A monitor for atmospheric sulphur dioxide,based on enrichment of SO2 by a polydispersive water aerosol

A monitor for continuous analysis of sulphur dioxide in the atmosphere at the ppb v/v level (1 ppb v/v = 2.62 g/m³ SO₂) is described. The apparatus operates on the principle of equilibrium accumulation of sulphur dioxide from the air by a polydispersive water aerosol which continuously transfers SO₂ from an air-flow of l/min into microlitre volumes of water condensate. High sensitivity (1 ppb v/v), low relative error (± 5% at 4 ppb v/v SO₂), high selectivity (CO₂ does not interfere at a concentration of 2 × 10³ ppm v/v, interference by NO _x and H₂S is acceptably low), and low response delay (10 s) are provided by a compact coupling of the enrichment procedure with conductivity detection of SO₂ in the film of water aerosol condensate formed directly on the wire-gauze sensor. The reliability of the method has been studied under simulated conditions, with spectrophotometric method as reference. The analyser is computer-controlled, and the detector response is processed on-line and displayed (as g/m³) in real-time on a screen or is transmitted telemetrically to a control centre. It is portable and suitable for use in both stationary and moving locations.The paper is dedicated to the 65th anniversary of the birthday of Prof. Josef F. K. Huber     

盐析辅助液液萃取交联聚维酮净化-靶向单一离子监测/高分辨质谱法测定蜂蜜中新烟碱类农药残留

基于盐析辅助液液萃取(LLE)交联聚维酮(PVPP)净化技术,建立了蜂蜜中7种新烟碱类农药的靶向单一离子监测(TSIM)/高分辨质谱检测方法。样品用乙腈基于盐析辅助LLE-PVPP提取净化,采用BEH C18色谱柱为分析柱,甲醇-水体系(两相均含0.1%甲酸和5 mmol/L甲酸铵)作为流动相,梯度洗脱,采用高分辨质谱TSIM模式检测目标化合物,内标法定量。结果表明,盐析辅助LLE-PVPP净化技术可实现提取净化一步式样品制备,TSIM扫描模式则显示了更宽的线性动态范围和更高的灵敏度与准确度。7种新烟碱类农药在0.01~100μg/L或0.02~100μg/L范围内具有良好的线性关系(r20.999);方法检出限为0.03~0.07μg/kg,定量下限为0.1~0.2μg/kg。在0.2、2、20μg/kg 3种加标水平下,7种新烟碱类农药在蜂蜜中的平均回收率为84.8%~112.7%,日内精密度(RSDr)为0.9%~5.7%,日间精密度(RSDR)为3.7%~9.7%。该方法前处理简单快速、成本较低,灵敏度高、重现性好,可广泛应用于蜂蜜中新烟碱类农药残留的快速检测。     

Recent trends in capillary and micro-chip electrophoretic instrumentation for field-analysis

Technical advances in the development of field-deployable capillary and microchip electrophoretic instruments and reports of their deployment between 2013 and 2017 were reviewed. Strategies and considerations in the design of the injection, separation and detection hardware, chemistry and associated infrastructure were discussed from an in-field perspective, with portability, robustness and automation/“ease of use” featuring as key requirements. Integration of functionality is important for adequate in-field performance. Progress was made towards the use of multiple channel devices for increased throughput and/or resolving power, mixing devices for on-line/in-line sample derivatization, battery operation and temperature control. The strengths and weaknesses of the various approaches described in the literature are discussed from the perspective of in-field operation. An overview of the applications of the field electrophoretic instruments is provided, including environmental science and planetary investigation.     

A rapid and simple HPTLC assay for therapeutic drug monitoring of capecitabine in colorectal cancer patients

Capecitabine is a prodrug of 5‐flurouracil, employed as a broad spectrum chemotherapeutic agent. It is also used as monotherapy or a combination chemotherapy agent for the treatment of colorectal cancer. Capecitabine is administered in combination with oxaliplatin and hence it is essential to determine that co‐administration does not affect its metabolism. To determine the plasma concentration of capecitabine a simple HPTLC method was developed and validated. Blood samples from 12 patients with colorectal cancer were collected and analyzed by the HPTLC method with a reference internal standard. Out of these 12 patients, six were treated with capecitabine monotherapy and another six were treated with capecitabine + oxaliplatin combination therapy. The results of analysis indicated that there was no significant drug–drug interaction and the co‐administration of oxaliplatin did not affect the metabolism of capecitabine. This method is sensitive, robust and specific and allows analysis of multiple samples simultaneously, making it suitable for therapeutic drug monitoring of capecitabine.     

Carbon‐nanotube Modified Screen‐printed Electrode for the Simultaneous Determination of Nitrite and Uric Acid in Biological Fluids Using Batch‐injection Amperometric Detection

