RESUMEN
Cronobacter spp. (Enterobacter sakazakii) is an emerging opportunistic pathogen with a 40-80% mortality rate in infants and immunocompromised crowd resulting from the consumption of contaminated food. A novel method for detecting Cronobacter spp. in food samples by duplex polymerase chain reaction (PCR) in combination with capillary electrophoresis-laser induced fluorescence (CE-LIF) detector has been developed. The specific gene sequences of 16S-23S rDNA internal transcribed spacer (ITS) and the outer membrane protein A (OmpA) of Cronobacter spp. were amplified by duplex PCR. The PCR products were separated and determined sensitively by CE-LIF within 12min. The relative standard deviations of migration time for the detected DNA fragments were 2.01-2.91%. The detection limit was as low as 1.6×10(1)cfu/mL of Cronobacter spp. Besides, the specificity of the method was verified by 24 non-Cronobacter bacterial strains. A total of 120 commercial infant food formula were tested for the presence of Cronobacter spp. by using the proposed method. This current study demonstrates that the combination of CE-LIF method with duplex PCR is rapid, sensitive and environmental friendly, and has the potential to be adapted for the routine detection of Cronobacter spp. in food samples. To the best of our knowledge, this is the first use of CE-LIF for the detection of Cronobacter spp.
Asunto(s)
Cronobacter/aislamiento & purificación , Electroforesis Capilar/métodos , Microbiología de Alimentos , Reacción en Cadena de la Polimerasa/métodos , Cronobacter/genética , Humanos , Lactante , Alimentos Infantiles/microbiología , Fórmulas Infantiles , Sensibilidad y EspecificidadRESUMEN
OBJECTIVE: To determine residues of multiple biphenyl ether herbicides simultaneously in water using high performance liquid chromatography (HPLC) with cloud-point extraction. METHODS: The residues of eight biphenyl ether herbicides (including bentazone, fomesafen, acifluorfen, aclonifen, bifenox, fluoroglycofenethy, nitrofen, oxyfluorfen) in water samples were extracted with cloud-point extraction of Triton X-114. The analytes were separated and determined using reverse phase HPLC with ultraviolet detector at 300 nm. Optimized conditions for the pretreatment of water samples and the parameters of chromatographic separation applied. RESULTS: There was a good linear correlation between the concentration and the peak area of the analytes in the range of 0.05-2.00 mg/L (r = 0.9991-0.9998). Except bentazone, the spiked recoveries of the biphenyl ether herbicides in the water samples ranged from 80.1% to 100.9%, with relative standard deviations ranging from 2.70% to 6.40%. The detection limit of the method ranged from 0.10 microg/L to 0.50 microg/L. CONCLUSION: The proposed method is simple, rapid and sensitive, and can meet the requirements of determination of multiple biphenyl ether herbicides simultaneously in natural waters.
Asunto(s)
Compuestos de Bifenilo/análisis , Cromatografía Líquida de Alta Presión/métodos , Herbicidas/análisis , Residuos de Plaguicidas/análisis , Contaminantes Químicos del Agua/análisis , Benzamidas/análisis , Benzotiadiazinas/análisis , Nitrobenzoatos/análisis , Sensibilidad y EspecificidadRESUMEN
OBJECTIVE: To develop an gas chromatography-electrophoretic capture detection (GC-ECD)method for determining dimethyl sulphate (DMS) in environmental samples. METHODS: The environmental samples were dissolved with acetone and the DMS was reacted with KI. The reaction product of methyl iodide was extracted with Hexane and determined by GC-ECD, with HP-5 (30.0 m x 0.32 mm x 0.25 microm) as column, high purity nitrogen as carries, 60 degrees C for column temperature and 240 degrees C for ECD and injector temperature, and 5:1 for split ratio. RESULTS: The linear range appeared from 0.05 microg/mL to 2.0 microg/mL. The detection limit was 0.0011 microg/mL. The precision [measured by relative standard deviation (RSD)] of peak area and reserved time for the standard solution was 4.95% and 0.15% respectively for intra-day detections, and 5.99% and 0.83% respectively for inter-day detections. Satisfactory results were obtained for the analysis of environmental samples. The RSD for the water and soil samples were 9.6% and 7.5% respectively and the recoveries were 76.0%-85.0% and 82.0%-110.0% respectively. CONCLUSION: The method was simple, accurate, sensitive and applicable for DMS analysis in environmental samples.
