Author: Anita Peterson, Ph.D.
Proper sample preparation is key to achieving high quality results for chemical analysis. However, this aspect of the overall analytical workflow has never received much attention. Instead, the focus is often placed on the development of instruments that can achieve lower detection limits (especially mass spectrometers) in a short amount of time, even though the sample preparation can take hours or even days. Some laboratories are staffed with highly trained analysts who are entirely dedicated to the preparation of samples for analysis by these instruments. Traditionally, sample preparation steps (weighing, solvent extraction, mixing, clean-up, etc.) are performed manually, which is time-consuming and requires great care in order to obtain precise and accurate results. Automating the sample preparation process has many advantages, including increased precision and accuracy, lower solvent use, and increased productivity (samples can be prepared overnight). Additionally, automation can free up staff to perform advanced tasks that can’t be automated, such as method development and data interpretation.
Fred Foster, an Analytical Scientist in GERSTEL’s Analytical Services Group, utilizes the MultiPurpose Robotic Sampler (MPS) to automate tedious and complex workflows, which would normally take up time that could be spent on more advanced analytical tasks. He can start a sequence before leaving the lab for the evening and be confident that he will return the next morning to precise and accurate analytical results. From opioids in urine to airborne aldehydes and ketones, the MPS has provided the means to automate the extraction of significant compounds from complex matrices and meet regulatory standards of precision, accuracy, and limits of detection. A manual method can be automated in a simple and efficient manner through the MAESTRO software, which operates all GERSTEL modules and system solutions. About the advantages of the MPS controlled through MAESTRO, Fred Foster says this:
“The nice thing about the MPS is you can talk to it while it’s working, and it will never get distracted. I can’t tell you how many times I’ve had to restart when manually creating my calibration standards because my mind wonders or I get distracted from interruptions. One of the best hidden gems of the MAESTRO software is the Dilution Wizard. It allows me to quickly setup the MPS to prepare calibration standards by just inputting a few basic parameters, like how many calibration standards I need to create and at what concentrations.”
The benefits of automating sample preparation methods are exemplified by countless applications performed by the GERSTEL Analytical Services Group. Liquid-liquid extraction techniques are extremely time consuming when performed manually, especially when emulsions form between the sample and extraction solvent. Emulsions must be broken up and the phases separated before the sample extract can be injected or removed for subsequent clean up. Automating this procedure eliminates human error and improves precision while increasing productivity. GERSTEL’s MPS robotic quickMIX option provides very thorough and efficient mixing and extraction, while the CF200 centrifuge separates the emulsified solvent and sample layers. This system (with an additional SPE option for cleanup) aided in the successful extraction of antibiotics in eggs for quantitation by LC-MS/MS (Application Note 204).
Residual pesticides can be determined in hemp oil and other cannabis concentrates by employing an extensive sample preparation procedure, involving liquid-liquid extraction and dispersive solid phase extraction (dSPE). Through the automation of this procedure, coupled with GC separation and mass selective detection (MSD) in single ion monitoring (SIM) mode, the limits of quantitation (LOQs) achieved for the pesticides in this study were well below those established by state regulations (Application Note 209).
In many instances, automation can greatly improve analytical results compared to manual preparation. Liquid samples with high viscosities pose several challenges to achieving accurate and precise delivery of desired volumes. Using the GERSTEL MPS roboticpro equipped with the Heated Liquid Syringe Module (HLM), viscous oil samples are heated so that they can be transferred accurately and precisely. As reported in Application Note 207, the HLM aided in the transfer of edible oil samples to be solvent extracted, centrifuged, evaporated, and reconstituted prior to direct introduction to LC-MS/MS for the measurement of mycotoxins. Implementation of this automated extraction procedure coupled with LC-MS/MS analysis enabled the determination of mycotoxins in edible oils with high precision (2.40 – 6.90% CV) and accuracy (87.9-122% recovery).
The addition of automation capabilities to the analytical laboratory has many clear advantages. Lab productivity is increased while continuing to meet required high standards. The GERSTEL MPS in combination with a multitude of options for sample preparation and introduction provides analysts with the means to overcome productivity bottlenecks in the lab and increase the quality of analytical results at the same time.