Second Derivative Spectrophotometry Research Articles

Synthesis of meso-tetra-(3,5-dibromo-4-hydroxylphenyl)-porphyrin and its application to second-derivative spectrophotometric determination of lead in clinical samples.

A new very sensitive and selective chromogenic reagent, meso-tetra-(3,5-dibromo-4-hydroxylphenyl)porphyrin [T(DBHP)P], was synthesized and studied for the determination of trace lead in detail. In 0.10 mol l-1 NaOH medium, lead reacts with T(DBHP)P to form a 1:2 yellow complex, which gives a maximum absorption at 479 nm; 0-0.48 microgram ml-1 Pb(II) obeyed Beer's law. The molar absorptivity of the complex and Sandell's sensitivity are 2.5 x 10(5) 1 mol-1 cm-1 and 0.000812 microgram cm-2, respectively. Second-derivative spectrophotometry is better than conventional spectrophotometry in sensitivity and selectivity, and its limit of quantification, limit of detection and relative standard deviation are 0.70 ng ml-1, 0.21 ng ml-1 and 1.0%, respectively. Ca (3250-fold), Mg (2000-fold), Sr (1000-fold), Ba (750-fold), Al (1000-fold), Bi (500-fold), Fe (2000-fold), Co (750-fold), Ni (1000-fold), Cu (750-fold), Zn (1250-fold), Cd (2500-fold) and Ag (550-fold) do not interfere with the determination of lead. The chromogenic system is remarkably superior to other reagents, especially porphyrin compounds. The influence caused by oxygen in air or in solution can be easily eliminated by adding Na2SO3. The reaction is very stable, the stability constant of the complex being 1.2 x 10(45). The chromogenic reaction is completed within 1 min at room temperature when 8-hydroxylquinoline is used as catalyst. The proposed method has been applied to the direct determination of trace lead in clinical samples. The accuracy and precision are both very satisfactory.

Quantitation of amphotericin B in plasma by second-derivative spectrophotometry

A method is described for determining amphotericin B in plasma using second-derivative spectrophotometry after deproteinization. The assay was based on the absorbance at 407.5 nm. The second-derivative spectrum recorded between 350 and 450 nm allowed identification of the analyte and showed absence of drug interference. Only bilirubin interfered at high concentration (≥50 μmol l −1). The linear concentration ranges were 0.05–5.0 mg l −1 ( r=0.999, slope=2.731, intercept=0.008). Between-day CV≤9.7%, withinday CV≤5.5%, analytical recovery close to 100% were suitable for clinical investigations. This method provides better specificity than direct absorbance, is simpler and faster than a high performance liquid chromatography assay and can be used routinely by any laboratory possessing a spectrophotometer with a derivative accessory.

Determination of diazepam and otilonium bromide in pharmaceuticals by ratio-spectra derivative spectrophotometry

Binary mixtures of diazepam and otilonium bromide are analyzed by ratio-spectra first- and second-derivative spectrophotometry. The procedures are accurate, non-destructive and do not require any separation step. Calibration graphs are linear with zero-intercept up to 50 μg/ml, r ranging from 0.9996 to 0.9999. Working wavelengths in the first- and second-derivative mode, respectively, are: diazepam 247 nm and 231 nm, otilonium bromide 262 nm and 226 nm. Limits of detection (LOD) are 0.30 and 0.12 μg/ml for diazepam and 0.063 and 0.30 μg/ml for otilonium bromide. The methods were successfully applied for determining the two drugs in laboratory mixtures and in pharmaceutical products.

Selective determination of neodymium and erbium in mixtures with other lanthanides by second-derivative spectrophotometry of complexes with benzoyl-indan-1,3-dione and cetylpyridinium chloride

The absorption spectra of 4f electron transitions of the neodymium and erbium complexes with benzoyl-indan-1,3-dione and cetylpyridinium chloride have been studied by conventional and derivative spectrophotometry. The second-derivative spectrum has been used to eliminate the interference of the other lanthanides, and to increase the sensitivity by a further factor of 4–6. Beer's Law is obeyed for 6–29 μg/ml Nd and 7–33 μg/ml Er. The relative standard deviations evaluated from 10 independent determinations of 5.0 μg/ml Nd and Er were 1.1% (Nd) and 1.6% (Er). The detection limits obtained from the sensitivity of the calibration graphs and 3sb, (standard deviation of the blank,n = 11) were 0.63 μg/ml Nd and 0.61 μg/ml Er. The quantification limits (10sb) were 2.1 μg/ml Nd and 2.0 μg/ml Er. A method for the direct determination of neodymium and erbium in rare earth mixtures with good accuracy and selectivity is proposed.