Asunto(s)
Cromatografía de Gases/métodos , Electroforesis/métodos , Contaminantes Ambientales/análisis , Ésteres del Ácido Sulfúrico/análisis , Mutágenos/análisisRESUMEN
OBJECTIVE: To establish a high performance anion chromatography method for the determination of adenosine in food. METHODS: Adenosine in the food sample was extracted with Acetonitrile-water, and separated with Amino PAC PA10 Amino acid-separation column, with 0.25 mol/L NaOH as the mobile phase. A pulse ampere detector with Au as working electrode was used throughout the experiment. RESULTS: A good linear result was produced for adenosine in the range of 1.00-20.00 microg/mL. The inner-day RSD of peak area and retention time for the standard adenosine solution were 4.97% and 0.47%, respectively. The intra-day RSD of peak area and retention time for the standard adenosine solution were 6.08% and 0.52%, respectively. The proposed method was applied to food and satisfactory results were obtained, with and average recoveries of 93.3%-106.7% and 8.86% of RSD. CONCLUSION: The high performance anion exchange chromatography method is a simple, accurate, and reliable method for measuring adenosine in food, which can be completed within 10 minutes.
Asunto(s)
Adenosina/análisis , Cromatografía Líquida de Alta Presión/métodos , Aditivos Alimentarios/análisisRESUMEN
OBJECTIVE: To develop a rapid method for determination of nicotine and its metabolite cotinine in human hair with capillary gas chromatography with flame ionization detector. METHODS: The hair sample was digested by 1.5 mol/L sodium hydroxide solution. The nicotine and cotinine in the hair sample were extracted with a mixed solvent of dichloromethane-methanol (3:1). Aliquot of the extraction solution was vaporized with nitrogen flow and then methanol was added to dissolve the analysts. The analysts were tested with capillary gas chromatography. RESULTS: The detection limits (signal to noise ratio of 3:1) were 4.3 ng/mL for nicotine and 10 ng/mL for cotinine, respectively. The spiked recoveries were 90.33%-113.1% for nicotine with relative standard deviation (RSD) of 2.1%-7.0% and 92.92%-117.4% for cotinine with relative standard deviation (RSD) of 4.4%-8.9%, respectively. CONCLUSION: The proposed method is sensitive, simple, easy and rapid. It can be easily extended to large scale applications in tobacco epidemiology studies.
Asunto(s)
Cotinina/análisis , Ionización de Llama/métodos , Cabello/química , Nicotina/análisis , Humanos , Límite de Detección , Sensibilidad y EspecificidadRESUMEN
OBJECTIVE: To develop a rapid approach of refractive index detection with high performance liquid chromatography (HPLC) for the determination of rhamnose, fructose, glucose, surose and maltose in Lycium barbarum L. METHODS: The sample was extracted with water and the analyte was separated by Zorbax Carbohydrate column with acetonitrile-water as mobile phase. RESULTS: Good linear correlations between the concentrations and the peak areas of the analyte were found, with the correlation coefficients ranging from 0.9976 to 0.9998. The spiked recovery rates ranged from 92.27% to 101.93%, with 1.85%-3.27% of relative standard deviations (n=5). The limits of detection (S/N =3) were 4-6 mg/kg. CONCLUSION: The proposed method is suitable for the determination of monosaccharide and oligosaccharide in Lycium barbarum L.
Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Lycium/química , Monosacáridos/análisis , Oligosacáridos/análisis , Límite de DetecciónRESUMEN
OBJECTIVE: To develop a method of detecting retinol (vitamin A), vitamin D3, alpha-tocopherol (vitamin E) and beta-carotene in human serums with HPLC. METHODS: Proteins were precipitated with anhydrous ethanol. Fat-solutable vitamins in human serums were extracted with aether/petroleum ether mixture and determined with HPLC. RESULTS: The linear ranges for the retinol, VD3, alpha-tocopherol and beta-carotene were 0.012 microg/mL-500 microg/mL, 0.030 microg/mL-500 microg/mL, 0.12 microg/mL-500 microg/mL, and 0.015 microg/mL-500 microg/mL, respectively. The detection limits for the retinol, VD3, alpha-tocopherol and beta-carotene were 0.012 microg/mL, 0.030 microg/mL, 0.12 microg/mL and 0.015 microg/mL, respectively. The relative standard derivations (RSD) for the retinol, VD3, alpha-tocopherol and beta-carotene were 0.75%, 0.54%, 2.06% and 2.74%, respectively. The proposed method recovered 92%-116%, 98%-112%, 84.8%-106%, and 90%-105% retinol, VD3, alpha-tocopherol and beta-carotene in human serums respectively. CONCLUSION: The method is simple, quick and applicable to all of the four fat-solutable vitamins.
