Flow injection spectrophotometric determination of copper, iron, manganese, and zinc in animal feeds using a common manifold

A rapid and simple procedure was developed for the determination of copper, iron, manganese, and zinc in animal feeds using an identical flow injection spectrophotometric manifold but different chromogenic reagents and different detection wavelengths. Bis(cyclohexanone)oxalydihydrazone, formaldoxime, 1,10-phenanthroline, and xylenol orange were adopted as chromogenic reagents for Cu, Mn, Fe, and Zn, respectively. Detection conditions such as manifold parameters, buffer pH, reagent concentration, temperature, and acidity of sample solution were optimized. Analytical characteristics of the method and interference of metal ions commonly present in feeds were studied. By changing the reagents and detection wavelengths, which can be done quickly, the proposed low cost flow injection system can determine Cu, Fe, Mn, or Zn in the range of 0.5-10 mg/L with a sampling throughput of 120/h.     

Identical flow injection spectrophotometric manifold for determination of protein, phosphorus, calcium, chloride, copper, manganese, iron, and zinc in feeds or premixes

A simple procedure using an identical manifold was developed for determination of nitrogen (protein) phosphorus, calcium, chloride, copper, manganese, iron, and zinc in feeds and feedstuffs. By changing appropriate reagents and detection wavelength, these 8 elements were determined successively with a simple identical double-line flow injection (FI) manifold. Fl spectrophotometric determinations were made by the blue indophenol reaction for ammonium, the molybdenum blue method for phosphate, the cresolphthalein complexone procedure for calcium, and the mercuric thiocyanate procedure for chloride. The chromogenic reagents for copper, iron, manganese, and zinc determination were bis(cyclohexanone)oxalydihydrazone (Cuprizone), 1,10-phenanthroline, formaldoxime, and xylenol orange, respectively. Sample digestion catalyst, Fl manifold, and some chemical parameters were optimized. The proposed procedure had a sampling rate of 90/h for each analyte. The determination ranges (mg/L) were 10-60 for N, 1-15 for P and Ca, 540 for Cl, and 0.5-15 for Cu, Fe, Mn, and Zn, respectively. Results of the analyses of animal feed and feedstuff samples by this procedure did not differ significantly from those obtained by proven manual methods.     

Clean analytical methodology for the determination of lead with Arsenazo III by cyclic flow-injection analysis

A clean analytical methodology, where the sample determined and the reagent used are both toxic, has been proposed. A cation exchange mini-column was incorporated after the flow-through cell for on-line regeneration of the main reagent and the accumulation of heavy metal ions. The method involves the spectrophotometric determination of lead with Arsenazo III, the accumulation of lead onto the cationic exchanger, and subsequent regeneration of the chromogenic reagent, which makes the system reversible and the reagents reusable. The developed method provides a satisfactory way to cut down on the toxic reagent consumption and the produced volume of waste, an important step towards the zero emissions research initiative concept. The excellent repeatability and reproducibility, and the simplicity of this method are well suited for continuous measurements. The method was successively applied to the assay of lead in high-octane gasoline.     

1-Phenyl-3-methyl-4-benzoylpyrazol-5-one as a group-extraction reagent for spectrophotometric determination of trace elements

1-Phenyl-3-methyl-4-benzoylpyrazol-5-one has been examined as a regent for detection and solvent extraction of metal ions. The reagent seems to be promising as a group-extraction reagent for the spectrophotometric determination of copper, nickel, cobalt, manganese, zinc, chromium(VI) and molybdenum(VI).     

Sequential determination of iron and titanium by flow-injection analysis

A flow-injection method has been developed for the sequential spectrophotometric determination of iron and titanium using 3,4 dihydroxybenzoic acid as chromogenic reagent. The system involves the sequential measurement of the absorbances of the complexes at 380 and 570 nm. The system is designed using a simultaneous injection of sample and reagent into separate carrier streams. The proposed method is characterized by a precision of about 2%, a sampling rate of about 50 samples per hour, and a reagent consumption of 200 mul (0.50% solution) per sample. It is relatively free of interferences and was used for the sequential determination of titanium and iron in rocks.     

