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dSPE (QuEChERS)

Resprep™ QuEChERS Products

QuEChERS Tubes For Extraction and Clean-Up of Pesticide Residues From Food Products

  • Fast, simple sample extraction and cleanup using dSPE.
  • Fourfold increases in sample throughput.
  • Fourfold decreases in material cost.
  • Convenient, ready to use centrifuge tubes with ultra pure, preweighed adsorbent mixes.

 

QuechersQuick, Easy, Cheap, Effective, Rugged, and Safe, the QuEChERS ("catchers") method is based on work done and published by the US Department of Agriculture Eastern Regional Research Center in Wyndmoor, PA.(1) Researchers there were looking for a simple, effective, and inexpensive way to extract and clean pesticide residues from the many varied sample matrices with which they routinely worked. They had been using the Modified Luke Extraction Method, which is highly effective and rugged, but is both labor and glassware intensive, leading to a relatively high cost per sample. Solid phase extraction also had been effective, but the complex matrices the investigators were dealing with required multiple individual cartridges and packings to remove the many classes of interferences, adding costs and complexity to the process. A new method would have to remove sugars, lipids, organic acids, sterols, proteins, pigments and excess water, any of which often are present, but still be easy to use and inexpensive.

 

The researchers developed a simple two-step procedure. First, the homogenized samples are extracted and partitioned, using an organic solvent and salt solution. Then, the supernatant is further extracted and cleaned, using a dispersive SPE technique. Multiple adsorbents are placed in a centrifuge tube, along with the 1mL of organic solvent and the extracted residues partitioned from step 1. The contents are thoroughly mixed, then centrifuged, producing a clean extract ready for a variety of GC or HPLC analytical techniques.(2) Validation and proficiency data for the QuEChERS method are available for a wide variety of pesticides in several common food matrices at www.quechers.com.

 

Using the dispersive SPE approach, the quantity and type of adsorbents, as well as the pH and polarity of the solvent, can be easily adjusted for differing matrix interferences and "difficult" analytes. Results from this approach have been verified and modified at several USDA and Food and Drug Administration labs, and the method now is widely accepted for many types of pesticide residue samples.

 

Restek products make this approach even simpler. The centrifuge tube format, available in 2mL and 15mL sizes, contains magnesium sulfate (to partition water from organic solvent) and PSA* adsorbent (to remove sugars and fatty acids), with or without graphitized carbon (to remove pigments and sterols) or C18 packing (to remove nonpolar interferences). Custom products are available by quote request. If you are frustrated by the time and cost involved with your current approach to pesticide sample cleanup, we suggest you try this simple and economical new method.

We have products compliant with AOAC, Multi-miniresidue and Draft European methods.

Inforamtion about products is available here.

References:

  1. Anastassiades, M., S.J. Lehotay, D. Stajnbaher, F.J. Schenck, Fast and Easy Multiresidue Method Employing Acetonitrile Extraction/Partitioning and "Dispersive Solid-Phase Extraction" for the Determination of Pesticide Residues in Produce, J AOAC International, 2003, vol 86 no 22, pp 412-431.
  2. Schenck, F.J., SPE Cleanup and the Analysis of PPB Levels of Pesticides in Fruits and Vegetables. Florida Pesticide Residue Workshop, 2002

Leak Free SilTite metal ferrules for GC & GC/MS

SilTite ferrules are a unique metal ferrule specifically designed for connecting fused silica GC columns and tubing to mass spectrometer interfaces and injectors. Once fitted, SilTite ferrules provide a continuous leak free connection without the need to re-tighten the nut after a few temperature cycles. SilTite ferrules make Graphite/Vespel® ferrules obsolete for use in GC-MS connections. Their performance and cost effectiveness also makes them ideal for connecting GC columns to injectors and atmospheric detectors.

Why choose SilTite ferrules?

  • Eliminates leaks (See figures below)
  • Never needs re-tightening, even after temperature cycling
  • Ferrule remains permanently fixed to the column but does not adhere to the SilTite nut
  • No contamination from Vespel or graphite materials - 100% metal
  • Ideal for high pressure applications
  • Also available for injector interfaces
  • >500°C maximum temperature

V/G ferrules after 5 cycles

Figure 1. MS trace using a graphite Vespel ferrule after 5 temperature cycles.

SilTite ferrules after 5 cycles

Figure 2. MS trace using a SilTite ferrule after 5 temperature cycles. (Using an MS, no leaks can be detected, even after 400 temperature cycles between 70ºC and 400ºC).


