At the start of June, Broughton began work with the new Vanquish Flex – Thermo Fisher Scientific's latest UHPLC instrument. With pressure capabilities of over 1000 bar, this equipment is a dream for any analyst doing routine HPLC work. When put through its Performance Qualification (PQ) tests, %RSD values of 0.1% were achieved for peak areas. This instrument – clearly accurate and precise enough – had endless possibilities for use in our lab and we were looking forward to testing it out.
The first task we challenged ourselves with was taking the British Pharmacopeia (BP) method for Ibuprofen and seeing if we could transfer this well-used test to UHPLC – maintaining a well-defined separation and ensuring high precision. With a run time of 10 minutes, a reduction in time was desirable but the main aim was dealing with some of the well-categorized impurities associated with ibuprofen. Although these impurities are well documented and available as reference standards, these often interfere with the chromatography and cause co-elution problems. After running some different parameters, the flow rate was reduced from 1.5 mL/min to 0.4mL/min. Injection volume was decreased from 20 µL to just 1 µL. This saved over 70% of the solvent. This method is still being developed in order to really improve the resolution between the impurities and the ibuprofen peak of interest. Still, all signs currently point towards a method with the same sensitivity and resolution as before, if not better.
The next method that was identified as one to work on was for the detection of Carbonyls in the aerosol of Electronic Cigarette Liquids. With the introduction of the Tobacco Products Directive in the U.K. over the past couple of years, the need for accurate, nicotine methods has increased. Most of the current methods for the Analysis of Carbonyls in E-Cig Liquid aerosols currently couple UHPLC with Mass Spectrometry (MS) as the detection method. This detection method, although sensitive, is not the most cost-efficient. Therefore, a UV-detection method coupled with the UHPLC was required as this would be a simpler method to run daily. Nicotine is a complex mix, with 15 carbonyls and ketones to be detected in a much simpler method than UHPLC-MS. So far, 13 out of the 16 ketone/carbonyl mix have been detected at 360nm. Further work is being carried out to detect the final three carbonyls and hopefully improve resolution between each of the peaks, to ensure the best separation possible.
As can be seen from each of these two projects, the Vanquish Flex is a highly sophisticated piece of equipment – its sensitivity, ease of use and high accuracy are attributes that are an asset to any company. Work has only just begun on the transfer and development of these methods – more are sure to follow.