. The volume of organic solvent used in the whole pretreatment procedure was only 6 mL. The method is accurate, highly sensitive and stable for the determination of flonicamid and its metabolites.

Determination of residues of pesticides and veterinary drugs in milk by ultra performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry

GAO Fudie1,2, ZHAO Yan3, SHAO Bing1,2*, ZHANG Jing1,2

2012, 30 (06): 560-567. DOI: 10.3724/SP.J.1123.2012.02021

Abstract ( 2263 ) [Full Text(HTML)] ()

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An analytical method was established for the simultaneous determination of 42 pesticides and veterinary drugs in milk by ultra performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry (UPLC-Q-TOF-MS). The target compounds are the commonly used drugs including 13 pesticides and 29 veterinary drugs. The QuEChERS （Quick, Easy, Cheap, Effective, Rugged, and Safe） method was used for sample preparation. The analytes in milk samples were extracted with acetonitrile containing 1.0% (v/v) formic acid, and were salted out by adding anhydrous sodium sulfate and potassium chloride. After that, the extract solution was purified by dispersive solid phase extraction with C18 sorbent. In the chromatographic analysis of 42 target compounds were separated on an ACQUITY UPLCTMBEH C18 column with the gradient elution using the mobile phases of acetonitrile and water containing 0.1% formic acid. MSE (where E represents collision energy)acquisition under positive ion mode was performed to obtain accurate relative molecular masses and fragment ions. As a result, the limits of quantification (LOQ, S/N=10) of the target compounds were from 1 μg/kg to 100 μg/kg in milk. The average recoveries of the 42 analytes spiked at three concentration levels were ranged from 68.2% to 129.1% with the relative standard deviations of 2.8%-30.8%. This method can be applied to the analysis of the 42 pesticides and veterinary drugs in milk due to its fastness, simplicity and relatively high sensitivity.

Determination of clavulanic acid residue in milk by high performance liquid chromatography-tandem mass spectrometry

YANG Gang, HUANG Xianhui*, GUO Chunna, FANG Qiuhua, HE Limin

2012, 30 (06): 568-571. DOI: 10.3724/SP.J.1123.2012.02003

Abstract ( 1693 ) [Full Text(HTML)] ()

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An analytical method was developed for the determination of clavulanic acid (CLAV) in milk by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). A 2 g milk sample was deproteinized by ethanol. The supernatant was transferred into a pear-shaped bottle to be evaporated to about 0.5 mL, and the residue was dissolved with ammonium acetate solution. The sample was determined by HPLC-MS/MS after the purification. The chromatographic separation was achieved on a Luna 5u C8 column using 0.1% formic acid in water and acetonitrile as mobile phases with gradient elution. The identification of CLAV was carried out by MS/MS equipped with electrospray ionization in negative scanning and multiple reaction monitoring (MRM) modes. Matrix-matched calibration standard was used for the quantification. The calibration curve showed perfect linear in the range of 10-400 μg/kg with the correlation coefficient of 0.999. The limit of detection (LOD, S/N≥3) was 10 μg/kg in milk, and the limit of quantification (LOQ, S/N≥10) was 20 μg/kg. The mean recoveries varied from 80.00% to 91.25% at the four spiked levels of LOQ, 1/2MRL (the maximum residue limit), MRL, and 2MRL with the relative standard deviations of 5.60%-8.77%. In conclusion, the established method can be applied for the determination of CLAV residues in milk.

