QuEChERS
QuEChERS is a sample preparation method for the determination of food residues in food. It was named after its positive properties with regard to previous methods: Qu ick, e asy, Ch eap, E fficient, R ugged, S afe (fast, easy, cheap, efficient, robust, secure).
history
The method was developed by Michelangelo Anastassiades during his postdoc period 2001–2002 in the research group of Steven Lehotay at the USDA / ARS-ERRC in Wyndmoor / Pennsylvania . The original goal of the method was to analyze veterinary drug residues in animal tissue. Because polar and also basic substances are generally extracted, the method was extended to pesticide analysis.
The extraction method for pesticide residues was first presented in Rome in 2002 and subsequently published in 2003.
In the years that followed, the method was further developed in order to be able to examine both additional active ingredients and other matrix groups. Acetate buffers were introduced in 2007 , which improved the recovery of pH-dependent analytes. After further optimization, citrate buffers were used and the method became the standard method in 2008 (European Standard EN 15662).
In 2007 the method was included for the first time in the official collection of examination procedures according to §§ 64 LFGB (method L 00.00-115).
principle
The substances to be examined are extracted using liquid-liquid extraction . The extract can then be further purified using different purification methods (for example using dispersive solid phase extraction ). The extract is then measured using chromatographic methods.
The main advantage of the QuEChERS method is that compared to other methods of residue analysis, the method requires less use of samples, less time for processing and less use of solvents and is therefore also more cost-effective.
execution
The implementation is exemplary and can be modified as required. For example, other or additional cleaning steps may be required for difficult matrices.
Sample preparation
The sample must be well ground and homogenized before extraction. The use of cryogenic mills is recommended for demanding matrices . The samples are mixed with liquid nitrogen or dry ice . Freezing can also be used to chop up tendons in meat or hard shells.
extraction
Acetonitrile and, if necessary, an internal standard are usually added to the sample as extraction agents . By adding a buffer-salt mixture (contains e.g. citrate buffer) the analytes are stabilized and the organic and aqueous phases are separated ( salting out ). The analytes are dissolved in the organic phase.
Clean-up
The organic phase can be purified by means of solid phase extraction . For the sake of simplicity, this can also be done by dispersive solid phase extraction. As a rule, sorbents such as PSA (primary secondary amine) are used. The aim of the clean-up is to eliminate matrix components of the sample that could interfere with the measurement from the extract without losing important analytes.
Measurement
Depending on the analytes to be measured, the extract can be analyzed using gas or liquid chromatographic methods. A mass spectrometer is usually used as the detector .
application
The QuEChERS method is one of the most widely used methods in the residue analysis of food today. Originally, the method was designed primarily for low-fat fruit and vegetable samples. Due to more recent developments and slight modifications in the implementation of the method, previously complicated matrices such as grain or fatty products such as oils or milk and meat products can now be recorded.
Individual evidence
- ↑ a b QuEChERS. Retrieved July 17, 2018 .
- ↑ Michelangelo Anastassiades, Steven J. Lehotay, Darinka Stajnbaher, Frank J. Schenck: Fast and easy multiresidue method employing acetonitrile extraction / partitioning and "dispersive solid-phase extraction" for the determination of pesticide residues in produce . In: Journal of AOAC International . tape 86 , no. 2 , March 2003, ISSN 1060-3271 , p. 412-431 , PMID 12723926 .
- ↑ Michelangelo Anastassiades: QuEChERS multi-method method development and use in routine. (PDF) In: CVUA Stuttgart. June 16, 2006, accessed October 30, 2018 .
- ↑ A Mini-Multiresidue Method for the Analysis of Pesticide Residues in Low-Fat Products. (PDF) In: CVUA Stuttgart. CVUA Stuttgart, accessed on October 30, 2018 (English).
- ↑ Picó, Yolanda ,: Food contaminants and residue analysis . 1st ed. Elsevier, Amsterdam 2008, ISBN 978-0-08-093192-0 ( limited preview in Google Book Search [accessed October 31, 2018]).