Simple in-line stopped flow photolysis of copper complexes in natural waters using a flow injection system

The development of an in-line digestion system based on simple UV lamp is reported. The effect of photolysis on the preconcentration of copper was investigated using an in-line Chelex-l00 ion-exchange column linked to an atomic absorption spectrometer. Three model ligands, glycine, NTA and EDTA, have been used to demonstrate the effect of the digestion system. In a stopped-flow mode, over 90% of the complexed copper was recovered in the presence of any of the three ligands. When the UV lamp was turned off, this changed to 84, 45 and 2% recovery for the glycine, NTA and EDTA complexed copper, respectively. The ability to analyse samples with the UV lamp on or off means that the device may be used to study the speciation of the copper.     

Design and operation of an autosampler controlled flow-injection preconcentration system for lead determination by flame atomic absorption spectrometry

Flow-injection manifolds are described which allow the preconcentration of lead for flame atomic absorption determinations, using columns contained within the sample loop of an injection valve. An interface was designed which allowed the valves and pump in the system to be controlled by an autosampler which enabled precise timing of preconcentration and elution steps. The effects of sample flow rate, buffer pH and buffer type for preconcentration and eluent concentration and flow rate were investigated in order to obtain optimum performance of the system. A 50-times improvement in detection limits over conventional sample introduction was obtained for a sample volume of approximately 12 ml, preconcentrated for 150 s. The injection of eluent, as opposed to the use of a continuously flowing eluent stream, enabled this reagent to be conserved.     

A multi-channel photometric detector for multi-component analysis in flow injection analysis

The detector, a multi-channel photometric detector, described in this paper was developed using multi-wavelength LEDs (light emitting diode) and phototransistors for absorbance measurement controlled by an Intel 8031 8-bit single chip microcomputer. Up to four flow cells can be attached to the detector. The LEDs and phototransistors are both inexpensive, and reliable. The results given by the detector for simultaneous determination of trace amounts of cobalt and cadmium in zinc sulphate electrolyte are reported. Because of the newly developed detector, this approach employs much less hardware apparatus than by employing conventional photometric detectors.     

A flow injection analysis system for on‐line monitoring of cutinase activity at outlet of an expanded bed adsorption column almost in real time

Expanded bed adsorption (EBA) was used to recover, concentrate and purify Fusarium solani pisi cutinase, secreted by a recombinant Saccharomyces cerevisiae strain, directly from a whole fermentation culture. A flow injection analysis (FIA) system for monitoring Fusarium solani pisi cutinase based on microencapsulation of p‐nitrophenylbutyrate (p‐NPB) in a micellar system (sodium cholate, tetrahydrofuran, phosphate buffer) was developed for monitoring this target enzyme at the outlet tube of the EBA column. Slight differences in yeast cultivation conditions during cutinase production may influence the fermentation performance, which affects directly the adsorption of cutinase during the loading step and consequently the efficiency of the EBA process. This effect can be especially relevant when it is necessary to stop the application of feedstock to the EBA column when the outlet concentration (A) of the desired product is lower than 5% of the feed concentration (A_o). Excellent correlations between the FIA system and the off‐line analytical method for monitoring cutinase activity during the different EBA steps were obtained. Additionally, the blocking/fouling of the sample injector and tubes of the FIA system initially observed were eliminated due to the excellent surfactant properties of the sodium cholate contained in the phosphate buffer and used to dilute the enzyme samples. This FIA system was shown to be a powerful analytical tool for monitoring cutinase activity almost in real time (45–60 s), maximizing enzyme adsorption while minimizing product loss and consequently maximizing the recovery yield of the product. Copyright © 2006 Society of Chemical Industry     

吸收稳定系统解吸塔双股进料工艺的探讨

以石家庄炼油厂技术改造为背景，通过正交设计法与模拟计算相结合，对解吸塔双股进料工艺进行了分析。结果表明：该工艺最佳操作条件为加热股流量取２／３，进料温度９０℃，进料位置Ｎ＝１０。在此操作条件下的双股进料工艺与原工艺模拟结果比较表明：能耗比原不加热单股进料工艺降低了３９％，解吸气量比原加热单股进料工艺降低了５６％。     

The role of flow injection analysis within the framework of an automated laboratory

Flow Injection Analysis (FIA) was invented at roughly the same time by two quite dissimilar research groups [1,2]. FIA was patented by both groups in 1974; a year also marked by the publication of the first book on automatic chemical analysis [3]. This book was a major undertaking for its authors and it is hoped that it has added to the knowledge of those analysts attempting to automate their work or to increase the level of computerization/automation and thus reduce staffing commitments. This review discusses the role of FIA in laboratory automation, the advantages and disadvantages of the FIA approach, and the part it could play in future developments.It is important to stress at the outset that the FIA approach is all too often closely paralleled with convention al continuous flow analysis (CFA). This is a mistake for many reasons, none the least of which because of the considerable success of the CFA approach in contrast to the present lack of penetration in the commercial market-place of FIA instrumentation.     

