University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Jose L.F. Costa Lima

Abbrev:
Lima, J.L.F.C.
Other Names:
Jose Luis Fontes Costa Lima
Address:
Faculdade de Farmacia, Universidade do Porto, Porto, Portugal
Phone:
+351-22-207-8900
Fax:
+351-22-200-3977

Citations 29

"Multi-pumping Flow Systems: An Automation Tool"
Talanta 2004 Volume 64, Issue 5 Pages 1091-1098
José L. F. C. Lima, João L. M. Santos, Ana C. B. Dias, Marta F. T. Ribeiro and Elias A. G. Zagatto

Abstract: Multi-pumping flow systems (MPFS) are one of the most recent developments in terms of the design, conception and implementation of continuous flow methodologies, for sample and reagent handling and for the automation of analytical procedures. Based on the utilisation of multiple solenoid micro-pumps they enable the configuring of fully automated and easily controlled and operated analytical systems since all the fundamental operations involved in carrying out a sample analysis, including sample insertion, reagent addition and signal measurement could be carried out by the same manifold component, reducing the number of system parts and minimising its control or the occurrence of mal-functions. On the other hand, micro-pumps actuation produce a pulsed flow characterized by a chaotic movement of the solutions, which contributes to a fast sample/reagent homogenisation with low axial dispersion yielding improved analytical signals. The combination of such advantageous features resulted in simple, compact, versatile, fast, low-cost analytical procedures, exhibiting low reagent and low sample consumption, reducing the production of undesirable wastes and minimising operator intervention.

"Evaluation Of A Mathematical Model To Simulate Dynamic Response Of Tubular Potentiometric Sensors In Flow Injection Systems"
Sens. Actuat. A 1993 Volume 37, Issue 1 Pages 607-611
J. de Gracia, J. L. Montesinos and M. Poch, J. Alonso and J. Bartrolí, I. M. P. L. V. O. Ferreira and J. L. F. C. Lima

Abstract: Potentiometric detectors based on ion-selective electrodes are specially suited to flow measurements because of their low cost and high selectivity. Simultaneously in flow analysis the use of tubular-electrode configuration seems ideal as the flow characteristics can be kept constant throughout the system. The design of very simple manifolds, which increases the robustness and the system reliability, is constrained by the knowledge of the influence of hydrodynamic parameters in the detector response. With the aim to optimize the design of this kind of systems a mathematical model, that simulates the response of tubular potentiometric detectors in flow-injection systems, has been developed and tested. Results provided by simulation are compared with experimental ones, and the model capabilities are discussed.
Potentiometry Electrode Sensor Modeling

"Trimipramine Determination In Pharmaceutical Preparations With An Automated Multicommutated Reversed-flow System"
J. Pharm. Biomed. Anal. 2003 Volume 33, Issue 5 Pages 903-910
João A. V. Prior, João L. M. Santos and José L. F. C. Lima

Abstract: In this work an automated multicommutated flow methodology was implemented for the spectrophotometric determination of trimipramine in pharmaceutical preparations by oxidation with ammonium monovanadate in acidic medium. The developed procedure exploits a new approach for sample/reagent intermixing by combining binary sampling with flow-reversal. Rather than inserting the sample as a single continuous volume the intercalation of multiple small sample and reagent aliquots, under a time-based control, created multiple reaction interfaces that promoted reaction zone homogenisation even in limited dispersion conditions. Additionally, the reaction interfaces were reversed, increasing mutual zone penetration, which contributed to a faster reaction development while assuring a low dispersion pattern. A linear range of determination was verified for trimipramine concentrations between 1.0 and 18.0 µg mL-1 with a relative standard deviation (n=10) lower than 1.69% and a sample throughput of about 26 samples per hour. The results were in agreement with those obtained by the reference procedure with relative deviations lower then 2.37%.

