Molecularly imprinted polymer sheathed mesoporous silica tube as SPME fiber coating for determination of tobacco-specific nitrosamines in water

Tobacco-specific nitrosamines (TSNAs) are probably carcinogenic disinfection byproducts eliciting health risk concerns. The determination and surveillance of TSNAs in water is still cumbersome due to the lack of advanced sample preparation methods. Herein, we prepared a solid phase microextraction (SPME) fiber coated with the molecularly imprinted polymer (MIP) sheathed mesoporous silica tube (MST) composite material, and developed a highly efficient, selective, and sensitive method for the determination of five TSNAs in water. Benefiting from the TSNAs-specific recognition of MIP and the increased specific surface area derived from MST, the MIP@MST fiber exhibited excellent extraction performance for TSNAs, which was much superior to the commercially available SPME fibers. By coupling to high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), the outstanding analytical merits such as low method detection limits (ranging 0.1-6.7 ng L-1) and good reproducibility (intra-fiber and inter-fiber relative standard deviations ranging 4.1 %-11.6 % and 3.5 %-12.2 %, respectively) were achieved with the consumption of 8 mL water sample and 100 μL methanol solvent in 50 min. The feasibility of the SPME-HPLC-MS/MS method was demonstrated in tap water and chloraminated source water, with relative recoveries for the five TSNAs ranging from 85.2 % to 108.5 %. In result, none of the TSNAs were found in the tap water samples, while 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-Butanol (NNAL) were detected in the chloraminated source water samples. The rapid and convenient SPME-HPLC-MS/MS method developed in this study offers a powerful tool for monitoring TSNAs in water.

Rapid and sensitive determination of free fatty acids based on in-source microdroplet-driven derivatization coupled with high-resolution mass spectrometry

Accurate and sensitive measurements of free fatty acids (FFAs) in biological samples are valuable for diagnosing and prognosing diseases. In this study, an in-source microdroplet derivation strategy combined with high-resolution mass spectrometry was developed to analyze FFAs in lipid extracts of biological samples directly. FFAs were rapidly derivated with 2-picolylamine (PA) in the microdroplet which is derived by electrospray. With the proposed method, twelve typical FFAs were determined reliably with high sensitivity and acceptable linearities (R2 ≥ 0.94). The LODs and LOQs for the twelve FFAs were 9-76 pg mL-1 and 30-253 pg mL-1, respectively. The developed method was applied to analyze the alteration of FFAs in liver and kidney samples of rats induced by perfluorooctane sulfonate (PFOS) exposure. The good results demonstrate that the established analysis technique is dependable and has promising applications in detecting FFAs associated with complex biological samples.

Detection of apple fruit damages through Raman spectroscopy with cascade forest

Apple fruit damages seriously cause product and economic losses, infringe consumer rights and interests, and have harmful effects on human and livestock health. In this study, Raman spectroscopy (RS) and cascade forest (CForest) were adopted to determine apple fruit damages. First, the RS spectra of healthy, bruised, Rhizopus-infected, and Botrytis-infected apples were measured. Spectral changes and band attribution were analyzed. Different modeling methods were combined with various pre-processing and dimension reduction methods to construct recognition models. Among all models, CForest constructed with full spectra processed by Savitsky-Golay smoothing obtained the best performance with accuracies of 100%, 91.96%, and 92.80% in the training, validation, and test sets (ACC_TE). And the modeling time is reduced to 1/3 of the full-spectra model with a similar ACC_TE of 91.56% after principal component analysis. Overall, RS and CForest provided a non-destructive, rapid, and accurate identification of apple fruit damages and could be used in disease recognition and safety assurance of other fruits.

