Pesticide sample

Betowski LD, Jones TL. 1988. Analysis of organophosphoms pesticide samples by high-performance liquid chromatography/mass spectrometry and high-performance liquid chromatography/mass spectrometry/mass spectrometry. Environ Sci Technol 22 1430-1434. 

For aerosols of nonvolatile pesticides (e.g., paraquat) and aerosols containing pesticides, sampling methods consisting of filtration and employing inertial samplers... 

Pesticide Samples Within MPC Exceeding MPC Samples Pesticide, %... 

Interpretation/report The GC retention time of a naphthalene standard and the mass spectrum of this peak confirm its presence. Because of the complexity of the chromatograms of the petroleum products and the pesticide sample, you find it impossible to examine the chromatogram of each. However, a comparison of the GC fingerprints (i.e., the matching of chromatographic peaks and comparison of peak ratios) clearly shows that the sample consists of naphthalene dissolved in kerosene. 

Fig. 21.14. Temperature-programmed capillary GC-MS total ion chromatograms for kerosene (upper trace) and Moth-Knox pesticide (lower trace). Note the similarity in the pattern of peaks, with the exception of the large peak in the pesticide sample (at a retention time of about 12.5 min). The mass spectrum and the retention time of this peak both corresponded to a standard of naphthalene.

Pesticide Sample Type PPM at Sampling Point Number ... 

In summary, it should be said that these methods may be applicable to other air sampling situations, not just workplaces, and the principles and problems involved in aerosol/vapor sampling are not in any way exclusive to pesticide sampling. 

Pesticide Sample Pesticide residues (mg/L) 0 days 7 days ... 

Fig. 15.3. Flow-injection analyser. (A) Pump set at 1ml min-1, (B) injection valves for substrate and pesticide samples, (C) one of eight potentiostats and (D) flow cell which comprises one sensor.

Table I summarizes the experimentally determined resistivity characteristics for the nine formulations investigated. On the basis of Equation 6 and these data, a high degree of spray charge-ability by the electrostatic induction process could be predicted for all the pesticide samples tested. For these particular pesticide formulations, laboratory spray tests confirmed excellent droplet charging to greater than 10 mC/kg. Similar electrical resistivity measurements will serve as a suitable predictor of the chargeability of other formulations of interest in the electrostatic pesticide-spraying process.

The thallium (present as T12S04) in a 9.486-g pesticide sample was precipitated as thallium(l) iodide. Calculate the mass percent of T12S04 in the sample if 0.1824 g of Til was recovered. 

Each laboratory prepared separate calibrants according with their own laboratory procedure. These were used for calibrating the detector within its dynamic range. Calibrants were prepared, avoiding serial dilution. A minimum of five calibration points were required. The coordinator supplied the participants with pure pesticides samples with certified purity. The participants were requested to use these calibrants or to check their own calibrants. For GC and HPLC analysis at least one internal standard was used for the final determination. 

Resnlts obtained by RE digestion of the PCR prodnct obtained for pesticides samples were different as the expected. In fact usually it is assumed the Bacillus species present in the preparations is B. thuringiensis instead of B. cereus. 

Sediments were sampled using a pre-cleaned stainless steel shovel and mixed on clean aluminium foil. Three representative samples, each of approximately 500 g, were taken and wrapped in aluminium foil, packed in black polythene bags and placed in an icebox containing wet ice. In the laboratory, sediment samples were stored at -20 C in a deep freezer prior to extraction. Extraction was done in triplicates using 25 g sample sizes following the AOAC method 970.52 for multi-residue analysis of pesticides. Sample extracts were cleaned by eluting through the Florisil column as described for water samples above. 

To check the application of the investigated method, carbaryl was determined in commercially available pesticide samples, Carbaryl was determined in Dongbu nac (Dongbuhitek South Korea) and the results are given in Table 1. As can be seen in Table 1, the concentration of carbaryl found with the new method were in close agreement with the label claims. The results confirm that the new method is reliable and may be applied for the determination of carbaryl in pesticide samples. 

Table 1. Analytical results in commercial pesticide sample...

Carbamate Pesticides Samples Extraction Technique Technique S... 

Pesticides Samples Techniques Pre treatment Detection Column/Mode Mobile Phase of Merit Ref. n ... 

Possibilities of sample losses on the surface of matrices used in solid sampling are of some concern. While such phenomena were not observed in work with urinary volatiles [49] and steroids [50], Lines et al. [51] found some response non-linearity with pesticide samples that appeared to originate from the excessive sample retention on the capsule wall. Silylation of the capsule material visibly improved quantita-... 

A 0.5990 g pesticide sample was decomposed by wet ashing and then diluted to 200.0 nil. in a volumetric flask. The analysis was completed by treating aliquots of this solulion as indicated. 