"Flow Injection Amperometric Determination Of L-dopa, Epinephrine Or Dopamine In Pharmaceutical Preparations"
J. Pharm. Biomed. Anal. 1997 Volume 15, Issue 6 Pages 845-849
E. Manuela Garrido, Jose L. F. C. Lima* and Cristina Delerue-Matos

Abstract: Samples were prepared by simple dilution in water or electrolyte and subjected to FIA with amperometric detection (diagram of FIA system presented) using 0.1 M phosphate buffer of pH 6.4 as support electrolyte. The system was applied to the determination of L-dopa, dopamine and epinephrine in pharmaceutical preparations available on the Portuguese market.
l-Dopa Dopamine Epinephrine Pharmaceutical Amperometry

"Vitamins B1 And B6 Tubular Electrodes As FIA Detectors; Their Use In The Analysis Of Pharmaceutical Products"
J. Pharm. Biomed. Anal. 1991 Volume 9, Issue 10-12 Pages 1041-1046
José L. F. C. Lima*, M. Conceição B. S. M. Montenegro and A. M. R. Silva

Abstract: Ion-selective electrodes without an inner reference solution and tubular potentiometric detectors for the determination of vitamins B1 and B6 in pharmaceutical preparations by flow injection analysis (FIA) are reported. The membranes were prepared with the vitamin tetra(2-chlorophenyl)borate (TCPB) dissolved in o-nitrophenyloctyl ether (o-NPOE) and immobilized on PVC. Intrinsic behavior of the tubular detectors was assessed using a low-dispersion single-channel FIA manifold and was compared with conventionally-shaped electrodes using the same membrane. Data obtained in the determination of vitamins B1 and B6 in pharmaceutical preparations with a double channel flow injection manifold incorporating the tubular detectors are presented and compared with those obtained by the U.S. Pharmacopeia method and by direct potentiometry with conventionally-shaped electrodes. Ion-selective electrodes without an inner reference solution and tubular potentiometric detectors were constructed using membranes prepared with tetra(2-chlrorophenyl)borate dissolved in o-nitrophenyloctyl ether and immobilized on PVC. The tubular detectors were used with a double channel flow injection manifold to determine vitamins B1 and B6 in pharmaceuticals.
Vitamin B1 Vitamin B6 Pyridoxine Thiamine Pharmaceutical Electrode Electrode Potentiometry Membrane Method comparison Standard method

"Solid-state PVC Flow-through Benzoate Electrode"
J. Pharm. Biomed. Anal. 1989 Volume 7, Issue 12 Pages 1499-1505
José L. F. C. Limaa,*, M. Conceição, B. S. Montenegroa, J. Alonsob, J. Bartrolib and J. G. Raurichb

Abstract: Flow injection manifolds are described which incorporate a tubular electrode of a construction based on that previously described by Alegret et al. (Anal. Chim. Acta, 1984, 164, 147) with PVC membrane electrodes comprising tetraoctylammonium benzoate and 2-nitrophenyl octyl ether. Response was rectilinear down to 0.1 and 0.3 mM benzoate (I) with single-channel and double-channel flow injection manifolds, respectively. Corresponding detection limits were 70 µM and 0.1 mM I. The double-channel system was applied in the determination of I in pharmaceuticals.
Benzoate Pharmaceutical Electrode Electrode Electrode Electrode

"Tubular Electrodes And Other Devices For Potentiometric Detection In FIA"
J. Flow Injection Anal. 1993 Volume 10, Issue 1 Pages 17-32
Isabel M. P. L. O. Ferreira and Jose L. F. C. Lima

Abstract: A review is presented on the use of ISE and other electrodes for potentiometric detection in FIA. The various types of detector are described and their design and method of attachment to the FIA manifold are discussed. Emphasis is placed on tubular-shaped electrodes and their potential for use in systems with sequentially placed detectors. (156 references).
Potentiometry Electrode Electrode Dual detection Review

"Use Of The Sandwich Technique In Flow Injection Systems For Extending The Range Of An Analytical Method. Application To Chloride Determination In Waters"
J. Flow Injection Anal. 1992 Volume 9, Issue 1 Pages 69-77
A. N. Arafijo, J. L. F. C. Lima, A. O. S. S. Rangel and M. T. M. Teixeira

Abstract: Trace Cl- was determined in water by flow injection absorption spectrometry at 463 nm using 15%(v/v) MeOH solution of Hg(SCN)2 and Fe(NO3)3. The determination range was 0.1-1000 mg/L with a coefficient of variation <1%. Cl- (10-560 mg/L) in water was determined by the method agreed with the values from argentometric titration; and the coefficient of correlation was 0.9998 with a relative standard deviation of <4%.
Chloride Environmental Spectrophotometry Sandwich technique Method comparison Linear dynamic range

