TALANTA
·
2019
·
IF 4.916
Lanxiu Ni,Xuhui Geng,Shenghong Li,Haijing Ning,Yan Gao,Yafeng Guan
A flame photometric detector with a silicon photodiode assembly instead of a photomultiplier tube for sulfur detection was developed and evaluated. The photosensitive area of photodiode, the optical design, and band-pass filters, were optimized. It was found that the optimal photosensitive area of the photodiode was 100 (mm) 2 , and three focus lenses combined with a broad band-pass filter of 378/52 nm and a QB21 glass yielded the best result. This design fully utilized the wide emission spectrum of S 2 *, the response characteristics of silicon photodiode, and effective absorption of strong emission spectrums of OH* at wavelength around 310 nm by QB21 glass. The limits of detection for nine kinds of sulfur containing compounds were between 5.8 × 10 −12 to 9.5 × 10 −12 g s −1 . This mode provided a linear response of 3 orders of magnitude for compounds being tested and a selectivity of sulfur over carbon of 10 5 . It is demonstrated for the first time that the overall performance of the flame photometric detector integrated with a silicon photodiode assembly work at room temperature was comparable to a conventional detector coupled with a photomultiplier tube, with advantages of short equilibration time, robust to electromagnetic interference and vibration, and low cost. The new detector can find wide application in gas chromatography and on-line monitoring instruments for sulfur measurement.
研究领域:
分析化学
·
环境科学
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DOI
高影响因子
JOURNAL OF CHROMATOGRAPHY A
·
2023
·
IF 4.1
Bangjie Yin,Zheng Zhang,Yingchun Wang,Hui Zeng,Jin Xu,Hongzhou Li,Yan Li,Min Zhang
The growing demand for tailored detectors in capillary electrophoresis (CE), addressing tasks like field deployment or dual-detection analysis, emphasizes the necessity for compact detection cells. In this work, we propose cost-effective and user-friendly additive manufacturing (3D-printing) approaches to produce such miniaturized detection cells suitable for a range of CE applications. Firstly, capacitively-coupled contactless conductivity detection (C 4 D) cells of different sizes are fabricated by casting low-melting-point alloy into 3D-printed molds. Various designs of Faraday shields are integrated within the cells and compared. A mini-C 4 D cell (9.5×7.0×7.5 mm 3 ) is produced, with limits of detection for alkaline cations ranging from 8-12 μM in a short–capillary based CE application. Secondly, ultraviolet photometric (UV-PD) detection cells are fabricated using 3D printing. These cells feature two narrow slits with a width of 60 μm, which are positioned along the path of incident and transmission light to facilitate collimation. A deep UV-LED (235 nm or 255 nm) is employed as the light source, and black resin is determined to be the optimal material for 3D printing the UV-PD cell, owing to its superior UV light absorption capabilities. The UV-PD cell is connected to the LED and photodetector through two optical fibers, making it easy to switch the light source and detector. The effective pathlength and stray light percentage for detecting on a 75 μm id capillary are 74 μm and 0.5 %, respectively. Thirdly, a dual-detection cell that combined C 4 D and UV-PD at a single detection point is proposed. The performance of direct detection by C 4 D and indirect detection by UV-PD is compared for detecting organic acids. The strategies for developing cost-effective compact detection cells facilitate the versatile integration of multiple detection methods in CE analysis.
