Sequential flow injection determination of iodate and periodate with spectrophotometric detection

A flow injection (FI) system is described for the sequential determination of periodate and iodate based on their reaction with iodide at pH 3.5. Two sample plugs were injected into the same carrier stream sequentially. One injection is for the iodate determination and the other for the sum of iodate and periodate determination. For iodate determination, molybdate solution buffered at pH of 3.5 was used for selective masking of periodate. The influences of reagent concentrations were studied by a univariable method and the influence of FI manifolds was studied using univariable and simplex method. Periodate and iodate can be determined in the range of 0.050-5.0 and 0.050-10 microg/ml, respectively. The 3 sigma limit of detection was 0.030 and 0.050 microg/ml for periodate and iodate, respectively. The proposed method has been applied for the sequential determinations of periodate and iodate in water samples.     

Spectrophotometric study of the reaction mechanism between DDQ as pi-acceptor and potassium iodate and flucloxacillin and dicloxacillin drugs and their determination in pure and in dosage forms

Two simple and accurate spectrophotometric methods are presented for the determination of beta-lactam drugs, flucloxacillin (Fluclox) and dicloxacillin (Diclox), in pure and in different pharmaceutical preparations. The charge transfer (CT) reactions between Fluclox and Diclox as electron donors and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) pi-acceptor and potassium iodate via oxidation reduction reaction where the highly coloured complex species or the liberated iodine have been spectrophotometrically studied. The optimum experimental conditions have been studied carefully. Beer's law is obeyed over the concentration range of 2-450 microg ml(-1) for Fluclox and 10-450 microg ml(-1) for Diclox using DDQ reagent and at 50-550 microg ml(-1) for Fluclox and 50-560 microg ml(-1) for Diclox using iodate method, respectively. For more accurate results, Ringbom optimum concentration range is calculated and found to be 6-450 and 15-450 microg ml(-1) for Fluclox and Diclox using DDQ, respectively, and 65-550 and 63-560 microg ml(-1) for Fluclox and Diclox using iodine, respectively. The Sandell sensitivity is found to be 0.018 and 0.011 microg cm(-2) for DDQ method and 0.013 and 0.011 microg cm(-2) for iodate method for Fluclox and Diclox, respectively, which indicates the high sensitivity of both methods. Standard deviation (S.D.=0.01-0.80 and 0.07-0.98) and relative standard deviation (R.S.D.=0.13-0.44 and 0.11-0.82%) (n=5) for DDQ and iodate methods, respectively, refer to the high accuracy and precision of the proposed methods. These results are also confirmed by between-day precision of percent recovery of 99.87-100.2 and 99.90-100% for Fluclox and Diclox by DDQ method and 99.88-100.1 and 99.30-100.2% for Fluclox and Diclox by iodate method, respectively. These data are comparable to those obtained by British and American pharmacopoeias assay for the determination of Fluclox and Diclox in raw materials and in pharmaceutical preparations.     

Spectrophotometric determination of periodate, iodate and bromate mixtures based on their reaction with iodide.

A rapid, simple, precise and accurate method is proposed for the determination of ternary mixtures of periodate-iodate-bromate based on their reaction with iodide ion at different pH values. The absorbance was measured at 352 nm. Three sets of reaction conditions were developed. In the first set of conditions, only periodate reacted with iodide, but in the second set the periodate and iodate reacted with iodide and in the third set the three ions reacted with iodide during the first 3 min after initiation of the reaction. The method could be used for individual determinations of periodate, iodate and bromate in the concentration range of 0.05-8.0 microg/ml, 0.05-5.0 microg/ml and 0.2-12 microg/ml, respectively. The data were evaluated by simultaneous equations.     

Spectrofluorimetric flow injection determination of trace amounts of periodate

A sensitive, rapid and selective procedure is proposed for the flow injection determinations of periodate by spectrofluorometric detection. The method is based on the reaction of periodate with Alizarin Navy Blue in basic solution. The reagents and manifold variables influence on the sensitivity have been investigated and the optimum conditions are established. Periodate can be determined for the range of 0.250-5.00 microg ml(-1) with a limit of detection of 0.08 microg ml(-1), and with a sample rate of 15 +/- 2 samples h(-1). The relative standard deviations for eight replicate determination of 0.500 and 5.00 microg ml(-1) was 1.3 and 1.1%, respectively. Periodate can be determined in the presence of iodate and bromate. The proposed method was used to determination of periodate in water samples.     

Indirect kinetic spectrophotometric determination of hydroxylamine based on its reaction with iodate.