"FIA Potentiometric Determination Of Salicylate In Pharmaceutical Preparations With A Tubular Detector"
J. Flow Injection Anal. 1990 Volume 7, Issue 1 Pages 19-33
Jose L.F.C. Lima*, M. Conceicaio B. M. Montenegro and A.M. Roque da Silva

Abstract: The construction of a tubular salicylate-selective electrode for use as a detector in flow injection analysis is described. The device is compared with a similarly constructed, but conventionally shaped, electrode. The quality of the determinations of salicylic acid and acetylsalicylic acid (after hydrolysis) in pharmaceutical preparations was assessed by comparison with the B.P. procedures. The proposed detector is simple and inexpensive and shows clear advantages over the use of conventionally shaped electrodes in a cascade arrangement.
Salicylate Salicylic acid Acetylsalicylic acid Pharmaceutical Electrode Electrode Potentiometry Detector

"Chloride Pseudotitration In Wines By FIA With A Silver Sulfide - Silver Tubular Electrode As Detector"
J. Food Comp. Anal. 1989 Volume 2, Issue 4 Pages 356-363
Jose L. F. C. Lima, and Ant&oacute;nio O. S. S. Rangel

Abstract: The tubular electrode was constructed (diagram given) and used in the analysis of wine which was introduced into the carrier stream (0.2 M KNO3 and 0.1 µM-AgNO3) in the FIA manifold. The concentration. profile, created in a well-stirred mixing chamber and generated by the decreasing Ag+ concentration. in the carrier stream was monitored by the variation of the potential between the tubular and reference electrodes. The calibration graph was rectilinear from 5 to 600 mg L-1 of Cl-. The within-run coefficient of variation was 1% (n = 10). Results compared well with those from a reference procedure (r = 0.990).
Chloride Wine Electrode Electrode Well stirred mixing chamber Method comparison Titrations

"An Automatic Flow Procedure For The Determination Of 3-Hydroxybutyrate In Animal Serum And Plasma"
J. Agric. Food Chem. 2003 Volume 51, Issue 9 Pages 2457-2460
Cherrine K. Pires, Patr&iacute;cia B. Martelli, Boaventura F. Reis, Jos&eacute; L. F. C. Lima and M. L&uacute;cia M. F. S. Saraiva

Abstract: An automatic flow procedure based on the multicommutation concept, comprising three-way solenoid valves, for the spectrophotometric determination of 3-hydroxybutyrate in animal serum and plasma is proposed. The 3-hydroxybutyrate was enzymatically converted to acetoacetate with the reduction of NAD+ to NADH monitored at 340 nm. It was possible to carry out up to 600 determinations without a significant decrease in the analytical signal, with 5 mg of 3-hydroxybutyrate dehydrogenase immobilized on porous silica beads and packed in a column. The system enabled 60 determinations/h of 3-hydroxybutyrate in the range of 10^-150 mg L-1, with a consumption of 0.9 mg of NAD+ and 200 µL of sample per determination. A detection limit of 2 mg L-1 for both animal serum and plasma and coefficients of variation of 1.4% and 1.2% (n = 17), respectively, were determined. Animal serum and plasma samples were analyzed without previous treatment, the results of which agreed with those obtained using the conventional method (UV kit, Sigma). Keywords: Flow analysis; multicommutation; 3-hydroxybutyrate; spectrophotometry; enzyme reactor; plasma and serum

"Potentiometric Flow Injection Determination Of Glycerol In Distilled Spirits"
J. Agric. Food Chem. 2002 Volume 50, Issue 1 Pages 74-77
Ana Paula G. Gervasio, Eduardo P. Borges, Elias A. G. Zagatto, Boaventura F. Reis, Rui A. S. Lapa, and Jos&eacute; L. F. C. Lima

Abstract: A single-line flow injection system including a tubular periodate-selective electrode without inner reference solution is proposed for glycerol determination in distilled spirits, based on oxidation of this polyol by periodate. Interferences due to 5.0 mg L-1 Cu, 5000 mg L-1 sucrose, and 3000 mg L-1 fructose plus glucose were investigated. The procedure is characterized by a linear response for 20-500 mg L-1 glycerol (r > 0.9999, n = 7), a relative standard deviation of results of <0.03, and an analytical throughput of 30 determinations per hour. Accuracy was assessed by applying the procedure to distilled spirits of sugarcane and grape already analyzed by HPLC; in addition, recoveries within 96 and 120% were obtained.

