固相微萃取/气相色谱-质谱检测纺织品中有机磷农药残留

采用PDMS萃取纤维一次吸附富集纺织品中马拉硫磷、甲基对硫磷、敌敌畏、三唑磷、对硫磷、喹硫磷、二嗪磷7种有机磷农药,在气相色谱-质谱(GC-MS)进样口热解吸后进行定性定量检测。筛选了几种商品化的萃取纤维,并优化了萃取时间、萃取温度、吸附时间、盐浓度以及pH值等萃取条件。本方法操作简单、快速、环保,检出限低,可适用于生态纺织品中物质的快速检测。     

Immobilization of acetylcholinesterase on functionalized SBA-15 mesoporous molecular sieve for detection of organophosphorus and carbamate pesticide

A novel method for the immobilization of acetylcholinesterase (AChE) on amino modified SBA-15 mesoporous molecular sieves was developed via electrostatic adsorption and glutaraldehyde crosslinking. The immobilized AChE could be exploited as a fast, sensitive and low-cost biocatalyst towards the detection of pesticides residues which could be stored at room temperature for a long time.     

Simultaneous extraction of norflurazon and oxadixyl residues from food crops with supercritical carbon dioxide

Summary Norflurazon and Oxadixyl residues have been analysed by HRGC-ECD after extraction from field-treated sugar cane and grapes using classical solid-liquid extraction or supercritical fluid extraction. The extraction techniques were compared; the results indicate the advantages of SFE as an alternative method for analysis of pesticides in these samples.     

Residue determination of cyromazine and its metabolite melamine in chard samples by ion-pair liquid chromatography coupled to electrospray tandem mass spectrometry

A method has been developed for the sensitive and selective determination of cyromazine and its metabolite melamine in chard samples. Both compounds are small polar basic molecules, making their determination at residue levels complicated. The method involves an extraction procedure with phosphate buffer and methanol using high-speed blender, the addition of tridecafluoroheptanoic acid (TFHA) as ion-pair reagent and the injection of the five-fold diluted extract on liquid chromatography coupled to electrospray tandem mass spectrometry (LC–ESI–MS/MS). The method has been validated for chard samples, spiked at 0.05 and 0.5 mg kg⁻¹. Quantification was carried out by using matrix-matched standards calibration and recoveries were satisfactory, with mean values for cyromazine of 103% and 93%, and relative standard deviations lower than 7%. In the case of melamine, recoveries were 89% and 86%, with relative standard deviations lower than 13%. A limit of quantification of 0.05 mg kg⁻¹ was obtained for both compounds, with the limit of detection below 0.01 mg kg⁻¹. The method, with very little sample handling and good sensitivity, was applied to the rapid determination of low residue levels of these compounds in chards from field residue trials. All the quality controls included during the analysis were satisfactory with average recoveries of 92% and 78% for cyromazine and melamine, respectively.     

A facile flow-through phosphorimetric sensing device for simultaneous determination of naptalam and its metabolite 1-naphthylamine

This paper presents the development of a single flow-through phosphorescence optosensor for simultaneous determination of pesticide N-1-naphthylphthlamic acid (NAP) and its metabolite 1-naphthylamine (NNA). The system works as a simple and rapid phosphorimetry-biparameter sensor. It is based in the on-line immobilization of the analytes onto a non-ionic resin solid support (Amberlite XAD 7) in a continuous flow system, followed by the measurement of their native phosphorescence. The determination was performed using 0.2 M TlNO₃ and 15 mM Na₂SO₃ in a carrier flow. The developed sensor was satisfactorily applied to the determination of these pesticides in drinking and mineral waters (recovery percentages between 82.8 and 114.1% with inferior relative standard deviations to 3.1%).     

