Acetaminophen – Alternate USP Method Acetaminophen and two of its major impurities were analyzed using a simple Mobile Phase. The Peak Shapes are very good and the Repeatability was good (%RSD = 0.01). Peaks: 1. 4-Aminophenol 1.072 minutes 2. Acetaminophen 4.668 minutes 3. 4-nitrophenol 7.588 minutes Method Conditions: Column: Cogent Bidentate C18™, 4µm, 100Å Catalog […]
All posts by Bill Ciccone
What are the Dimensions of 4.6mm ID, 5um Frits for PEEK Columns? – FAQ
The Frit itself has an outer diameter of 0.188” and a thickness of 0.062” and is in a PEEK Ring with 0.25” O.D. and 0.181” I.D. The Frit is Press-Fit into the Ring without glues or binders. Click HERE for PEEK Column Hardware Ordering Page.
What are the Temperature and Pressure Limits for Amber Glass Autosampler Vials? – FAQ
Amber Glass Vials are manufactured with 51-Expansion, Borosilicate Glass, and according to the recommended exposure this glass is rated to 230°C for normal service or 490°C for extreme service. Please always verify the temperature limits of Caps and Septa, as each material will have different specifications. We do not recommend pressurizing Autosampler Vials above 1 […]
Comparison of Extracts in Jaboticaba Fruit Powder with LCMS – AppNote
Phenolic Compounds Separated with HPLC with LCMS This simple Analytical Method was used to determine the content of very potent compounds present in Jaboticaba extracts and quantified some its Phenolic contents in fermented/non-fermented fruit; estimated by using standard addition. It is important to know the quantitation of compounds before and after fermentation to optimize the […]
My Analyte is Only Soluble at Basic pH. Do I Need to use a Basic Mobile Phase for my Method? – FAQ
Use of a strongly basic Mobile Phase is not recommended for any Silica based HPLC Column because the underlying Silica of the Stationary Phase is prone to dissolution at pH above 8 when the solution has a strong ionic strength. This may seem problematic for some analytes that you want to use in Aqueous Normal […]
Troubleshooting Problems with HPLC Columns Before the Column – Tips & Suggestions
When having poor chromatographic results, before you spend time troubleshooting the HPLC column, rule out other easier to fix, possibilities first. Problems you can encounter with peak shape, retention, and so on can often be traced to a component of the HPLC system. For example, consider the following real-world situation which we encountered in our […]
How to Back Flush and Wash an HPLC Column for Reuse – Tips & Suggestions
1. Reverse the Flow Direction in the Column. Attach the Column fitting that is normally at the outlet to the tubing that is normally connected to the inlet. Direct the Column Outlet to Waste, not to the tubing leading to the detector. The reason for this is so any contaminants coming off the Column don’t end […]
How can I reduce tailing for Atomoxetine, Reboxetine, and Maprotiline in a Reversed Phase C18 HPLC method? – FAQ
How can I reduce Tailing for Atomoxetine, Reboxetine, and Maprotiline in a Reversed Phase C18 HPLC method? I am using a pH 4 Phosphate/Acetic Acid Buffer. Atomoxetine, Reboxetine, and Maprotiline all have Amine Groups. Standard C18 phases may have Residual Silanols on the surface which can interact Electrostatically with the Amines from these analytes. These […]
Fosetyl-Aluminum Analysis with HPLC. Optimizing Tips – AppNote
You can use the Cogent Bidentate C18™ column in reversed phase (RP) with a high water content method. According to a 2014 third-party research article, if the analysis is done by reversed phase an ion pair agent is recommended to increase retention and reduce peak tailing. Here, 8 mM sodium sulfate was used in a […]
Can the L3 Linearity Solution Supplied in the HSQ Kit be used for UV Wavelength Accuracy? – FAQ
The short answer is yes. Many other Qualification vendors use only Caffeine for Wavelength Accuracy, at 205nm and 273nm. Holmium oxide of course covers 241-641nm, and is directly traceable to NIST standards. However, if you want, there is no reason you could not simply take the spectrum of Caffeine as well. The L3 Solution provides […]
Can I use the UV Calibration Kit to Qualify Detection at 200nm? – FAQ
The Caffeine Standard provides two data points at 205nm and 273nm. The Holmium Oxide Solution covers 14 absorbance bands in the range of 241nm – 641nm. Hence, you can obtain a calibration curve from these various data points and then extrapolate down to 200nm. This is the lowest you would need to go because of […]
Can I Use the Standard, HPLC Column Supplied in the HSQ Kit for UHPLC Instrument Qualification? – FAQ
Yes, the MicroSolv HSQ Kit is supplied with a 5um Particle Size HPLC Column that can be used to qualify a UHPLC instrument; you do not need a 2um particle size in a UHPLC column. Many qualification parameters are detector related such as Absorbance Linearity, Wavelength Accuracy, etc. Column-related aspects are not involved in the […]