"Flow Injection System With Multisite Detection For Spectrophotometric Determination Of Calcium And Magnesium In Soil Extracts And Natural Waters"
J. Agric. Food Chem. 1996 Volume 44, Issue 1 Pages 165-169
Ana Rita A. Nogueira, Sandra M. B. Brienza, Elias A. G. Zagatto, Jos&eacute; L. F. C. Lima, and Alberto N. Ara&uacute;jo

Abstract: A flow system with a relocatable detector for spectrophotometric determination of calcium (Ca) and magnesium (Mg) in KCl soil extracts and natural waters is presented. O-Cresolphthalein complexon (CPC) was selected as the chromogenic reagent, ammonium-ammonia as the buffer system, and EGTA or 8-hydroxyquinoline as the masking agents for Ca or Mg, respectively. Linearity of the calibration equations was observed for Ca and Mg concentrations up to 80.0 and 15.0 mg/L, respectively. Slight variations in the coefficients of the calibration equations (usually <3%) were found after 4-h working periods. Recoveries between 97.5 and 104.1% were calculated after adding 10.0 mL of Ca at 15.00 mg/L or Mg at 5.00 mg/L Mg to 50.0 mL sample solutions. Precise results (relative standard deviation, <0.02) in agreement with flame atomic absorption spectrometry were obtained. With multisite detection, washing time was not a relevant factor in sampling rate, and an improved sample throughput of 160/h (corresponding to 0.8 mg of CPC per sample) was obtained.
Calcium Magnesium Environmental River Spectrophotometry 8-Hydroxyquinoline

"FIA Tubular Potentiometric Detectors Based On Homogeneous Crystalline Membranes - Their Use In The Determination Of Chloride And Sulfide Ions In Water"
Int. J. Environ. Anal. Chem. 1990 Volume 38, Issue 2 Pages 127-133
Jos&eacute; L. F. C. Lima; L&iacute;vio S. M. Rocha

Abstract: Tubular detectors were constructed by welding a silver plate (2 mm x 4 mm) to a shielded electrical cable, then attaching a membrane containing AgS or AgCl to the plate using a Ag-based conductive epoxy-glue. The detector was cast in non-conductive epoxy and holes were made to receive the PVC connectors of the FIA manifold. The detection limits for Cl- and S2- were 50 and 10 µM, respectively, in standard solution; durability of the detectors was >1 year. Similar detectors can be made for Br-, I-, Cd, Cu2+ and Pb2+. Results for natural and waste water agreed with those by conventional ion-selective electrode procedures. The advantages of FIA are discussed.
Chloride Sulfide Environmental Waste Potentiometry Electrode Electrode Membrane Detector Method comparison

"Construction And Evaluation Of Tubular Potentiometric Detectors Sensitive To Chloride, Bromide And Iodide And Based On Homogeneous Crystalline Membranes"
Fresenius J. Anal. Chem. 1993 Volume 347, Issue 8-9 Pages 314-319
Isabel M. P. L. V. O. Ferreira, Jos&eacute; L. F. C. Lima Contact Information and Livio S. M. Rocha,

Abstract: A 0.25 g portion of an equimolar mixture of Ag2S and the appropriate Ag halide was compressed into a disc (10 mm diameter x 0.4 mm thick) under a pressure of 19 000 kg/cm2. A 3 mm x 3 mm portion of the crystalline membrane was fastened, using Ag-based epoxy resin, to a rectangular Ag plate (1.5 mm x 3 mm) with electrical lead wires attached. The membrane was housed in a small perspex cylinder (1 cm diameter x 7 mm) with a rectangular cavity (3 mm x 4.5 mm x 7.5 mm) filled with non-conductive epoxy resin. After hardening the resin in an oven, a hole (0.8 mm diameter) was drilled so that it passed through the centre of the membrane. The sensor was then mounted in a support unit and connected to a flow injection system with the flow stream passing through the hole in the membrane. With 0.1 M KNO3 as carrier (8.4 ml/min) and 200 µL sample injection the electrodes exhibited rapid, near-Nernstian responses with detection limits of 50 µM-chloride, 5 µM-bromide and 20 µM-iodide. Electrode response was independent at pH 2.2-9.8, 2.2-11 and 2.5-11 for the chloride, bromide and iodide electrodes, respectively. Sampling rates were 360 and 200 samples/h for bromide and chloride, respectively.
Chloride Bromide Iodide Potentiometry Electrode

