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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Nicholaos P. Evmiridis

Abbrev:
Evmiridis, N.P.
Other Names:
Evmiridis, Nick P., Nickolaos P. Evmiridis
Address:
Laboratory of Analytical Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece
Phone:
+30-651-98404
Fax:
+30-651-44831

Citations 19

"Program Based On The Pattern-search Method: Application To Periodate Determination Using Flow Injection Analysis And Chemiluminescence Detection"
Trends Anal. Chem. 1988 Volume 7, Issue 10 Pages 366-370
Emmanuel M. Papamichael and Nicholaos P. Evmiridis

Abstract: The BASIC program presented, which requires 4K of memory, permits any multi-parameter function with a discontinuous derivative to be fitted. Its use is illustrated by the fitting of a chosen model function to the non-rectilinear calibration graph in the flow injection chemiluminescence determination of IO4- described previously [Evmiridis, Analyst (London), 1987, 112, 825].
Periodate Chemiluminescence Computer Calibration

"Dialysis Membrane Sampler For On-line Flow Injection Analysis/chemiluminescence-detection Of Peroxynitrite In Biological Samples"
Talanta 2003 Volume 59, Issue 1 Pages 55-65
Kang Dai, Athanasios G. Vlessidis and Nicholaos P. Evmiridis

Abstract: Peroxynitrite, as a derivative of nitric oxide, is a potent oxidant. It reacts with several biological molecules, makes cellular and tissue damages, and is related with many diseases; therefore, it is of major concern in current medical research works. In this work, a special perm-selective cellulose acetate membrane sampler is used to implement flow injection analysis (FIA)/chemiluminescence (CL)-detection method for the detection of peroxynitrite with Luminol CL-reagent. Optimum detection conditions were established, and the permeability of peroxynitrite through cellulose acetate (CA) membrane, as well as the interference from matrix constituents were studied. The proposed method has the high sensitivity of the CL-detection and the selectivity of perm-selective membrane sampler. The obtained detection limit of 1 x 10^-11 M (without dialysis membrane) and 1 x 10^-10 M (with dialysis membrane), makes it possible to monitor the elusive peroxynitrite in biological samples. The mechanism of luminol CL-emission generated during oxidation by peroxynitrite and the kinetics of peroxynitrite decomposition were also studied using FIA/CL-detection set-up.

"Chemiluminescence Emission Generated During Oxidation Of Pyrogallol And Its Application In Analytical Chemistry. 1. Effect Of Oxidant Compound"
Talanta 1998 Volume 46, Issue 1 Pages 179-196
Nicholaos P. Evmiridis*, Nicholaos K. Thanasoulias and Athanasios G. Vlessidis

