QuEChERS-超高效液相色谱串联质谱法快速测定婴幼儿奶粉中5种黄曲霉毒素含量

建立QuEChERS-超高效液相色谱串联质谱法(UPLC-MS/MS)快速测定婴幼儿奶粉中5种黄曲霉毒素的方法.样品采用QuEChERS法提取之后,使用分散式固相萃取管(EMR-Lipid dSPE)进行净化,选择ACQUITY BEN C18色谱柱(1.7μm,2.1 mm×100 mm)分离,多反应监测采集模式(M...     

Screening of salbutamol residues in swine meat and animal feed by an enzyme immunoassay in Taiwan

An ELISA was developed for routine examination for extensive monitoring and screening programs for the residues of salbutamol in swine serum, animal feed, meat, and meat-related products destined for human consumption in Taiwan. Objectives of the study were to investigate the use of a new immunoassay for the detection of salbutamol residues in swine meat and animal feed samples, and to compare with a commercial kit in field test screens. A fast, simple and reliable sample preparation method for the determination of salbutamol was established. Field trials with 222 swine meat and 120 animal feed samples that were taken from local meat markets, auction markets and feed mills. The application and the results of two ELISA kits (a homemade and a commercial kit) for the screening of salbutamol were presented. Adopting 2 μg kg⁻¹ salbutamol as a cut-off value for swine meat, the commercial β-agonist ELISA had a sensitivity of 85.3% and a specificity of 95.2% versus GC-MS at a cut-off of 2 μg kg⁻¹. The homemade salbutamol ELISA had a sensitivity of 100% and a specificity of 90.9% and gave no false-negative rate results. Furthermore, adopting 20 μg kg⁻¹ salbutamol as a cut-off value for animal feed, both the commercial and homemade ELISA showed 100% sensitivity and 100% specificity of the assays. In conclusion, a sensitive, specific salbutamol polyclonal antibody-based ELISA has been developed that could serve as a rapid screening assay, and the detection of positive samples at the place of sampling can result in more effective control of the illegal use of β-agonists.     

Quantification of fatty acid ethyl esters (FAEE) and ethyl glucuronide (EtG) in meconium from newborns for detection of alcohol abuse in a maternal health evaluation study

Fatty acid ethyl esters (FAEE) and ethyl glucuronide (EtG) were determined in 602 meconium samples in a maternal health evaluation study for detection of gestational alcohol consumption. A validated headspace solid phase microextraction method in combination with GC-MS was used for FAEE and the cumulative concentration of ethyl palmitate, ethyl linoleate, ethyl oleate, and ethyl stearate with a cut-off of 500 ng/g was applied for interpretation. A new and simple method was developed and validated for quantification of EtG from 10–20 mg meconium with D ₅-EtG as internal standard consisting of 30 min. extraction with methanol/water (1:1, v/v), evaporation of methanol, filtration of the aqueous solution through a cellulose filter and injection into LC-MS-MS. The limits of detection and quantification for EtG were 10 and 30 ng/g, the recovery 86.6 to 106.4% and the standard deviation of the concentrations ranged from 13% at 37 ng/g to 5% at 46,700 ng/g (N?=?6). FAEE above the cut-off were found in 43 cases (7.1%) with cumulative concentrations between 507 and 22,580 ng/g and with one outlier of about 150,000 ng/g (EtG not detected). EtG was detected in 97 cases (16.3%) and concentrations between LOD and 10,200 ng/g with another outlier of 82,000 ng/g (FAEE 10,500 ng/g). Optimal agreement between the two markers was obtained with a cut-off for EtG of 274 ng/g and 547 cases with both FAEE- and EtG-negative, 33 cases with both FAEE- and EtG-positive, nine cases with FAEE-positive and EtG-negative, and seven cases with FAEE-negative and EtG-positive. Differences in physical, chemical, and biochemical properties and in the pharmacokinetic behavior are discussed as reasons for the deviating cases. In none of the 602 cases, serious alcohol consumption was reported by the mothers and no evidence for gestational ethanol exposure was observed in the medical investigation of the newborns. It is concluded that the combined use of FAEE and EtG in meconium as markers for fetal alcohol exposure essentially increases the accuracy of the interpretation and helps to avoid false positive and false-negative results.     

