Real-Time and Online Monitoring of Hazardous Volatile Organic Compounds in Environmental Water by an Unmanned Shipborne Mass Spectrometer System

Portable solvent-assisted thermal desorption ionization mass spectrometry for highly sensitive detection of illicit drugs in hair

Portable mass spectrometers have played an important role in the rapid field detection of drugs; however, interference from matrix components, such as salts, solvents, and other metabolites, often leads to high rates of false positives and false negatives, making it challenging to meet the requirements for rapid field detection. To mitigate these challenges, a solvent-assisted thermal desorption ionization source has been developed, which enables rapid screening, improved accuracy and quantitative MS analysis. This ionization source is designed to allow the introduction of sample solution into the thermal desorption chamber with coaxial solvent and gas flows. The sample is introduced into a closed high-temperature thermal desorption chamber by the coaxial gas flow, where it is rapidly vaporized, enabling a concentrated ionization and avoiding chemical interferences from the environment. The use of both a solvent flow and a guiding gas flow in the new ion source design effectively reduces the sample deposition on the inner surface of the glass liner in the thermal desorption chamber and minimize cross contamination and the interferences from salts in the sample, a significant 1.8-5 fold enhancement in the signal intensity of the drug was observed, and accommodates a large sample volume injection for a significantly increased sensitivity, repeatability, and accuracy of MS detection. By integrating this novel solvent-assisted thermal desorption ionization source with a portable mass spectrometer and employing a selected ion monitoring (SIM) mode, the linear dynamic ranges of detection for ketamine, cocaine, and morphine in the hair matrix have shown to be 1-20 ng/mg, with R2 > 0.99. The recovery rates for the three tested illicit drugs are all within the range of 92.28 %-104.66 %. Both intra-day and inter-day precision remain to be below 10 %, indicating high measurement accuracy and stability. The limit of detection (LOD) for ketamine, cocaine, and morphine at 0.2 ng/mg has also been achieved, which is significantly better than those by using conventional methodologies. The technique developed through this study provides a reliable tool for in situ rapid analysis of illicit drugs in hair.

Lab-on-Robot: Unmanned Mass Spectrometry Robot for Direct Sample Analysis in Hazardous and Radioactive Environments

Onsite, safe, and reliable mass spectrometry (MS) analysis of hazardous and radioactive samples plays a crucial role in timely chemical emergency management and response in real environments. The current study reports the development of a smart MS robot by integrating miniature MS, quadruped robot, switchable robotic arm sampler, and direct ionization for remote-controlled chemical analysis of complex samples in inaccessible hazardous and radioactive environments. High automation and excellent analytical performance have been achieved in the real-time analysis of volatile toxic substances in air and onsite detection of explosive particles in air aerosols. Successful detection of hazardous compounds has been performed from raw wastewater. The chemical analysis of radioactive ore samples has also been demonstrated. Low limits of detection at ng/g or ng/mL (signal-to-noise ratio, S/N = 3) and good relative standard deviation (RSD < 12.0%, n = 6) were obtained by the MS robot for analyzing different gaseous, aerosol, liquid, and solid samples. The remote detection results of the MS robot were further validated. The reported study encourages the future development of a smart lab-on-robot, which functions with smart operation to replace the traditional laboratory procedures for MS analysis of dangerous chemical and environmental samples.

Real-Time Visual Monitoring and High Spatiotemporal-Resolution Mapping of Air Pollutants Using a Drone-Mass Spectrometer System

Volatile organic compounds (VOCs) play multifaceted roles in the formation of air pollutants. Real-time online monitoring of VOCs is highly needed for understanding their emission sources, environmental impacts, health effects, and climate changes, as many analytical methods are limited to field detection. In this work, a flying-drone-based mass spectrometer (drone-MS) system was developed for visual real-time monitoring of complex VOCs and mapping their diffusions and distributions in the air along with spatiotemporal, geospatial, and environmental information that varies with the flight paths. Analytical performances of the drone-MS system were investigated by detecting a mixture of 18 VOCs, showing high sensitivity (limits of detection, LODs: 1.10-17.91 μg/m3; limits of quantification, LOQs: 3.84-37.61 μg/m3), good reproducibility (relative standard deviations, RSDs, intraday: 0.96-16.49%; interday: 1.17-18.28%; n = 7), and excellent quantitative ability (R2 > 0.99). Online monitoring of complex VOCs was successfully obtained at high temporal resolution (1.0 s) and high spatial resolution (2.0 m), providing an accurate source apportionment of different VOC emissions. Furthermore, practical applications of urban air quality monitoring and spatial distribution mapping of complex VOCs in air were also demonstrated. Overall, this methodology offers new possibilities for the online monitoring of complex VOCs in the air, effectively tackling the longstanding challenge of accurately characterizing complex VOCs and their diffusions and distributions.