Abstract: An investigation of chemiluminescence (CL)-emission generated by the oxidation of pyrogallol using various inorganic oxidant compounds is reported in this flow injection anal.-merging zone application. The oxidant compounds that showed measurable CL emission were permanganate, periodate, hypochlorite anions, cerium(IV), and hydrogen peroxide. The different oxidant compounds showed CL emissions at different pH ranges. The CL emission was limited by the inner filter effect, and this was more intense for oxidants of selective oxidation Kinetic effects were also found in the case of oxidation by permanganate. Plots of CL emission against pH give evidence of speciation and or deactivation mechanism effects. The anal. parameters for the determination of the oxidants are given. Sensitivities of 895,600, 19,500, 33,723, 10,680, and 56,703 mV M-1 were found for the determination of permanganate, cerium(IV), periodate, hypochlorite and hydrogen peroxide, respectively. The calibration curves of the oxidant determination were generally S-shaped; the S-shaped calibration curve of periodate was closer to a straight line relationship, while that of hypochlorite was almost a straight line; detection limits in the range of 10^-4 M oxidant concentration. were found for nearly all oxidants. The anal. parameters for determination of pyrogallol by the CL emission generated through oxidation by the different oxidants at optimum conditions were 1.16 x 106 mV M-1 for permanganate; 0.086 x 106 mV M-1 for cerium(IV); 0.91 x 106 mV M-1 for periodate; 0.012 x 106 mV M-1 for hypochlorite; and 0.25 x 106 mV M-1 for hydrogen peroxide. The detection limit was 1.0 x 10^-4M. The nearly straight-line relationship (initial part of the plot) for CL emission with oxidant concentration. gives an indication that the CL reaction of pyrogallol oxidation by hypochlorite proceeds through a process that involves energy transfer, while the pronounced S-shaped curve produced by permanganate gives the indication that the reaction proceeds through a process that does not involve energy transfer according to the math. model of CL emission that controls the flow injection anal.-merging zone technique of the flow app. used in this work. The sequence of completeness of the oxidation process by each oxidant was MnO4- > H2O2 > IO4- > ClO-; the stoichiometric quantity of the oxidant per pyrogallol mol. for the rapid part of the overall oxidation by each different oxidant was attempted; this is an index value of the oxidation state of the fluorescent excited mol. Finally, the impact of the above findings for further anal. applications is discussed.
Permanganate Periodate Hypochlorite Cerium(4+) Hydrogen peroxide Chemiluminescence Indirect Optimization Merging zones Sensitivity

"Periodate Determination By FIA With Chemiluminescence Emission Detection And Its Application To Ethylene Glycol [ethanediol]"
Talanta 1989 Volume 36, Issue 3 Pages 357-362
N. P. Evmiridis

Abstract: The method is based on measurement of the chemiluminescence generated by the oxidation of pyrogallol (I) by IO4-. A 40 µL sample is injected into a carrier stream of phosphate buffer solution of pH 8.0, which is then mixed with a reagent stream of 1 mM I - 1 mM hydroxylamine. The detection limit is 0.35 µg of IO4-, and the coefficient of variation is 3%. The method can be applied in the determination of ethanediol (II). II is treated with an excess of IO4- in buffer solution of pH 8.0, and residual IO4- is determined as before. The detection limit of II is 0.5 µmol. The sampling rate is 15 min-1.
Periodate 1,1-Ethanediol Chemiluminescence Redox Buffer

"Chemiluminescence Detection Of Peroxynitrite With Flow Injection"
Proc. SPIE 2001 Volume 4414, Issue 1 Pages 104-107
Dai Kang, Nick P. Evmiridis, Athanasios Vlessidis, Yikai Zhou

Abstract: Peroxynitrite is an important derivative made by nitric oxide in vivo. It can make damages in many kinds of tissue and cells. Its research value in heart disease and cancer is a very high. A sensitive, specific method for analysis of peroxynitrite is described. In this method, chemiluminescence reaction between perodynitrite and luminol was used to detect with flow injection system. The assay has a detection limit of 2 by 10^-8 mol L-1, and linear range of 5 by 10^-8 mol L-1 to 5 by 10^-5 mol L-1. The application o f flow injection system offers the possibility to establish biosensor for real-time detection of perodynitrite.

"A Study For The Validation Of Spectrophotometric Methods For Detection, And Of Digestion Methods Using A Flow Injection Manifold, For The Determination Of Total Phosphorus In Wastewaters"
J. Anal. Chem. 2004 Volume 59, Issue 1 Pages 77-85
A. G. Vlessidis, M. E. Kotti and N. P. Evmiridis

Abstract: A study for the validation of orthophosphate determination using an FI-manifold/spectrophotometric detection set-up is made. Under optimized conditions, the method with the largest valid range (0-50 mg L^-1), with the possibility of extending it even higher) is the molybdate/ascorbic acid method; its reproducibility and interferences are similar to other tested methods. A study among the conventional digestion methods is then made to test the adaptability of the method to FI systems. The persulfate digestion method was found to be more suitable for use with flow systems. The persulfate digester was connected in-line with the FI-manifold; under optimized conditions, the sensitivity of the method is decreased, especially when used with organic phosphorus compounds, but it is still reasonable for use. The sensitivity is also dependent on the nature of the phosphate species attached to the organic residue. In addition, it was found that colloid precipitate phase in the sample decreases the sensitivity. Finally, real wastewater samples were tested using the UV radiation-assisted, persulfate digester-implemented FI-system method, and using the batch method. It was found from the correlation of the two methods that the fraction of P-recovery in the FIA system was 2/3 of the total phosphate, suggesting that the rest was due to the polyphosphate content.

