微全分析系统在环境污染物检测中的研究与应用

环境污染物的高效检测是分析领域关注的焦点,微全分析系统(μTAS)为现代环境监测提供了良好的技术平台和新的技术途径.本文综述了近年来μTAS在小分子环境样品检测和分析方面的研究进展,重点针对有机磷类、含硝基化合物、酚类、氨基甲酸酯类、芳香胺等有机污染物,各类阴离子和金属阳离子等无机污染物,氮氧化物、二氧化硫、硫化氢、甲...     

Multiplex bioanalytical methods for food and environmental monitoring

Recent advances in miniaturization of analytical systems and newly emerging technologies offer platforms with greater automation and multiplexing capabilities than traditional biological binding assays. Multiplexed bioanalytical techniques provide control agencies and food industries with new possibilities for improved, more efficient monitoring of food and environmental contaminants. This review deals with recent developments in planar-array and suspension-array technologies, and their applications in detecting pathogens, food allergens and adulterants, toxins, antibiotics and environmental contaminants.     

Portable,Ambient PM2.5 Sensor for Human and/or Animal Exposure Studies

A field-portable device for logging PM_2.5 mass concentration data has been developed. The device combines the Arduino microprocessor with an SD card, a Sharp DN7C3CA006 optical dust monitor, and 10,000-mAh battery. The dust sensor uses a virtual impactor to size select particles <2.5 microns prior to illuminating the selected fraction with an LED. The LED is triggered by a circuit controlled with the Arduino. Nephelometric detection at 120° referenced to incidence is used. The voltage signal reported by the dust sensor is converted to PM_2.5 mass through calibration onboard the Arduino. Data points can be saved to the SD card as rapidly as 0.3?s, although averaging signals over 60?s produced more optimal detection limits. For a 60?s average, the PM_2.5 mass limit of detection was 9?µg?m^?3, indicating that the sensor will be useful for monitoring human exposure to fine particles. Portable exposure monitoring has been demonstrated with the sensing platform as several individuals carried the device with them during daily activities in Lubbock, TX and Atlanta, GA. For this group of test subjects, values of PM_2.5 exposure varied from 0 to 1000?µg?m^?3 during the sampling periods. It was observed that, by far, the highest levels of PM_2.5 occur during periods of cooking, or being near cooking operations. Other periods of high PM_2.5 occurred during ground transportation, use of personal care products, vacuuming, and visiting restrooms. When hourly personal exposure data were correlated with hourly average PM_2.5 for outdoor air for the Atlanta data set, a very weak correlation was found (R²?=?0.026). Only two out of eight sampling periods did the personal monitoring estimate of exposure agree with that predicted by outdoor monitoring to within 15%. Personal exposure was often affected by circumstantial, short-term, high exposure events that are difficult to model or predict effectively. The short-term exposure events generally cause true exposure to be higher than that predicted by using outdoor ambient PM_2.5 to generate estimates. This finding complicates interpretation of epidemiological studies that find links between ambient outdoor PM_2.5 levels and human health, while it buttresses the case for using personal ambient monitors.     

CARBONIZED FIBROUS RESIN AS A NEW SORBENT FOR SAMPLING POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) IN AMBIENT AIR

1. INTRODUCTION When investigating contaminated sites it is often essential to determine specific pollutants in a large number of ambient air samples. Amongst these sites, polycylic aromatic hydrocarbons (PAHs) are a major class of compounds that hav…     

Electrochemical detection of nitrate,nitrite and ammonium for on-site water quality monitoring

This review examines the most recent electrochemical developments for nitrate, nitrite and ammonium detection for on-site water monitoring. There remains a high demand for effective field-based detection of the dissolved inorganic nitrogen (DIN) analytes to aid in mitigating nitrogen loading. Electrochemical approaches show increasing potential to fill this role as advancements in nanotechnology continually improve analytical performance and on-site applicability. However, translating these improvements into the field still faces the resonating challenges of reaching analytical proficiency (selectivity, sensitivity, robustness, stability), practical end-user functionality, minimal matrix interferences and cost effectiveness. Herein, we elaborate on these challenges via a critical evaluation of current studies and examine how realistic the prospects of on-site nitrate, nitrite and ammonium are. We also present recommendations in addressing these gaps to conclude the review.     

Vapor deposition of ultrathin hydrophilic polymer coatings enabling candle soot composite for highly sensitive humidity sensors

Candle soot (CS) is a desirable carbon nanomaterial for sensors owing to its highly porous nanostructure and large specific surface area. CS is advantageous in its low-cost and facile preparation compared to graphene and carbon nanotubes, but its pristine nanostructure is susceptible to collapse, hampering its application in electronic devices. This article reports conformal coating of nanoscale crosslinked hydrophilic polymer on CS film using initiated chemical vapor deposition, which well preserved the CS nanostructure and obtained nanoporous CS@polymer composites. Tuning coating thickness enabled composites with different morphologies and specific surface areas. Surprisingly, the humidity sensor made from composite with the lowest filling degree, thus largest specific surface area, showed relatively low sensitivity, which is likely due to its discontinuous structure, thus insufficient conductive channels. Composite sensor with optimum filling degree shows excellent sensing response of more than 10³ with the linearity of R² = 0.9400 within a broad relative humidity range from 11% to 96%. The composite sensor also exhibits outstanding sensing performance compared to literature with low hysteresis (3.00%), a satisfactory response time (28.69 s), and a fast recovery time (0.19 s). The composite sensor is fairly stable and durable even after 24 h soaking in water. Furthermore, embedding a humidity sensor into a face mask realizes real-time monitoring of human breath and cough, suggesting promising applications in respiratory monitoring.     