阳树脂合成柠檬酸钙的电化学自动分析系统

基于流动注射流通式Na/Ca微电极串联动态电化学自动检测系统,给出了一种阳树脂在线离子交换连续合成高纯度柠檬酸钙的新方法,并实现了对阳树脂柱的运行状态及流出液中柠檬酸钙含量的同时自动在线监测。通过对此系统的相关影响因素进行了考察和优选,得到的结果是:检测系统的总离子强度调节缓冲液由80 mmol·L^-1 tris、175 mmol·L^-1 H₃BO₃、1 mmol·L^-1 KCl和0.025 mmol·L^-1 CaCl₂的混合液(pH 8.0)构成,样品注入体积为150 μl,总流量为2.26 ml·min^-1,混合盘管长度为120 cm(I.D.0.5 mm);检测系统的测定范围分别为2.0～1000 mmol·L^-1 Na⁺,0.2～50 mmol·L^-1 Ca²⁺;相对标准偏差(RSD)小于 0.68%;其检测下限分别为1.12 mmol·L^-1 Na⁺,0.093 mmol·L^-1 Ca²⁺。     

A portable battery-powered flow injection monitor for the in situ analysis of nitrate in natural waters

The design and performance of a portable, automated flow injection (FI)-based photometric monitor are described. The system is controlled by an in-house microcomputer system that enables the monitor (including a solid state detector) to operate from a 12 V battery supply. The monitor uses the cadmium reduction/diazotization method to analyse for nitrate with a linear range of 0 to 12 mg l^-1 and a limit of detection of 0.05 mg l^-1 (NO₃-N). The hardware and software design, monitor performance and results obtained during unattended operation are presented.     

A simple,automated device for the precise addition of liquids

Metering liquid reagents into reaction mixtures in a controlled and reproducible manner has often been a problem in synthetic chemistry. Carrying out the real simultaneous addition of two or more liquid reagents (concurrent additions) is even more inconvenient. Difficulties increase when addition volumes become small, when addition times become long, or when the reagents are corrosive or air-sensitive. We have constructed and tested an inexpensive, automated device for the slow, precise delivery of liquid reagents into laboratory-scale reaction mixtures. Controlled by a standard personal computer, this slow adder can accommodate liquid volumes from hundreds of microlitres to litres and addition times from minutes to days. Its glass and Teflon construction makes it useful for nearly all reagents. By using multiple slow adders, true concurrent addition of several liquids can be easily achieved.     

A submersible battery-powered flow injection (FI) sensor for the determination of nitrate in estuarine and coastal waters

The design, construction and performance of a remotely deployed submersible flow injection-based nutrient (total oxidized nitrogen) sensor are described. The sensor featured a custom-built microcomputer and a solid-state, flow-through spectrophotometric detector, and the derivatization chemistry was based on in-line coppercadmium reduction of nitrate to nitrite, and diazotization with N1NED and sulphanilamide. The limit of detection was 0.0014 mg l(-1) NO(3)-N and the linear range was 0.0014- 0.77 mg l(-1) with a 260 mul sample volume and a 20 mm path length flow cell. Results from submersed deployments in the Tamar estuary and North Sea are also reported.     

A computer-controlled data acquisition and analysis system for use in the characterization of plasma atomic emission sources

The characterization of new spectroscopic plasma sources for use in atomic emission spectroscopy often presents the need for information about the spatial emission characteristics of the source. In addition, information about the variation of the emission over time is often beneficial. It is also useful to be able to graphically see, in real-time, the effects of varying a particular experimental parameter. This paper describes a flexible data acquisition system in which an echelle spectrometer is interfaced to an IBM-PC compatible microcomputer. The FORTH-based ASYST software, which proves real-time display of acquired data, allows any point in the emission source to be imaged on the entrance slit of the spectrometer by using the cursor keys of the PC and a computer-controlled mirror. The different acquisition modes of the system are illustrated with examples of two-dimensional spatial profiles of the plasma and monitoring of plasma stability over time. In addition, an illustration of the optimization of the echelle''s aperture plate and photomultiplier tube positions in the focal plane is presented.     