Rapid determination of illegally added Sudan I in cake by triphenylamine functionalized polyhedral oligomeric silsesquioxane fluorescence sensor

Triphenylamine functionalized polyhedral oligomeric silsesquioxane (POSS@TPA) was prepared using the Friedel-Crafts reaction with tris(4-bromophenyl)amine (TPA) as the functional monomer and polyhedral oligomeric silsesquioxane (POSS) as the framework. The as-prepared POSS@TPA has a stable structure and accomplished pore performance, allowing for the selective adsorption of Sudan I and result in the fluorescence quenches of POSS@TPA. Thus, the POSS@TPA could be used as sensors to fluorescence detect 0.12-7.4 mg/L Sudan I, with a detection limit of 0.091 mg/L. Moreover, the POSS@TPA have good reuseability can be reused more than 5 cycles after washing. Noteworthily, the response time of POSS@TPA for determination was as short as 1 min. Furthermore, the sensor was effectively used to determine Sudan I in cakes with excellent recoveries (86.4-108.8 %) and relative standard deviations (2.5-4.9 %). The results matched those of high-performance liquid chromatography (HPLC). Our work shows great potential in terms of the rapid detection of food safety.

Novel approach for strontium preconcentration from seawater and rapid determination of 89,90Sr in emergency situations

A novel approach for rapid ^89,90Sr determination in seawater samples is developed. For the first time in the radioanalytical application, the features of the synthetic zeolite Z4A and a highly selective material for Sr separation were synergically employed. Seawater composition significantly reduces Sr yield on highly selective solid-phase extraction materials, making the preconcentration step essentially important but laborious and time-consuming. To address this issue, the ability of zeolite 4A to concentrate the Sr from the seawater matrix was employed. With the proposed method, two important goals were achieved: (i) simple preconcentration of Sr that can be conducted directly at the sampling site, enabling a rapid procedure for ^89,90Sr determination in emergencies, and (ii) high and stable Sr recoveries (89 ± 4%) necessary for lowering detection limits. Strontium is effectively separated from 1 L of seawater in less than 1.5 h, which is especially important in emergency situations, such as the Fukushima Daiichi Nuclear Power Plant accident. Minimum detectable activities achieved for ⁸⁹Sr:⁹⁰Sr activity ratio ∼10:1 were 0.74 Bq/L for ⁸⁹Sr, and 1.47 Bq/L for ⁹⁰Sr, detected by Cherenkov counting, 36-38 h after separation, and 30 min counting time.

A portable electromagnetic heating-microplasma atomic emission spectrometry for direct determination of heavy metals in soil

In this work, electromagnetic heating was firstly explored as sample introduction approach in portable microplasma-atomic emission spectrometer to achieve the direct, rapid analysis of soil sample. The device primarily consists of an electromagnetic heating unit, a dielectric barrier discharge (DBD) excitation source and an optical signal acquisition unit. A W-boat was used as an electromagnetic heating medium and sample carrier, and copper coil spiraled around the tube was used as magnetic induction coil. With applying a voltage on copper coil, W-boat was electromagnetically heated to vaporize analyte-containing species for sample introduction into the microplasma. The portable battery-powered device is controlled by a miniature touch screen computer with the main advantages of small size (40.5 cm (l) × 30 cm (w) × 15 cm (h).), light weight (less than 7 kg), low-power consumption (the average power consumption is 118 W). By this method, Hg, Cd and Pb in soil were simultaneously analyzed within 4 min. Under the optimal conditions, the limits of detection for Hg, Cd and Pb in soils were 8.0 μg/kg, 17.8 μg/kg and 3.5 mg/kg, respectively, meeting the requirements for environmental quality standards for soils of China. Different types of CRM soils were analyzed, demonstrating good accuracy, stability and utility of this method. This technique could be a promising and powerful tool for on-site, rapid analysis of heavy metals in soil even other solid samples. Electromagnetic heating mode provides a good alternative for solid sampling to develop portable, miniaturized atomic spectrometers for solid sample analysis.