A simple, precise and accurate method is proposed for rapid determination of trace amounts of hydroxylamine based on the reaction of hydroxylamine with iodate in acidic media. The reaction of neutral red by the produced nitrite ion was used to monitor the reaction spectrophotometrically at 525 nm by a fixed time method. Hydroxylamine in the range of 0.0400-1.200 microg mL(-1) could be determined. The relative standard deviation for 10 determinations of 0.500 microg mL(-1) hydroxylamine was 1.81% and the limit of detection was 0.010 microg mL(-1). The proposed method was applied to the determination of hydroxylamine in water samples with satisfactory results.     

Spectrophotometric determination of iodine species in table salt and pharmaceutical preparations

A sensitive spectrophotometric method for the determination of iodine species like iodide, iodine, iodate and periodate is described. The method involves the oxidation of iodide to ICl(2)(-) in the presence of iodate and chloride in acidic medium. The formed ICl(2)(-) bleaches the dye methyl red. The decrease in the intensity of the colour of the dye is measured at 520 nm. Beer's law is obeyed in the concentration range 0-3.5 microg of iodide in an overall volume of 10 ml. The molar absorptivity of the colour system is 1.73 x 10(5) l mol(-1) cm(-1) with a correlation coefficient of -0.9997. The relative standard deviation is 3.6% (n=10) at 2 microg of iodide. The developed method can be applied to samples containing iodine, iodate and periodate by prereduction to iodide using Zn/H(+) or NH(2)NH(2)/H(+). The effect of interfering ions on the determination is described. The proposed method has been successfully applied for the determination of iodide and iodate in salt samples and iodine in pharmaceutical preparations.     

A simple and sensitive analytical method for the determination of antimony in environmental and biological samples.

The results of a study and application of leucocrystal violet for the determination of antimony in parts per million levels is described here. The proposed method is based on the reaction of antimony(III) with acidified potassium iodate to liberate iodine. The liberated iodine selectively oxidizes leucocrystal violet to crystal violet dye. The formed dye shows maximum absorbance at 590 nm. The color system obeys Beer's law in the concentration range from 0.4 - 3.6 microg antimony per 25 ml of final solution. The molar absorptivity and Sandell's sensitivity were found to be 7.32 x 10(5) l mol(-1) cm(-1) and 0.0016 microg cm(-2), respectively. All variables were studied in order to optimize the reaction. The proposed method is satisfactorily applicable for the analysis of antimony in various environmental and biological samples. The method is simple, highly sensitive, accurate and reliable.     

Kinetic spectrophotometric method for the determination of oxalic acid by its catalytic effect on the oxidation of safranine by dichromate

A new catalytic kinetic spectrophotometric method for the determination of oxalic acid has been described based on its catalytic effect on the redox reaction between safranine and dichromate in dilute sulfuric acid media. The reaction is monitored photometrically by measuring the decrease in absorbance of safranine at the maximum wavelength of 530 nm. Under the optimum conditions, a calibration graph from 0.10 to 10.00 microg ml(-1) of oxalic acid with a detection limit of 0.08 microg ml(-1) was obtained. The relative standard deviation (R.S.D.) for ten replicate measurements of 1.0 and 5.0 microg ml(-1) oxalic acid was 2.7 and 2.5%, respectively. The purposed method is simple, sensitive, selective and inexpensive. The applicability of the proposed method was determined by the determination of oxalic acid in spinach and wastewater samples with satisfactory results.     

Spectrophotometric determination of periodate and iodate by a differential kinetic method

A rapid, simple and sensitive differential kinetic method is presented for the determinations of periodate and iodate ions. The method is based on their reaction with iodide in the presence of methylene blue. The reactions can be monitored spectrophotometrically by measuring the decrease in absorbance at 665 nm. Two sets of conditions were established that in one set of conditions only periodate reacted with iodide but in the other set both the ions reacted with iodide during the first 180 s after initiation of the reaction. The data were evaluated by proportional equations. The method allowed the determination of periodate and iodate at concentrations between 0.1 and 1.0 and 0.1 and 1.3 mug ml(-1), respectively. The method was applied to the determination of periodate and iodate in tap water and spring water with satisfactory results.     

Catalytic-kinetic determination of trace amount of formaldehyde by the spectrophotometric method with a bromate-Janus green system

A new simple and rapid catalytic kinetic method for the determination of trace amount of formaldehyde is described. The method is based on the catalytic effect of formaldehyde on the oxidation of Janus green by bromate in the present of sulfuric acid. The reaction monitored spectrophotometrically by measuring the decrease in absorbance of the reaction mixture at 618 nm. The fixed-time method was used for the first 150 s. For initiation of the reaction, under the optimum conditions, in the concentration range of 0.003-2.5 microg ml(-1) formaldehyde can be determined with a limit of detection 0.0015 microg ml(-1). The relative standard deviation of five replicate measurements is 2.3% for 1.0 microg ml(-1) of formaldehyde. The method was used for the determination of formaldehyde in real samples with satisfactory results.     