"Determination Of Calcium, Magnesium, Sodium And Potassium In Wines By FIA Using An Automatic Zone Sampling System"
Food Chem. 1996 Volume 55, Issue 4 Pages 397-402
Rui A. S. Lapa, Jos&eacute;L. F. C. Lima* and Jo&atilde;o L. M. Santos

Abstract: An automatic FIA unit based on the zone sampling technique is described. The sample was injected into a first carrier stream and dispersed on a dilution coil. By rotating the injection valve, a portion of the dispersed sample plug was introduced into a second carrier stream and directed towards the detector. A microcomputer was used as the control unit. Ca and Mg were determined by AAS whilst Na and K were determined by flame photometry. The results agreed well with those obtained by reference methods. RSD were 1.6% for Ca, 2.7% for Mg, 1.4% for Na and 3.2% for K.
Calcium Magnesium Potassium Sodium Wine Spectrophotometry Spectrophotometry Zone sampling Method comparison Computer

"Flow Injection Titration Of Chloride In Food Products With A Silver Tubular Electrode Based On An Homogeneous Crystalline Membrane"
Food Chem. 1994 Volume 50, Issue 4 Pages 423-428
Isabel M. P. L. V. O. Ferreira, Jos&eacute;L. F. C. Lima* and Ant&oacute;nio O. S. S. Rangel

Abstract: Wine, milk, beer and vinegar were tested for chloride by pseudo-titration using FIA and potentiometric detection. Sample was injected into a carrier stream composed of 20 µM-AgNO3/0.1 M KNO3 and directed to a well-stirred mixing chamber. The decrease in the Ag concentration was monitored by an Ag tubular electrode with a crystalline membrane of AgS prepared by mixing equal volumes of equimolar (0.1M) AgNO3 and Na2S solution, filtering and drying at 100°C for 24 h. After grinding, the membrane discs were prepared by pressing 0.25 g of sensor at high pressure to produce discs 10 mm in diameter and 0.4 mm thick. The membrane was set into a support (details given). The operating characteristics of the tubular electrode were compared with conventional electrodes and found to be similar. The optimum Ag concentration in the carrier stream was 0.1 mM and optimum carrier flow rate was 8.1 ml/min. Calibration graphs were linear from 10^-500 mg/l, 100-1800 mg/l and 40-500 mg/l for wine, milk and beer, and vinegar, respectively. Sampling rate varied from 120-136 samples/h. A comparison with reference procedures showed maximum RSD of 6, 0.3 and 1% for wine and milk, beer, and vinegar, respectively.
Chloride Wine Beer Milk Food Electrode Potentiometry Titrations Well stirred mixing chamber Optimization Indirect

"An Automatic Determination Of Caffeine In Soft Drinks Using Flow Injection System With Amperometric Detection"
Food Addit. Contam. 1998 Volume 15, Issue 3 Pages 265-269
Lima JL, Delerue-Matos C, Nouws HP, Vaz MC

Abstract: An automatic procedure based on a flow injection analysis manifold was developed for the determination of caffeine in soft drinks using an amperometric detection (+1.70 V vs. AgCl/Ag). The sample and standards were injected without pre-treatment, with a sampling rate of 120 determinations per h. The determination of caffeine in several soft drinks available in Portugal using the developed automatic system provided results with mean recovery values between 98% and 103% and a mean standard deviation between 2% and 5%. The results obtained were compared with those given by the reference method recommended by AOAC. Relative deviation was always <4%. Reproducibility of the method was assessed by the relative standard deviation (relative standard deviation%), values of which were <2%.
Caffeine Soft drink Amperometry Method comparison

