Acetonitrile Prices Increased During The Pandemic 

During the Coronavirus Pandemic there is a worldwide shortage of Acetonitrile as manufucturing slows down all across the globe.  China and the USA have greatly reduced their manufacturing across all industries as the world tries to combat the Covid-19 virus.  Anything that affects manufucatruring and mass production subsequently affects the production of Aceonitrile. 

While we are experiencing daily increases in the price of solvents it is important that laboratories, both in Research Labs and manufacturing plants monitor their solvent usage and try as best they can to anticipate their solvent usage.  Greyhound Chromatography is using their UK warehouse to stock solvents at today's prices and is organising call off orders with its stakeholders. 

If you have a need for solvents, whether you are a new customer or existing customer with an established call off arrangement now is the time to discuss with Greyhound's Sales Team how your supply chain can be protected. 

Why is Acetonitrile Used in HPLC?

Acetonitrile together with Methanol are the most commonly used solvents for HPLC and UHPLC Chromatography processes because most substances are easily soluble in both solvents, but not saturated hydrocarbons.  Acetonitrile has a low wavelength which means that the solvent will elute first from the column, therefore pressure is reduced on the column.  Lower pressure in the column will have the long term effect of prolonging the life of the column, pressure within the column varies depending on the solvent used and the mixture ratio between the solvent and the sample.  An Acetonitrile based solution generally has a higher elution strength against the same strength solution using Methanol. Some scientists report that the same retention times can be achieved using acetonitrile with less than half the ratio of methanol.  Operator errors can have a significant impact of reproduceable results.  

Acetonitrile produces less pressure than Methanol, however the choice between using Acetonitrile against Methanol should not be made on price, (Acetonitrile is generally more expensive than Methanol), choice should be made on performance for your particular instrument and the effect of the chromatography process on the durability of the column.  High grade Acetonitrile has a lower absorbance in routine HPLC and UHPLC procedures and causes less interference than other solvents that can be used.

Biosolve solvents, including Acetonitrile, supplied by Greyhound Chromatography, are filtered at 0.1µm and are packed under inert nitrogen gas for longer shelf life, with very low amounts of inorganic metallic contaminants.  Acetonitrile is bottled in pure glass containers to minimise leaching and degradation of the solvent.  Acetonitrile is a clear colourless liquid with an acidity as low as 0-0.001% depending on the grade.  The presence of acid in the solvent improves the chromatographic peak shape.  Full certificates of analysis are available to view before selecting the right grade of solvent for your application.   Acetonitrile Surpa-gradient grade, available from Biosolve, is the highest-grade Acetonitrile solvent available for HPLC and UHPLC in today's worldwide market. 

Acetonitrile is shipped under Dangerous Goods regulations as it is a highly flammable liquid and vapour.  Safety procedures should be closely followed for the safe handling of Acetonitrile, including keeping away from sparks and open flames, hot surfaces and heated storage rooms.  When handling take reasonable precautions to ensure that it does not go on skin or near eyes.  If Acetonitrile does come into contact with clothes, remove the clothing and rinse thoroughly in water.  If it comes into contact with the skin, wash cautiously with water.  If acetonitrile comes into contact with the eyes, remove contact lenses if they are present, rinse with water for several minutes and seek medical advice. 

Is there a need to wash columns frequently during HPLC

It is important to look after your columns to prolong their life and also their integrity.  Washing a column is an important process that should be done regularly.  Depending on how many samples you are processing and how often you are using them will determine how many times you wash the column.  Storage of the cleaned columns should also be considered.  It is important to establish a wash cycle in the laboratory, if you do not you will notice a gradual pressure build up and you may experience ghost peaks after the first injection.   Ghost peaks are caused by compounds eluting off the column in later runs despite being injected in a previous analysis. 

This is the recommendation for a column that is to be stored over a long period.  Replace buffers and modifiers at the end of the day, it is recommended that you wash the column with 70% water, 15% methanol and 15% acetonitrile.  divert the eluent from the column to waste so as not to contaminate the detectors.  Wash the column in 100% methanol and 100% acetonitrile, both for at least 15 minutes.  Store the column subject to the manufacturers recommendations, this will preserve the column, which may last for years depending on the number of samples processed and the care you give to your column.   For daily use, wash the column in 70% water, without using an acid or modifier, and store overnight subject to manufacturer's instructions. 