Determination of bisphenol A in milk by solid phase extraction and liquid chromatography-mass spectrometry

A simple and reliable analytical method based on solid phase extraction (SPE) and liquid chromatography coupled with electrospray ionization mass spectrometry was developed for the determination of bisphenol A (BPA) in milk. The effects of the experimental parameters of the LC-ESI-MS system (mobile phase and additives, flow rate, temperature of the ionization source, cone voltage and capillary potential) on the obtained signal were assessed and the parameters were optimized to provide maximum sensitivity and detectability. In addition, the performance of three commercial SPE sorbents (C18, PS-DVB and hydroxylated PS-DVB) was evaluated using spiked water and milk, diluted with a mixture of water-methanol (8:1). By using C18 cartridges and BPA-d(16) as internal standard, the mean relative recoveries at three fortification levels ranged between 97 and 104% and the corresponding inter-day precision (RSD%) was below 6% for 50 and 500 ng/g and below 20% for 5 ng/g fortification levels. It is shown that the ion suppression during ESI, the losses from the sample preparation procedure and the inter-day instability of LC-ESI-MS were overcome by the use of the deuterated internal standard. The concentration of BPA found in commercial canned milk samples ranged from <1.7 to 15.2 ng/g.     

Determination of the enantiomeric purity of amphetamine after derivatization with Sanger’s reagent (2,4-dinitrofluorobenzene [DNFB]) by simultaneous dual circular dichroism and ultraviolet spectroscopy

Determination of Se in biological materials was attempted by microwave-induced plasma mass spectrometry (MIP-MS). (1) Serum samples were available after 10 times dilution with 0.5% nitric acid solution containing 0.1% Triton X-100. When oxygen gas was inserted into the plasma gas (nitrogen) in order to improve the combustion, the sensitivity was reduced to 45%. The detection limit of this method was 0.5 ng/mL. (2) Standard reference materials on commercial base were used to evaluate the accuracy of the Se determination by MIP-MS after microwave digestion. In samples like bovine liver and human hair with Se concentrations of more than 0.7 μg/g, the standard curve method after internal standard (IS) correction was acceptable. This procedure was unsuitable for samples with low Se concentrations such as milk powder (certified value of Se 0.11 μg/g), or plant leaf samples. (3) Instead of IS correction, the peak height of the spectrum was used for calculations from the matrix matched calibration curve. The results of all materials were close to the certified values, even at 25 ng/g. The detection limit of the MIP-MS with microwave digestion and IS correction was 0.05 ng/mL in standard solutions. The detection limit of the peak height method was 0.1 ng/mL and was estimated to be < 20 ng/g in plant materials.     

Determination of carbendazim in blueberries by reversed-phase high-performance liquid chromatography.

A fluorescent reversed-phase high-performance liquid chromatographic method was developed for the analysis of carbendazim in blueberries. Recoveries of fortified blueberries at 27 and 810 ng/g were more than adequate with good precision. Forty commercial blueberry samples were analyzed and the amount of carbendazim ranged from none detected (detection limit of 15 ng/g) to 155 ng/g. Confirmation of carbendazim in the blueberry samples was made by enzyme immunoassay and UV photodiode array.     

Determination of the enantiomeric purity of amphetamine after derivatization with Sanger’s reagent (2,4-dinitrofluorobenzene [DNFB]) by simultaneous dual circular dichroism and ultraviolet spectroscopy

Determination of Se in biological materials was attempted by microwave-induced plasma mass spectrometry (MIP-MS). (1) Serum samples were available after 10 times dilution with 0.5% nitric acid solution containing 0.1% Triton X-100. When oxygen gas was inserted into the plasma gas (nitrogen) in order to improve the combustion, the sensitivity was reduced to 45%. The detection limit of this method was 0.5 ng/mL. (2) Standard reference materials on commercial base were used to evaluate the accuracy of the Se determination by MIP-MS after microwave digestion. In samples like bovine liver and human hair with Se concentrations of more than 0.7 μg/g, the standard curve method after internal standard (IS) correction was acceptable. This procedure was unsuitable for samples with low Se concentrations such as milk powder (certified value of Se 0.11 μg/g), or plant leaf samples. (3) Instead of IS correction, the peak height of the spectrum was used for calculations from the matrix matched calibration curve. The results of all materials were close to the certified values, even at 25 ng/g. The detection limit of the MIP-MS with microwave digestion and IS correction was 0.05 ng/mL in standard solutions. The detection limit of the peak height method was 0.1 ng/mL and was estimated to be < 20 ng/g in plant materials. Received: 25 September 1998 / Revised: 15 February 1999 / Accepted: 18 February 1999     

Rapid high-performance liquid chromatographic method for the determination of propranolol levels in canine and feline plasma.