Synthesis of o,o′-dihydroxyazo compounds and their application to the determination of magnesium and calcium by flow injection analysis

Seven _o,o′-dihydroxyazo dyes were synthesized and examined as spectrophotometric reagents for magnesium and calcium. These reagents are highly sensitive for magnesium (? = 47 000) and calcium (? = 39 000 l mol^?1 cm^?1). Of the reagents synthesized, 2-(2-hydroxy-3,6-disulfo-1-naphthylazo)-5-(N,N-diethylamino)phenol was the best because of its ease of preparation and purification, and its stability in alkaline solution. This dye was applied in the determination of magnesium and calcium by flow injection analysis. The total concentration of magnesium (0.1–1.2 mg 1^?1) and calcium (0.4–4.0 mg 1^?1) was determined by masking iron(III), aluminium(III), copper(II), zinc(II), manganese(II) and cadmium(II) with 2,3-dimercapto-1-propanol (DMP) and triethanolamine (TEA). Magnesium was determined by masking calcium and the other metal ions with a ligand buffer containing barium(II)—EGTA, DMP and TEA. The amount of calcium was obtained as the difference between the two peak heights. Results for the determination of magnesium and calcium in potable water and serum are presented.     

Determination of transition metal ions in tobacco as their 2-(2-quinolinylazo)-5-dimethylaminophenol derivatives using reversed-phase liquid chromatography with UV-VIS detection

This paper reports the utilization of solid-phase extraction and the reversed-phase high-performance liquid chromatography for the determination of six important transition metal ions: iron, cobalt, nickel, copper, zinc and manganese in tobacco with 2-(2-quinolinylazo)-5-dimethylaminophenol (QADMAP) as chelating reagent. Iron, cobalt, nickel, copper, zinc and manganese ions react with QADMAP to form colored chelates in the medium of acetic acid-sodium acetate buffer solution (pH 4.0). These chelates can be enriched by solid-phase extraction with Waters Sep-Pak-C18 cartridge, and eluted the retained chelates from cartridge with tetrahydrofuran. The chelates were separated on a Waters Nova-Pak-C18 column (150x3.9 mm, 5 microm) by gradient elution with methanol (containing 0.5% of acetic acid) and 0.05 mol/l pH 4.0 acetic acid-sodium acetate buffer solution as mobile phase at a flow-rate of 0.5 ml/min. The detection limits of iron, cobalt, nickel, copper, zinc and manganese are 10, 12, 8, 13, 17 and 22 ng/l, respectively. This method had been applied to the determination of iron, cobalt, nickel, copper, zinc and manganese in tobacco with good results.     

A robust multi-syringe system for process flow analysis. Part 3. Time based injection applied to the spectrophotometric determination of nickel(II) and iron speciation.

A new software-controlled time-based system for sample or reagent introduction in process flow injection analysis was developed. By using a multi-syringe burette coupled with one multi-port selection valve, the time-based injection of precise known volumes was accomplished. Characteristics and performance of the injection system were studied by injecting an indicator in a buffered carrier. Two multi-syringe time-based injection (MS-TBI) systems were implemented: first, the injection of a sample in a multiple-channel manifold where the sample would sequentially merge and react with different reagents, and second, the sequential injection of several solutions (sample and reagents) into a particular flowing stream. The first system was applied to the spectrophotometric determination of nickel(II) in diluted samples from the acidic nickel ore leaching process, by using ammonium citrate as carrier, a saturated solution of iodine as oxidizing agent and alkaline dimethylglyoxime as chromogenic reagent. The sampling frequency attained was 57 h-1. Determinations on process samples compared well at the 95% confidence level with the reference values obtained by ICP-OES. The second time-based injection system was applied to the speciation of iron. Total iron and iron(II) concentrations were separately and sequentially determined using 1,10-phenanthroline in acetic buffer medium as reagent. The developed manifold allowed the optional use of two different carrier solutions, containing or not containing ascorbic acid, for performing the separate determinations. Also, in the sequential procedure, plugs of reducing carrier were alternatively intercalated before the sample injections used for total iron determinations. Sampling frequencies of 68 injections per hour were routinely used. Accuracy was assessed by analyzing synthetic known mixtures of Fe(III) and Fe(II) standard solutions. Recoveries of 98-100.5% with a maximum relative standard deviation of 3.6% were found. Results obtained for various samples of fertilizers agreed well with those attained by the standard batch procedure.     

Synthesis and characterization of 2-(5-Bromo-2-Pyridylazo)-5-[(N,N-dicarboxylmethyl) amino]- phenol as a water-soluble chromogenic reagent

A new water soluble chromogenic reagent, 2-(5-bromo-pyridylazo)-5-[(N,N-dicarboxylmethyl)amino]-phenol has been synthesized. Its colour reaction with various metal ions was tested, and the acid dissociation constant of the reagent, and the stability constants of the chelates of Ni²⁺, Co²⁺, Cu²⁺, Mn²⁺, Pb²⁺, Zn²⁺ and UO ₂ ²⁺ were determined. The application of the reagent to spectrophotometric determination of nickel in irons is presented.     