About Solvents 

Solvents are liquids which dissolve other substances with water a common example. The selection of a solvent will depend on whether or not something dissolves in it (solvency), its evaporation rate, boiling point, viscosity, surface tension and many other factors.

Acetonitrile together with Methanol are the most commonly used solvents for HPLC and UHPLC Chromatography processes because most substances are easily soluble in both solvents, but not saturated hydrocarbons.  Acetonitrile has a low wavelength which means that the solvent will elute first from the column, therefore pressure is reduced on the column.  Lower pressure in the column will have the long term effect of prolonging the life of the column, pressure within the column varies depending on the solvent used and the mixture ratio between the solvent and the sample.  

Isopropanol (IPA) is used as a solvent in cosmetics and personal care products, de-icers, paints and resins, pharmaceuticals, food, inks and adhesives. A pharmaceutical grade of IPA is used in products such as medicinal tablets as well as disinfectants, sterilisers and skin creams. IPA is used in de-icers and cleaning products because it stays in liquid form well below the freezing point of water.

Acetone is a widely used solvent. Pharmaceuticals is the largest consumer of acetone solvent with significant quantities also being used in glass reinforced plastics, cigarette tow, rubber chemicals and household, cosmetic and personal care products.

Ethyl acetate has applications as a solvent in inks for flexographic and rotogravure printing. It is used as an extraction solvent in the production of pharmaceuticals and food, and as a carrier solvent for herbicides.

All of the above solvents are seeing dramatic price increases in 2020 as demand grows worldwide for products that are used to combat the effects of Covid-19.  Many manufacturers are switching production from their regular products to producing hand and surface sanitizers that are in high demand worldwide.  The price of these products has more than trebled since the start of 2020.  Many alcohol manufacturers have ceased production of commercial alcohol products because of the closure of bars and restaurants and are now producing sanitizers either comercially or as a product they can donate to the health service to assist the fight against Covid-19.    

Historic World Shortage of Acetonitrile

In 2008 there was a world shortage of Acetonitrile, (a by-product from the manufacture of acrylonitrile) because of several factors, including, Chinese manufacture being shut down because China was hosting the Olympics and all industry within China was either closed down or drastically reduced in an attempt to improve the standard of air during the Olympics.  Also, during Hurricane Ike in the USA an Acetonitrile factory was damaged in Texas causing further shortages.  As Methanol is an acceptable substitute in most HPLC methods the shortage can be overcome.  Acetonitrile is seen as a valuable commodity due to the volume used worldwide for a variety of purposes other than Laboratory analysis.  The 2020 Coronavirus Pandemic is again causing shortages worldwide. 

Author:

Susan Massie, Sales & Marketing Director

Greyhound Chromatography and Allied Chemicals

www.greyhoundchrom.com

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How to Prepare a Sample for HPLC Analysis

High-performance liquid chromatography (HPLC) is a analytical chemistry technique used to separate, quantify and identify each component in a mixture. Components are mixed in a pressurized liquid solvent which pass the sample through a HPLC column filled with a solid  adsorbent material. Each component in the sample interacts slightly differently with the adsorbent material, causing different flow rates for the different components and leading to the separation of the components as they flow out of the column.  The sample is mixed with solvents in varying dilutions and can be pre-filtered before the sample is put into the column to ensure purity of the results, where a sample has to pass through the column at a regular or fast speed a HPLC pump is used.  

Sample preparation is vital to high quality reproducable and specific results, often overlooked methodical sample preparation can improve efficiency in the laboratory.  Sometimes seen as a laborious task sample preparation isn't always viewed as the most efficient use of time in the laboratory.  HPLC and increasingly UHPLC is one of the most commonly used high pecision analytical methods in today's fast paced modern laboratory.  A sample needs to be prepared so that it can be directly injected into a HPLC column.  Firstly the sample needs to be dissolved in an appropriate solvent; methanol and acetonitrile are favourite choices, for a variety of reasons; there are many guides available as to the proportion on solvent in relation to your sample; some methods are tried and tested some are just a matter of trial and error.  Chromatography forums provide a wealth of experience that is freely shared via the Internet.

Depending on the sample to be analysed, whether it be for animal biological fluids, drinks, food, human biological fluids, petrochemical residues, pharmaceutical analysis, toxicological residues, waste waters, the sample will need to be filtered prioir to injection.  Solid Phase Extraction (SPE) tubes provide an excellent clean up method or a syringe filter with a suitable membrane to ensure that your sample is free of particles that may cause intereference during detection and will prevent blockages to your column.   Syringe filters are the most efficient method of pre-filtering the sample for sample with complex properties or for small volumes, they come in a variety of membranes and differing porisities.  It is important that the sample is a clean as possible before it is introduced to the column, taking time at this stage to ensure that the sample is a clean as it can be is worth the extra time.  