"Determination Of Ascorbic Acid In Pharmaceutical Products By Flow Injection Analysis Using An Amperometric Detector"
Il Farmaco 1995 Volume 50, Issue 12 Pages 881-884
E.M. Garrido, J.L.F.C.Lima, C.M Delerue-Matos

Abstract: This paper reports the development of amperometric detection using a double channel FIA manifold for the control of vitamin C in pharmaceutical formulations. This method enables direct determination of aqueous solutions by simple solubilisation of pharmaceutical formulations. As sample filtration is not required, addition of the support electrolyte is carried out within the FIA manifold. Reliable ascorbic acid determinations in several pharmaceutical formulations were carried out in a double channel manifold with a sampling rate of about 120 samples/hour. (21 References)
Ascorbic acid Pharmaceutical Amperometry

"Applications Of Flow Injection Analysis In Enology"
Cienc. Tec. Vitivinic. 1990 Volume 9, Issue 1-2 Pages 95-113
Lima, J.L.F.C.;Rangel, A.O.S.S.

Abstract: A review with 27 references discussing the use in wine analysis of flow-injection techniques coupled with spectrophotometry, amperometry, enthalpimetry, atomic absorption spectrometry, flame emission spectrometry, and potentiometry. (SFS)
Wine Spectrophotometry Amperometry Enthalpimetry Spectrophotometry Spectrophotometry Potentiometry Review

"Flame AAS Determination Of Copper In Urine Using A Flow Injection On-line Preconcentration System Based On A Polyamine Chelating Ion Exchange Column"
Atom. Spectrosc. 2000 Volume 21, Issue 5 Pages 187-193
Almeida, A.A.;Jun, X.;Lima, J.L.F.C.

Abstract: A flow injection system incorporating a polyamine chelating ion exchange column for the flame atomic absorption determination of copper in urine is proposed. At a 5 mL sample volume, the procedure yielded a detection limit of I µg/L and a sample frequency of 20/h. Repeatability (%RSD, n=10) was 0.9% at a 100-mug/L level and 1.4% at a 20-mug/L level. Reproducibility (%RSD; n=3) was 5% for a mean sample concentration of about 33.8 µg/L. For maximum accuracy, a rapid wet sample digestion with H2O2 had to be performed. Results obtained by the proposed methodology (n=20) were in good agreement with those provided by graphite furnace atomic absorption spectrometry.
Sensitivity Extraction

"Simultaneous Determination Of Potassium And Sodium In Vegetables By Flame Emission Spectrometry Using A Flow Injection System With Two Dialysis Units"
Anal. Sci. 1996 Volume 12, Issue 1 Pages 81-85
J. L. F. C. LIMA, A. O. S. S. RANGEL and M. R. S. SOUTO

Abstract: Dried vegetable (2 g) was digested overnight with 30 mL 60% HClO4/70% HNO3 (1:4) and the digest was heated at 100°C for 2 h. The solution was evaporated at 180-200°C initially and the temperature was raised to 240°C until a dry residue was obtained. The residue was dissolved in 10 mL 2 M HCl with gentle heating and diluted to 50 mL with water. Portions (278 µL) of the solution were injected into a flow injection manifold (schematic shown), mixed with a carrier stream of water (5 ml/min) and driven to a dialysis unit (35 x 2 x 0.5 mm) previously described by Lima et al. (in: Automatic Control of Food and Biological Processes, 1994, 67). The ions diffused to the acceptor channel across the membrane and the dialysate was directed to a Corning 410 spectrometer for detection of K by AES. The undialysed solution was transferred by the carrier to a second dialyser (70 x 2 x 0.5 mm) and the new dialysate was transferred to a Buck Scientific PFP-7 spectrometer for the detection of Na by AES. Calibration graphs were linear from 24.6-230 and 60.6-14,700 mg/l, respectively, for Na and K. RSD (n = 10) were 1.7 and 1.6%, respectively, for 2.3-16 and 31-55 mg/g of Na and K, respectively. Sampling rates were 120-150 samples/h (corresponding to 240-300 determinations/h).
Potassium Sodium Vegetable Spectrophotometry Dialysis Membrane