An intelligent flow analyser for the in-line concentration, speciation and monitoring of metals at trace levels

An intelligent and versatile flow system is proposed for the in-line speciation and/or concentration of metal ions at a wide range of concentrations without requiring manifold reconfiguration. On one hand, sample enrichment strategies are accomplished using packed-bed reactors, on the other hand speciation procedures are readily performed exploiting the selective complexation of the different oxidation states with the appropriate chromogenic reagents.

The potentials of the automated methodology were evaluated using the spectrophotometric monitoring of iron as a model of chemistry. Under the optimised physical and chemical variables, linear analytical curves over the ranges 0.025–0.5 or 2.0–40 mg l⁻¹ Fe were attained. The 3σ detection limit, the repeatability at the 0.5 mg l⁻¹ level, the enrichment factor for a sampling volume of 10 ml, and the maximum injection throughput were 8.4 ng ml⁻¹ Fe, 2.5%, 58.6 and 22 h⁻¹, respectively. The flowing system was applied to the speciation analysis of iron in waters, pharmaceutical formulations and agricultural products, using ICP-OES detection as an external reference method for total iron determination.

A remarkable feature of the expert system hereby presented is the ability to decide by itself if the pre-concentration and/or oxidation of the sample zone is required.     

Thin-Layer Chromatographic Separation of Copper and Mercury Chelates

Abstract

Thin-layer chromatographic separation of metal ions has become immensely popular in analytical chemistry in view of its speed, selectivity and applicability at tracer level. Quinoline-2-aldehyde thiosemicarbazone^1,2 was found to form yellow coloured chelates with metal ions such as copper, nickel, zinc, mercury, iron and lead at pH 7.5 and extract into chloroform. This, however reduces the sensitivity of the reagent as a chromogenic agent but the chromatographic run of the chelates on a thin layer of silica gel coated on glass plate increases the specificity and selectivity of the reagent. In this article we propose a method for separation of copper and mercury chelates from binary mixtures containing chelates of zinc, lead, iron and nickel. The method is applicable for analysis of synthetic mixtures and standard samples.     

Simultaneous determination of iron and copper ions by low-injection analysis with a multichannel photodiode-array detector

Iron(II) and copper(II) ions are determined simultaneously in a simple manifold by using a multichannel photodiode-array detector. 1-(2-Pyridlazo)-2-hydroxy-7-sulfonaphthalene (PAN-7S) is used as the sole chromogenic reagent. The absorbance at 550 nm is related to the PAN-7S chelates of iron(II) and copper(II)and that at 764 nm to the iron(II) chelate alone. Calibrations are linear over the range 0–8.0 x 10^?6 M for each metal. Interference from zinc is avoided by addition of nitrilotriacetic acid; nickel interferes. Appliation to the determination of iron and copper ions in blood serum is discussed.     

PLS—分光光度法同时测定铜锌锰

偏最小二乘法(PLS)是用于多组份混合体系同时测定的十分有效的统计学方法。本文将PLS法与光度分析相结合,以5Br-PADAP为显色体系同时计算测定了铜、锌、锰,并应用于铸铝样品的分析,都获得了较满意的结果。还用不相容因子(DF)自检分析结果的可靠性。     

A cleaner and simple spectrophotometric micro-fluidic procedure for copper determination using nitroso-R salt as chromogenic agent

A cleaner and simple spectrophotometric method using microflow analysis (muFA) was performed. It consisted of a T-junction with microcoil on a polymethyl methacrylate (PMMA) chip which was fabricated by laser ablation and a molded polydimethylsiloxane (PDMS) as top plate. The fabricated PMMA chip was integrated with light emitting diode (LED) as light source and spectrometer as detector. The proposed device was applied to determining copper in water samples using nitroso-R salt as chromogenic reagent at 495nm. It was found that the proposed muFA system was with less reagents and samples consumption with tiny waste generation. The relative standard deviation (R.S.D.) was less than 2% (n=11) with the percentage recovery of 98.0+/-1.7% (n=7). The linear range for determination of copper in water samples was over the range of 0.05-3.0mugmL(-1) with a correlation coefficient (r(2)) of 0.999. The limit of detection (3sigma) was 47ngmL(-1) with a sample throughput of 30h(-1).     