A sensitive high-performance liquid chromatographic method that does not require organic extraction has been developed for the determination of propranolol levels in canine and feline plasma. Equal volumes of plasma and a mixture of methanol-acetonitrile-0.1 M sodium hydroxide (3:3:4, v/v/v) were added to a microseparation unit with a 10,000 molecular mass cut-off filter. The ultrafiltrate was analyzed by reversed-phase liquid chromatography with fluorimetric detection. The consistency of the recoveries obtained eliminated the need for an internal standard (coefficients of variation less than 4%). Linear regressions for the standard curves (2.5-100 ng/ml) gave correlation coefficients above 0.9955. The detection limit was 1 ng/ml. The assay retains high sensitivity while eliminating laborious sample preparation.     

A rapid LC-MS/MS method for determination of urinary EtG and application to a cut-off limit study

Ethyl glucuronide (EtG) is a metabolite and a specific marker of alcohol consumption that can be detected days after the complete elimination of alcohol after drinking. A rapid, simple, and sensitive LC-ESI-MS/MS method for the determination of urinary ethyl glucuronide was developed and fully validated in accordance with analytical standards, using the C₁₈ column. The whole process including sample preparation and LC-MS/MS lasted 10 min. A comprehensive validation including HorRat, measurement uncertainty, system suitability and intermediate precision calculations among analysts, and a cut-off limit study was performed. The method was applied to real samples and a cutoff limit determination study. The LOD and LOQ (using the IUPAC and Eurachem methods) were determined as 104.21 ng mL^?1 and 165.00 ng mL^?1. A cut-off limit of ≈ 818 ng mg^?1 (normalised to creatinine) was found for urinary EtG. The results showed that the cut-off limits currently in use should be re-considered in further studies and standardised on a global scale. Normalisation to creatinine is important because of the risk of the dilution of urine intentionally or with a change of diet. The concentrations of real samples from subjects who had consumed alcohol were successfully predicted using this method, after zero HS-GC/MS results of urine alcohol concentration.     

高效液相色谱串联质谱法测定牛奶中的高氯酸盐

建立了高效液相色谱-串联质谱测定牛奶中高氯酸盐的方法.样品经1%乙酸-乙腈(体积比1:4)混合溶液提取,于6 000 r/min离心20 min后,经0.2μ m的尼龙滤膜、On-GuardⅡRP柱、On-GuardⅡAg柱和On-GuardⅡBa柱净化,最大反相性能色谱柱C12(Synergi 4u MAX-RP 8...     

Determination of ultratrace bismuth in milk samples by atomic fluorescence spectrometry

A sensitive procedure was developed for determination of bismuth (Bi) in milk samples by hydride generation atomic fluorescence spectrometry (HG-AFS) after microwave-assisted sample digestion with HNO3 and H2O2. The method provides a sensitivity of 1832 fluorescence units (ng/mL) with a detection limit of 0.01 ng/mL, which corresponds to 20 pg absolute limit of detection, equivalent to 0.50 ng/g in the original sample. Application of the methodology to cow milk samples from the Spanish market showed the presence of Bi at a concentration of 11.8-28.8 ng/g, which compared well with data obtained after dry ashing of samples and with data obtained by inductively coupled plasma-mass spectrometry after microwave-assisted digestion.     