Determination of 11 anabolic hormones in fish tissue by multi- function impurity adsorption solid-phase extraction-ultrafast liquid chromatography-tandem mass spectrometry

YAO Shanshan*, ZHAO Yonggang, LI Xiaoping, CHEN Xiaohong, JIN Micong

2012, 30 (06): 572-577. DOI: 10.3724/SP.J.1123.2012.02014

Abstract ( 1736 ) [Full Text(HTML)] ()

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A method was developed for the determination of 11 anabolic hormones (boldenone, androstenedione, nandrolone, methandrostenolone, methyltestosterone, testosterone, testosterone acetate, trenbolone, testosterone propionate, stanozolol, fluoxymesterone) in fish by multi-function impurity adsorption solid-phase extraction-ultrafast liquid chromatography-tandem mass spectrometry. After the sample was extracted by methanol, the extract was cleaned-up quickly by C18 adsorbent, neutral alumina adsorbent and amino-functionalized nano-adsorbent. The separation was performed on a Shim-Pack XR-ODSIIcolumn (100 mm×2.0 mm, 2.2 μm) using the mobile phases of 0.1% (v/v) formic acid in acetonitrile and 0.1% (v/v) formic acid solution in a gradient elution mode. The identification and quantification were achieved by using electrospray ionization in positive ion mode (ESI+) in multiple reaction monitoring (MRM) mode. The matrix-matched external standard calibration curves were used for quantitative determination. The results showed that the calibration curves were in good linearity for the eleven analytes with the correlation coefficients (r) more than 0.999. The limits of detection (LODs, S/N＞3) for the 11 anabolic hormones were from 0.03 μg/kg to 0.4 μg/kg and the limits of quantification (LOQs, S/N＞10) were from 0.1 μg/kg to 1.5 μg/kg. The average recoveries ranged from 80.9% to 98.1% with the relative standard deviations between 5.2% and 11.5%. The method is simple, rapid, sensitive, accurate and suitable for the quantitative determination and confirmation of the 11 anabolic hormones in fish.

Determination of kojic acid in foods using high performance liquid chromatography-tandem mass spectrometry

HUANG Juan*, LIU Yan, DING Tao, ZHANG Xiaoyan, CHEN Huilan, SHEN Chongyu, WU Bin, NIU Wen

2012, 30 (06): 578-583. DOI: 10.3724/SP.J.1123.2012.02002

Abstract ( 2496 ) [Full Text(HTML)] ()

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The quantification method for the determination of kojic acid in foods using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. For solid samples, the kojic acid was extracted with acetonitrile; for liquid samples, they were diluted with water, then deproteinized by the deposition with zinc acetate and potassium ferrocyanide. The analytes were determined by HPLC-MS/MS on a C18 column with 5 mmol/L ammonium acetate/formic acid solution as mobile phases. The analysis of kojic acid was performed under selected reaction monitoring (SRM) mode by selecting one parent ion and two daughter ions as qualitative ions with ［13C6］-kojic acid as the internal standard, and the most abundant daughter ion as quantitative ion. The limits of quantification (S/N>10) were 0.1 mg/kg for the solid samples, and 2.5 mg/kg for the liquid samples. The good linearity (r＞0.99) was achieved for the target compound over the range of 0.1-2.0 mg/L. The recoveries at three levels for kojic acid were from 72.6% to 114% with the relative standard deviations no more than 11.4%. The method is simple and practical, and can be applied to most of matrices which may contain kojic acid as food additives. It can meet the qualitative and quantitative requirements for import and export foods.

Determination of 7 microcystins in Spirulina health food products by ultra performance liquid chromatography-tandem mass spectrometry

LI Bing, LIU Wei, FAN Sai, ZHAO Rong*, WU Guohua

2012, 30 (06): 584-589. DOI: 10.3724/SP.J.1123.2012.01018

Abstract ( 2032 ) [Full Text(HTML)] ()