"Design Of Experiments For A Precise Estimation Of The Calibration Curve Of Periodate In Its Determination By Flow Injection Analysis And Chemiluminescence Detection"
Chemom. Intell. Lab. Syst. 1995 Volume 30, Issue 2 Pages 227-237
Emmanuel M. Papamichaela, Nickolaos P. Evmiridisb,*, Nickolaos Thanasouliasb and Despina Stefanoua

Abstract: A design of experiments method based on the criterion of D-optimality is presented. It is applied to the estimation procedure of the parameters of a periodate calibration curve described by a model equation of the form y = ax(2)/(bx + c root x + 1) and giving the maximum possible precision using three experimental measurements. The use of four or five experimental measurements for producing the calibration curve was not found more advantageous than that of three. Simulated data were generated, for the three optimal points, and a large number of parameter estimates were obtained under constant and/or relative errors (in y) showing a robust behaviour. The %-bias and the %-excess variance based on the simulated data were found to be non-significant. An experimental design method based on the D-optimality principle was developed. The method was applied to the estimation of the calibration curve of periodate. The use of three optimal-design points were found to be as good as the use of four or five points. The advantages of the method are discussed and parameter estimates obtained with the optimal experimental design exhibited %-bias and %-excess variance based on the simulated data which were not significant. (10 references)
Periodate Chemiluminescence Experiment design Signal processing Curve fitting Calibration Optimization

"Investigation Of The Error Structure Of The Calibration Curve For Periodate Determination By Flow Injection Analysis And Chemiluminescence Detection"
Chemom. Intell. Lab. Syst. 1991 Volume 12, Issue 1 Pages 39-47
N. P. Evmiridis* and E. M. Papamichael

Abstract: Experimental data on periodate determination by flow injection analysis and chemiluminescence detection is fitted to a model equation using the pattern search method. A large number of parameter estimates are obtained from simulated data generated by means of a computer program implemented by a random number generator and their parameter estimate means and variances are compared with the set of parameters obtained from the experimental data. The %-bias, %-excess variance, skewness and excess kurtosis, of the parameter estimates from the simulation study are also calculated to determine the effect of errors on the parameter values. The procedure was followed for different criteria of convergence of the fitting routine and type of errors in the response value and outliers selected at random. The statistical parameters of the model equation parameter estimates are compared in relation to the various convergence criteria for best performance.
Chemiluminescence Calibration Modeling

"Development Of A Sensitive Flow Injection-chemiluminescence Detection Method For The Indirect Determination Of Propranolol"
Anal. Chim. Acta 2005 Volume 541, Issue 1-2 Pages 151-157
George Z. Tsogas, Dimitrios V. Stergiou, Athanasios G. Vlessidis and Nicholaos P. Evmiridis

Abstract: A highly sensitive flow injection-chemiluminescence detection (FI-CL) method based on pyrogallol (Pg) chemiluminescent reagent (CL-reagent) oxidized by periodate for the determination of propranolol is presented. The presented method is an indirect CL detection method based on the CL emission generated during the oxidation of Pg with the excess of periodate that remains after oxidation of propranolol within the time period of 10 min. The obtained propranolol calibration curve is linear up to 1.0 mg L-1 with a sensitivity of -0.95 V mg-1 l. At higher than 1.0 mg L-1 propranolol concentrations the propranolol calibration curve is still linear up to 20.0 mg L-1 with a sensitivity of -0.05 V mg-1 l. The detection limit is restricted from the noise level and at S/N = 3 was found to be 37.4 ?g L-1 (3.74 ng) with RSD% = 0.34 for seven replicate measurements. © 2004 Elsevier B.V. All rights reserved.