Will your Qualification Kits for UV-vis be Appropriate for my Spectrophotometer? – FAQ
The new USP <857> guidelines are somewhat complicated, such that it is not easy to provide a simple answer. As an overview, in the old Monograph, it was possible to simply qualify a Spectrophotometer using a single stray light, Wavelength and Absorbance Accuracy Solution. The recent changes in the USP<857> states one must Qualify over […]
How does a Pulse from an HPLC Pump Affect the Column and its Performance? – FAQ
If your HPLC pump produces a “pulse” (i.e. cyclic fluctuation in flow/pressure), this can cause problems for your Method and Column. The pump will not be delivering optimally Precise/Accurate Flow and this can cause your system to not meet System Suitability Criteria as well as other issues. Sudden changes in the Pressure can also cause […]
Will a Different Guard Column Hardware System Different from the Cogent System Affect my Results When Using a Cogent HPLC Column? – FAQ
If the Guard Column is packed well with the same stationary phase as the Analytical column and the Guard System Hardware has no or very little inherent dead volume, it should not affect the results you get compared to the Cogent Guard System. It is important to note that any Guard Column or extra tubing […]
What Does the Specification 9-425mm for Screw Top Autosampler Vials Mean? – FAQ
The first number refers to the “Major Diameter” of the Screw Thread, (Major Diameter is the OD / outside diameter of the screw top vial (not the OD of the vial) at the thread line, measuring on the outside of the threads, Minor Diameter is the smaller diameter, measuring OD between the threads). We use […]
PFAS Analysis using Glass or Plastic Vials – Tips and Suggestions
In order to take the most accurate accurate analysis of PFAS Special Care must be taken for storage and sampling. Glass and also low-density polyethylene (LDPE) materials are not recommended for storing PFAS samples. PFAS can adsorb to glass, particularly when the chemicals are stored in a glass container for extended periods of time. Recommended […]
EDTA Analysis with HPLC – AppNote
EDTA does not have a significant Chromophore, so to achieve UV Detection, in the Method shown below we used a pre-Column reaction of a Solution of Ferric Chloride with the Sample. The resulting EDTA/Fe3+ has significant UV Absorbance making this a very Sensitive Method. Ethylenediaminetetraacetic acid is extremely difficult to analyze by itself however in […]
Dursan Coated HPLC Columns Comparison to PEEK Column Performance
Dursan is Excellent for any Compound that will Chelate with Stainless Steel PEEK is a highly inert material which has been used in HPLC applications for years. However PEEK has some limitations: Mechanical strength: PEEK begins to flex at 3000 to 5000 PSI, making it unsuitable for UHPLC and other applications where high pressure is […]
I heard that there is Not a Good Alternative to HILIC to Achieve Sufficient Retention for some compounds. Is this true? – FAQ
This is an untrue statement that can lead chromatographers to frustration as THERE IS an alternative mode of chromatography that surpasses HILIC in reproducibility, precision and the ability to separate both hydrophobic and hydrophilic compounds. It is well documented that Aqueous Normal Phase HPLC (ANP) is a very viable alternative to HILIC for polar compounds and in many cases superior […]
Column Cleaning and Care in the Reduced Particle Sized UHPLC Columns – Tips and Suggestions
Despite meticulous care, sometimes non-dissolved chemicals and sample particulates may adsorb onto your UHPLC Column, causing high pressure issues and ultimately making the Column ineffective. Before cleaning your Column, it is suggested to remove the Column from the Detector and allow your wash solvents to flow through the UHPLC tubing. Following this, it may be […]
Does the UV-Vis Calibration Kit Operate in all Three Ranges, UV, Vis and Vis/NIR? – FAQ
Not all Three… The MicroSolv UV Calibration Kit contains Potassium Dichromate for Absorbance Accuracy, Holmium Oxide for Wavelength Accuracy and Potassium Iodide for Stray Light measurements. It will not cover the other Wavelength Ranges and can be used to comply with USP <857> for the ranges where the supplied solutions are applicable. The Chart below […]
Is Formic Acid Compatible with Borosilicate Glass? – FAQ
Yes, Formic Acid is Generally Compatible with Borosilicate Glass. There are two aspects that one needs to be mindful of when storing Formic Acid in Glass Vials or Glass Inserts: Formic Acid gradually decomposes to Carbon Monoxide (CO) and Water, building up pressure inside the container. The warmer the solution the faster the process. Therefore, […]