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Soil analysis is routine testing for both research and farm communities. Understanding the nutrient components in soil as well as testing biosolids (often used as fertilizers) and plants are necessary in order to determine how much fertilizer is needed. The levels of pesticides and contaminating metals are also routinely evaluated.
This application note presents data on nitrogen determination in soil and plant reference materials with different nitrogen concentrations to demonstrate the performance of the system using argon as an alternative carrier gas and show the reproducibility of the results obtained.
This application note evaluates the effectiveness of a system that combines the Atomx nitrogen purge option with the Helium Saver Module for VOC analysis using U.S. EPA method 8260C. Purge and trap coupled with GC-MS enables the greatest potential selectivity and sensitivity for the analysis
Organic contaminants encompass a wide array of compounds determined as harmful or detrimental to human and environmental health. Many of these compounds are human-made chemicals that are used and produced in industrial, manufacturing and agricultural activities. Due to the potentially drastic impact of contamination and high susceptibility of soil to pollution accumulation such as agricultural runoff of pesticides, this environmental matrix is routinely analyzed for the presence of xenobiotic compounds. Exposure to contaminated soil has the potential to directly affect human health through either direct contact or indirect contamination of ground and surface water systems.
Regulatory bodies attempt to streamline the cost of known contaminant compliance monitoring by regulating them as groups with similar health effects, co-occurrence, common analytical methods, and common treatment or control practices. In addition to known contaminants, unknown compounds pose a serious threat to environmental protection and create a growing challenge across the globe.
To analyze soil for the presence of a vast assortment of compound classes and meet regulatory requirements a robust strategy is needed that employs various analytical techniques. Workflows that support sample preparation and analysis for different soil types have to be considered in order to successfully extract, identify and quantitate compounds. Extraction approaches typically include solvent exchange, solid phase extraction (SPE), accelerated solvent extraction (ASE) and/or microwave extraction methods. Chromatographic separations and Mass spectrometry techniques provide the bulk of identification and quantitation data for these compounds in environmental matrices. Common analytical methods for analyzing organic contaminants in soil include GC, HPLC, IC, GC-MS, IC-MS and LC-MS. The Thermo Fisher Scientific environmental analysis portfolio provides tailored systems for all of these routine chromatographic and mass spectrometry techniques with comprehensive workflows that enable laboratories to effectively and efficiently meet today’s organic contaminant regulations and prepare for the evolving needs of tomorrow.
Download application note AN10441 and AN20677
To accurately analyze the pesticides in soil, the pesticides must first be extracted from soil using accelerated solvent extraction (ASE) and applied to gas chromatography-mass spectrometer for targeted or untargeted analysis.
Download flyer SS52180
LC and LC-MS | |
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Routine HPLC | Vanquish™ Flex UHPLC System |
Routine / research LCMS low level and high matrix | TSQ Endura™ Triple Quadrupole Mass Spectrometer |
Targeted / untargeted and unknown research applications accurate mass requirements | Q Exactive™ Hybrid Quadrupole-Orbitrap Mass Spectrometer |
LC and LC-MS Sample prep | |
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SPE | HyperSep™ Hypercarb™ SPE Cartridges |
GC and GC-MS | |
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Routine SA GC | TRACE™ 1300 Gas Chromatograph |
Routine GCMS spec | ISQ™ LT Single Quadrupole GC-MS System |
Routine GCMS low level and high matrix | TSQ™ 8000 Evo Triple Quadrupole GC-MS/MS |
Targeted / untargeted and unknown research applications accurate mass requirements | Q Exactive™ GC Orbitrap™ GC-MS/MS |
GC and GC-MS Sample prep | |
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Volatiles | TriPlus RSH™ Autosampler |
Semivolatiles | Dionex™ ASE™ 350 Accelerated Solvent Extractor |
SPE | HyperSep™ Hypercarb™ SPE Cartridges |
At least 17 nutrients are essential for plant growth. Some are macronutrients (existing in larger amount), such as nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur, while others are micronutrients, including boron, copper, iron, manganese, and molybdenum, and others. It is critically important to know the quantity of available nutrient in both soil and compost (such as biosolids) so the right kind and amount of fertilizer can be applied. Overuse or lack of nutrients will reduce the plant growth potential, and leads to resource waste and even contamination of the soils. For soil and compost nutrient analysis, multiple routine parameters need to be measured with different technologies.
Macronutrients are necessary to measure for identification of soil quality. They can be quantified by element analyzers using combustion to convert the elements to gaseous form and further separated by gas chromatography.
For additional information, download the cook book.
All of these analyses can be performed by the following instruments:
MAS 200R autosampler → FLASH 2000 NC Soils Analyzer
In addition to element analyzers, discrete analyzers can also be used for potassium and phosphorus analysis. Different from the element analyzers that determine the nutrients by the property of the elements, the discrete analyzers use specific chemical reactions from nutrients and certain chemicals to generate colors that can be detected by discrete analyzers. Besides testing the soil, discrete analyzers are also used for drinking water and wastewater analysis.
View the case study for fertilizer analysis.
The growth of plants needs mineral elements. These mineral nutrients are micronutrients as they are required in very small amount (often in the ppm level). The mineral elements are metal elements and often are analyzed by ICP-OES.