Multiresidue method using SPME for the determination of various pesticides with different volatility in confined atmospheres

An analytical method is described for assessing the vapour concentration of 11 pesticides (bioallethrin, chlorpyriphos methyl, folpet, malathion, procymidone, quintozene, chlorothalonil, fonofos, penconazole and trimethacarb) in confined atmospheres (e.g. a greenhouse after pesticide application). This study is a successful extension of a method previously developed by the authors for dichlorvos to much less volatile pesticides. Sampling was performed by using polydimethylsiloxane–solid phase micro-extraction (PDMS–SPME) fibres immersed in a 250-mL sampling flask through which air samples were dynamically pumped from the analysed atmosphere. After a 40-min sampling duration, samples were analysed by GC/MS.Calibration was performed from a vapour-saturated air sample. The linearity of the observed signal versus pesticide concentration in the vapour phase was proved from spiked liquid samples whose headspace concentrations were measured by using the proposed method. This procedure gave calibration curves with regression coefficients (R²) greater than 0.98, and the repeatability of these measurements was found with RSDs of 1.9–7.6%. As a field application test, this analysis procedure was used for the determination of gaseous procymidone concentrations as a function of time in the atmosphere of an experimental 8-m² and 20-m³ greenhouse. The pesticide was sprayed according to real cultivation conditions, and measurements were made for 80 h after application (8 measurements). The observed concentrations found ranged from 200 to 500 µg m^–3, thus indicating the level of contamination of the air breathed by people in such working conditions.Abbreviations GC/MS gas chromatography/mass spectrometry - SIM selective ion monitoring - FC43 perfluorotributylamine - RSD relative standard deviation - LOD limit of detection - LOQ limit of quantification     

微分脉冲溶出伏安法测定除草通

提出了苹果、土豆、西红柿中除草通残留量的电分析化学测定方法，研究了除草通在汞电极上的电化学行为，探讨了其电极反应机理。结果表明，除草通在汞电极上具有吸附性质，其电极反应为不可逆的还原过程。本方法的测量线性范围为0．01～0．16mg/L，检出限为9．1μg/L.     

Potential of short-column liquid chromatography with tandem mass spectrometric detection for the rapid study of pesticide degradation

Summary The applicability of solid-phase extraction-LC using two short columns (SPE-LC) and/or single-short-column liquid chromatography (SSC) combined on-line with tandem mass spectrometry (MS) was demonstrated for the rapid study of pesticide degradation. A fast analytical procedure was developed to provide preliminary information concerning experimental conditions, approximate rates of degradation and identity of the degradation products. Surface water samples were spiked at relevant concentration levels with well-known microcontaminants and photolysis was used to transform parent compounds into their degradation products. In general, the strategy was as follows: at 30-min intervals 10-mL samples were on-line enriched, separated by short-column LC and recorded in full-scan MS to obtain information on the disappearance of the parent compound and the appearance of breakdown products. To obtain structural information, product-ion spectra of selected compounds appearing in the full-scan MS chromatogram were recorded; this enabled the identification of several degradation products. Total analysis time of enrichment/separation and detection was about 10–15 min.     

Determination of N-Methylcarbamate Pesticides in Vegetables by Solid-phase Extraction and Pressurized Capillary Electrochromatography

Introduction Capillary electrochromatography(CEC) is a hybrid technique that couples the good selectivity of high-performance liquid chromatography(HPLC) and the high separation efficiency of capillary electrophoresis(CE).Both charged and uncharged compou…     

Uncertainties of gas chromatographic measurement of troublesome pesticide residues in apples employing conventional and mass spectrometric detectors

In recent years the declaration of estimated uncertainty of measurement has become an integral part of analytical results. This study presents the assessment of results generated within the analysis of selected pesticides represented by carbamates, pyrethroides and azoles, residues of which may be found in treated apples. Multiresidue method used for analysis of spiked samples (residues at levels 0.040–0.163 mg/kg) consisted of (i) ethyl acetate extraction, (ii) GPC clean-up and (iii) identification/quantification of residues by GC. Procedures utilizing either conventional (electron-capture, nitrogen–phosphorus) or mass-selective detectors (quadrupole and ion trap analyzer) were evaluated. The results generated through alternative strategies of uncertainty estimation (“bottom-up”, “top-down”) were compared.

Using the “bottom-up” approach uncertainty of extraction which comprises two components—(i) repeatability of extraction and (ii) uncertainty of extraction recovery was shown to represent the main source of combined standard uncertainty (values of uncertainty of extraction for tested pesticides ranged from 4.6% to 21.6%). On the other hand, uncertainties associated with the GC calibration (uncertainties of weighing and diluting standards, uncertainties of purity of standards) were not so important (most of them did not exceed 2%). Combined standard uncertainties associated with the described analytical method ranged for individual compounds from 9.3% to 24.3%. Similar values of combined standard uncertainties were obtained using the alternative “top-down” approach.