A multicommutation-based flow system for multi-element analysis in pharmaceutical preparations

A flow system exploiting multicommutation and multidetection is proposed for sequential determinations in pharmaceutical preparations. The feasibilities were demonstrated by the determination of zinc, iron, copper, calcium and magnesium without changing the flow set-up. The gravitational flow of the solutions was exploited for addition of different chromogenic reagents and sample aliquots, thus avoiding the use of a propulsion unit. Transient signals at different wavelengths were measured simultaneously employing a fiber-optic multichannel spectrophotometer. Coefficients of variation of 1.0, 1.5, 1.4, 2.5 and 2.0% were obtained for iron, zinc, copper, calcium and magnesium, respectively. The mean sampling rate for the five species was 60 determinations per hour. In comparison to continuous reagent addition systems, the consumption was up to 160-fold lower. Results for pharmaceutical preparations agreed with those obtained by Flame atomic absorption spectrophotometry (FAAS) at the 95% confidence level.     

Partial least-squares regression for the simultaneous determination of aluminum and beryllium in geochemical samples using xylenol orange

A partial least-squares regression (PLS) was developed for the simultaneous spectrophotometric determination of aluminum and beryllium in geochemical samples by xylenol orange as the chromogenic reagent in water media and in micellar media. The effects of pH, xylenol orange concentration and surfactant concentration on the complexes formation reactions were studied. In the absence of surfactant the complex color development takes place at 2 h after mixing the reagents. By using CTAB as micellar media the complexes formation was improved and the rate of the complexation reactions increased. By using PLS-1 algorithm satisfactory results were obtained. The proposed procedure showed to be useful for prediction of Al and Be values from 0.1 to 1.0 mg L(-1).     

茶叶中微量营养元素的原子吸收光谱分析

茶叶中的微量元素与茶叶的营养和药理作用有密切关系^[1],与茶树生长的生化活动也有密切关系^[2,3]。对茶叶中的微量营养元素的分析有助于了解茶叶的品质,研究茶叶的营养药理作用,促进茶叶生产的发展。为此,我们研究提出了用火焰原子吸收光谱法测定茶叶中铜、锰、铁、锌,方法简便、准确。     

全自动流动注射-分光光度法测定土壤中氨氮

传统的氯化钾溶液提取分光光度法测定土壤中氨氮时,需要加入硝普钠-苯酚显色剂混匀后一定时间再加入二氯异氰尿酸钠显色剂,这个过程中人为接触苯酚等有机试剂的时间较长,对人体和环境有一定的危害;且传统的比色法显色时间至少需要5h,显色时间较长,分析效率较低.应用全自动流动注射-分光光度法测定土壤中氨氮,考察了提取试剂的厂家、浓...     

主成分-偏最小二乘分光光度法同时测定饲料中的痕量铁、锰、铜、锌

痕量Fe^3＋、Mn^2＋、Cu^2＋、Zn^2＋与2-（5-溴-2-吡啶偶氮）．5-二乙氨基苯酚（5-Br-PADAP）和对．（1,1,3,3．四甲基丁基）苯基醚（Triton X-100）在pH8．3发生高灵敏显色反应,所形成的三元胶束络合物的吸收光谱严重重叠。本文采用主成分-偏最小二乘法（PC—PLS）辅助分光光度法成功地测定了合成试样及饲料中上述4种痕量组分。结果表明,PC—PLS法是化学计量学法中一种可适用于基体较复杂的实际试样中痕量组分同时分光光度测定的优良的多元计算方法。     

Simultaneous determination of Cd(II), Cu(II) and Pb(II) in surface waters by solid phase extraction and flow injection analysis with spectrophotometric detection

A method for heavy metal monitoring using spectrophotometric detection is presented. Traces of Cu(II), Pb(II) and Cd(II) at the low microg l(-1) level can be determined simultaneously after both selective removal of metal interferences and preconcentration using 'extraction chromatographic resins'. Lewatit TP807'84, which contains di(2,4,4-trimethylpentyl)phosphinic acid as active component, was used as solid adsorbent. Two minicolumns containing this resin were used: one at pH 3.2 for the removal of interferences, such as Zn(II) and Fe(III), and the other at pH 5.5 for the selective preconcentration of the target analytes. Spectrophotometric determination used FIA methodology with sulfarsazene as chromogenic reagent and partial least-squares multivariate calibration. The method was successfully applied to the analysis of surface waters from the Llobregat river and ground water samples from wells in the Guadiamar basin. Accuracy, expressed in terms of recoveries, was in the range 80-120% and relative standard deviations were below 10%.