"Possible Mechanism For Nitric Oxide And Oxidative Stress Induced Pathophysiological Variance In Acute Myocardial Infarction Development: A Study By A Flow Injection-chemiluminescence Method"
Anal. Chim. Acta 2004 Volume 505, Issue 1 Pages 115-123
Dachun Yao, Athanasios G. Vlessidis, Nicholaos P. Evmiridis, Stavros Siminelakis and Niokou Dimitra

Abstract: The acute myocardial infarction (AMI) model was established through rabbits, and this kind of model was used to investigate the possible mechanism for the AMI mediated damage, induced by NO release and oxidative stress. The biomedical parameters nitric oxide (NO), total antioxidant capacity (TAC) variation in vivo and the enzymatic activity of nitric oxide synthase (NOS) and superoxide dismutase (SOD), which are considered as the major markers for pathophysiological variation, were detected. The results obtained gave evidence that AMI can lead to the NO excess release and compensation by excess cellular respiration, and both of them can result in oxidative stress and further generation of reactive oxygen species (ROS). The latter can bring a series of damages to the organism, including decrease of the TAC value, and NOS and SOD activity. © 2002 Elsevier Science B.V. All rights reserved.

"Membrane Sampler For Interference-free Flow Injection NO Determination In Biological Fluids With Chemiluminescence Detection"
Anal. Chim. Acta 2001 Volume 450, Issue 1-2 Pages 63-72
Dachun Yao, Mamas I. Prodromidis, Athanasios G. Vlessidis, Miltiades I. Karayannis and Nickolaos P. Evmiridis

Abstract: The development of a chemiluminescence (CL) method based on the perm-selective properties of a Nafion-cellulose acetate (CA) composite membrane for the monitoring of nitric oxide (NO) in biological fluids is described. Horseradish peroxidase (HRP) was used as NO trapping solution, forming the stable compound HRP-NO. The HRP was denatured and the trapped NO was released and detected by using the luminol-H2O2 system. Using a mixed (size-exclusion and polar-based) transport control, the interference effects of various compounds were minimized. The method was used for NO monitoring in simulated samples, by using a blood specimen as sample matrix. The 3s detection limit is 0.9 x 10^-6 mol and linear semi-log calibration plot in the range 1.8 x 10^-6 to 2.7 x 10^-3 mol NO was constructed. The applied methodology was further used to prolong the NO lifetime in order to increase the sensitivity of its determination. This was based on the increase of the response in the presence of certain reductive species, which act as NO preservatives in biological fluid samples.

"On-line Monitoring Of Nitric Oxide Complexed With Porphyrine-bearing Biochemical Materials By Using Flow Injection With Chemiluminescence Detection"
Anal. Chim. Acta 2001 Volume 435, Issue 2 Pages 273-280
Dachun Yao, Athanasios G. Vlessidis and Nicholaos P. Evmiridis

Abstract: An on-line nitric oxide (NO) monitoring method is described employing a flow injection manifold with chemiluminescence (CL) detection. The method is tailored for monitoring the NO from its complexes with porphyrin ring-bearing (PRB) biochemical materials. The method is optimized for sensitivity and detection limit. The method is quite sensitive, simple, rapid, and precise. A sensitivity of 2.63 x 10(5) mV mol-1 NO, a range of 2.0 x 10^-5 up to 1.0 x 10^-2 mol NO (under the conditions used) a reproducibility of 1.0% over the range 1.0 x 10^-3 up to 1.0 x 10^-2 mol NO, a frequency of ~five samples per minute and a detection limit of 1.0 x 10^-5 mol NO are the analytical figures of merit for the proposed method.