A simple method of isolation of chloramphenicol in honey and its estimation by liquid chromatography coupled to electrospray ionization tandem mass spectrometry

To detect sub-ppb levels of the antibiotic chloramphenicol in honey matrix, a convenient method of extraction and measurement using liquid chromatography with detection by tandem mass spectrometry (LC/MS/MS) was developed. Honey samples fortified with chloramphenicol and isotopically labeled chloramphenicol were extracted using diatomaceous-based supported liquid-liquid extraction cartridges to generate a standard calibration curve. Four MS/MS transitions were used for quantification and four other transitions for confirmation of chloramphenicol. The limit of detection for chloramphenicol was 0.05 ng/g and the lower limit of quantification was 0.1 ng/g. Several commercial honey samples were analyzed for chloramphenicol content using this method.     

Determination of the LOQ in real-time PCR by receiver operating characteristic curve analysis: application to qPCR assays for Fusarium verticillioides and F. proliferatum

Real-time PCR (qPCR) is the principal technique for the quantification of pathogen biomass in host tissue, yet no generic methods exist for the determination of the limit of quantification (LOQ) and the limit of detection (LOD) in qPCR. We suggest using the Youden index in the context of the receiver operating characteristic (ROC) curve analysis for this purpose. The LOQ was defined as the amount of target DNA that maximizes the sum of sensitivity and specificity. The LOD was defined as the lowest amount of target DNA that was amplified with a false-negative rate below a given threshold. We applied this concept to qPCR assays for Fusarium verticillioides and Fusarium proliferatum DNA in maize kernels. Spiked matrix and field samples characterized by melting curve analysis of PCR products were used as the source of true positives and true negatives. On the basis of the analysis of sensitivity and specificity of the assays, we estimated the LOQ values as 0.11 pg of DNA for spiked matrix and 0.62 pg of DNA for field samples for F. verticillioides. The LOQ values for F. proliferatum were 0.03 pg for spiked matrix and 0.24 pg for field samples. The mean LOQ values correspond to approximately eight genomes for F. verticillioides and three genomes for F. proliferatum. We demonstrated that the ROC analysis concept, developed for qualitative diagnostics, can be used for the determination of performance parameters of quantitative PCR.     

Immunoassay for acetamiprid detection: application to residue analysis and comparison with liquid chromatography

This work describes the fundamental ability of a commercial ELISA to determine acetamiprid and the application of the ELISA to residue analysis in fruit and vegetable samples. The ELISA exhibited satisfactory sensitivity (I ₅₀ 0.6 ng/g; limit of detection 0.053 ng/g) and a high selectivity for acetamiprid versus other neonicotinoid analogs (thiacloprid amide). Methanol, which influenced the sensitivity of the ELISA the least, was selected as the extractant for the ELISA analysis. Simple dilution of sample extracts with water eliminated matrix interferences. Average recoveries from the acetamiprid-spiked agricultural samples were >95% using a simple extraction method. Analytical results obtained from the ELISA were comparable to those obtained from the reference HPLC method (r>0.99). The ELISA applied to the residue analysis of acetamiprid in agricultural products is a rapid, simple, and cost-effective method, and could be successfully applied to the detection of acetamiprid before the distribution of produce.     

Determination of astaxanthin in feeds using high performance liquid chromatography and an efficient extraction method

A high performance liquid chromatography method using an efficient extraction method was developed for the determination of astaxanthin in eight kinds of animal feed. The chromatographic separation was achieved using a C₁₈ reversed-phase column, using methanol and acetonitrile as the mobile phases with a flow rate of 1 mL/min. The feeds containing astaxanthin were first treated with maxatase, to cause enzymatic hydrolysis, and then extracted with dichloromethane. The optimized method produced recoveries of between 82.4% and 100% for all eight kinds of feed, and the coefficients of variation were lower than 4.28%. The limit of detection, defined as the concentration that gave a signal-to-noise ratio of 3, for astaxanthin was estimated to be 0.1 µg/g. The limit of quantification, defined as the lowest spiked concentration that gave an appropriate level of precision and accuracy, was 0.3 µg/g. Finally, the method developed was used to determine astaxanthin in real, commercially sourced, feed samples. The method met the requirements for the determination of astaxanthin in feed, providing satisfactory recoveries of 70–110%.     