Method for determination of Pu isotopes in soil and sediment samples by inductively coupled plasma mass spectrometry after simple chemical separation using TK200 resin

Plutonium has been extensively studied in the environment, for the purpose of radiological assessment, environmental behavior study and nuclear emergency response. To determine Pu isotopes in environmental soil and sediment, a novel analytical method was established in this study using a new type of extraction resin, TK200 resin. Firstly an investigation was performed to study the extraction behaviors of Pu, U, Th, Hg, Tl, Pb, Bi and Hf on TK200 resin. On the basis of the results, a new chromatographic procedure was then proposed to separate Pu from the elements that interfere the accurate determination of Pu isotopes by mass spectrometry. Owing to the excellent separation efficiency between Pu and interfering elements (IEs) of the developed procedure, high decontamination factors (DFs) were obtained for IEs, e.g. the DF(U) (>7.5 × 10⁷) was the highest reported value. The separation procedure was finally combined with HNO₃ leaching, CaF₂/LaF₃ coprecipitation and sector field-inductively coupled plasma mass spectrometry (SF-ICPMS) measurement to establish a complete method. The established method was evaluated by analyzing four standard reference materials (soil, sediment), and the results showed that both ^239+240Pu activity and ²⁴⁰Pu/²³⁹Pu isotopic ratio were accurately determined, with stable and high Pu chemical recoveries (81-91%). The whole analytical method only took about 15 h, and the limits of detection were calculated to be 0.13-0.24 fg g^-1 for Pu isotopes (for 2 g soil or sediment), guaranteeing the rapid determination of ultra-trace level Pu in soil and sediment samples.

Rapid determination of cadmium in rice by portable dielectric barrier discharge-atomic emission spectrometer

In this work, a home-made portable dielectric barrier discharge-atomic emission spectrometer (DBD-AES) was explored to the determination of heavy metal in foodstuffs. A rapid and simple method was developed for Cd determination in rice based on this instrument. Rice was pretreated with diluted acid dissolution without complex operations and apparatus. The detection time by DBD-AES is about 3 min and the total analysis time for rice sample is within 11 min. The effects of some key experiment parameters were investigated. The limit of detection was 11.9 μg kg^-1 for Cd in rice, much lower than the maximum allowable level established by EC (200 μg kg^-1). The practical performance of this method was demonstrated by analyzing real and CRM rice samples. With the portability of DBD-AES, the method is suitable for rapid and in-field analysis of Cd in rice. It will be a useful tool for the routine analysis of rice.

The Control of Glucose and Lactate Levels in Nutrient Medium After Cell Incubation and in Microdialysates of Human Adipose Tissue by Capillary Electrophoresis with Contactless Conductivity Detection

Two methods of capillary electrophoresis with contactless conductivity detection have been developed for monitoring the levels of glucose and lactate in clinical samples. The separations are performed in uncoated fused silica capillaries with inner diameter 10 or 20 μm, total length 31.5 cm, length to detector 18 cm, using an Agilent electrophoretic instrument with an integrated contactless conductivity detector. Glucose is determined in optimized background electrolyte, 50 mM NaOH with pH 12.6 and 2-deoxyglucose is used as an internal standard; the determination of lactate is performed in 40 mM CHES/NaOH with pH 9.4 and lithium cations as an internal standard. Both substances are determined in minimal volumes of (1) nutrient media after cell incubation, and (2) microdialysates of human adipose tissue; after dilution and filtration as the only treatment of the sample. The migration time of glucose is 2.5 min and that of lactate is 1.5 min with detection limits at the micromolar concentration level. The developed techniques are suitable for sequential monitoring of glucose and lactate over time during metabolic experiments.

