The application of gas chromatography to environmental analysis

Liquid chromatography-electrospray quadrupole ion-trap mass spectrometry of nine pesticides in fruits

A liquid chromatographic method, with electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS), has been developed for determining acrinathrin, carbosulfan, cyproconazole, lambda-cyhalothrin, kresoxim methyl, pyrifenox, pyriproxyfen, propanil, and tebufenpyrad in fruits. The ions prominent in ESI spectra were [M + H]+ and [M + Na]+. In the mass analyzer, collision-induced dissociation fragmentation involved common pathways, for example, product ions of [M + H]+ resulted from the cleavage of the carbamic group or an oxygen bound. The utility of the method is demonstrated by the analysis of crude extracts obtained by matrix solid-phase dispersion (MSPD) using C18 as dispersant and dichloromethane-methanol as eluent, and by solid-liquid extraction (SLE) with ethyl acetate and anhydrous sodium sulfate. Mean recoveries ranged from 51.5 to 108%, with relative standard deviations <16%, were obtained for MSPD and from 59 to 101% with relative standard deviation <17% for SLE. However, for most compounds, limits of quantification are better by SLE (0.01-4.4 mg kg(-1)) than by MSPD (0.05-2 mg kg(-1)). During the validation process, the procedure was tested for matrix effects, blanks and stability of the system. Considerably matrix effects in the ESI ionization process were detected by comparing standard calibration, and matrix calibration. Because of this, detected residues were quantified from interpolation against calibration data obtained using matrix matched standards.

Fast chromatographic determination of polycyclic aromatic hydrocarbons in aerosol samples from sugar cane burning

Sugar cane burning in Brazil causes remarkable amounts of organic compounds to be emitted amongst which the polycyclic aromatic hydrocarbons (PAHs) represent serious health hazards. Therefore, 24-h aerosol samples (< 10 microm aerodynamic diameter) were collected in Araraquara city (São Paulo state) during the harvest season using a Hi-Vol sampler. PAHs were recovered using an Accelerated Solvent Extractor and analyzed by low-pressure gas chromatography-ion trap mass spectrometry (LP-GC-IT-MS). The fully automated extraction process was performed in less than 25 min with a solvent consumption of approximately 20 ml. The use of a deactivated 0.6 m x 0.10 mm i.d. restrictor coupled to a 10 m wide-bore analytical column allowed most of the 16 PAHs in EPA's priority list to be identified and quantified in only 13 min. Concentrations of PAHs in Araraquara aerosols ranged between 0.5 and 8.6 ng m(-3).

Determination of Polycyclic Aromatic Hydrocarbons in Water by Solid-Phase Microextraction and Liquid Chromatography

This study describes the determination of polycyclic aromatic hydrocarbons (PAHs) in water using high-performance liquid chromatography (HPLC) coupled with fluorescence detection (FLD). Because individual PAHs are generally present in water only at trace levels, a sensitive and accurate determination technique is essential. The separation and detection of five PAHs were run completely within 25 min by the HPLC/FLD system with an analytical C18 column, a fluorescence detection, and acetonitrile-water gradient elution. Calibration graphs were linear with very good correlation coefficients (r > 0.9998), and the detection limits were in the range of 2-6 ng/l for five PAHs. Solid phase microextraction (SPME) was performed for sample pretreatment prior to HPLC-FLD determination, and the governing parameters were investigated. Compared to conventional methods, SPME has high recovery, saves considerable time, and reduces solvents waste. The extraction efficiencies of five PAHs were above 88% and the extraction times were 35 min in one pretreatment procedure. One particular discovery is that 1.5 M sodium monochloroactate (ClCH2COONa) can improve the extraction yield of PAH compounds more than other inorganic salts. The SPME-HPLC-FLD technique provides a relatively simple, convenient, practical procedure, which was here successfully applied to determine five PAHs in water from authentic water samples.