Bulk derivatization and cation exchange restricted access media-based trap-and-elute liquid chromatography–mass spectrometry method for determination of trace estrogens in serum

Estrone (E1), estradiols (α/β-E2), and estriol (E3) are four major metabolically active estrogens exerting strong biological activities at very low circulating concentrations. This paper reports a sensitive and efficient method with automated, on-line clean-up and detection to determine trace estrogens in a small volume of serum samples using liquid chromatography–electrospray ionization–tandem mass spectrometry directly, without off-line liquid–liquid or solid-phase extraction pretreatments. Serum aliquots (charcoal stripped fetal bovine serum, 100 μL) were spiked with four estrogen standards and their corresponding isotope-labeled internal standards, then bulk derivatized with 2-fluoro-1-methyl-pyridium p-toluenesulfonate (2-FMP) to establish the calibration curves and perform method validation. Calibration was established in the concentration ranges of 5–1000 pg mL⁻¹, and demonstrated good linearity of R² from 0.9944 to 0.9997 for the four derivatized estrogens. The lower detection limits obtained were 3–7 pg mL⁻¹. Good accuracy and precision in the range of 86–112% and 2.3–11.9%, respectively, were observed for the quality control (QC) samples at low, medium, and high concentration levels. The stability tests showed that the derivatized serum samples were stable 8 h after derivatization at room temperature and at least to 48 h if stored at −20 °C. The method was applied to measure trace estrogens in real human and bovine serum samples, and three of four estrogen compounds studied were observed and quantified.     

New approach for natural products screening by real-time monitoring of hemoglobin hydrolysis using quartz crystal microbalance

The hemoglobin (Hb) released from erythrocytes is a primary nutritive component for many blood-feeding parasites. The aspartic protease cathepsin D is a hemoglobinase that is involved in the Hb degradation process and is considered an interesting target for chemotherapy intervention. However, traditional enzymatic assays for studying Hb degradation utilize spectrophotometric techniques, which do not allow real-time monitoring and can present serious interference problems. Herein, we describe a biosensor using simple approach for the real-time monitoring of Hb hydrolysis as well as an efficient screening method for natural products as enzymatic inhibitors using a quartz crystal microbalance (QCM) technique. Hemoglobin was anchored on the quartz crystal surface using mixed self-assembled monolayers. The addition of the enzyme caused a mass change (frequency shift) due to Hb hydrolysis, which was monitored in real time. From the frequency change patterns of the Hb-functionalized QCM, we evaluated the enzymatic reaction by determining the kinetic parameters of product formation (k_cat). The QCM enzymatic assay using immobilized human Hb was shown to be an excellent approach for screening possible inhibitors in complex mixtures, opening up a new avenue for the discovery of novel inhibitors.     

Tutorial review on validation of liquid chromatography–mass spectrometry methods: Part I

This is the part I of a tutorial review intending to give an overview of the state of the art of method validation in liquid chromatography mass spectrometry (LC–MS) and discuss specific issues that arise with MS (and MS/MS) detection in LC (as opposed to the “conventional” detectors). The Part I briefly introduces the principles of operation of LC–MS (emphasizing the aspects important from the validation point of view, in particular the ionization process and ionization suppression/enhancement); reviews the main validation guideline documents and discusses in detail the following performance parameters: selectivity/specificity/identity, ruggedness/robustness, limit of detection, limit of quantification, decision limit and detection capability. With every method performance characteristic its essence and terminology are addressed, the current status of treating it is reviewed and recommendations are given, how to determine it, specifically in the case of LC–MS methods.     

Monitoring and classification of wastewater quality using supervised pattern recognition techniques and deterministic resolution of molecular absorption spectra based on multiwavelength UV spectra deconvolution

A field flow approach for the in situ monitoring of wastewater quality is developed and assessed in this work, based on a combination of methods employing deconvolution of molecular absorption spectra and in situ/on-line analysis of wastewater effluent of various origin. The approach involves in situ immersion probes to monitor basic physicochemical parameters followed by UV spectrum deconvolution in order to provide a rapid estimate of organic matter, suspended solids and nitrate and on-line analysis of phosphates in a fully automated setup. The collected data are then treated with a series of supervised pattern recognition techniques in order to classify wastewater effluent according to their origin in three major categories namely municipal, industrial and hospital. The results suggest that the method affords a good approximation of realistic concentrations, as determined by reference methods, while it affords a good classification among various wastewater effluents of different origin. In that manner, the method enables a rapid inference of treated wastewater quality and a robust assessment of treatment process state, especially with regards to violations of effluent quality parameters.