Agilent S/SL inlet seal improvment

Dual Vespel Ring SealWasherless, Leak-Tight Seal for Agilent GCs ensures better tightness and easier handling than original part.

  • Prevents oxygen from permeating the carrier gas, increasing column lifetime.
  • Vespel® ring in top surface reduces operator variability by requiring minimal torque to seal.
  • Vespel® ring in bottom surface simplifies installation—eliminates the washer.

In Agilent split/splitless injection ports, it can be difficult to make and maintain a good seal with a conventional metal inlet disk. The metal-to-metal seal dictates that you apply considerable torque to the reducing nut, and, based on our testing, this does not ensure a leak-tight seal. Over the course of oven temperature cycling, metal seals are prone to leaks, which ultimately can degrade the capillary column and cause other analytical difficulties.

Agilent and Restek seal tightness comparison

Tightness

Patented Dual Vespel® Ring Inlet Seal (Restek) greatly improves injection port performance—it stays sealed, even after repeated temperature cycles, without retightening the reducing nut| This seal features two soft Vespel® rings, one embedded in its top surface and the other embedded in its bottom surface. These rings eliminate the need for a washer, and ensure very little torque is needed to make a leak-tight seal. The rings will not harm the critical seal in the injector body, or any other surface, and are outside the sample flow path. Tests using a high sensitivity helium leak detector show Dual Vespel® Ring Inlet Seals will seal equally effectively at torques from 5 in. lb. to 60 in. lb.

Why trust a metal-to-metal seal when you can make leak-tight seals quickly and easily—and more reliably—without a washer, with a Restek Dual Vespel® Ring Inlet Seal. Use a stainless steel seal for analyses of unreactive compounds. To reduce breakdown and adsorption of active compounds, use a gold-plated or Siltek®-treated seal. The gold surface offers better inertness than untreated stainless steel. Siltek® treatment provides inertness similar to that of a fused silica capillary column.

Seal options

  • Stainless Steel
  • Gold plated
  • Siltek deactivated

 

 


Dosing pumps

Dosing pumps

Dosing pumps are used in many applications, in laboratories and within industry. Often we see the needs, when we require dose liquids under specific conditions:

  • High pressure dosing (reaction chambers, aparatures)
  • High temperatures dosing
  • Injection of reactive substances
  • Dosing of viscous media

Pump HeadFor all above mentioned applications it is possible to use technology that has been proven in the area of high performance liquid chromatography (HPLC). These are double-piston pumps AZURA (Knauer), which use sphire pistons enabling precise continuous dosing under high pressure. These pumps can work with flow of 0,01 to 1000 ml/min, under temperatures of -10°C to +120°C and with viscous media up to 1000 mPa.s.

The pumps can be especially equipped so they can be used in specific application like hazardous areas.

Nice example of use of AZURA pumps is dosing of sulphur trioxide in production of methanesulfonic acid (MSA).

Materials

Pump head are available in following materials:

  • Ceramic
  • Hastelloy C-276
  • Stainless steel
  • Titanum
  • Stainless steel/Titanum

Further information about models are available here.

 



ZB-MultiResidue 1

(Application Specific Phase)GC columns

  • Proprietary phase specially designed for the separation of all types of pesticides.
  • When used in parallel with the Zebron MR-1 and MR-2 column, provides baseline resolution and confirmation of all 20.chlorinated pesticides regulated under EPA Method 8081 in <10 min.
  • MS Certified phases provide low bleed performance for pesticide confirmation by MS.
  • Low activity, decreased breakdown of sensitive pesticides such as DDT.
  • Provides robust column performance for high temperature bake outs.
  • ESC Equipped.

Zebron MultiResidue columns provide baseline resolution of all EPA Method 8081A chlorinated pesticides in less than 10 minutes. In calibration curves ranging from 5-250 ppb, the columns provided results that far exceeded the EPA requirements for % breakdown of DDT and Endrin, linearity (% RSD), and resolution of critical isomers.

The unique selectivity offered by each phase allows for increased resolution of critical compounds vs. standard 5ms type phases. Retention time data is available for over 300 different pesticides on GC/MS, further simplifying new method development.