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Ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) combined with solid phase extraction (SPE) has been developed for the determination of 7 microcystins (MCs) in Spirulina health food products. The sample was extracted by 70% (v/v) methanol. The lipid substances were isolated by centrifugation under freezing condition, and then followed by clean-up with a Waters Oasis HLB solid phase extraction cartridge. The separation was performed on a Waters ACQUITY UPLCBEH C18 column with gradient elution using acetonitrile and 0.2 mmol/L ammonium acetate. The electrospray ionization (ESI) source in positive ion mode was used for multiple reaction monitoring (MRM). The external standard method was used for the quantification. The linear ranges for 7 MCs were 20-400 μg/kg, and the correlation coefficients were not less than 0.995. The limits of detection were 6.7-33.3 μg/kg. The limits of quantification were 20.0-100.0 μg/kg. The recoveries of the 7 MCs spiked in blank Spirulina samples ranged from 87.5% to 97.9% with the relative standard deviations of 1.6%-6.9%. The results demonstrated that the method is easy, fast, sensitive, and suitable for the confirmation and quantification of the 7 MCs in Spirulina samples.

Determination of carbon-centred radicals in mainstream cigarette smoke using spin-labelled fluorophore

BIAN Zhaoyang*, TANG Gangling, YANG Fei, PANG Yongqiang, ZHANG Hongfei, HU Qingyuan

2012, 30 (06): 590-595. DOI: 10.3724/SP.J.1123.2012.01007

Abstract ( 1916 ) [Full Text(HTML)] ()

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A method of the determination of the carbon-centred radicals in mainstream cigarette smoke using a spin-labelled fluorophore, 4-((9-acridinecarbonyl)amino)-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO-9-AC), as a fluorescent probe is presented. After being producted by smoking in International Organization for Standardization (ISO) mode, the carbon-centred radicals in mainstream cigarette smoke were trapped by TEMPO-9-AC, a carbon-centred radical probe with a low fluorescence intensity. Then the latter was transformed to a stable diamagnetic o-alkoxyamine, a high-fluorescence compound. Finally, high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to demonstrate the structures of the carbon-centred radicals, and high performance liquid chromatography with a fluorescence detector (HPLC-FLD) was used to determine the concentration of the carbon-centred radicals. The results showed that the 10 carbon-centred radicals were detected in the mainstream cigarette smoke, and the total carbon-centred radicals concentrations for 1R5F, 3R4F, CM6, and two Virginia type cigarettes, were 52.5 nmol/cig, 214.6 nmol/cig, 424.1 nmol/cig, 68.6 nmol/cig, and 334.2 nmol/cig, respectively; and there was positive relation between the concentrations of the total amount of carbon-centred radicals and the tar amounts in the mainstream cigarette smoke. The detection limit was 0.318 nmol/cig, and the relative standard deviations (RSDs) ranged from 3.5% to 9.7%. This method is suitable for the determination of the carbon-centred radicals in the mainstream cigarette smoke.

Determination of chlorophenol and pyrethroid preservatives in wooden furniture by solid phase extraction coupled with gas chromatography-mass spectrometry

LI Haiyu, ZHANG Qing*, KANG Suyuan, LV Qing, BAI Hua, WANG Chao

2012, 30 (06): 596-601. DOI: 10.3724/SP.J.1123.2012.02013

Abstract ( 2053 ) [Full Text(HTML)] ()

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A method for the determination of 10 wood preservatives of chlorophenols (2,4-dichlorophenol, 2,4,6-trichlorophenol, 2,4,5-trichlorophenol, 2,3,4,6-tetrachlorophenol, pentachlorophenol, lindane) and pyrethroids (permethrin, cyfluthrin, cypermethrin, deltamethrin) in furniture by solid phase extraction (SPE) coupled with gas chromatography-mass spectrometry (GC-MS) was developed. The furniture samples were extracted twice by ultrasonic extraction in methanol. The extract was then evaporated and acetylated by the acetic anhydride and potassium carbonate. Finally the reaction solution was purified by Oasis HLB SPE column. The wood preservatives were eluted by ethyl acetate and collected for analysis by GC-MS. The ten wood preservatives can be separated and determined successfully by this method. Under the optimized conditions, the detection limits of the six chlorophenol compounds were 1 mg/kg, and the four pyrethroid compounds were 5 mg/kg, and the spiked recoveries of the 10 wood preservatives in samples were in the range of 76.0%-108.8%. Forty commercial wooden furniture samples were tested and lindane was found in some samples. The results showed that the method is accurate, rapid and sensitive. It can be effectively used to analyze the wood preservatives in wooden furniture.

