Accelerate Workflows Without Compromising Data Quality

Jan. 15, 2021
By combining modern gas chromatography-mass spectrometry (GC-MS) systems with suitable complementary technologies, high-performing water testing laboratories can sustain increasing throughput demands while maintaining data accuracy.

Analytical water testing laboratories monitor drinking and surface water for the presence of contaminants to ensure high safety standards for the community. Traces of volatile organic compounds (VOCs) and purgeable organic compounds (POCs) in drinking water or semi-volatile organic compounds (SVOCs) in drinking, surface and wastewater are potentially detrimental to consumer health and the environment.

To safeguard the public from negative effects, water testing laboratories need to ensure accurate detection and quantitation of these contaminants under strict regulatory guidelines. This has become even more challenging as the recent burst in urban development has resulted in a growing list of emerging contaminants and a higher demand for reliable water testing. As laboratories navigate the need to perform a wide array of tests and process a higher throughput of samples, they are also required to uphold high quality standards.

Using modern gas chromatography–mass spectrometry (GC-MS)-based methods to analyze water samples can generate analytical results in a timely and consistent manner, offering unmatched levels of sensitivity, robustness and reproducibility. Moreover, most experimental bottlenecks that impede operational efficiency in water testing laboratories can be readily eliminated with befitting workflow enhancements. Here, we present two GC-MS water analysis methods coupled with relevant technologies to speed up operations and minimize running costs, without compromising quality.

Analyzing VOCs and POCs in Drinking Water: Faster, Reproducible and More Efficient Workflows

Drinking water samples are commonly subjected to purge and trap (P&T) analytical testing to quantify volatile and purgeable contaminants at part-per-trillion (ppt) levels. In this method, water samples stored in sealed vials are automatically transferred to a dedicated vessel and purged with an inert gas at appropriate temperature, transferring VOCs and POCs in the sample to the gas stream into an analytical trap that adsorbs and enriches the extracted contaminants. Heating the trap releases the VOCs and POCs, which are then injected into the GC system to be detected and quantified by GC-MS.

Since its invention in the 1960s, P&T has proven to be an effective method to extract and measure volatile and purgeable contaminants at low concentration levels, and its protocol requirements are now regulated by the United States Environmental Protection Agency (EPA) methods 524.2 and 524.4. Routine monitoring of VOCs and POCs, however, brings common challenges that can impact reproducibility and turnaround time. For instance, when water samples are analyzed, any moisture introduced into the GC column can damage it, disrupting the chromatographic process and causing unexpected downtimes. Additionally, as samples from diverse sources bear a wide concentration range of volatiles, the entire P&T-GC-MS system needs to assure low detection limits to offer adequate sensitivity and a wide linearity range to ensure the reported numbers are accurate. Moreover, as regular testing occurs day after day, the system needs to sustain the load of continuous operations and produce consistent results that meet EPA acceptance criteria.

These challenges can be solved by coupling modern P&T systems to advanced single quadrupole GC-MS capable of boosting efficiency in both contaminant extraction as well as detection and quantitation. Upon evaluation, these workflows not only meet but exceed all the EPA-mandated detection requirements, making them ideal for water testing laboratories to thoroughly ensure public and environmental safety.

One of the technical factors that contributes toward greater method efficiency is the moisture control mechanism designed into contemporary P&T systems that minimizes water transfer to the GC column. With no more water interferences, peak shapes are maintained, and the resulting data are reliable. Minimal risk of column damage eventually extends its lifespan and eliminates frequent repair-related downtimes. Additionally, a built-in trap cooling function in modern P&T systems minimizes the time required to bring down the trap temperature. This reduction in individual sample cycle time ultimately makes room for processing a higher number of samples per day without requiring any extra resources.

Single quadrupole GC-MS systems, specifically designed to meet the evolving analytical needs of high-performance laboratories, provide the robustness and sensitivity required for uninterrupted, routine testing of VOCs and POCs. Repeatability tests with up to 120 consecutive injections demonstrate high levels of accuracy and precision, and relative standard deviation (RSD) of less than 9 percent, with no maintenance performed on any part of the system. Even during scheduled, preventive maintenance, users can easily swap out ionization sources or replace columns without venting the whole system, thereby, significantly reducing instrument downtime.