Asunto(s)
Colecalciferol/análisis , Cromatografía Líquida de Alta Presión/métodos , Vitamina A/análisis , alfa-Tocoferol/análisis , beta Caroteno/análisis , Humanos , Límite de DetecciónRESUMEN
A flow injection-CCD-diode array detection spectrophotometric method using partial least squares (PLS) algorithm for the simultaneous determination of iron, copper and cobalt in food samples has been established. The method was based on the chromogenic reaction between metallic ions and 5-Br-PADAP in the presence of acetic acid-acetic sodium buffer solution (pH 5) containing 30 g x L(-1) ascorbic acid and 2% (phi) Triton X-100. The overlapped spectra of these complexes were collected by CCD diode array detector and the multi-wavelength absorbance data were processed using partial least squares algorithm. The reaction conditions and analytical parameters of FIA were investigated. The food samples can be analyzed without any separation after digestion, and the sampling rate was 45 x h(-1). The linear ranges of Fe2+, Cu+ and Co2+ were 0.2-10.0 microg x mL(-1), 0.1-5.0 microg x mL(-1), and 0.01-1.0 microg x mL(-1) and the detection limits were 0.2, 0.1 and 0.01 microg x mL(-1), respectively. The average recoveries of spiked samples were 89.4%-110.8% for the three elements. The relative standard deviation (RSD) of samples was in the range of 1.1%-12.1%. Comparing the proposed method with ICP-AES, the relative error was below 12.1%. Above all, this method is simple, quick, sensitive, selective, and easy to be apply and generalize.
Asunto(s)
Análisis de los Alimentos/métodos , Análisis de los Mínimos Cuadrados , Metales Pesados/análisis , Espectrofotometría/métodos , Calibración , Cobalto/análisis , Cobre/análisis , Fabaceae/química , Análisis de Inyección de Flujo , Análisis de los Alimentos/instrumentación , Concentración de Iones de Hidrógeno , Hierro/análisis , Reproducibilidad de los Resultados , Espectrofotometría/instrumentación , Espectrofotometría Atómica/métodos , Té/químicaRESUMEN
OBJECTIVE: To develop a capillary gas chromatographic method for the determination of mannitol in health food. METHODS: Mannitol was extracted from the sample with water by ultrasonic wave. The aliquot of sample solution was acetylated to form mannitol hexacetate with lower boiling point. Then the derivative was separated with the use of SPB-608 capillary chromatographic column and determined by flame ionization detector (FID) at the column temperature of 180 degrees C, the detector temperature of 210 degrees C and the nitrogen flow rate of 30 mL/min. RESULTS: The linear range of this method was 0.05-10.00 mg/mL and the limit of detection of was 0.01 mg/mL. The within-day and between-days precisions were 4.4% and 7.3%-7.6%, respectively. The average recoveries were 84.6%-107.6%. Mannitol could be separated from glucose, inositol and sorbitol under the optimum chromatographic condition. CONCLUSION: The results demonstrate that the method has the advantages of simplicity, accuracy and sensitivity. It is suitable for the determination of mannitol in health food.