"Development Of A Tubular Fluoride Potentiometric Detector For Flow Analysis. Evaluation And Analytical Applications"
Anal. Chim. Acta 2007 Volume 583, Issue 2 Pages 429-436
Jo&atilde;o Rodrigo Santos, R.A.S. Lapa and Jos&eacute; L.F.C. Lima

Abstract: In this work a construction procedure for tubular fluoride electrode to be used in flow systems is outlined. The electrode was constructed from a commercially available, LaF3 single crystal. Principal advantages of the flow detector presented include simplicity of construction, robustness, durability, low cost and easy coupling into any point of a flow manifold. Evaluation of the intrinsic working characteristics of the potentiometric detector in a low dispersion manifold is presented with respect to analytical and dynamic parameters. The constructed detector has similar working characteristics to those of the conventional fluoride electrodes, namely the detection limit, lower limit of linear response and operational pH range. The analytical usefulness of the constructed device was assessed in a flow system developed for fluoride determination in toothpaste, tablet, collutory and water samples for which the reference procedures suggest the determination of fluoride ion with a conventional ion selective electrode. © 2006 Elsevier B.V. All rights reserved.

"Multicommutated Flow System For The Chemiluminometric Determination Of Clomipramine In Pharmaceutical Preparations"
Anal. Chim. Acta 2004 Volume 518, Issue 1-2 Pages 31-36
Karine L. Marques, Jo&atilde;o L. M. Santos and Jos&eacute; L. F. C. Lima

Abstract: A continuous flow methodology for the chemiluminometric determination of clomipramine in pharmaceutical preparations is described. Clomipramine acts as a sensitizer on the chemiluminescent oxidation of sulphite by Ce(IV). The developed procedure is based on the multicommutated flow concept whose versatility was fully exploited by using a single solution propelling device for the insertion of multiple solutions in propulsion mode. The utilisation of a binary sampling approach enabled sample/reagent mixing within the flow cell with a significant reagent saving. A time-based sample insertion assured an effective control of sample dispersion, enabling the attainment of distinct working concentration ranges by means of the selection of appropriate sampling times.Linear calibration plots were obtained for clomipramine hydrochloride concentrations ranging 2.5-60 mg l-1, depending on sampling time, with good reproducibility and RSD lower than 4.6% (n = 4). The developed methodology was applied in the analysis of pharmaceutical preparations and the obtained results were in good agreement with those furnished by the reference procedure with R.D. lower than 3.3% and a sampling rate between 19 and 32 samples per hour.

"Multi-pumping Flow System For Spectrophotometric Determination Of Bromhexine"
Anal. Chim. Acta 2003 Volume 499, Issue 1-2 Pages 107-113
Ana C. B. Dias, Jo&atilde;o L. M. Santos, Jos&eacute; L. F. C. Lima and Elias A. G. Zagatto

Abstract: A novel flow-based procedure involving the multi-pumping approach was developed for the spectrophotometric determination of bromhexine in pharmaceutical preparations. The method is based on reaction with 3-methyl-2-benzothiazolinone hydrazone (MBTH) and Ce(IV). Several solenoid micro-pumps are present in the manifold in order to provide improved system control. Critical tasks in continuous flow analysis, sample-reagent introduction and solution propelling, are then efficiently carried out. Moreover, the pulsed flow inherent to the mini-pumps ensures good mixing conditions, thus improving the reaction zone homogenisation. This aspect becomes particularly attractive for the implementation of analytical procedures involving several consecutive reactions as it happens with the proposed procedure.Linear calibration plots (r>0.995, n=6) were obtained for bromhexine concentrations up to 400 mg l-1. Detection limit was 2 mg L-1 and the sampling rate was about 45 samples h-1. Results are precise (RSDn=10) and in agreement with those furnished by the reference procedure involving a potentiometric titration.