"On-line Detection Of Nitric Oxide Generated By The Enzymatic Action Of Nitric Oxide Synthase On L-arginine Using A Flow Injection Manifold And Chemiluminescence Detection"
Anal. Chim. Acta 2000 Volume 410, Issue 1-2 Pages 167-175
Nicholaos P. Evmiridis and Dachun Yao

Abstract: A study of the catalytic activity of nitric oxide synthase (NOS) on the conversion of arginine to NO and citrulline is made. The target of this report is to establish a method for on-line monitoring the reaction process using the chemiluminescence (CL) generated from NO in the luminol-H2O2 system. The NOS-catalytic activity is found to decrease with time on stream in a flow enzymatic reactor but the activity is recovered by proper treatment with restoring solution. For on-line detection of NO formed in-situ, using how injection with CL detection, the response is found more sensitive if a pulsed sampling procedure is employed rather than a continuous one; the sample in the former is small and is injected periodically between regeneration cycles. The optimal pH, temperature and flow rate were determined. The calibration graph under optimal conditions is linear for arginine concentration; the relative standard deviation is <1% and the effect of interferents present in biological fluids is found to be much different to those for the native enzyme in solution. The immobilized NOS-reactor was long lived.
Nitric oxide l-arginine Biological fluid Chemiluminescence Immobilized enzyme Optimization Process monitoring

"Determination Of Glucose And Fructose In Mixtures By A Kinetic Method With Chemiluminescence Detection"
Anal. Chim. Acta 1999 Volume 398, Issue 2-3 Pages 191-203
Nicholaos P. Evmiridis, Nicholaos K. Thanasoulias and Athanasios G. Vlessidis

Abstract: A kinetic method of analysis is described, based on oxidation by periodate for the determination of glucose and fructose in sample solutions. The method combines flow injection and chemiluminescence (CL) detection. The detection is based on the CL signal generated during oxidation of pyrogallol by periodate. The method is selective for the determination of vic-diols and polyols; the method is designed to determine hexose contents as low as 200 µg. However, the method can be tailored for even lower amounts (10 times less). When the total hexose concentration is known, the individual fructose and glucose content can be determined from the rate constant that best-fits the kinetic data; the relative standard deviation of three independent kinetic experiments with the same ratio of concentrations was found to be within 2% and the standard error of the rate constant from the fitting treatment was found to be less than 10% in all samples of different concentration ratios between glucose and fructose. The method can be automated and controlled by computer software. Data points from two kinetic experiments with different sample quantities in the reaction mixture are required for the determination of the total hexose content and the individual fractions of glucose and fructose.
Glucose

"Spectrophotometric Method For Rate Determination Of The Ion-exchange Process In Solid - Liquid Heterogeneous Systems"
Analyst 1990 Volume 115, Issue 6 Pages 771-777
Nicholaos P. Evmiridis and Athanasios G. Vlessidis

Abstract: A flow manifold is described that allows the combination of spectrophotometric detection with flow injection analysis for the monitoring of metal ions in the mobile phase of ion-exchange systems. The manifold involves crossing the tube containing the metal ion stream with the tube containing the reagent stream for subsequent detection. The wall of the former PVC tube is thinned to about half its thickness and a minute hole punctured in it. The hole is closed unless a back-pressure is applied to the sample stream by means of a clip. The method is rapid, simple, accurate and reasonably sensitive, and the reproducibility was reasonable, but could be improved. The flow manifold system could be used as a detector for HPLC.
Ion exchange Spectrophotometry Sensitivity Detector Pneumatic

"Flow Apparatus For Monitoring Dissolution Rate Curves Using Ion-exchange Resins. 1. Phosphite Dissolution Rate Curve"
Analyst 1990 Volume 115, Issue 6 Pages 765-769
N. P. Evmiridis and E. D. Economou