Asunto(s)
Alimentos Orgánicos/análisis , Manitol/análisis , Cromatografía de Gases/métodos , HumanosRESUMEN
<p><b>OBJECTIVE</b>To compare the long-term results of laparoscopic and open radical resection for colorectal carcinoma.</p><p><b>METHODS</b>Two hundred and fifteen patients with colorectal cancer from January 1996 to September 2000 were non-randomly divided into laparoscopic and open operation groups. Local recurrence, distant metastasis, 5-year survival rate and long-term postoperative complications were compared between the two groups.</p><p><b>RESULTS</b>Eighty-seven cases received laparoscopic resection and 128 cases received open operation. There were no statistical differences in age, sex and tumor stage between the two groups (P > 0.05). The 5-year-survival rate was 70% in open operation group, and 78% in laparoscopic group (P > 0.05). There were no significant differences in the incidences of local recurrence, distant metastasis, incision seeding, and incision hernia between the two groups (P > 0.05). The complication rate of postoperative adhesive intestinal obstruction was significantly lower in laparoscopic group than that in open operation group (P< 0.05).</p><p><b>CONCLUSIONS</b>Long-term results of laparoscopic resection are similar to those of open resection for colorectal carcinoma, but laparoscopic surgery has less long-term complications.</p>
Asunto(s)
Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neoplasias Colorrectales , Cirugía General , Estudios de Seguimiento , Laparoscopía , Resultado del TratamientoRESUMEN
OBJECTIVE: To develop a rapid detection method for genetically modified soybean resistant to glyphosate. METHODS: A duplex PCR was performed with primers designed in this study to simultaneously amplify heterogenous genes in transgenic soybean: CaMV-35S promoter, NOS terminator and CP4-EPSPS gene. And a simple capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was developed and applied to the rapid analysis of the above PCR products by using a 50 cm length x 100 microm i.d. capillary coated with linear polyacrylamide and an 8 g/L HPMC-4000 sieving buffer under 200 V/cm electric field strength. RESULTS: The proposed method was able to simultaneously detect the three heterogenous genes existing in genetically modified soybean under the optimization conditions of PCR and capillary electrophoresis. The measured sequences of the duplex PCR products were identical with the original genes' sequences. Moreover, the sample volumes required were not more than 5 nl and the detection could be completed in less than 24 min. The relative standard deviations (R. S. D.) of the migration times for the PCR products were < or = 3.2%. CONCLUSION: In comparison with agarose gels electrophoresis, the duplex PCR-based capillary electrophoretic method with laser-induced fluorescence detection is rapid, sensitive and accurate, and it is suitable for detection of genetically modified soybean.
Asunto(s)
Electroforesis Capilar/métodos , Glycine max/genética , Plantas Modificadas Genéticamente/genética , Reacción en Cadena de la Polimerasa , ADN de Plantas/análisis , Electroforesis Capilar/instrumentación , Lactosa/análogos & derivados , Metilcelulosa/análogos & derivados , Oxazinas , Reacción en Cadena de la Polimerasa/métodosRESUMEN
A flow-injection-CCD array detection spectrophotometry for the determination of oligomeric proanthocyanidin (OPC) in health foods was developed in the present paper, based on the reaction that OPC can form red anthocyanidin in hydrochloric acid medium with ferric ion as a catalytic agent. The absorption spectrum of OPC was scanned and the absorbance at 545 nm was determined by flow injection with CCD-array detector. The influencing factors of the chromogenic reaction and parameters of the flow injection analysis were optimized. There is a good linear relationship between the absorbances and the concentrations of OPC in the range of 0.010-0.20 mg x mL(-1). The detection limit of the method was 5 microg x mL(-1). The recoveries were 82.47%-98.18% with the relative standard deviation (RSD) of 1.5%-4.9%. The proposed method is sensitive, accurate and rapid with the sampling frequency of 10 samples-h(-1) and suitable for the determination of OPC in the health food.
Asunto(s)
Análisis de Inyección de Flujo/métodos , Análisis de los Alimentos/métodos , Proantocianidinas/análisis , Análisis de Inyección de Flujo/instrumentación , Análisis de los Alimentos/instrumentación , Proantocianidinas/químicaRESUMEN
OBJECTIVE: This study was directed to the development of a simple and highly sensitive method for determination of 4-nonylphenol (4-NP) and bisphenol A (BPA) in rat serum using HPLC with fluorescence detector. METHODS: 4-NP and BPA in serum samples were extracted by a mixed solvent of n-hexane and diethyl ether (70:30), the organic layer was dried with nitrogen flow and dissolved with mobile phase. The operating conditions such as C18 column (250 mm x 4.6 mm, 5 microns), acetonitrile-ammonium acetate buffer (pH 4.5) as mobile phase at a flow rate of 1 ml/min and fluorescence detector with the excitation and emission wavelength at 227 nm and 313 nm respectively were used for the determination. RESULTS: There was good linear relationship between the concentrations of the analytes in rat serum and their peak areas in the ranges of 0.013-5.0 micrograms/ml for 4-NP and 0.004-3.0 micrograms/ml for BPA. The detection limit of the method was 13 ng/ml for 4-NP and 4 ng/ml for BPA. Recoveries of rat serum samples were 83.8%-100.0% for 4-NP and 83.3%-100.0% for BPA. The intra-day precision was 1.70%-2.70%, the inter-day precision was 2.06%-9.78%. CONCLUSION: The results showed that the method is suitable for the determination of BPA and 4-NP in serum.
