QUECHERS Method (Part 2 of 2)
To meet the demand on a quick, easy, but effective and safe sample preparation also for complex samples, special CHROMABOND® QuEChERS mixes were developed.
The food sample is homogenized in a 50 ml centrifuge tube (REF 730223) and then efficiently and economically cleaned up with pre-weighed mixes of salts and adsorbents in a 15 ml centrifuge tube.
- high-precision weighted mixtures
- high reproducibility
- individual combinations possible
- economical, because less time- and personnel-consuming
For standard samples of food with low fat content, the sample is:
- homogenized in acetonitrile,
- mixed with the ready-to-use acetate extraction mix (II)
- and centrifuged.
Then 1 ml supernatant is transferred to the centrifuge tube, which is pre-filled with Diamino clean-up mix (III). It is shaken and again centrifuged.
Instead of (III), the Diamino/Carbon Clean-up mix (IV) with a low amount of graphitized carbon is used for standard samples of food with low content of chlorophyll and/or carotinoids.
Further QuEChERS mixes, like combinations of citrate extraction mix (I) and e.g. Diamino/Carbon Clean-up mix (V) with higher amount of graphitized carbon or Diamino/C18 ec Clean-up mix (VI) are used for complex food samples depending on their properties.
The detailed composition of the mixes is described on the CHROMABOND® Diamino/QuEChERS website.
Since its introduction the QuEChERS method, especially with the high-precision weighted ready-to-use mixes, meets the demands on an economical and environmentally compatible sample analysis. Numerous publications and applications, not only for pesticide analysis of fruit and vegetables, show the importance of QuEChERS and comparable methods in the future . Also further foodstuffs, like (instant) coffee or cacao will be brought into the focus of QuEChERS – thus, further interesting applications can be expected.
 M. Anastassiades, S.J. Lehotay, D. Stajhbaher, F.J. Schenk, Fast and Easy Multiresidue Method Employing Acetonitrile Extraction/Partioning and “Dispersive Solid-Phase Extraction” for the Determination of Pesticide Residues in Produce, Journal of AOAC Int. 86(2): 412-431
 CVUA Stuttgart, Pesticide Residue Laboratory, Participation in Proficiency Tests using the QuEChERS-Method, April 2006, 1-5
 QuEChERS – A Mini-Multiresidue Method for the Analysis of Pesticide Residues in Low-Fat Products, M. Anastassiades, CVUA Stuttgart, 1-12
 R.E. Majors, Sample Preparation Perspectives: QuEChERS – A New Technique for Multiresidue Analysis of Pestcides in Foods and Agricultural Samples, LCGC Asia Pacific, February 2008, 22-31
CHROMABOND® QuEChERS – Special Pre-Mixes for Determination of Pesticides in Food Samples
Since the QuEChERS method was introduced a few years ago it has been readily accepted by many analysts working in the pesticide residue area.
The QuEChERS method (Quick Easy Cheap Effective Rugged Safe) involves specially modified silica with primary and secondary amine function (CHROMABOND® Diamino) and removes polar compounds (e.g. organic acids, pigments, sugars) from matrices like fruit or vegetables with low fat content.
Aside from a special CHROMABOND® Diamino adsorbent SORBTECH offers a broad range of different QuEChERS Pre-Mixes, containing precisely weighted salts and buffers (e.g. magnesium sulfate, black carbon, C18 silica, sodium citrate or acetate)