Applications
  • Aroclors/PCBs
  • Multi-pesticide Residue Methods
  • Haloacetic Acids
  • Nitrogen Containing Pesticides
  • Organochlorine Pesticides
  • Organophosphorous Pesticides
  • Herbicides
  • Insecticides
Temperature limits
ID (mm) df(µm) Temperature limits (°C)
0.25 0.25 -60 to 320/340
0.32 0.50 -60 to 320/340
0.53 0.50 -60 to 320/340

ZB-35 HT Interferno

(35% Phenyl 65% Dimethylpolysiloxane Phase)GC columns

  • First non-metal, 35 % phenyl columns stable to 400 ˚C
  • Robust column for high temperature analysis
  • Great for high molecular weight compounds
  • Eliminate carry-over with high temperature bake outs
  • Longer lifetime with rugged high temperature, polyimide coated, fused silica tubing
  • Temperature Limits: -60 to 400 °C (Isothermal/TPGC)
  • Equivalent to USP Phase G42

 

High temperature stable intermediate polarity GC column used to effectively resolve compounds that have similar boiling points, but different functionalities. High temperature limits also allow you to bake off contaminants and extend column lifetime.

Applications
  • Amines
  • Pesticides
  • Aroclors
  • Semivolatiles
  • Drugs of Abuse
  • Steroids
Temperature limits
ID (mm) df(µm) Temperature limits (°C)
0.25 0.25 -60 to 400
0.32 0.25 -60 to 400

ZB-MultiResidue 2

(Application Specific Phase)GC columns

  • Proprietary phase specially designed for the separation of all types of pesticides, herbicides, and insecticides.
  • When used in parallel with the Zebron MR-1 and MR-2 column, provides baseline resolution and confirmation of all 20 chlorinated pesticides regulated under EPA Method 8081 in <10 min.
  • MS Certified phases provide low bleed performance for pesticide confirmation by MS.
  • Low activity, decreased breakdown of sensitive pesticides such as DDT.
  • Provides robust column performance for high temperature bake outs.
  • ESC Equipped.

Zebron MultiResidue columns provide baseline resolution of all EPA Method 8081A chlorinated pesticides in less than 10 minutes. In calibration curves ranging from 5-250 ppb, the columns provided results that far exceeded the EPA requirements for % breakdown of DDT and Endrin, linearity (% RSD), and resolution of critical isomers.

The unique selectivity offered by each phase allows for increased resolution of critical compounds vs. standard 5ms type phases. Retention time data is available for over 300 different pesticides on GC/MS, further simplifying new method development.

Applications
  • Aroclors/PCBs
  • Multi-pesticide Residue Methods
  • Haloacetic Acids
  • Nitrogen Containing Pesticides
  • Organochlorine Pesticides
  • Organophosphorous Pesticides
  • Herbicides
  • Insecticides
Temperature limits
ID (mm) df(µm) Temperature limits (°C)
0.25 0.20 -60 to 320/340
0.32 0.25 -60 to 320/340
0.53 0.50 -60 to 320/340

ZB-BAC 1&2

(Application Specific Phases)GC columns

  • Proprietary phase specially designed for blood alcohol analysis.
  • Fast run time with baseline resolution of key components in just 2 min.
  • Enhanced resolution of ethanol and acetone peaks.
  • Achieve confirmation with two elution order chenges when running columns in paraller.
  • Allows for the use of t-butanol ir n-propanol as internal standard.
  • Enhanced accuracy for post mortem samples.

The Zebron ZB-BAC-1 and -BAC2 columns efficiently separate methanol, acetaldehyde, ethanol, isopropanol and acetone. It also resolves t-butanol from other volatile solvents, enabling the use of this compound as the internal standard. This avoids the problems associated with using propanol, the traditional standard.

Applications
  • Blood Alcohol Analysis
  • Glycerols
  • Abused Inhalant Anesthetics
  • Industrial Solvents
Temperature limits
ID (mm) df(µm) Temperature limits (°C)
0.32 1.20 -20 to 260/280
0.32 1.80 -20 to 260/280
0.53 2.00 -20 to 260/280
0.53 3.00 -20 to 260/280

ZB-Drug-1

(Application Specific Phase)GC columns

  • Optimized phase for the sepration drugs of abuse.
  • Provides fast analysis with greats shape.
  • Improves resolution of targed analytes from matrix interferencies.
  • Specially deactivated fo improve quantification for drug compounds.
Applications
  • Drugs of Abuse
Temperature limits
ID (mm) df(µm) Temperature limits (°C)
0.18 0.18 -60 to 320/340
0.32 0.25 -60 to 320/340

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