Analysis of 112 pesticide residues in vegetables using dispersive-solid phase extraction and gas chromatography-triple quadrupole mass spectrometry

SHI Jiawei*, LI Jige, WANG Yufei, FAN Jianzhong

2012, 30 (06): 602-612. DOI: 10.3724/SP.J.1123.2012.02019

Abstract ( 2039 ) [Full Text(HTML)] ()

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A method was developed and validated for the simultaneous analysis of 112 pesticide residues in vegetables by gas chromatography coupled with triple quadrupole mass spectrometry (GC-QQQ-MS/MS). It is demonstrated that the optimized conditions could provide a more accurate quantitation and lower limit of quantification of the analysis by dispersive-solid phase extraction (D-SPE) cleanup. The samples were extracted with acetonitrile and toluene (8:1, v/v), and cleaned up by D-SPE. To every 5 mL extraction solution, 0.8 g MgSO4、0.05 g graphitized carbon black (GCB), 0.1 g ethylenediamine-N-propyl silyl (PSA) and 0.05 g C18 were added. The extracts were analyzed by GC-QQQ-MS/MS using internal standard method. The recoveries of the 112 pesticides at three spiked levels of 20, 50 and 200 μg/kg were ranged from 53.1% to 138.7%, and among which those of 86 pesticides were from 65.0% to 120.0%. The relative standard deviations (RSD) were less than 12%. The limits of quantifications (LOQs) (signal/noise at 10) were between 1.6 and 13.4 μg/kg. The vegetable samples collected from the market such as garlic chives, cucumber and purple cabbage were analyzed, and the residues of triazophos and fenpropathrin were detected in some of these samples. The method can be applied to the routine analysis for the determination of the 112 pesticides in vegetable samples.

Determination of homocysteine in plasma by precolumn derivatization-high performance liquid chromatography with fluorescence detection

TANG Xiufang1, ZHEN Qianna2, FAN Zimian1, FENG Chengya1, DING Min1*

2012, 30 (06): 613-617. DOI: 10.3724/SP.J.1123.2012.03026

Abstract ( 1934 ) [Full Text(HTML)] ()

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A precolumn derivatization-high performance liquid chromatographic method for the determination of homocysteine (Hcy) in plasma was established. Tris(2-carboxyethyl)phosphine hydrochloride (TCEP) and N-(1-pyrenyl)maleimide (NPM) were used as the reduced reagent and derivatization reagent, respectively. The separation was carried out on an Agilent Hypersil C-18 column (250 mm×4.0 mm, 5 μm) in gradient elution mode. The mobile phase consisted of A (15 mmol/L sodium acetate solution), B (acetonitrile) and C (300 mL water containing 1 mL acetic acid and 1 mL phosphoric acid). The eluate was monitored by the fluorescence detector at an excitation wavelength of 330 nm and an emission wavelength of 380 nm. The mean recovery of Hcy was (102.08±4.94)%. The linear range was from 0.500 μmol/L to 100 μmol/L, with a detection limit of 0.016 μmol/L. The intra-day and inter-day relative standard deviations (RSDs) for Hcy were less than 5%. Seven plasma samples of patients with hypertension and seven plasma samples of healthy controls were tested, and the results demonstrated that the Hcy in the plasma from the hypertension group was significantly different from that of the control group (p＜0.05). The developed method is simple, fast, accurate, and suitable for clinical measurement.