Rapid and Sensitive Determination of Branched-Chain Amino Acids in Human Plasma by Capillary Electrophoresis with Contactless Conductivity Detection for Physiological Studies

Capillary electrophoresis (CE) with contactless conductivity detection (C⁴D) represents a strong tool for determining amino acids in clinical samples. This chapter provides detailed instructions for CE/C⁴D determination of the branched-chain amino acids (BCAAs) valine, isoleucine, and leucine in human plasma, which can be readily employed in physiological studies. Baseline separation of all the BCAAs is achieved on a short separation length equal to 18 cm in optimized background electrolyte consisting of 3.2 M acetic acid dissolved in 20% v/v methanol with addition of 1.0% v/v INST-coating solution. The analysis time does not exceed 3 min and the limit of detection is 0.4 μM for all BCAAs. The pretreatment of human plasma is very simple and is based on fourfold plasma dilution by acetonitrile and subsequent filtration. Only 50 μL of plasma is used for the analysis. The high sensitivity of the CE/C⁴D method is achieved by injecting a large volume of sample, combined with application of negative pressure to flush the acetonitrile zone out of the capillary.

Determination of the gross activity of uranium, plutonium, americium and strontium in environmental samples using solid-state scintillation

Rapid determination of selected gross alpha and beta emitters in environmental matrices by solid-state scintillation technique is discussed. This method is based on sample treatment using microwave reactor and direct measurement of digested products using powder scintillator and alkaline solution as a substitute for traditional liquid scintillation cocktail. The selected group of radionuclides was chosen with respect to their use in nuclear industry, high radiotoxicity, and the possibility of potential misuse. The work aimed at verifying the connection of microwave decomposition using alkaline solution with solid-state scintillation using a powder scintillator YAP:Ce together with an alkaline medium.

Iron oxyhydroxide nanorods with high electrochemical reactivity as a sensitive and rapid determination platform for 4-chlorophenol

Iron oxyhydroxide (FeOOH) nanorods were prepared through solvothermal reaction, and characterized using Raman spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy and scanning electron microscopy. Thereafter, the prepared FeOOH nanorods were used as sensing material to construct a novel detection platform for 4-chlorophenol (4-CP). The electrochemical behaviors of 4-CP were studied, and the oxidation peak currents increased greatly on the surface of FeOOH nanorods. The signal enhancement mechanism was studied for 4-CP, and it was found that the prepared FeOOH nanorods remarkably improved the electron transfer ability and surface adsorption efficiency of 4-CP. The influences of pH value, amount of FeOOH nanorods and accumulation time were examined. As a result, a highly-sensitive electrochemical method was developed for the rapid determination of 4-CP. The linear range was from 10 to 500nM, and the detection limit was 3.2nM. It was used in different water samples, and the results consisted with the values that obtained by high-performance liquid chromatography.

Development and characterisation of a new Sr selective resin for the rapid determination of ⁹⁰Sr in environmental water samples

A new resin selective for Sr has been developed and characterised for the direct binding of (90)Sr from environmental waters with minimal pre-treatment. The new selective resin comprises of a mixture of two extractants, 4,4'(5')-bis-t-butylcyclohexano-18-crown-6 and di(2-ethyl-hexyl)phosphoric acid, sorbed onto Amberchrom CG-71. Sr uptake is shown to be high (the distribution weight coefficient Dw >100 mL g(-1)) across a range of environmentally realistic conditions (pH 2-8 and up to 11,500 mg L(-1) NaCl, 500 mg L(-1) Ca, 400 mg L(-1) K and 1300 mg L(-1) Mg). The Sr capacity of the resin is shown to be 7.7±0.4 mg g(-1), meaning that the resin has a sufficient capacity to quantitatively remove Sr from most environmental water samples. The reasonably fast uptake kinetics of the resin (95±4% of strontium bound within 30 min) results in a resin that is applicable to both batch- and column-type separation procedures. A range of potentially co-extracted radio-elements have been identified and an elution scheme has been developed to separate interferences, including (90)Y, from (90)Sr. The clean elution of (90)Sr permits immediate measurement by radiometric means, with no need for complicated spectral processing or waiting for secular equilibrium between (90)Sr and (90)Y. The characterised resin is applicable for use in rapid determination procedures, enabling the swift analysis of water samples required by monitoring schemes at contaminated nuclear sites and in the aftermath of nuclear accidents.