Kinetic spectrofluorimetric determination of trace ascorbic acid based on its inhibition on the oxidation of pyronine Y by nitrite

A highly sensitive spectrofluorimetric method is proposed for the determination of trace amount of ascorbic acid using a new indication. The method is based on the inhibition of ascorbic acid on the oxidation of pyronine Y (PRY) by nitrite. The detection limit for ascorbic acid is 0.012 microg ml(-1), the linear range of the determination is 0.02-0.36 microg ml(-1). Analytical parameters, such as reagent concentration, pH, reaction temperature and time, were optimized. The relative standard deviations of eleven replication determinations of 0.12 and 0.24 microg ml(-1) ascorbic acid were 1.4 and 0.72%, respectively. This method has been used to determine ascorbic acid in pharmaceuticals, vegetables, fruits and soft drink with satisfactory results.     

Highly sensitive and selective spectrophotometric and spectrofluorimetric methods for the determination of ropinirole hydrochloride in tablets

Three sensitive, selective, accurate spectrophotometric and spectrofluorimetric methods have been developed for the determination of ropinirole hydrochloride in tablets. The first method was based on measuring the absorbance of drug solution in methanol at 250 nm. The Beer's law was obeyed in the concentration range 2.5-24 microg ml(-1). The second method was based on the charge transfer reaction of drug, as n-electron donor with 7,7,8,8-tetracyanoquinodimethane (TCNQ), as pi-acceptor in acetonitrile to give radical anions that are measured at 842 nm. The Beer's law was obeyed in the concentration range 0.6-8 microg ml(-1). The third method was based on derivatization reaction with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in borate buffer of pH 8.5 followed by measuring the fluorescence intensity at 525 nm with excitation at 464 nm in chloroform. Beer's law was obeyed in the concentration range 0.01-1.3 microg ml(-1). The derivatization reaction product of drug with NBD-Cl was characterized by IR, 1H NMR and mass spectroscopy. The developed methods were validated. The following analytical parameters were investigated: the molar absorptivity (epsilon), limit of detection (LOD, microg ml(-1)) and limit of quantitation (LOQ, microg ml(-1)), precision, accuracy, recovery, and Sandell's sensitivity. Selectivity was validated by subjecting stock solution of ropinirole to acidic, basic, oxidative, and thermal degradation. No interference was observed from common excipients present in formulations. The proposed methods were successfully applied for determination of drug in tablets. The results of these proposed methods were compared with each other statistically.     

Flow injection determination of formaldehyde by its catalytic effect on the oxidation of sulfonazo III by bromate with spectrophotometric detection.

A simple and sensitive flow injection method with spectrophotometric detection was developed for the determination of formaldehyde. The method is based on the catalytic effect of formaldehyde on the oxidation of sulfonazo III with bromate in acidic media. The decrease in absorbance of the reaction mixture was measured at 566 nm. The calibration graph was linear in the range of 0.005 to 2.80 microg ml(-1) formaldehyde at a rate of 38 +/- 4 samples h(-1). The limit of detection was 4 ng ml(-1). The relative standard deviations for ten replicate measurements of 0.20, 0.50 and 1.00 microg ml(-1) formaldehyde were 1.3, 0.8 and 0.7%, respectively. The method was applied to the determination of formaldehyde in river water, shampoo and melamine-formaldehyde resin.     

Kinetic-spectrophotometric determination of palladium in hydrogenation catalyst by its catalytic effect on the oxidation of pyrogallol red by hydrogen peroxide

A new kinetic-spectrophotometric method is described for the determination of ultra trace amounts of Pd(II). The methods based on catalytic action of Pd(II) on the oxidation of pyrogallol red (PGR) with hydrogen peroxide at pH 9.7. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of the PGR at 540 nm, for the first 4.5 min from initiation of the reaction. Calibration curve was linear in the range of 0.02-1.00 microg ml(-1) Pd(II). The limit of detection is 0.017 microg ml(-1) Pd(II). The relative standard deviation (R.S.D.) for ten replicate analyses of 0.03 and 0.60 microg ml(-1) Pd(II) was 1.5 and 0.9%, respectively. The influence of more than 40 potential interfering ions was studied for the selectivity. The proposed method was used for the determination of palladium in catalytic material.     

Simultaneous kinetic spectrophotometric determination of periodate and iodate based on their reaction with pyrogallol red in acidic media by chemometrics methods

The univariate and multivariate calibration methods were applied for the simultaneous determination of iodate and periodate in water. The method is based on the reaction of periodate and iodate with pyrogallol red in sulfuric acid media. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of pyrogallol red at 470 nm. The calibration curve was linear over the concentration ranges of 0.1-12 and 0.1-14 μg ml⁻¹ for iodate and periodate, respectively. The experimental calibration matrix for partial least squares (PLS) and orthogonal signal correction (OSC-PLS) method was designed with 35 mixtures. The results obtained by the PLS and OSC-PLS were statistically compared. The effects of various cations and anions on iodate and periodate determination have been investigated.     