研究领域:
分析化学
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生物分析
·
仪器科学与技术
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DOI
PubMed
高影响因子
CHEMICAL PAPERS
·
2022
·Vol. 77
·期 3
·1631-1644
·
IF 2.146
Zuo Xiong Jun,Liu Jinhui,Gu Feng Long
A new method of how to use high concentrations of UV–Vis absorbable components in mobile phases for ion chromatographic separation of anions with indirect photometric detection (IPD) was developed. The UV–Vis absorption curves, the signal strengths at selected wavelengths, and the response ranges at different wavelengths of three organic salts, sodium benzoate, sodium 4-nitrobenzoate and sodium 3,5-dinitrobenzoate were detected using a photodiode array detector. Mobile phases containing these three organic salts at concentrations as high as 20 mM were used for ion chromatographic separations of inorganic anions, such as F − , Cl − , NO 2 − , Br − , NO 3 − , and SO 4 2− . Separation characteristics detected at different wavelengths such as, the baseline stability, signal to noise levels shown as detection limits, linearity, etc., were investigated. It is found that the best wavelength used for IPD may not be the maximum or near the maximum absorption wavelength, but definitely not the non-absorptive wavelength of the eluent. Therefore, the best wavelength should be optimized. With the optimized wavelength at 385 nm, anions of sub-nanomoles were able to be quantitatively detected, and a good linear relationship with a correlation coefficients, ( r > 0.9998), within the sample ranges from 0.5 to 200 ng was available. By using the optimized wavelength, the threshold of the detector will no longer be a strict restriction factor of using high concentrations of UV–Vis absorbable components. Consequently, columns with different ion exchange capacities can be used for separations with IPD. Furthermore, because the separation system can be fast re-equilibrated after sample injection using high concentrations of monovalent ion eluent, the separation efficiency can be highly improved. This method is promising for developing mobile phases for other chromatographic separations with IPD.
研究领域:
分析化学
·
色谱技术
✓ 已验证
产品关联
DOI
高影响因子
ANALYTICA CHIMICA ACTA
·
2021
·
IF 6.558
Liye Yang,Guangchao Pan,Piwang Zhang,Qiang Liu,Xing Liu,Yan Li,Ying Liang,Min Zhang
In this work, for the first time, a 3D printed two-in-one on-capillary detector, combining contactless conductometric detection (C 4 D) and photometric detection (PD), is fabricated for capillary electrophoresis (CE). The C 4 D Faraday shield (FS) is printed using electrically conductive composite polylactic acid (PLA) to minimize the stray capacitance. Non-conductive PLA is also used to print the insulator of FS to prevent the electrical conduction with two stainless steel electrodes. A novel collimator , consisting of two partially aligned pinholes, is printed by conductive material to collimate the light-emitting diode beam. The C 4 D detection has a signal-to-noise ratio of 1092 ± 2 for 200 μM potassium on a 25 μm id capillary. The PD detection shows excellent linearity with stray light down to 8% and an effective path length at 73% of a 75 μm id capillary. The analytical performance is demonstrated by CE separation and detection of cations. PD shows limits of detection (LODs) of 1.3, 0.9, and 1.7 μM for cobalt, copper and zinc, which are complexed with 4-(2-Pyridylazo) resorcinol , while C 4 D shows LODs of 1.2, 1.4, 21 and 2.6 μM for potassium, sodium , cobalt and zinc, respectively.
研究领域:
分析化学
·
生物医学工程
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产品关联
DOI
PubMed
高影响因子
SENSORS AND ACTUATORS B-CHEMICAL
·
2018
·
IF 5.667
Bo Liang,Ge Wang,Lu Yan,Han Ren,Ruirui Feng,Zhong Xiong,Aihua Liu
The inhibition of acetylcholinesterase (AChE) activity based methods have been widely used for rapid detection of organophosphate (OP) pesticide residues. However, the sensitivity of the enzyme toward pesticides is not desirable and complex purification steps increase production cost. In this study, we optimized and synthesized the cDNA of carp AChE based on the preferred codon using Saccharomyces cerevisiae , which was ligated into expression vector pYD1.The AChE was successfully presented on yeast surface through a-agglutinin mediated display system. In shake-flask after induction with galactose in YPD medium for 24 h, this strain expressed AChE activity at a high level of 0.15 U/OD 600 /ml. The correct location of AChE was confirmed by immunofluorescence analysis. The whole cell catalyst was applied to visible spectrophotometry detection for OP pesticides based on inhibition rate. The inhibition rate was linear with paraoxon concentration in the range of 0.5 ng/ml–10 μg/ml and parathion concentration in the range of 5 ng/ml–10 μg/ml. The low detection limit was 0.136 ng/ml paraoxon and 3.72 ng/ml parathion (S/N = 3). The proposed method is applicable to analyzing OP pesticides in real samples. Therefore, the recombinant strain developed could be an efficient and affordable biomaterial for rapid and accurate detection of OP pesticide residues.