An early exan plc of the applicaiam of IR emission spectroscopy is found In a paper that describes the use of a Fourier transform spcclroineter for the iden-tilicaiion of microgram quantities of pesticides. Samples were prepared by dissolving them in a suitable solvent followed by evaporation on a NaCI or KBr plate, fhe plate was then heated electrically near the spectrometer entrance. Pesticides such as DD T. malaihion. and dieidrin were identified in amounts as low as I to 10 fjg. 

Inhalation exposures to pesticides in the work area can be c.stimated from measuremcnt-s of concentrations of vapor, aerosol, or dust in environmental air (Ballantyne and Marrs, 2004). This can be done using passive samplers in the general work area or personal samplers in the employees breathing zone (Griffith and Duncan, 1992). However, in field situations in which pesticide samples are not of uniform size, and there may be moving variable concentrations in the air, the estimates may be misleading. 

Pesticide Sample. The pesticide mixture consists of aldicarb (5.6 mg/ml), methomyl (5.3 mg/ml), captan (5.0 mg/ml), and phenmedipham (5.1 mg/ml) prepared in dichloromethane. Samples were provided courtesy of Lee Scientific. This sample was separated using an SB-Methyl-100 10 meter 100 micron I.D. column with a 0.5 micron film (Lee Scientific). The chromatograph was programmed from an initial density of 0.180 g/ml to 0.360 g/ml at 0.010 g/ml/min after a 6.0 minute initial hold. The program rate was then immediately increased to 0.040 g/ml/min to a final density of 0.600 g/ml and held for 10 minutes. The oven temperature was maintained at lOO C throughout the experiment. The sample was delivered to the column using a 200 nL injection loop and a 22 1 split ratio. 

Reuke, S. Hauck, H.E. Thin layer chromatography as a pilot technique for HPLC demonstrated for pesticide samples. Fresenius J. Anal. Chem. 1995, 351, 739 744. Guiochon, G. Katti, A. Preparative liquid chromatography. Chromatographia 1987, 24,165-189. 

Organophosphate pesticides studied in this work were the model low-toxic OPC trichlorfon, and some common organophosphate pesticides malathion, parathion, dichlorvos, and diazinon (Table I). Calibration curves for these pesticides (dependences of the sensor inhibition response on the analyte concentration) were obtained for all of these OPCs. These calibration curves were obtained under conditions (time of inhibition, pH and temperature) optimize with the model analyte trichlorfon. All of the pesticide calibration curves are similar and Fig. 4 illustrate the method by the example of malathion. The lowest concentration of pesticide samples assayed with 10 min. of incubation of the electrode in inhibitor containing solution was 5 ppb. This resulted in approximately 10 % of the relative inhibition signal. Fig. 4 predicts much better performance of our system compared with the literature data. For example, trichlorfon detection by means of ISFET had a reported limit of detection of ca 250 ppb (5), while conductometric sensor assay registered trichlorfon at ca. 25 ppb (5), still an order of magnitude higher than the described sensor. An amperometric sensor was used to detect dichlorvos with a limit of detection of 350 ppb (2J) and a potentiometric (pH-sensitive) sensor was shown to detect parathion at 39 ppm and diazinon at 35 ppb (9). 

EnviroGard. The imaging ELISA values correlated well with the values obtained with the commercial kit The within-assay CV were between 6.4 and 11.4% while the day-to-day assay results were between 9,6 and 14.4%. A similar approach could be extended for simultaneous detection of multi-pesticide samples such as Atrazine, Simazine and 2,4-D employing the respective conjugate. The initial optimization of such assays are currently in progress (see Figure 4). 

The TLC/MS method combines the ability to separate small amounts of polar samples with the specificity of mass spectrometric identification of those materials. Fogy et al. (35) have used TLC/MS to study degradation products of organophosphorus pesticides. Polyamide 6 was used as the TLC layer material for separation of the degradation products of several organophosphorus pesticides. Samples were located on the TLC plate with a sensitive enzymatic inhibition method. The areas containing the samples of interest were removed from the plate with a spatula, and the mix of sample and support introduced on the direct insertion probe. A temperature of 1S0°C was sufficient to evaporate the sample into the electron ionization source. 

Special focus has been set to the widely used and popular sample preparation methods as there are the pressurized liquid extraction (RLE), the thermal extraction of materials and food (outgassing), and in detail on the QuEChERS pesticide sample preparation used for GC-MS and LC-MS. As a consequence of the higher matrix load of these extracts and the recommended GC injection techniques, concurrent backflush, preventive maintenance and inlet deactivation became current topics of discussion. Olfactometry solutions have been added for apphcations in flavour analysis. 

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