AQ™ Brand Polypropylene Vial Study (LC-MS) compared to market leading vial

Many scientists use a very common 300µL plastic (polypropylene) vial for chromatography (HPLC) when they have compounds that stick to glass. With the advancement of LCMS, HILIC and ANP chromatography these vials are not useable because they produce spurious peaks. The peaks are due to common chemicals used to make these vials at a low cost. The peaks shown below are from injection mold release agents, clarifiers and antioxidants are added to manufacturing process.

The MicroSolv Advanced Quality™ (AQ) LCMS compatible vials, both screw top and snap top, are made from a proprietary blend of virgin polypropylene that cannot be made with the same speed as our process does not include mold release agents, clarifiers or antioxidants. The higher cost of production is due to slow speed of production but the resulting product is much cleaner than others and can be used confidently with LCMS and HPLC solvents.

Advantages of AQ™ Brand NDX™-Depth Filters

Some analysts may think that selection of a syringe filter for their sample preparation step is of trivial importance. However, there is more to the syringe filter than just membrane material (e.g. nylon vs. PTFE). For instance, lower quality syringe filters may have extractable compounds that can end up in your filtrate. These extractables then show up as unknown peaks in your chromatograms, potentially interfering with peaks of interest. In a study comparing AQ™ Brand NDX filters to those of market leaders, the AQ™ Brand was shown to produce a lower peak area of the extractable and even more so after an initial wash step.

                Another aspect to consider is the hold-up volume. Suppose you have a sample that is available in limited supply. It could be expensive or simply rare. In this case, you don’t want to waste any of the sample and that is exactly what happens in a low quality filter. After the filtration, the amount of liquid remaining in the filter membrane is called the hold-up volume. It is best to minimize this volume and the MicroSolv AQ™ Brand NDX™ Depth Filters outperform competitive filters in this respect.

                If you have to filter a large amount of liquid with a single syringe filter, then lifetime becomes significant. The AQ™ Brand was shown to have a comparable lifetime to competitive filters. These three aspects of the syringe filter should not be overlooked as they can all cause unnecessary problems for the analyst.

                Click the link for more info:

http://mtc-usa.host4kb.com/article/AA-02363 

Method Transfer from 4um to 2.o™ HPLC column

Methods developed on the 4um Cogent™ line of HPLC column products can be readily adapted with near-UHPLC Cogent 2.o™ phases. In this blog, we have a method for forced degradation of atorvastatin (Lipitor®). The gradient separates the main API (atorvastatin) from its more hydrophobic lactone degradant.  The retention is comparable between the 2.2um column (Figure A) and 4um column (Figure B). However, efficiency is higher on the 2.2um phase which is a significant advantage for the user. With higher efficiency, you can obtain better resolution from closely eluting peaks. Also, you will get higher sensitivity due to the increased peak height. The efficiencies for the API were 88,420 plates/meter for the 4um column but 134,800 plates/meter for the 2.o™ phase.

                In this application, a standard HPLC (Agilent HP 1100) was used in both cases. With near-UHPLC columns, you don’t need a full UHPLC system to obtain the benefits of efficiency, resolution, and sensitivity. This is an important aspect since many QC laboratories don’t use UHPLC instrumentation in their routine assays. The only thing to keep in mind is that your column pressure will be higher and you should not exceed 120 bar on a regular HPLC system.

1 - Atorvastatin

2 - Atorvastatin Lactone

Limonin Content in Citrus Juices

We used the Bidentate C18 2.o™ column to separate limonin from matrix components in citrus juice extracts. The column produces high-efficiency, sharp peaks which is important in order to obtain good limits of quantitation. The quantitaitve studies first used limonin standard solutions covering a range of 2.0–200ppm in order to establish a calibration curve. The detector response was shown to be linear in this range. Next, a non-citrus juice was chosen to serve as a matrix blank (apple juice). This juice extract had no peaks in the region where limonin elutes and therefore would be a good candidate for percent recovery studies. The extract was spiked at both 5 and 10ppm levels. Recovery was observed to be within 97.8–100.2% at these levels. Finally, two orange juice samples were analyzed and the limonin peak was correlated with the calibration cruve. The amounts of limonin were found to be 1.20 and 3.70ppm in two different juices. The approach can be used towards development of a fully validated method for limonin quantitation.

 

New Retention Possibilities for Polar Compounds using Cogent Diol Column

TYPE-C Silica™ columns can be used for separation of a variety of polar compounds.  The new Cogent Diol™ column makes an excellent addition to these stationary phases. Consisting of a short alkyl chain with vicinal alcohol groups, this material has additional separation capabilities compared to other phases. Since it is on a TYPE-C Silica™ surface, the bonding is very strong and durable. The diol group can interact with analytes via hydrogen-bonding interactions, resulting in new selectivity. 

In the following example, we demonstrate the capabilities of this intriguing material. The test solutes chosen for the separation were seven common hydrophilic vitamins. The results show that baseline separation could be obtained for all seven analytes. The retention range is adequate as well, with no analytes eluting at the solvent front or sticking to the column. Peak shapes were sharp and symmetrical, and no tailing was observed. 

This column makes a wonderful addition to the TYPE-C Silica™ line of HPLC columns and should be a great benefit to every chromatographer’s toolbox. 

1. Ascorbic acid
2. Niacin
3. Riboflavin
4. Folic acid
5. Pyridoxine
6. Metformin
7. Thiamine

See the following link for full details:

http://kb.mtc-usa.com/article/AA-02102/0/