Separation of coagulation factor VIII with high activity using gigaporous anion exchange chromatography

KANG Limei1,2, ZHANG Yan2*, LUO Jian2, LI You2,3, ZHOU Yuefang2,4, YU Rong1*, SU Zhiguo2

2012, 30 (06): 618-623. DOI: 10.3724/SP.J.1123.2012.01036

Abstract ( 2487 ) [Full Text(HTML)] ()

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A purification process to obtain coagulation factor VIII (FVIII) with high activity from human plasma was established. Based on the analysis of the size ratio between FVIII and matrix porous medium and its effect on the protein activity, a novel purification process designed was superporous ion exchange chromatography (IEC). The operating conditions of gigaporous and traditional anion exchange chromatography were optimized separately. The chromogenic substrate, gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were used to monitor the bioactivity and purity of the chromatographic products. The results showed that the superporous medium could not only protect structure of macro-protein but also enhance its mass transfer, finally giving FVIII product with high activity. The yield of FVIII in superporous chromatography was about five times of commercially agarose chromatography and the specific activity was up to 154 IU/mg protein. Furthermore, we studied the regeneration process of the superporous medium, washing the column with 5 column volumes of 1 mol/L NaOH at a low flow rate, to ensure the chromatographic stability. This purification process is simple, reproducible and suitable for large-scale production.

Determination of four Sudan dyes in chili oil by high performance liquid chromatography with on-line photochemical derivatization and fluorescence detection

LIU Jun1, GONG Zhenbin1,2*

2012, 30 (06): 624-629. DOI: 10.3724/SP.J.1123.2012.01015

Abstract ( 1862 ) [Full Text(HTML)] ()

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A method for the measurement of Sudan I, Sudan II, Sudan III and Sudan B in chili oil using high performance liquid chromatography (HPLC) with on-line photochemical derivatization and fluorescence detection has been developed. The Sudan dyes were separated on an SB-C18 column in a single run by the mixed mobile phase of acetonitrile-water with a gradient program. A laboratory-built time/energy programmed photochemical reactor (PCR) with an ultraviolet mercury lamp was installed between a photodiode array detector (PDA) and a fluorescence detector (FLD), and it was applied to convert the non-or weakly fluorescent Sudan dyes into fluorescence emission components. The photochemical derivatization conditions and fluorescence detection parameters have been investigated and optimized. The recoveries of the standards spiked in real chili oil samples for all the dyes were 81.3%-100.4%. The relative standard deviations (RSDs, n=6) of the fluorescence signal intensity at the spiked level of 0.8 mg/kg were 2.6%-3.8%. The limits of detection (LODs) were in the range of 0.009-0.054 mg/kg and the limits of quantification (LOQs) were 0.030-0.181 mg/kg, which were better than those of the commonly used HPLC coupled with PDA. The developed method which is simple, sensitive, and selective can be applied to the routine analysis of Sudan dyes.

Simultaneous determination of seven naphthalenediols in cosmetics by reversed-phase high performance liquid chromatography

CHEN Lijian, HUANG Jinfeng, HE Minheng, LIN Senyu, GUO Xindong*

2012, 30 (06): 630-634. DOI: 10.3724/SP.J.1123.2012.02015

Abstract ( 2162 ) [Full Text(HTML)] ()

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A novel analytical method for the simultaneous determination of seven naphthalenediols (2,6-naphthalenediol, 1,5-naphthalenediol, 1,6-naphthalenediol, 2,7-naphthalenediol, 1,7-naphthalenediol, 1,3-naphthalenediol and 2,3-naphthalenediol) in cosmetics by reversed-phase high performance liquid chromatography (RP-HPLC) with a diode array detector was established. The moisturizer, cream, emulsion and water-like cosmetic samples were extracted with 95% ethanol (v/v), and the powder-like cosmetic samples were extracted with 95% ethanol-0.1% acetic acid (3:2, v/v), then the extracts were centrifuged, filtrated, and analyzed by RP-HPLC using a C18 column, employing methanol-0.1% acetic acid aqueous solution as the mobile phases under the condition of gradient elution. The naphthalenediols were qualitatively determined by retention times, and confirmed by ultraviolet spectra. The external standard method was applied for the quantification. The results indicated that the limits of quantification (LOQs) of the seven naphthalenediols were ranged from 0.5 mg/kg to 1.2 mg/kg (S/N=10); meanwhile, the linear correlation coefficients of them were all no less than 0.9990 within the linear ranges. Their recoveries in spiked samples at the levels of 5.0-50 mg/kg were ranged from 84.0% to 102% with the relative standard deviations (RSDs) of 1.3%-5.7% (n=6). The method is simple, precise and suitable for the determination of naphthalenediols in cosmetic samples.