Problems with peaks, particularly Ghost Peaks can be detected either with the first injection or problems may present themselves during the course of your analysis leading to a gradual deterioration in your results.  A poorly prepared sample may lead to you having to repeat the whole process, it may even involve you having to clean the column if the sample is too contaminated.  Taking extra time to clean the sample will save valuable laboratory time in the long run. 

A clean sample will help to ensure:

• High sensitivity of the HPLC Column
• Accurate, reproducable results
• Fewer false-positive peaks
• Reduced leachables
• Low background noise
• No blockages in the column

Using ultra pure water can also have its advantage particularly for pharmaceutical analysis where the need for the purest water is paramount.  Scientific research has proved that more than 80% of problems experienced during HPLC analysis are directly attributable to water purity.  Biosolve Ultra Pure water is supplied by Grehoyhound Chromatography in the UK and to laboratories world-wide.  With less than 0.0002%w/w residues after evaporation, the HPLC grade water from Biosolve is filtered through 0.2µm and bottled under inert gas.  

Some scientists prefer to use an automated sample preparation methods to eliminate human error, samples can become unreliable where dilution has been carried out manually use hand to eye determination of sample size and not a regulated reproduction of a sample using a elctronic pipette, for example.  Automated sample preparation can aid productivity by speeding up the analysis process, this is partciularly useful for UHPLC where speed of analysis under high pressure is essential.  Triple quad systems provide increased sensitivity at lower analyte concentrations, allowing high throughput of smaples.  The laboratory environment is increasingly complex, particularly in the field of biological research and analysis.  The need for research and drug development in the area of Cancer research alone is driving new developments every day at the edge of treatment devlopment. 

PFAS and Other Toxic Chemicals in our Drinking Water 

For over 30 years the European Union have worked tirelessly to protect the integrity of our drinking water.  EU officials have recently reached a provisional agreement to update the Union's 1998 Drinking Water Directive to tighten up the permissible limits allowed for both PFAS and several other drinking water contaminants, including bisphenol-A, microplastics, lead and chromium.   The at the time of writing the European Parliament and Council are still to formally approve the proposal. 

European drinking water standards currently far exceed the standards set in the United States but this is a changing picture as state by state new instances of contaminants are emerging.  Currently, the U.S. Environmental Protection Agency has only issued a nonenforceable health advisory of 70 ppt for PFOA, formerly used by DuPont to make Teflon, and PFOS, formerly an ingredient in 3M’s Scotchgard. Those compounds are no longer manufactured in the U.S., but they and other PFAS contaminate the drinking water for an estimated 110 million Americans. PFOA, PFOS and some other PFAS chemicals have been linked to cancer, thyroid disease, reproductive and immune system problems, and other health harms.

The european Parliament and the Council of the European Union have released new requirements for the analysis of per- and perfluoroalkyl substances (PFAS) in water intended for human consumption (5813/20).  This amendment to Council Directive 98/83/EC included perfluoroalkanesulfonates that are not commercially available.  In response to this Wellington Labroatories, Canada, is pleased to announce that its chemists have synthesized, purified, characterized and prepared accurate certified reference standards of the required substances: sodium perfluoro-1-undecanesulfonate (L-PFUds) and sodium perfluoro-1-tridecanesulfonate (L-PFTrDS).  Wellington Laboratories have also prepared a native solution/mixture (EU-5813-NSS) that contains all of the PFAS listed in the drinking water directive (5813/20) for your convenience.  This solution/mixture can be used in conjunction with two of Wellington's existing mass-labelled PFAS mixtures to easily prepare a calibration set for quantification. 

Suggested extraction standard mixture :  MPFAC-C-ES

Suggested injection standard mixture:     MPFAC-C-IS

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It is widely considered that labour is one of the most significant factors in the cost of traditional microbial testing.  The ready to use format of Petrifilm count plates can greatly reduce the labour time involved in traditional testing, saving valuable laboratory hours and freeing technicians to undertake other testing.  In an industry study conducted with 292 food processing plants, companies saved an average of 3.7 hours per day of technician time and all improved efficiency testing by using Petrifilm count plates. 

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