The mineral nutrients have to be extracted from the soils before they are analyzed. There are multiple extraction methods, such as DTPA-TEA, HCL solution, Mehlich-1, Mehlich-3, and total digestion (EPA 3050B, 3051A, and 3052 Method). Depending on the requirement, different extraction methods can be used.
Mineral analysis can be performed using the following instruments:
Microwave digestion system (from CEM) → CETAC™ Autosamplers → iCAP™ 7600 ICP-OES Analyzer
In addition to the mineral metal elements, toxic heavy metals in soils, such as arsenic (metalloid), cadmium, lead, and mercury, can also be analyzed using the same technology, or more sensitive cold vapor atomic absorption spectrometer, cold vapor atomic fluorescence spectrometer, or ICP-MS technology. Quantifying these elements is required for biosolids used as fertilizer and the soil screening by the U. S. EPA. It is necessary to keep these toxic metals in really low level to keep the soil and plants away from contaminants and prevent us from eating polluted food.
Multiple technologies have been used for heavy metal analysis based on chromatography, spectroscopy, and electrochemistry.
When using ICP-MS for soil sample analysis, it is important to keep in mind the limitation of the ICP-MS for total dissolved solid (TDS). Typical ICP-MS can handle less than 0.2% TDS. However, with argon gas dilution or autodilution techniques, tolerance to high matrix is improved for ICP-MS analysis.
Instruments for ICP-MS analysis of toxic heavy metals:
CETAC™ Autosamplers → iCAP™ Q ICP-MS
Haxavelent chromium (Cr (VI)) is also a toxic species from different industries such as chemical and leather tanning industries. It is regulated in California in drinking water and soil.
The U.S. EPA has approved:
We also developed ion chromatography method using accelerated solvent extraction (ASE) to prepare the samples and further quantify Cr (VI) by ion chromatography via post-column derivertization. Download the poster note 70729.
Instruments for Cr (VI) determination in soil:
Dionex™ ASE™ 350 Accelerated Solvent Extractor → Dionex™ ICS-5000+ Hybrid HPIC™ System → Dionex™ Chromeleon™ 7.2 Chromatography Data System
Portable XRF is a powerful tool to detect heavy metal elements in soil. Analyzing up to 25 metals at one time, the XRF analyzers can analyze soil samples on the spot without the need of sample digestion. The EPA SW846 Method 6200 uses XRF for metal analysis in solid waste and soil analysis. However, the method’s low detection limit is usually higher than the regulatory level for most analytes regulated in RCRA (Resource Conservation and Recovery Act). It is used as a confirmatory method for atomic absorption technologies (such as ICP-OES and ICP-MS) in determination of metals. Nevertheless, the instrument is a great tool for on-site screening and quality control applications.
Not only is XRF used for heavy metal analysis, other elements such as S, P, Al, Mg, Si, and U, can also be analyzed.
For more information on XRF in soil applications, visit X-Ray Fluorescence (XRF) page.
Sorbents and post extraction clean-up cartridges can be used to cleanup unwanted interferences.
Thermo Scientific™ Dionex™ ASE™ Prep MAP Dispersant and Sorbent is a unique polymer designed to remove moisture and increase extraction efficiencies from wet samples including soils and food products. This unique formulation allows moisture removal up to 5 g of water per gram of polymer (at room temperature) under a variety of ionic strength conditions and using accelerated solvent extraction conditions. The polymer is a free flowing white granular material that can be easily mixed with the Thermo Scientific™ Dionex™ ASE™ Prep DE (diatomaceous earth) dispersant in a 1:1 ratio and used for improved moisture removal under accelerated solvent extraction conditions.
This is a selective normal-phase sorbent used to remove polar interferences and concentrating pesticides, alcohols, aldehydes, amines, herbicides, PCBs, ketones, nitro compounds, organic acids, and phenols from extracts prior to GC or GC-MS analysis. The Thermo Scientific™ Dionex™ ASE™ Prep Florisil cartridge is specially processed to give consistent results when used for column cleanup and separation of chlorinated pesticide residues prior to quantification by GC and is recommended for cleanup of soil extracts for pesticide analysis.
Thermo Scientific™ Dionex™ ASE™ Prep MAP Dispersant and Sorbent is a unique polymer designed to remove moisture and increase extraction efficiencies from wet samples including soils and food products. This unique formulation allows moisture removal up to 5 g of water per gram of polymer (at room temperature) under a variety of ionic strength conditions and using accelerated solvent extraction conditions. The polymer is a free flowing white granular material that can be easily mixed with the Thermo Scientific™ Dionex™ ASE™ Prep DE (diatomaceous earth) dispersant in a 1:1 ratio and used for improved moisture removal under accelerated solvent extraction conditions.
This is a selective normal-phase sorbent used to remove polar interferences and concentrating pesticides, alcohols, aldehydes, amines, herbicides, PCBs, ketones, nitro compounds, organic acids, and phenols from extracts prior to GC or GC-MS analysis. The Thermo Scientific™ Dionex™ ASE™ Prep Florisil cartridge is specially processed to give consistent results when used for column cleanup and separation of chlorinated pesticide residues prior to quantification by GC and is recommended for cleanup of soil extracts for pesticide analysis.