To greatly facilitate method setup, sequences programming and data processing, the entire P&T-GC-MS system is controlled by a single chromatography data system, assuring maximum levels of compliance and ease of use.

Updating analytical workflows with these fit-for-purpose technologies not only offers reliable results but also maximizes sample throughput without ever affecting data quality. As workflows become more efficient and maintenance needs decrease, laboratories become more cost-effective and productive, and are better equipped to handle increased demands in the future.

Analyzing SVOCs in Water Samples: Save Time and Minimize Costs with Automation

Semi-volatile organic compounds (SVOCs) represent a significant source of contamination, causing concern for public health. SVOCs include chlorobenzenes, pesticides, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and phenols, which are not purgeable but require solvent extraction procedures followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. These manual sample preparation protocols represent critical bottlenecks for busy laboratories. As laboratory personnel spend more and more time on tedious routine activities pertaining to preparing samples, this diminishes the overall productivity of the testing facility.

State-of-the-art technology offers modern laboratories the possibility to automate manual extraction procedures, with a significant reduction of sample and solvent consumption. The automated workflow for SVOC analysis in drinking, surface or wastewater samples involves automated in-vial liquid-liquid extraction as a part of the sample preparation process and on-line GC-MS/MS analysis.

Programming routine sample handling operations into the autosampler not only speeds up the protocol, but it also reduces overall costs, minimizes human errors, provides precise control, and prevents human exposure to hazardous chemicals and solvents.

Implementing an automated liquid-liquid extraction workflow through a robotic autosampler allows laboratories to significantly reduce manual input. Sample throughput levels will also increase with this process.

Thanks to the robotic sample handling, it has been possible to scale down sample and solvent volumes at VERITAS. For instance, dichloromethane was used in the facility with a consumption of about 50 liters per month. Thanks to the automated workflow, it was possible to replace dichloromethane with the much less hazardous n-pentane and reduce its consumption to about 1 liter per month. Along with the direct reduction in inventory costs, this has also brought indirect logistical benefits by way of reduced storage and transportation costs.

A fully unattended sample preparation workflow, with automated steps also reduces sample-to-sample variability otherwise at risk by manual pipetting or washing steps.

Consistent, reliable automated sample preparation coupled with highly sensitive GC-MS/MS ultimately results in efficient, fast, and cost-effective SVOC analyses in compliance with demanding regulations, offering the additional valuable opportunity for consolidated analysis covering different classes of SVOC in the same injection. Adopting this advanced technological solution, water testing laboratories can strike the right balance between high throughput and data accuracy, especially when faced with increased demands.

Improve GC-MS Workflows While Meeting Safety Requirements

As the list of water contaminants continue to increase and regulatory requirements become more stringent, water testing laboratories must adapt to changes by making valuable technical improvements that not only serve current needs but also the projected growth in business. Modern GC-MS workflows are designed to address common time-sinking and unproductive barriers to routine water testing, all while meeting the EPA guidelines. These fit-for-purpose technical updates, such as coupling GC-MS instrumentation to the latest P&T system or adopting automated sample preparation into the workflow, can make a significant difference to the operational capacity and long-term output of laboratories. WW

About the Authors: Gilberto Pintonello is supervisor of the chromatography department at Veritas SpA.

Daniela Cavagnino is product marketing manager GC and sampling solutions for Thermo Fisher Scientific

Adam Ladak is product marketing manager GC-MS for Thermo Fisher Scientific.

About the Author

Gilberto Pintonello

Gilberto Pintonello is supervisor of chromatography department, Veritas SpA.

About the Author

Daniela Cavagnino

Daniela Cavagnino is product marketing manager GC and sampling solutions for Thermo Fisher Scientific

About the Author

Adam Ladak

Adam Ladak is product marketing manager GC-MS for Thermo Fisher Scientific.

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