A portable electroanalytical system applied for rapid and simultaneous determination of uric acid (UA) and nitrite (NIT) in human biological fluids (urine, saliva and blood) is reported. The system is based on batch‐injection analysis with multiple‐pulse amperometric (BIA‐MPA) detection using screen‐printed electrodes (SPEs) modified with multi‐walled carbon nanotubes. Sample dilution in optimized electrolyte (0.1 mol L⁻¹ Britton‐Robinson buffer pH 2) followed by injection of 100 μL on the electrode surface using an electronic micropipette is performed. UA is detected at +0.45 V and both UA+NIT at +0.70 V. Linear calibration plots for UA and NIT were obtained over the range of 1–500 μmol L⁻¹ with detection limits of 0.05 and 0.06 μmol L⁻¹, respectively. For comparison, a differential‐pulse voltammetric (DPV) method was optimized, and linear calibration plots for UA and NIT were obtained over range of 1–30 μmol L⁻¹ and 1–40 μmol L⁻¹ with detection limits of 0.1 and 0.3 μmol L⁻¹, respectively. BIA‐MPA is highly precise (RSD<1.3 %), fast (160 h⁻¹) and free from sample‐matrix interferences as recovery values ranged from 77 to 121 % for spiked samples (short contact time of sample aliquot with SPE). Contrarily, recovery tests conducted using DPV did not provide adequate recovery values (>150 %), probably due to the longer contact time of the SPE with the biological samples during analysis leading to a severe interference of sample matrices.     

Intermediate detection in real time using reactive surface desorption dielectric‐barrier discharge ionization mass spectrometry

Reactive intermediates play key roles for reaction mechanism elucidation. A suitable tool for identifying the key intermediates is crucial and highly desirable. In this study, surface desorption dielectric‐barrier discharge ionization (reactive SDDBDI) was developed for characterization of the reactive intermediates. In reactive SDDBDI, the plasma is doped with a reagent before the plasma ions are directed at a cover slip surface bearing another analyte. Different from SDDBDI, reactive SDDBDI can be used both as an ambient ionization source and as a means to produce reagent ions for ambient ion/molecule reactions. The online derivation of 4‐aminophenol with trifluoroacetic anhydride demonstrated that reactive SDDBDI can be used for chemical analysis where improved specificity or sensitivity is required. The utility of this approach for real‐time detection of reactive intermediate was demonstrated by the Schiff‐base and Eberlin reactions. The formed intermediates and products could be readily detected and identified by tandem mass spectrometry. These results indicate that reactive SDDBDI can be used to generate reagent ions that undergo ion/molecule reactions in the open air with an analyte at condensed phase on a surface. Reactive SDDBDI has high‐efficiency ion transmission and high MS sensitivity. It is thus a potential tool to perform ambient ion/molecule reactions and detect reactive intermediates.     

Rapid high-performance liquid chromatography determination of lopinavir, a novel HIV-1 protease inhibitor, in human plasma

Summary Lopinavir is a new specific and potent HIV-1 protease inhibitor. A rapid high-performance liquid chromatographic method using UV detection, has been developed and validated for the analysis of lopinavir in plasma. This involved a single liquid-solid extraction on an OASIS^? HLB column in the presence of an internal standard. Separation was achieved on a Xterra^?, C₈ (150×3.9 mm I.D.) column with a mobile phase consisting of acetonitrile and water (41∶59, v/v). The detection wavelength was 210 nm. The assay was linear from 0.187 to 10.0 μg.mL⁻¹ and the limit of quantification was 0.187 μg.mL⁻¹. Mean recovery was ranged from 90.7% to 97.8% for lopinavir and 97.1% for the internal standard. Day to day precision and accuracy were less than 9.6% and 7.3% respectively. This rapid and simple method can readily be used for drug monitoring of lopinavir, in HIV-1 infected patients.     

TiO2光催化降解4-氯苯酚过程中的电分析监测

采用循环伏安法和紫外光谱法对有机物的光催化降解进行机理研究和在线监测.以标准光催化剂DegussaP25在紫外光照射下催化降解4-氯苯酚,发现在降解过程中至少有两对氧化还原中间产物对苯二酚-苯醌和羟基氢醌-羟基苯醌.由4-氯苯酚及中间产物的电极响应,可以观测到它们在光催化降解过程中的含量变化,从而对整个过程实现在线监测,并由此全面了解光催化反应机理.从不同反应时间后测得的紫外光谱可以看到,苯环特征峰逐渐消失.这表明4-氯苯酚的苯环逐渐被打开,直至被彻底降解.     

HPLC method for determination of moxifloxacin in plasma and its application in pharmacokinetic analysis

Moxifloxacin is a representative of the fourth generation of fluoroquinolones. It possesses bacteriostatic activity against Gram-positive and Gram-negative bacteria. A simple and fast high performance liquid chromatography-ultraviolet detection (HPLC-UV) method was developed for moxifloxacin analysis. The separation was performed on C18 column. The mobile phase was a mixture of acetonitrile and 0.4% triethylamine solution. The regression curve was linear over the range 0.2–10.0?µg/mL. The validation parameters obey the European Medicine Agency limits. The in vivo study confirmed the practical application of the method.     

基于高分辨质谱技术的婴幼儿食品中过敏原蛋白质的高灵敏检测

基于高效液相色谱-串联质谱(LC-MS/MS)技术,选择稳定性好、灵敏度高的特征肽段,利用平行反应监测(PRM)技术,实现了多类过敏原蛋白质的高灵敏度同时检测,并成功应用于婴幼儿食品中过敏原成分的分析。对于婴幼儿食品中蛋白质的提取,与传统的丙酮沉淀法比,采用膜上原位样品预处理方法(i-FASP)可实现更高的蛋白质提取效率和抗干扰能力。所检测的过敏原蛋白质的定量限(LOQ)最小可达到0.028 mg/L,其线性范围最宽可跨越4个数量级,且线性关系良好(相关系数R~2≥0.99)。该方法为食品中过敏原蛋白质组学快速分析提供了一种可靠的分析方法。