Real-time detection of organophosphorus pesticides in water using an unmanned boat-borne Raman spectrometer

Organophosphorus pesticides (OPs) have been widely used in agricultural production. However, their potential harm to human health and the environment cannot be ignored. On-site detection of OPs in water is valuable for pollution source tracing and early warning of environmental pollution. We design an unmanned boat detection system equipped with a Raman spectrometer, which can achieve automated sampling and real-time detection of OPs in water. The unmanned boat detection system integrates automatic sampling, chemical reaction, spectral detection, and signal transmission modules. This method can specifically detect OPs in water by utilizing the inhibition effect of OPs on acetylcholinesterase activity. The minimum detection concentration is 700 nM for parathion-methyl. This method shows good anti-interference ability for other kinds of pesticides, demonstrating its applicability for rapid detection of OPs under complex water environmental conditions. Our strategy provides an efficient solution for real-time and flexible monitoring of OPs in water environments.

Onsite Analysis of Complex Samples Using Miniature Mass Spectrometry With Direct Sampling and Ionization

RATIONALE

Miniature mass spectrometry (mini-MS) is a powerful method for onsite analysis of complex. The onsite sampling/ionization approach is critical in rapid screening of complex samples by mini-MS in field environments. Therefore, new development of direct ionization/sampling method coupled with mini-MS is needed for direct sample analysis.

METHODS

A direct sampling/ionization kit using wooden tip or plant tissue was developed to couple with mini-MS for onsite analysis of complex samples. Targeted analytes were detected and identified by mini-MS/MS.

RESULTS

Various raw samples including powders, liquid, and viscous samples were directly sampled and ionized using wooden tip. Direct pesticide detection in juice was used to further evaluate the analytical performances of the newly developed wooden tip kit, obtaining excellent sensitivity, reproducibility, and quantitation capacity for direct sample analysis. Furthermore, direct tissue analysis was also successful demonstrated by direct ionization, showing a fast, simple, and efficient method for onsite analysis of biological tissue.

CONCLUSIONS

Overall, our data showed that this direct sampling/ionization method using wooden tip or plant tissue coupled with mini-MS approach is simple, fast, and sensitive method for onsite direct analysis of raw samples in field environments.

Portable Miniature Mass Spectrometry for Enhanced On-Site Detection of Analytes in Complex Samples by Integrating Solid-Phase Microextraction and Nano-Electrospray Ionization

On-site mass spectrometry (MS) analysis plays a crucial role in timely understanding chemical compositions of field samples but presents a challenge to miniaturization, portability, and sensitivity. In this work, a portable MS approach was developed by integrating biocompatible solid-phase microextraction (SPME) and a nano-electrospray ionization (nESI) emitter into a kit to couple miniature MS (mMS). The SPME fiber was used for on-site extractive sampling of analytes from complex liquid samples and living organisms and was then inserted into an nESI emitter for on-site MS analysis via the facile kit. The limit of detection was found to be at the pg/mL level for various compounds tested. Acceptable relative standard deviation (RSD) values (5.5-7.6%, n = 6) were obtained for direct measurement of analytes in complex matrixes; acceptable linear responses (0.1-50 ng/mL) and matrix effects (76.0-82.6%) were also found. Enhanced detection of compounds of interest in various real samples, such as food samples, human fluids, environmental water, and living organisms, was unambiguously demonstrated. Our experimental data showed that SPME-nESI-mMS is a promising tool for on-site analysis of various complex samples in significant applications including but not limited to food safety, environmental monitoring, forensic investigation, and bioanalysis.

Sensitive and isotopic interference-free analysis of Sb using hydride generation-microwave plasma torch-mass spectrometry under ambient condition

A sensitive and isotopic interference-free analysis method for Sb was developed based on hydride generation-microwave plasma torch-mass spectrometry (HG-MPT-MS). Compared to the conventional ICP-MS, MPT coupled to an ion trap mass spectrometer enabled much "softer" ionization of Sb under ambient condition, which provided multi-detection modes and various ion forms, such as Sb+, SbO+, SbO2-, SbO++H2O and so on. These ion formations can be easily regulated by tuning capillary voltage and tube lens voltage, which facilitated elimination of isotopic interference during analysis, for instance the interference of 123Te on 123Sb could be effectively excluded by optimizing parameters of capillary voltage and tube lens voltage. The potential application of HG-MPT-MS for Sb isotope ratio analysis was also demonstrated, which could be determined in different forms, e.g., 123Sb/121Sb or 123Sb16O/121Sb16O. The value of 123Sb/121Sb was determined to be 0.75110 ± 0.00038 (2σ, n > 50). In addition, the detection limit, linearity and spike recovery were also studied. Overall, HG-MPT-MS performed equally well on detection limit (0.05 μg/L) with ICP-MS or HG-AFS. The linearity (R2 = 0.998) was checked in the concentration range of 10-500 μg/L. Spike recovery were evaluated with two soil samples, and the obtained spike recovery ranged 90-100 %. In general, HG-MPT-MS was expected to be a versatile tool for study the biochemical or geochemical behaviors of Sb and other hydride forming elements under ambient condition in a much simpler and more efficient way.