Asunto(s)
Fenoles/sangre , Animales , Compuestos de Bencidrilo , Cromatografía Líquida de Alta Presión , Éter , Hexanos , Distribución Aleatoria , RatasRESUMEN
OBJECTIVE: To develop a setup of capillary electrophoresis with laser induced fluorescence detector for separating and detecting DNA fragments and protein. METHODS: The setup is assembled of He-Ne Laser with 543.5 nm as the excitation light, filter, monochromator, photomultiplier tube and a computer for controlling the system and collecting the electropherograms. RESULTS: The design of the setup and the analytical parameters were optimized. The electropherograms with high Signal-to-Noise were obtained by the laser induced fluorescence detector-capillary electrophoretic setup. For Sulforhdamine B, the detection limit was 10(-9) mol/L, and the linear range from 1 x 10(-6) mol/L to 1 x 10(-9) mol/L. The PCR products, the digested products by Hae III and BstE of mycobacterium DNA, and the human serum albumin were determined by the successful application of this setup. CONCLUSION: The setup is characterized by simple structure, low cost and high sensitivity. Compared with traditional agarose gel electrophoresis, capillary electrophoresis with laser induced fluorescence detector is more remarkable in resolution and detection time. It can be applied as a more effective means for analysis of DNA fragments and protein.
Asunto(s)
Electroforesis Capilar/instrumentación , Fluorescencia , Rayos Láser , ADN/análisis , Electroforesis Capilar/métodos , Diseño de Equipo , Proteínas/análisis , Sensibilidad y Especificidad , Espectrometría de Fluorescencia/instrumentaciónRESUMEN
The simultaneous determination of copper and iron by catalytic kinetic spectrophotometric method with back propagating artifical neural net (BP-ANN) was studied based on the catalysis of Cu(II) and Fe(III) to the reaction of rhodamine B hydrogen peroxide in the range of pH 3-9. The determination was performed by the construction of pH gradient and a CCD-diode array detector with a microcomputer. The optimum conditions of reaction and flow injection were studied. The determination limits for copper and iron were 0.10 and 0.21 microgram.L-1, respectively. The sampling rate was 10 samples per hour. The proposed method has been used to determine Cu(II) and Fe(III) in certified reference materials and food samples with satisfactory results. The average values of spiked recovery were 93.3%-100.2% with RSD of 0.6%-7.5%.
Asunto(s)
Cobre/análisis , Hierro/análisis , Animales , Catálisis , Análisis de Inyección de Flujo , Peróxido de Hidrógeno , Concentración de Iones de Hidrógeno , Cinética , Carne/análisis , Redes Neurales de la Computación , Oryza/química , Rodaminas , Espectrofotometría/métodos , PorcinosRESUMEN
A method for the determination of methanol and fusel oils in alcohol beverages using headspace solid-phase microextraction and gas chromatography (HS-SPME-GC) is presented. The solid phase was a coated epoxy resin. The extraction and chromatography conditions were optimized. Limits of detection were 0.02 mg/L-0.04 mg/L and relative standard deviations were in the range of 1.4%-4.1%. The proposed method showed better sensitivity in comparing with direct headspace gas chromatography(HS-GC, the National Standard method). This method was applied to evaluate real samples. The spiked recoveries in beer, wine and functional alcohol samples ranged from 80.8% to 110.3% for methanol and fusel oils. The results by HS-SPME-GC and HS-GC for alcohol samples coincided very well. The proposed method is simple, fast and accurate with high reproducibility, high sensitivity and low cost. It extends the applications of SPME.