Soil sample analytical procedure

The results have shown that we have developed a sensitive and specific ELISA assay for the analysis of clomazone residues from soil samples. The procedures have demonstrated good recovery of clomazone from soil, and excellent correlation of the ELISA test results with standard GLC methodology. In addition, the results of the ELISA tests demonstrate good correlation between the observed soil levels of clomazone, and crop injury when the bioassay is performed under controlled, greenhouse conditions. This assay could, therefore, be used as a more rapid and convenient analytical method over the standard GLC technique after further validation. 

PCBs are nonpolar compounds and consequently can be extracted from samples with nonpolar solvents. The efficiency of extraction procedure depends on the nature of the sample, which in turn determines the avaUabihty of native analyte toward the extrachon process. For example, in sediment or soil samples, analytes tend to be very hghtly bound to the matrix and the yield of the extraction may be lower than the same analyte added as spike, so it should be noted that spiking the samples tends to give higher recovery values. In such cases, the availabihty of a reference material may be crucial in order to evaluate the correct recovery of the extraction process. 

Eichrom Technologies, Uranium in soil (2 gram sample). Analytical Procedures, ACS07,Rev. 1.5,2005. 

A soil sample was taken from a field, transported back to the laboratory by road and stored for three weeks prior to analysis. The analytical procedure consisted of drying the soil in an oven at 100°C for 24 h before the analyte was extracted using 200 cm of dichloromethane. This extract was reduced in volume to 200 til and a 20 p.l aliquot then analysed by HPLC. A calibration was set up by measuring the response from a number of solutions containing known concentrations of the analyte. The resnlt obtained from the unknown , after suitable mathematical manipulation, indicated the original soil sample contained 20 0.05 mgkg of the analyte. Comment on the accuracy of this result. 

The method for chloroacetanilide soil metabolites in water determines concentrations of ethanesulfonic acid (ESA) and oxanilic acid (OXA) metabolites of alachlor, acetochlor, and metolachlor in surface water and groundwater samples by direct aqueous injection LC/MS/MS. After injection, compounds are separated by reversed-phase HPLC and introduced into the mass spectrometer with a TurboIonSpray atmospheric pressure ionization (API) interface. Using direct aqueous injection without prior SPE and/or concentration minimizes losses and greatly simplifies the analytical procedure. Standard addition experiments can be used to check for matrix effects. With multiple-reaction monitoring in the negative electrospray ionization mode, LC/MS/MS provides superior specificity and sensitivity compared with conventional liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/ultraviolet detection (LC/UV), and the need for a confirmatory method is eliminated. In summary,... 

Anticipated persistence and mobility of agrochemical and degradates Anticipated variability in soil residues and cost constraints Depends upon specific analytical procedures (and associated LOQ) and available sample storage and processing capabilities Necessary for most dryland and irrigated cropping scenarios... 

Residue analytical methods for neonicotinoids in crops, soil and water samples have been developed. The basic principle of these methods consists of the following steps extraction of the crop and/or soil samples with acetone or the other organic solvent, cleanup by liquid-liquid partition or column chromatography, and quantitative analysis by high-performance liquid chromatography with ultraviolet detection (HPLC/UV). Simple column cleanup procedures are used to improve the accuracy and sensitivity of these methods. 

The analysis of steroid sexual hormones and related synthetic compounds in WW, soil, sludge, and sediment samples is a challenging task. This is due to both the complex environmental matrices and the requirement of low detection limits. Therefore, the use of complicated, time- and labor-consuming analytical procedures is necessary. 

The fact that soil always contains water, or more precisely an aqueous solution, is extremely important to keep in mind when carrying out an analytical procedure because water can adversely affect analytical procedures and instrumentation. This can result in an over- or under-determination of the concentrations of components of interest. Deactivation of chromatographic adsorbents and columns and the destruction of sampling tools such as salt windows used in infrared spectroscopy are examples of the potential deleterious effects of water. This can also result in absorbance or overlap of essential analytical bands in various regions of the spectrum. 

It is possible to place a soil sample in an Erlenmeyer flask or other suitable container, add the desired extractant, stopper and shake for a specified period of time, filter, and analyze the extract for the analyte of interest. For an example of this type of extraction, see Procedure 12.1.4 The extract obtained from the simple extraction of 10 g of soil with water using a magnetic stirrer is shown in the right-hand flask in Figure 12.4 (see also Section 12.2.2). 