研究领域:
生物化学
·
环境科学
·
生物技术
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产品关联
DOI
高影响因子
SENSORS AND ACTUATORS B-CHEMICAL
·
2017
·
IF 5.401
Xiangheng Niu,Yanfang He,Wenchi Zhang,Xin Li,Fengxian Qiu,Jianming Pan
Prussian blue (PB) is widely used as an artificial peroxidase for electrochemical biosensors, yet it is rarely utilized in photometric detection because of its intrinsic color interference. Herein, we proposed a new strategy, growing PB on common carbon cloth (CC), to obtain a monolithic peroxidase mimic with no background interference for colorimetric detection. Through a one-pot two-step electrodeposition procedure, a robust PB film composed of compactly assembled cubes was coated on CC surface. Since the active PB is immobilized on a bulk substrate (not like previous nanozymes that were dispersed in solution), the color interference from PB itself is efficiently avoided. In addition, the obtained monolithic nanozyme can be put into and taken out from reaction systems expediently and promptly with just a tiny pair of tweezers, which makes it possible for on-demand detection. As demonstrated, the PB-based nanozyme exhibited excellent peroxidase-like activity and could trigger the color reaction of 3,3′5,5′-tetramethylbenzidine in the presence of H 2 O 2 , leading to a detection limit of as low as 1.7 μM for H 2 O 2 sensing. A uric acid (UA) colorimetric assay was further established by incorporating the PB/CC peroxidase mimic with natural uricase, providing a linear absorbance response in the analyte concentration scope of 10–700 μM. Reliable analysis of UA in human serum and urine verified the practicability of the fabricated assay.
研究领域:
分析化学
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生物传感器
·
纳米材料
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DOI
高影响因子
JOURNAL OF CHROMATOGRAPHY A
·
2018
·
IF 3.716
Dandan Li,Man He,Beibei Chen,Bin Hu
In this work, magnetic nanoporous carbons (MNPCs) based on Zn/Co-MOFs was synthesized via a facial one-step carbonization method. The prepared MNPCs exhibited high specific surface areas, good chemical stability and high extraction efficiency for interest organophosphorus pesticides (OPPs). The good extraction performance of the MNPCs for interest OPPs can be primarily attributed to π-π interaction and hydrophobic interaction between MNPCs and OPPs. Based on it, MNPCs-based MSPE-GC-FPD method was established for the quantification of five OPPs in fruit samples. The main experimental conditions for MSPE of five target OPPs were investigated systematically and optimized, such as the desorption solvent and volume, extracted volume, ionic strength, extraction time and desorption time. Under the optimal conditions, the limits of detection (LODs, S/N = 3) were found to be in the range of 0.018 (ethion) -0.045 (malathion) μg/L. The linearity was 0.05-100 μg/L for phorate, diazinon, ethion and 0.1-100 μg/L for malathion, fenthion respectively. The reproducibility of the method was in the range of 3.5-9.7%. The recovery experiments were carried out by spiking target OPPs at three concentration levels to validate the accuracy of the proposed method, and the recoveries for target OPPs were 84-116%. The results show that the proposed method in this work can be successfully used to analyze OPPs residue in fruit sample.