Determination of nitrite and nitrate in dairy products by improved ion chromatography

ZHONG Yingying, CHEN Ping, YU Xuejun, XU Diming, FANG Keteng, PENG Jinfeng*

2012, 30 (06): 635-640. DOI: 10.3724/SP.J.1123.2011.12086

Abstract ( 2536 ) [Full Text(HTML)] ()

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Nitrite and nitrate are common inorganic salts in the diet and drinking water. It is generally believed that excessive intake of these substances may result in methemoglobinemia or other diseases. However, the traditional detection methods for nitrite and nitrate in dairy products restrain their applications to routine analysis due to the presence of certain limitations. In order to solve this problem, an improved national food safety standard method for the determination of nitrite and nitrate in dairy products has been studied. After water extraction, protein precipitation and centrifugation, the supernatant was cleaned up by a solid phase extraction (SPE) column. The eluent mainly composed of sodium hydroxide with acetonitrile as organic modifier. External water mode was used for suppressor. An AS 19 column was used as the analytical column, and the oven temperature was 30 ℃ while the cell temperature was 35 ℃. The detection wavelength was 225 nm and the injection volume was 200 μL. The results showed that good linearity existed when the concentrations of nitrite and nitrate were between 0.005-0.50 and 0.05-1.50 mg/L respectively. The detection limits of nitrite and nitrate were 0.2 and 0.04 mg/kg respectively when using a conductivity detector; while the values were only 0.02 and 0.01 mg/kg using an ultraviolet (UV) detector. The recoveries were between 84.0% and 104.1% when analyzing dairy products. It is a simple, fast and highly sensitive way for nitrite and nitrate detections.

Simultaneous determination of 6 antibiotics and metronidazole in acne removal products by high performance liquid chromatography

LU Jun*, PANG Yanjun, LI Yanbo, WANG Chao

2012, 30 (06): 641-646. DOI: 10.3724/SP.J.1123.2012.02024

Abstract ( 2155 ) [Full Text(HTML)] ()

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An analytical method for the simultaneous determination of 6 antibiotics (minocycline, oxytetracycline, tetracycline hydrochloride, chlorotetracycline hydrochloride, doxycycline hydrochloride and chloramphenicol) and metronidazole in acne removal products of cosmetic was established using high performance liquid chromatography (HPLC). The drugs in the sample were extracted with methanol. The separation was performed on an Agilent ZORBAX SB-C18 column (250 mm×4.6 mm, 5 μm) at 20 ℃ with methanol, acetonitrile and 0.002 mol/L oxalic acid solution as mobile phases with gradient elution at a flow rate of 0.8 mL/min. The detection was performed by a diode array detector (DAD) at 268 nm. The injection volume was 10 μL. The quantification was performed by external standard method. The calibration curves showed good linearity within the range of 1-30 mg/L with the correlation coefficients no less than 0.9970. The detection limits were in the range of 1.1-1.2 μg/g. The recoveries were between 91.9% and 107.7% in three spiked levels of 5, 10 and 20 mg/L with the relative standard deviations (RSDs) of 0.13%-1.74%. The method was used in the analysis of acne removal products, and metronidazole was found in 15% of the total test samples. The method is rapid, sensitive, accurate, effective in separation, and can be used in the determination of the six antibiotics and metronidazole in acne removal products.

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