Boosting the sensitivity of single photon ionization time-of-flight mass spectrometry using a segmented focus quadrupole-ion guide

Single photon ionization time-of-flight mass spectrometry (SPI-TOF-MS) is a powerful analytical technique for real-time detection of trace VOCs. However, efficient ion transmission within the ionization chamber has always been a challenging issue in SPI-TOF-MS. In this study, a novel ion guide termed the Segmented Focus Quadrupole Ion Guide (SFQ-IG) was introduced for SPI-TOF-MS. The SFQ-IG device consists of 12 printed circuit boards (PCB), each containing four quarter-ring electrodes with inner diameters progressively decreasing from 26 to 4 mm. The simulation results demonstrated that SFQ-IG exhibited superior ion transmission efficiency than both ion funnel (IF) field and direct current-only (DC-only) field. By integrating into a SPI-TOF-MS, this ion guide was optimized in terms of the ionization source pressure, direct current gradient, and radio frequency amplitude. Further comparative experiments demonstrated that the SPI-TOF-MS with the SFQ-IG exhibited higher sensitivity than both the IF field (1.3-7.4 times) and DC-only field (3.5-8.8 times) for the test VOCs. The improvements in limit of detection (LOD) with the SFQ-IG ranged from 1.6 to 5.3 times compared to the DC-only field for the test VOCs. Fabricated using PCB technology, the SFQ-IG is characterized by its cost-effectiveness, compact size, and high transmission efficiency, facilitating its integration into other mass spectrometers.

Portable Mass Spectrometry for On-site Detection of Hazardous Volatile Organic Compounds via Robotic Extractive Sampling

Various hazardous volatile organic compounds (VOCs) are frequently released into environments during accidental events that cause many hazards to ecosystems and humans. Therefore, rapid, sensitive, and on-site detection of hazardous VOCs is crucial to understand their compositions, characteristics, and distributions in complex environments. However, manual handling of hazardous VOCs remains a challenging task, because of the inaccessible environments and health risk. In this work, we designed a quadruped robotic sampler to reach different complex environments for capturing trace hazardous VOCs using a needle trap device (NTD) by remote manipulation. The captured samples were rapidly identified by portable mass spectrometry (MS) within minutes. Rapid detection of various hazardous VOCs including toxicants, chemical warfare agents, and burning materials from different environments was successfully achieved using this robot-MS system. On-site detection of 83 typical hazardous VOCs was examined. Acceptable analytical performances including low detection limits (at subng/mL level), good reproducibility (relative standard deviation (RSD) < 20%, n = 6), excellent quantitative ability (R2 > 0.99), and detection speed (within minutes) were also obtained. Our results show that the robot-MS system has excellent performance including safety, controllability, applicability, and robustness under dangerous chemical conditions.

On-site monitoring of nandrolone in cattle farming samples by portable atmospheric pressure chemical ionization mass spectrometry with ambient sampling

Nandrolone (NT) is a type of androgen anabolic steroid that is often illegally used in cattle farming, leading to unpredictable harm to human health via the food chain. In this study, a rapid detection method for NT in the samples of cattle farming was established using a portable mass spectrometer. The instrument parameters were optimized, including a thermal desorption temperature of 220 °C, a pump speed of 30 %, an APCI ionization voltage of 3900 v, and an injection volume of 6 μL. The samples of bovine urine, feed, sewage, and tissue were selected, and extracted using a solution of methanol:acetonitrile (1:1, v/v), followed by spiking a NT standard solution (1000 ng·mL-1) and ionization through the APCI ion source for detection. The results showed that NT could not be detected in beef and feed due to the complexity of the matrix, while clear signals of NT ions were observed in bovine urine and sewage samples, with LODs of 1000 and 100 ng·mL-1, respectively. Furthermore, quantitative analysis was attempted, and a good linear relationship (R2 = 0.9952) was observed for NT in sewage within the range of 100 to 1000 ng·mL-1. At spiked levels of 100, 500, 1000 and 2000 ng mL-1, the recovery rates ranged from 74.3 % to 92.8 %, with a relative standard deviation (n = 6) of less than 15 %. In conclusion, this detection method offers the advantages of simplicity, rapidity, strong timeliness, and specificity, making it suitable for on-site detection. It can be used for qualitative screening of nandrolone in bovine urine and quantitative analysis of nandrolone in sewage.