Stationary phases

MetAmino FAQ

What is the type of membrane inside the spin filter?

• The membrane is made of NYLON material and its porosity is 0.22 µm. Its diameter is optimized for use with a given spin filter.

It is possible to expand the MetAmino^® kit with other analytes.

• Yes, the MetAmino^® kit can be further expanded. Contact us with detailed information.

May I use the kit for urine as well?

• Yes, the MetAmino^® kit can be used with urine. The matrix should be without proteins. So, the sample has to be prepared accordingly (centrifugation, filtration).

Can we order the reagents separately?

• Yes, the entire set of reagents can be ordered under catalog number MAK-5857-L002.

What is the back pressure of the LC/MS column?

• The pressure is 380 bars during the beginning of the analysis, at the end it is 200 bars.

Are MRMs for amino acids given in the MetAmino^® Kit were made after derivatization of the standards or before?

• The MRM transitions for AAs given in the kit manual are given as transitions of the AA derivatives and not of the native AA

Should the sample of feed be hydrolyzed before working with the MetAmino^® Kit?

• Precipitation with Precipitation medium (PM) is not an essential step for successful derivatization of the sample. The kit was tested mainly for the analysis of biofluids, which often contain peptides. To avoid their precipitation during derivatization, the precipitation step was included in the sample preparation protocol.
• A total analysis of the free and peptide-bound amino acids is required. In this case, we would recommend hydrolyzing the sample and then drying the aliquot of hydrolyzed sample under a nitrogen stream or in a speedvac. We would then dissolve the dried residue in 25 µL of deionized water or 0.1M aqueous HCl (better solubility) and follow the procedure in the manual by adding 10 µL of the IS solution.
• As for the peptide hydrolysis, the additives (phenol, thiodiglycol) in the hydrolysis medium could also be derivatized (although they are probably not visible in the full scan). Therefore, we would simply recommend 6M HCl as the hydrolysis medium.

Can we order a MetAmino^® GC/MS sample preparation kit for 400 samples?

• Not yet, we currently only have a MetAmino^® GC/MS sample preparation kit for 100 samples. The kit can be ordered under catalog number MAK-5857-BA01.

There are 78 amino acids in table 1, some of which are not in the available mixes of standards - should we therefore rely on MRM transitions and look at the retention time or are these the standards that we should buy if we want to determine them?

• For quantification purposes the MetAmino kit contains - one bottle of SD1 standard solution included in the kit contains 33 amino acids: AAA, ABA, ALA, APA, ARG, ASP, BAIBA, CC, CIT, CTH, GABA, GLU, GLY, GPR, HIS, HLY, HYP, ILE, LEU, LYS, MET, 1MHIS, 3MHIS, ORN, PHE, PHP, PRO, SAR, SER, THR, TPR, TYR, VAL and bottle of SD2 with lyophilized mixture of 3 amino acids: ASN, GLN, TRP. However, the amino acid set can further be expanded to other compounds containing primary or secondary amino functional groups.
• The masses (m/z) reported in the manual are correct and represent M+H+ ions. The masses (m/z) and the retention times from the manual were obtained from the linear ion trap LTQ instrument however, the data from the Certificate of analysis were obtained from Q Exactive plus HRMS instrument. In both cases, the same column, flow rate, and mobile phase composition were used. The retention times (RT) are experimental values and the discrepancy especially for late eluting compounds would be caused by using different LC/MS instruments.

How can I predict how much to dilute a sample?

• It depends on the concentration of analyzed amino acids in the sample. The total amount of amino acids in the sample taken to the reaction should not exceed 1.2 μmoles. The amount of sample also depends on the LCMS instrument.

How much sample we need to take to hydrolisys with 6M HCl to use it with MetAmino^® kit?

• You can take a higher amount of sample for AA hydrolysis (e.g. 50 micrograms in 300 microliters of 6M HCl) and finally take a few microliters (remove the acid in the speedvac or under the nitrogen stream) for the Metamino workflow.

In which point should the sample be diluted? After hydrolysis of the sample and before applying the kit? Or is it possible after the complete application of the kit (finished sample)?

• The reaction is designed to analyze aqueous samples, so if 25 μL of the sample gives an overloaded signal, I would recommend diluting the sample with deionized water. It is also possible to dilute the finished sample.

How much derivatizing reagent is used during derivatization process of the sample? How can I be sure that the reaction is 100%?

• The derivatization agent is sufficient to derivatize 1.2 μmol total amount of amino acids. The derivatization and the purification don´t always proceed at 100%. If you perform the derivatization of samples and calibration points in the same way, you should obtain the correct values. (Even if the effectivity of the derivatization and the micro spin purification is lower than 100%).

Overview of MSPE sorbents

Sorbents for the MSPE technique are chosen to cover the widest possible field of applications. MSPE SpeExtra C18 is a hydrophobic type of octadecyl silica gel with a special endcapping. It is suitable for a wide range of analytes, showing lower retention for polar compounds. MSPE SpeExtra C18-P is a polar modified monomeric octadecyl silica gel. It offers different types of interactions: dipole-dipole, π-π and hydrophobic. It is therefore suitable for aromatic and polar compounds. MSPE SpeExtra HLB polymer sorbent with high specific surface area and special endcapping. It has a hydrophilic and lipophilic modification ensuring universal use and a higher capacity than C18 silica gel.

SPE Phases

This site encloses SPE phases overview includint their technical parameters. Further information about the products are available in the product catalogue.

Clean up SPE columns

Reverse phase hydrophobic

Normal phase hydrophilic

Ion Exchange - Anion Exchange

Ion Exchange - Cation Exchange

Copolymeric phases

GC Phases

On this page we provide an overview of the supplied stationary phases for gas chromatography (GC). Each is given details of its properties and the applications that are suitable for them. In the product catalog you can then choose a suitable quartz or metal capillary column for GC.

Stationary phases LION

Fused silica capillary columns

UHPLC Phases

Raptor - RESTEK

Raptor maximum pressure: 1,034 bar (1.8 μm), 600 bar (2.7 μm); 400 bar (5 μm). For maximum lifetime recommended maximum pressure for 1.8 µm particles is 830 bar.

PINNACLE DB - RESTEK

puriFlash

puriFlash^® Flash Cartridges

Interchim developed new technique for flash chromatography - Ultra Performance Flash Purification (UPFP) using special flash cartridges. The flash cartridges are in the form of regular or irregular silica. UPFP enables to run purifications with high purity of the yield and less solvent use.

Flash column selection

Flash column celection is available at this page.

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.

Quick, 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

MEPS Phases

SGE

*C8+SCX BINS are labelled as M1.

The BINs can be used up to 40 - 100 extractions. General preparation time is 1 - 2 minutes.

Stationary phases

Chromatography, either GC, HPLC, SPE, FLASH or preparative, uses many types of stationary phases. Here you wil find detailed information about stationary phases.

Stationary phases for analytical separation

• Core-shell technology
• GC
• HPLC
• UHPLC

Stationary phases for sample preparation

• SPE
• dSPE (QuEChERS)
• IAC (Immunoaffinity Columns)
• MEPS (Micro Extraction by Packed Sorbent)
• FLASH
• BULK (media for preparative chromatography)

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

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