A Disposable Carbon Nanotubes‐screen Printed Electrode (CNTs‐SPE) for Determination of the Antifungal Agent Posaconazole in Biological Samples

For the first time, the use of carbon nanotubes was exploited for the development of a sensitive electrochemical method for determination of the newly antifungal posaconazole (POS). The electrochemical activity of POS was investigated at the surface of multi‐walled nanotubes (MWNTs) modified electrode. The cyclic voltammograms showed a sharp oxidation peak at potential around 671 mV vs. Ag/AgCl. To reach the assay optimization, factors affecting the method sensitivity have been investigated, such as types of carbon nanotubes and its concentration in the electrode matrix, type of supporting electrolyte, pH, accumulation time and scan rate. A good linear relationship was obtained within the concentration range from 32–1280 ng/ml with the limit of detection and quantification of 11 ng/ml and 33 ng/ml, respectively. The proposed method was successfully applied for the determination of POS in its commercial dosage form, spiked human plasma samples, and dried blood spots. The in vivo results obtained were also used to study the pharmacokinetics of POS in human plasma. The results obtained were validated and found to be in accordance with those obtained by the reference methods.     

Separations radiochimiques rapides par echange sur le mercure : Échange redox de l'or et du platine et dosage très sélectif de ces éléments par activation aux neutrons thermiques

A rapid extraction method of platinum and gold ions by means of a mercury drop is proposed. This is based on the different redox potentials of the various couples present and gives a separation from most other elements. The phenomenon is rapid and quantitative between defined concentration limits. The selectivity is good; silver interferes but this can be avoided. The sensitivity is excellent; with neutron activation in a flux of 7.7·10¹² n.cm^-2.sec^-1 for 2 h, the lower limit is about 5 ng/ml.     

Determination of erythromycin and related substances in commercial samples using liquid chromatography/ion trap mass spectrometry

A sensitive, precise and accurate quantitative liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the measurement of erythromycin A (EA) and related substances in commercial samples was developed and validated. The samples were chromatographed on a reversed-phase column with a polar endcapping and analyzed by ion trap tandem mass spectrometry in the multiple reaction monitoring (MRM) mode using positive electrospray ionization. The method showed high recovery (>or=98.82%), high sensitivity (lower limit of quantitation of 0.25 ng/mL for EA and less than 7.3 ng/mL for the related substances) and high precision (or=0.991) with a run time of only 13 min. The method was successfully applied to the determination of EA and related substances in commercial samples. Moreover, using the advanced data-dependent acquisition capability of the ion trap software two new unexpected EA related substances could be detected and possible structures for these substances were postulated.     

Determination of palladium by flame atomic absorption spectrometry combined on-line with flow injection preconcentration using a micro-column packed with activated carbon fibre

The versatility of flow injection as a procedure for enhancing the performance of atomic spectrometry is demonstrated by the on-line separation and preconcentration of analyte ions of interest for methods employing atomic spectrometric measurements. In this paper, a sensitive method for the determination of palladium by flame atomic absorption spectrometry associated on-line with the flow injection technique has been developed. A flow system comprising a micro-column packed with activated carbon fibre was used for the concentration of palladium. In order to further enhance the performance of the analysis a new manifold with an additional column has been designed to increase the sensitivity by doubling the analytical signals. The method is sensitive and easily operating with a sampling rate of 15-20/h. The detection limit of this method is 0.3 ng/ml in standard solution and the precision is 3.9% relative standard deviation at 50 ng/ml. Recoveries of palladium in spiked solutions are 103-107%.     

Quantitative analysis of diclazuril in animal plasma by liquid chromatography/electrospray ionization mass spectrometry

A novel, sensitive and specific method for the quantitative determination of diclazuril in animal plasma using liquid chromatography combined with electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) with negative ion detection is presented. Extraction of the samples was performed with a rapid deproteinization step using acetonitrile. Chromatography of diclazuril and the internal standard was achieved on a Nucleosil ODS 5-microm column, using a gradient elution with 0.01 M ammonium acetate and acetonitrile. To obtain the highest sensitivity and specificity possible, the mass spectrometer was operated in the multiple reaction monitoring (MRM) mode. The method was validated according to the requirements defined by the European Community. Calibration curves using plasma fortified between 1-100 ng/mL and 100-2000 ng/mL showed good linear correlation (r >or= 0.9991, goodness-of-fit coefficient 相似文献