"Flow Injection Analysis Of Kjeldahl Nitrogen In Milk And Dairy Products By Potentiometric Detection"
Anal. Chim. Acta 1999 Volume 385, Issue 1-3 Pages 437-441
Jos&eacute; F. C. C. Lima, Cristina Delerue-Matos and M. Carmo Vaz

Abstract: A flow injection analysis (FIA) system with a potentiometric tubular detector and a gas diffusion unit was developed for the determination of Kjeldahl nitrogen in milk and dairy products. The samples were digested by the Kjeldahl method and afterwards injected into the RA system without prior treatment. NaOH solution was introduced into the system to promote the conversion of ammonium ions to ammonia gas. The gas produced diffused through a gas-permeable membrane towards an acceptor channel (Tris-HCl, pH=7.5). When in contact with this solution, ammonia gas was reconverted to ammonium cation and carried to a tubular electrode sensitive to this species. Therefore, a PVC tubular ammonium ion-selective electrode was prepared without inner reference solution and with the sensor system based on nonactine and monactine dissolved in Tris-(2-ethylhexyl) phosphate. The results obtained with the developed FIA system were in good agreement with those of the reference method the relative deviations being less than 4%. Reproducibility of the method was assessed by the relative standard deviation, which was always less than 0.5% for 12 consecutive injections of sample digests. A sampling rate of 100 samples h-1 was obtained.
Ammonia Dairy Products Potentiometry Electrode Gas diffusion Kjeldahl Volatile generation Method comparison

"Tubular Potentiometric Detector For Flow Injection Based On Homogeneous Crystalline Membranes Sensitive To Copper, Cadmium And Lead"
Analyst 1994 Volume 119, Issue 2 Pages 209-212
Isabel M. P. L. V. O. Ferreira and Jos&eacute; L. F. C. Lima

Abstract: Homogenous crystalline membranes were pressed from ~0.25 g of MS/Ag2S (M = Cu, Cd or Pb) mixtures at 19 000 kg/cm2, and fabricated into tubular potentiometric detectors (TPD). The internal conductor of a shielded cable was fixed to a small silver plate to which a portion of the membrane was attached with epoxy resin. After baking overnight at 70°C, the device was housed in a perspex cylinder which was filled with a non-conductive epoxy resin. This unit was hardened by baking and a hole was drilled lengthwise through the middle of the sensor membrane. The performance of the resulting TPD was compared with conventional ISE prepared from the same membranes in FIA (details given). Using the TPD, response times ranged from 0.4-4.8 s and RSD were 0.4%, 1% and 0.9% for Cu, Cd and Pb, respectively. The lower limit of linear response 50 µM-Cu and 0.2 mM Cd and -Pb. Detection limits were not determined. The overall performance of the two detector geometry types were broadly similar.
Cadmium Copper Lead Potentiometry Electrode

"Enzymatic Determination Of L(-)malic And L(+)lactic Acids In Wine By Flow Injection Analysis"
Am. J. Enol. Vitic. 1992 Volume 43, Issue 1 Pages 58-62
Jos&Eacute; L. F. C. Lima and Ant&oacute;nio O. S. S. Rangel

Abstract: The enzymatic determination of L-(-)-malic and L(+)lactic acids in several types of wines by flow injection analysis (FIA) with spectrophotometric detection is described. This flow injection system, which incorporates a dialysis unit for adjusting the composition of the injected solutions to the requirements of the measuring system, enables determinations of these two organic acids without the need for any prior treatment of the wine samples, with a concentration. interval of between 0.02 and 4 g/L, and a sampling rate of approximately 20 determinations per h. The results obtained with this FIA method for various types of Portuguese wines are in good agreement with those of the batch method which uses the same enzymatic technique and are quite precise as they present a coefficient of variation below 2.5%.
l-Malic acid l-Lactic acid Wine Spectrophotometry Dialysis Method comparison Enzyme

"Determination Of Metallic Cations In Wines By Flow Injection Analysis"
Am. J. Enol. Vitic. 1990 Volume 41, Issue 4 Pages 284-288
Jos&eacute; L. F. C. Lima and Ant&oacute;nio O. S. S. Rangel

Abstract: Four flow-injection manifolds were developed aiming to automate the determination of metallic cations (Na, K, Ca, Mg, Fe, Mn, Zn, and Cu) in wines using atomic absorption (AAS) and flame emission (FES) spectrometry as detection processes. Good agreement was obtained between the results of FIA methods and by the reference methods, in which samples are prepared in a discrete manner and then introduced into the detection system. The FIA methods developed present good quality results (relative standard deviation between 0.57% and 1.4%) with high sampling rates (180 to 360 samples per hour) and a low reagent consumption.
Metals Wine