Construction and evaluation of an automated flow injection-stopped flow analyser for multipoint reaction rate spectrophotometric methods. Determination of ammonia nitrogen,creatinine and phosphate

The construction and evaluation of a fully automated Flow Injection-Stopped Flow (FI-SF) spectrophotometric analyser is described. A microcomputer (Rockwell AIM 65) is used to control the analyser (sample injection, stop and start of the pump) through a suitable interface. Data acquisition is achieved using a 12 bit ADC card and a suitable subroutine in 6502 assembly language, allowing data sampling at a frequency of 7.5 kHz. The measurement interface and software were evaluated using a voltage ramp generator. A precision of 0.02-1.1% RSD (N =10) was obtained for voltage ramps in the range of 1-37 mVs^-1. The FI-SF analyser was evaluated in routine analysis by developing FI-SF kinetic spectrophotometric methods for the determination of ammonia nitrogen (20-250 ppm, 0.4-2.5% RSD) based on the Berthelot reaction, creatinine (20-220 ppm, 0.9-3.6% RSD) based on the Jaffé reaction, and phosphate (5-30 ppm, 1.0-3.3% RSD) based on the phosphomolybdenum blue reaction. The reaction rate is measured by linear fitting of multiple absorbance readings vs time. Algorithms for automated estimation of the residence time, the linear range of the reaction curve, and data treatment are presented.     

Development and analytical performance of an automated screening method for cannabinoids on the Dimension clinical chemistry system

A fully automated, random access method for the determination of cannabinoids (UTHC) was developed for the Dimension AR and XL clinical chemistry systems. The method utilizes Abuscreen ONLINE reagents and a multianalyte liquid calibrator containing 11-nor-Δ⁹-THC-9-carboxylic acid. Within-run and total reproducibility, determined using NCCLS protocol EP5- T2, was less than 0.6% and 1.6% CV, respectively, at all concentrations. Calibration stability was retained for at least 30 days. An extensive evaluation of non-structurally related drugs and various physiological substances indicated lack of interference in the method. No sample carry-over was observed following a specimen containing 1886 ng/ml 11-nor-Δ⁹-THC-9-carboxylic acid. A 99.1% agreement (N = 445 samples) was found between an EMIT based method on the aca discrete clinical analyser and the Dimension UTHC method.Dimension clinical chemistry system and aca discrete clinical analyser are registered trademarks of Dade International.     

Pectic acid–graphene oxide nanocomposite as an adsorbent in vortex-assisted dispersive solid-phase extraction for preconcentration of copper ion followed by flame atomic absorption spectrometry

Polymer Bulletin - An efficient, green, novel and rapid vortex-assisted dispersive solid-phase extraction (VADSPE) technique was used for the preconcentration and determination of trace levels of...     

Automation of flow injection gas diffusion-ion chromatography for the nanomolar determination of methylamines and ammonia in seawater and atmospheric samples

The automation and improved design and performance of Flow Injection Gas Diffusion-Ion Chromatography (FIGD-IC), a novel technique for the simultaneous analysis of trace ammonia (NH₃) and methylamines (MAs) in aqueous media, is presented. Automated Flow Injection Gas Diffusion (FIGD) promotes the selective transmembrane diffusion of MAs and NH₃ from aqueous sample under strongly alkaline (pH > 12, NaOH), chelated (EDTA) conditions into a recycled acidic acceptor stream. The acceptor is then injected onto an ion chromatograph where NH₃ and the MAs are fully resolved as their cations and detected conductimetrically. A versatile PC interfaced control unit and data capture unit (DCU) are employed in series to direct the selonoid valve switching sequence, IC operation and collection of data. Automation, together with other modifications improved both linearily (R² > 0.99 MAs 0-100 nM, NH₃ 0-1000 nM) and precision (<8%) of FIGD-IC at nanomolar concentrations, compared with the manual procedure. The system was successfully applied to the determination of MAs and NH₃ in seawater and in trapped particulate and gaseous atmospheric samples during an oceanographic research cruise.