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@#Abstract: Nitrobenzene compounds (NBCs) are widely used in the world. It has 40 isomers such as nitrobenzene, dinitrobenzene and nitrotoluene, that are highly toxic and difficult to degrade and can cause harm to human health in different degrees. At pres⁃ ent, there is no unified standard method and occupational exposure limit for the detection of NBCs in the air. In terms of sampling medium, solid adsorption tube is mostly used for trapping vapor state NBCs, and filter membrane and solid adsorption tube are mostly used in series for sampling coexist NBCs in vapor state and aerosol state. In the detection methods, gas chromatography and liquid chromatography are common, and ultraviolet spectrophotometry, Raman spectroscopy, ion migration spectrometry and some other rapid response methods and technologies are also used in the detection of NBCs. In the detection of NBCs by gas chro⁃ matography, capillary column separation is commonly used, and the main detectors are flame ionization detector, electron capture detector and mass spectrometry detector. It is of practical significance to establish a method with high sensitivity, strong practica⁃ bility, convenient operation, and can simultaneously collect and detect a variety of NBCs in different states.
RESUMO
@#Abstract: Objective - - To establish a pre column derivatization high performance liquid chromatography method for detecting Methods dimethyl sulfate (DMS) in workplace air. DMS in workplace air was collected with mercaptopyridine impregnated （ silicone tube. The derivative of DMS and mercaptopyridine was eluted by mobile phase phase A: water, phase B: acetonitrile, ∶ the volume ratio was 40 60) , and separated with a C18 column, then detected with diode array detector and quantitated by a Results - standard curve. The linear range of DMS was 0.17 40.00 mg/L, with the correlation coefficient of 0.999 95. The detection limit and the lower limit of quantitation were 0.05 and 0.17 mg/L respectively. The minimum detection concentration and minimum quantitation concentration were 0.02 and 0.04 mg/m³, respectively (air sample volume of 4.5 L, 1.0 mL sample - - - solution). The average desorption efficiency was 98.40% 102.00%. The within run and between run relative standard deviations - - were 0.61% 3.92% and 1.71% 6.00%, respectively. The samples could be stored at room temperature for at least 14 days. Conclusion This method can be used to detect DMS in workplace air.
RESUMO
@#Objective - - To prepare the GDH 5 air sampling tube for simultaneous collection of eight kinds of chloro nitrobenzene （ ） ， compounds CNBs in the air of workplace and establish a matching determination method using gas chromatography. Methods - - ， Eight kinds of CNBs in vapor and aerosol state were collected by self developed GDH 5 air sampling tube desorbed ， ， ， by toluene separated by polysiloxane gas chromatography column detected by microcell electron capture detector and Results - （ - quantified by external standard method. It was determined that the air sampling tube was assembled by XAD 2 ion ） - ， exchange resin and glass fiber filter membrane. The linear range of CNBs was 0.80 240.00 mg/L and the linear correlation - - coefficients were greater than 0.999 9. The detection limit was 7.87 13.03 μg/L. The minimum detectable concentration was 0.60 3， - 3（ ） 1.33 μg/m and the minimum quantitative concentration was 2.00 4.22 μg/m sample 45.00 L . The average desorption - - （RSD） - ， - RSD efficiency was 101.2% 110.0%. The within run relative standard deviation was 0.8% 4.1% and the between run - Conclusion - was 0.3% 5.8%. The samples could be stored for more than 30 days at room temperature. GDH 5 air sampling tube and its associated determination method can be used for the collection and determination of eight kinds of CNBs in workplace air.
RESUMO
In this study, magnetic single-walled carbon nanotubes (MSWCNTs) were prepared by impregnating magnetic Fe3O4 nanoparticles onto the surfaces of carboxylic single-walled carbon nanotubes based on electrostatic interactions. The prepared MSWCNTs were used as the adsorbent for the dispersive solid-phase extraction (DSPE) of paraquat from human urine. After adsorption, the paraquat was quantitatively desorbed with 5%TFA in acetonitrile and determined by HPLC-MS. Extraction parameters such as the type of CNT adsorbent, extraction time, sample volume, wash solvent, and the type and volume of desorption solvent were optimized to obtain high DSPE recoveries and extraction efficiencies. Under the optimized conditions, the calibration curve was linear in the range 3.75-375.0 µg/L with a correlation coefficient of 0.999 45. The LOD (S/N=3) and LOQ (S/N=10) were 0.94 and 2.82 µg/L, respectively. The recoveries ranged from 92.89 to 108.9% for spiked real urine samples with RSDs below 3.21%. Finally, the new method was successfully used to determine paraquat in urine samples of suspected paraquat poisoning patients. The MSWCNTs exhibited suitable properties and a high adsorption capacity for the extraction of paraquat.