Abstract: The system comprised a carrier stream of water or aqueous acidic solution, flowing through a cell containing a glass pH micro-electrode, and a syringe containing Dowex HGR-W2 ion-exchange resin, for exchange of metal ions for H+ for subsequent injection into the carrier stream. Two injections were made per sample, one before and one after ion exchange. The calibration graph was rectilinear for pH 1 to 5. The method was reasonably accurate, reproducible, rapid and simple. The method can be applied to determine a wide range of metal ion concentration. and can be made selective for one ion in the presence of others by pre-complexation. The method is applicable to study dissolution rate curves, and was applied to the dissolution of CaCO3 in H3PO4 as an example.
Calcium carbonate Inorganic compound Resin Dissolution rate pH Calibration Selectivity Complexation Dowex

"Prospects Of Using Chemiluminescence Emission Generated During Oxidation Of Pyrogallol With Periodate For The Determination Of Pyrogallol With Flow Injection"
Analyst 1988 Volume 113, Issue 7 Pages 1051-1056
Nicholas P. Evmiridis

Abstract: The chemiluminescence generated by the oxidation of pyrogallol(I) with IO4- in a flow injection system was investigated with respect to sensitivity and selectivity. Under optimum conditions, i.e., flow rate 1 mL min-1, pH 8 and IO4- concentration. of 0.01M, response was rectilinear up to 1 mM I with a detection limit of 10 µM and a coefficient of variation of 3% (n = 7). Most of the cations and anions studied interfered. In the presence of a sensitizing species, e.g., hydroxylamine, the sensitivity of the calibration graph was improved considerably and the detection limit was 10 µM. However, the rectilinear calibration range was decreased.
Pyrogallol Chemiluminescence Interferences Optimization Selectivity Sensitivity

"Effect Of Hydroxylamine On Chemiluminescence Intensity Generated During The Oxidation Of Pyrogallol With Periodate"
Analyst 1987 Volume 112, Issue 6 Pages 825-829
Nicholaos P. Evmiridis

Abstract: The chemiluminescence generated by the reaction of pyrogallol with 10 mM IO4- at pH 8 is enhanced 4- to 5-fold by the addition of 0.1 mM hydroxylamine(I). I forms a complex with pyrogallol or its oxidation product which acts as a sensitizer. The possible analytical applications, e.g., for determination of IO4- and organic compounds, of this enhanced chemiluminescence emission by using a flow injection technique are considered.
Organic compounds Periodate Chemiluminescence Sensitivity

"Chemiluminescence Detection Of Superoxide Anion Release And Superoxide Dismutase Activity: Modulation Effect Of Pulsatilla Chinensis"
Anal. Bioanal. Chem. 2004 Volume 379, Issue 1 Pages 171-177
Dachun Yao, Athanasios G. Vlessidis, Yulan Gou, Xinrong Zhou, Yikai Zhou and Nicholaos P. Evmiridis

Abstract: A novel flow-injection chemiluminescence-based method has been developed for determination of superoxide dismutase (SOD) activity. An in-vitro superoxide anion generation xanthine/xanthine oxidase stable source was established on line with FIA/CL-detection apparatus, for measuring SOD activity. This method can detect SOD in the linear range of 0.002-2.00 U mL-1 with a detection limit of 0.001 U mL-1. Another method for detection of superoxide anion is based on the luminol-FeCl3 chemiluminescence (CL) reaction. This method was used to evaluate superoxide release and SOD activity in rats treated with the traditional Chinese herb Pulsatilla chinensis, which resulted in high clearance of hepatitis B virus (HBV) after treatment of a hepatitis B patient. Interestingly, we found that treatment with Pulsatilla chinensis can specifically increase superoxide release by liver tissues and, at the same time, slightly increase extracellular SOD (ECSOD) activity in plasma; in particular it can markedly increase MnSOD activity in mitochondria in liver tissue. This work revealed a possible mechanism whereby Pulsatilla chinensis prevents possible infection (for example HBV) by specifically increasing superoxide release in the liver and increasing MnSOD activity to minimize superoxide-mediated toxicity.