Highly selective spectrophotometric flow-injection determination of trace amounts of bromide by catalytic effect on the oxidation of m-cresolsulfonephthalein by periodate

A new flow-injection method is reported for the determination of bromide. The method is based on catalytic effect of bromide on the oxidation of m-cresolsulfonephthalein by periodate in acidic media. The reaction was followed spectrophotometrically by measuring the decrease in absorbance at 528 nm. The influence of pH, reagent concentration and manifold variables on the sensitivity was studied. Under optimum conditions, a calibration graph was obtained in the range of 0.160-20.00 microg ml(-1) bromides with a limit of detection of 0.150 microg ml(-1) bromide. The relative standard deviation for ten replicate measurement of 1.0 microg ml(-1) bromide was 2.1%. The influence of potential interfering ions on the selectivity was studied. The method successes to measure bromide in the presence of other halide ions. The method was used to measure bromide in river water and tap water.     

Rapid determination of chromium(VI) in electroplating waste water by use of a spectrophotometric flow injection system

A new rapid and sensitive FI method is reported for spectrophotometric determination of trace chromium(VI) in electroplating waste water. The method is based on the reaction of Cr(VI) with sodium diphenylamine sulfonate (DPH) in acidic medium to form a purple complex (lambda(max) = 550 nm). Under the optimized conditions, the calibration curve is linear in the range 0.04-3.8 microg ml(-1) at a sampling rate of 30 h(-1). The detection limit of the method is 0.0217 microg ml(-1), and the relative standard deviation is 1.1% for eight determinations of 2 microg ml(-1) Cr(VI). The proposed method was applied to the determination of chromium in electroplating waste water with satisfactory results.     

Flow injection chemiluminescence analysis of some penicillins by their sensitizing effect on the potassium permanganate-glyoxal reaction.

A new chemiluminescence method using flow injection is described for the determination of four penicillins, namely: phenoxymethylpenicillin potassium, amoxicillin, ampicillin, and ampicillin sodium. The method is based on sensitizing effect of these drugs on the chemiluminescence reaction of potassium permanganate in sulfuric acid with glyoxal. The different experimental parameters affecting the chemiluminescence intensity were carefully studied and incorporated into the procedure. The method allows the determination of 0.1-1.0 microg/ml phenoxymethylpenicillin potassium, 0.1-1.0 microg/ml amoxicillin, 0.1-1.0 microg/ml ampicillin, and 0.1-1.0 microg/ml ampicillin sodium. The method was successfully applied to the determination of four penicillin antibiotics in pharmaceutical preparations.     

Determination of trace amounts of thiocyanate by a new kinetic procedure based on an induction period

A new, simple and sensitive kinetic spectrophotometric method with no need for removing of interfering substances is proposed for the determination of thiocyanate ion in biological and water samples. The procedure is based on the inhibiting effect of thiocyanate on the sodium periodate-potassium bromide-meta cresol purple (MCP) system in acidic media. The induction period of the reaction is proportional to the SCN- concentration. The decolorization of meta cresol purple by the reaction products was used to monitor the reaction spectrophotometrically at 525 nm. Under optimum conditions, thiocyanate can be determined in the range of 0.02-0.8 microg ml(-1) with a 3sigma detection limit of 5 ng ml(-1). The relative standard deviations for 10 replicate determinations of 0.060, 0.10 and 0.50 microg ml(-1) thiocyanate are 3.7, 2.4 and 1.0%, respectively. This method has been successfully used to the determination of thiocyanate content in smokers and non-smokers saliva and spiked water sample.     

Determination of iodate and sulphate in iodized common salt by ion chromatography with conductivity detection

A simple, rapid and accurate method for the determination of iodate in iodized common salts has been developed. The quantitative determination of iodate was accomplished by anion exchange chromatography with conductimetric detection. The method requires a sample pretreatment for the removal of large excess of chloride from the sample matrix. Onguard silver cartridges were found most suitable for this purpose. The sulphate content in the salt was simultaneously determined. The lower limits for the determination of iodate and sulphate in solution are 0.5 and 0.05 mug ml(-1), respectively. Quantitative recovery of the anions in synthetic samples has been obtained and the interferences from different cations and anions have been studied. The method has been successfully applied to the determination of iodate and sulphate in the commercially available salts. The concentrations of iodate measured by this method are in good agreement with those claimed by the manufacturer.