研究领域:
分析化学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
TALANTA
·
2025
·
IF 6.1
Xiaodi Yan,Yiyu Jiang,Jin Zhang,Xuejia Chen,Wenshan Liang,Hui Zeng,Min Zhang
Gas diffusion enables ammonium determination by converting it to ammonia gas under alkaline conditions. Ammonia is typically transferred across membranes or air gaps and absorbed by an acceptor phase, inducing measurable changes. This study presents a novel donor-oil-acceptor system for ammonium determination. Immiscible fluorinated oils, such as FC-40, which dissolve ammonia, are used to efficiently segment donor and acceptor droplets within a single flow stream. These oils act as liquid membranes, facilitating ammonia transfer from the donor phase to the acceptor phase through both diffusion and inner droplet circulation. An automated flow-through analyzer, incorporating peristaltic micro-pumps, was developed to generate multiple paired donor-acceptor droplets, enabling concurrent gas diffusion and enhancing sample throughput. Bromothymol blue (BTB) was used as a pH indicator for absorbance-based detection, while o-phthalaldehyde (OPA)-sulfite reagent served as a selective reagent for fluorescence-based detection. The limits of detection were determined to be 14 μmol L -1 for the absorbance method and 2 μmol L -1 for the fluorescence method. Interference studies revealed that precipitation from alkaline earth metals had minimal effect on recovery, while amines exhibited significantly higher transfer efficiency through the oil phase. To address this, the OPA-sulfite reagent in the acceptor phase effectively mitigated interference from amines. The proposed droplet-based system provides an innovative and versatile platform for analyzing volatile compounds in complex sample matrices.
研究领域:
分析化学
·
流动分析
·
微流控技术
·
环境分析
·
化学传感器
✓ 已验证
DOI
PubMed
高影响因子
TALANTA
·
2024
·
IF 5.6
Hangqian Li,Shu Wang,Shulu Zheng,Tengyue Fang,Huilin Shu,Yi Xu,Xianghui Guo,Eric P. Achterberg,Liyang Zhan,Jian Ma
The development of field-deployable methods and instruments for the measurement of pH and other carbonate parameters is important for the assessment of the marine carbon cycle , ocean acidification and marine carbon dioxide removal techniques. In this study, a high-precision fully automated integrated syringe-pump-based environmental-water analyzer for pH ( i SEA-pH) was developed. The pH is determined spectrophotometrically using purified indicator dye with a high precision (better than ±0.001) and high frequency (3.5 min/sample). For the short-term analysis, the measurement frequency was 18 h −1 , which revealed pH = 7.8148 ± 0.0005 (n = 104) for aged surface seawater (S = 35) from the western Pacific. For long-term analysis, the measurement frequency was 2 h −1 for 4 days, and the results showed that pH = 7.8148 ± 0.0010 (n = 200). Three commonly used pH indicators (meta-cresol purple, thymol blue and phenol red) were purified with improved flash chromatography procedures. The autonomous i SEA-pH can automatically correct for the influence of temperature, salinity and other factors on pH measurements to achieve rapid and accurate on-site measurements, which meet the “climate” goal of the Global Ocean Acidification Observing Network (uncertainty is ±0.003). Three identical i SEA-pH systems were developed and successfully applied in mesocosm experiments and several coastal and open ocean cruises with excellent in field performance.
研究领域:
环境科学
·
海洋化学
·
海洋学
·
分析化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2020
·
IF 4.192
Yujiao Cheng,Russell Rouseff,Guijie Li,Houjiu Wu
The off-flavor produced after thermal stabilization of mandarin (Citrus reticulata, Blanco) juices has limited the production of commercial juices. Methanethiol, a putrid-smelling sulfur volatile, has been identified for the first time in heated mandarin juices. Identification was achieved using a combination of capillary gas chromatography with two dissimilar columns and a dual sulfur-specific pulsed flame photometric detector and selected ion mass spectrometry detection. Static headspace solid-phase microextraction quantitation found that average odor activity values (OAVs) in heated juices were 25.5 for methanethiol compared to 10.8 for dimethyl sulfide. OAVs for methanethiol and dimethyl sulfide in fresh juices were ND (not detected) and 5.5, respectively. Hydrogen sulfide, carbonyl sulfide, carbon disulfide, and dimethyl disulfide were also identified and quantitated. Thermal decomposition studies of nonvolatile sulfur-containing potential precursors indicated that methionine was the major source of methanethiol. Additional heating studies with model juices demonstrated that ascorbic acid greatly accelerated the formation of methanethiol and methional, as well as dimethyl di and tri sulfides.
研究领域:
食品科学
·
分析化学
·
农业化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）