17 Chromatography
or better for recovery than LLE. This was the case for every class of analyte - acidic, basic and neutral. This is due to the better extraction effi ciency present in the Microlute™ SLE, offering a more effective solution to gain better recoveries in a shorter period with less repetitive processes in place. This is especially clear when looking at the more hydrophilic compounds (caffeine, procainamide and acetaminophen) which have a 10-20% increase in recovery in the SLE method.
averaged 4.8% and had a range from 1.2% to 12.5%. This difference has likely come from LLE having more steps which rely on the analyst’s technique to ensure sample-to-sample extraction steps of reproducible – shaking and then extracting the organic layer.
Processing time
Another area in which SLE outperforms LLE is the time to perform the sample preparation. Figure 9 highlights the difference in processing times for both sample preparation methods. To prepare 96 plasma samples for SLE it is three times quicker when compared to the equivalent number of samples for LLE (40 minutes versus 129 minutes respectively). The biggest time saving element arises from the lack of labour- intensive steps of sample shaking and transfer of organic solvent layers in LLE.
Figure 7. Mean recoveries for all analytes in plasma samples using Microlute™ SLE 200mg and LLE (N=6). The error bars represent the standard deviations of the recovery results. Analytes are ordered in increasing Log P values.
For reproducibility, results are shown in Figure 8 which is represented as relative standard deviation (%RSD). The lower the %RSD value, the more reproducible the recovery is. Reproducibility is an important metric to allow confi dence in results. If recovery is high but reproducibility is low, it can lead to questions on if the result was correct and could be acquired again. The average %RSD for the SLE recoveries was 3.2% which ranged from 0.7% to 6.9%. These values showed SLE was more reproducible than the LLE work which
Figure 9. Protocols and the processing times for each step of the LLE and SLE procedures for 96 samples.
Conclusion
This application note compared SLE and LLE methods for recovery, reproducibility and methodology using pig plasma on a range of compounds from acidic, basic and neutral classes. The comparison of the two methods demonstrated that the Microlute™ SLE plate is superior both in performance (able to obtain higher and more reproducible results) and the time taken to complete the sample preparation, compared to the equivalent LLE method performed. Using Porvair Sciences Microlute™ SLE plate allows greater sensitivity and more confidence in the results. With the ability for high throughput by reducing the labour-intensive steps associated with LLE it should be the sample preparation method of choice for any analyst.
Related Products: Microlute™ SLE 200 mg, 3 ml cartridge (PSLE2003-050), Microlute™ SLE 400 mg, 3 ml cartridge/plates (PSLE4003-050/ PSLE400P-001), 1.1 ml 96-well Low Profile Collection Plate (#219250), 2.2 ml, 96 well, V-bottom Collection Plate (#219009).
References: 1. Ramirez C, Peters K. Extraction Techniques for Food Processing. ED-Tech Press; 2018.
Figure 8. Relative Standard Deviations (%RSD) for all analytes in plasma samples using Microlute™ SLE 200 mg and LLE (N=6). Analytes are ordered in increasing Log P values.
Automation-ready Sample Evaporator for Microplates
Porvair Sciences has launched a new second generation model of its Ultravap® Mistral - an automation-ready sample evaporator that offers throughput advantages to laboratories looking to optimise and accelerate sample preparation.
Designed to remove the traditional laboratory ‘bottleneck’ of solvent evaporation, industry-leading sample drying reproducibility has been achieved by recent advancements in gas injection technology. The new and improved Ultravap Mistral directly and consistently delivers heated gas up to 80°C in each microplate well or tube allowing most common chromatography solvents including dichloromethane, methanol, acetonitrile, hexane and water to be evaporated with speed and ease. A choice of straight or spiral needles allows users to choose between faster dry down (spiral) and better final drying in V-well plates (straight).
Highly intuitive software, and simple operation from up to 15 stored multi-step evaporation programs, means that even occasional users can gain the full benefits from an Ultravap® Mistral. For regular users, the Ultravap® Mistral offers the versatility of fully flexible programming, for example enabling the evaporation stage to operate at an optimised rate for each solvent type being evaporated.
From the responsive colour touch screen display - gas temperature, pressure and flow rate can all be programmed individually and saved in stored programmes on the instruments controller. Each programme allows up to 5 distinct ramped phases, so that a fast initial drying period can be followed by a gentle final drying phase. Standard control commands stored on Ultravap® Mistral are compatible with drivers of most robot manufacturers making integration a seamless process.
The new Ultravap® Mistral is designed with a flat front profile and platform shuttle making interfacing with almost any liquid-handling robot even easier. The slim benchtop-friendly design of the 2021 version has built-in LED lights that provide great sample visibility.
More information online:
ilmt.co/PL/oDXy 54187pr@reply-direct.com
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