Two-dimensional GC can be used to separate complex mixtures of polyaromatic compounds, and MS used to subsequently identify the compounds. In this method, the original sample is injected into a gas chromatograph with one type of column. As the components exit the first GC, they are fed into a second GC, with a different column, for further separation and finally into a mass spectrometer. In this way, compounds that coeluted from the first column are separated on the second. Focant et al. [19] were able to separate polychlorinated dibenzo-p-dioxin (PCDD), polychlorinated dibenzofuran (PCDF), and coplanar polychlorinated biphenyl (cPCB) using this type of analytical procedure, including isotope dilution TOF-MS. These compounds are frequently found as contaminants in soils surrounding industrial settings thus, the ability to separate and identify them is extremely important [6,12,19],... 

In order to determine chemical elements in soil, samples of the soil must undergo a solid-liquid extraction. Sometimes the extracts resulting from this procedure have analyte concentrations that are too high to be measured accurately by the chosen method. Therefore, they must be diluted. At the Natural Resources Conservation Service (NRCS) Soil Survey Laboratory in Lincoln, Nebraska, an automated diluting device is used. Using this device, the analyst accurately transfers aliquots of the extract and a certain volume of extraction solution to the same container. This dilutor may also be used to pipet standards and prepare serial dilutions. 

Sediment and soil samples are homogenized and extracted. Clean-up procedures are required prior to analysis by GC/ECD or GC/MS techniques (Lopez-Avila et al. 1992 Moseman et al. 1977 Saleh and Lee 1978 Tiernan et al. 1990). For sediment, soil, and sludge, recoveries were good (>85%) with sensitivity in the low ppb range (Moseman et al. 1977 Saleh and Lee 1978). Precision is good ( <6% RSD) (Saleh and Lee 1978). Analytical difficulties (unacceptable recovery not detectable using second capillary GC column) were reported (Lopez-Avila et al. 1992 Tiernan et al. 1990). 

Analytical Procedure. After thawing, each field sample was immediately divided into 4 quarters and subsamples of approximately lOOg of moist soil taken from each for analysis. A... 

Method Performance. A blank sample, prepared using the same procedure as for the samples, was included with every five samples. PCB 28 and y-HCH were the only compounds detected in the blanks. Detection limits, calculated as mean blank +3 SD, were typically 2.3-13.3 pg/pF = 0.02-0.12 ng/g soil. Results were not blank corrected. Replicate analysis (the same soil sample extracted three times) was done for several samples. The relative standard deviation (RSD) for replicate analysis was always less than 20% (n = 3). Analytical recoveries were monitored with the aid of two recovery standards mirex for FI and 5-HCH for F2. The mean recovery for mirex was 100 ... 

The determination of volatile elemental species in biological or environmental samples, such as body fluids, tissues, soils, plants or water, generally requires a careful preconcentration and clean-up procedure in order to separate the analytes from matrix material. Several existing sample preparation procedures and applied measurement techniques (especially GC-ICP-MS in combination with... 

This relatively new technique has been proposed as an alternative to the Soxhlet procedure [92-94]. In this technique the soil sample is packed into an extraction cartridge and the analytes are extracted from the matrix with conventional low... 

Sampling procedures and, where applicable, methods of preliminary extraction of the analyte from the soil sample are reviewed in Chap. 1. Analytical methods are discussed in an order that is as logical as possible over the next sections. 

Cahill et al. [241] have developed a simple and sensitive analytical procedure for determining the concentration of trifluoroacetic acid in plant, soil, and water samples. The analysis involves extraction of trifluoroacetic acid by sulfuric acid and methanol followed by derivatisation to the methyl ester of trifluoroacetic acid. This is accomplished within a single vial without complex extraction procedures. The highly volatile methyl ester is then analysed using headspace gas chromatography. The spike recovery trials from all media ranged from a low of 86.7% to a high of 121.4%. The relative standard deviations were typically below 10%. The minimum detectable limit for the method was 34 ng/g for dry plant material, 0.20 ng/g for soil and 6.5 ng/1 for water. 

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