Simultaneous determination of aluminium and iron in glasses,phosphate rocks and cement using first- and second-derivative spectrophotometry.

First- and second-derivative spectrophoto-metric methods for the simultaneous determination of aluminium and iron in their mixtures are described. The methods are based on the colored complexes formed by aluminium and iron with hematoxylin in the presence of cetyltrimethylammonium bromide as a surfactant. The zero-crossing method has been utilized to measure the first- and second-derivative value of the derivative spectrum. Aluminium (0.05-1 microg ml(-1)) could be determined in the presence of iron (0.09-1.6 microg ml(-1)) and vice versa. The detection limits of aluminium and iron are 0.01 and 0.09 microg ml(-1), respectively in the first-derivative mode and 0.014 and 0.1 microg ml(-1) in the second-derivative mode. The proposed method has been applied to the simultaneous determination of aluminium and iron in glasses, phosphate rocks, cement and magnesite alloy.

Selective determination of holmium in rare earth mixtures by second-derivative spectrophotometry with benzoylindan-1,3-dione and cetylpyridinium chloride

The absorption spectra of 4f electron transitions of the holmium complex with benzoylindan-1,3-dione and cetylpyridinium chloride were studied by conventional and derivative spectrophotometry. The molar absorptivity of the complex at the maximum absorption band was about 22 times greater (at 450 nm) than that in the absence of the complexing agent. The use of second-derivative spectra both eliminates the interference from other rare earths and improves the sensitivity for holmium. The calibration graph showed that the complex obeys Beer's law up to 25 µg cm–3 of holmium. The corresponding value of Sandell's sensitivity is 0.36 µg cm–2. The RSD evaluated from 11 independent determinations of 10 µg of holmium is 0.96%. The detection limit, obtained from the sensitivity of the calibration graph and for 3sb(sb= standard deviation of a blank without holmium, n= 11), was found to be 0.43 mg dm–3 of holmium. The quantification limit, obtained for 10sb, was 1.43 µg cm–3 of holmium. A method for the direct determination of holmium in rare earth mixtures with good selectivity and accuracy is described.

Simultaneous determination of cefepime and l-arginine in injections by second-derivative spectrophotometry

A simple spectrophotometric assay for the determination of cefepime and l-arginine in injections is described. Since zero-order spectra showed considerable overlap, second-derivative spectrophotometry was used to enhance the spectral details. A linear relationship between second-derivative amplitude and concentration of each compound was found. Beer's law was obeyed up to 50 and 22 μg ml −1 of cefepime and arginine, respectively, in the second-derivative mode. Detection limits were 0.31 and 0.58 μg ml −1 for cefepime and arginine, respectively. The method, which is rapid, simple and does not require any separation step, has been successfully applied to the assay of commercial injections containing cefepime and arginine.

Column preconcentration of cobalt with the ion pair of 2-nitroso-1-naphthol-4-sulfonic acid–tetradecyldimethylbenzylammonium chloride supported on naphthalene using second-derivative spectrophotometry

Cobalt is quantitatively retained on 2-nitroso-1-naphthol-4-sulfonic acid–tetradecyldimethylbenzylammonium (TDBA+)–naphthalene adsorbent in a chromatographic column in the pH range 6.1–9.0 at a flow rate of 1 ml min–1 from a large volume of aqueous solutions of various alloys. The solid mass consisting of the cobalt complex and naphthalene was dissolved out of the column with 5 ml of dimethylformamide (DMF) and the metal was determined by second-derivative spectrophotometry in the concentration range 1.0–60.0 µg per 5 ml of the final DMF solution. Seven replicate determinations of 20 µg of cobalt gave a mean peak height of 0.128 with a relative standard deviation of 1.4%. The sensitivity of the method is 0.019 µg ml–1, found from the slope of the calibration graph. The interference of a large number of anions and cations was studied and the optimized conditions have been utilized for the trace determination of cobalt in standard reference materials. The method may also be applied to the trace determination of cobalt in various biological and environmental samples.

Spectrophotometric and Simultaneous Derivative Spectrophotometric Determination of Gold(III) and Silver(I) with Rhodanine Derivative in Micellar Medium

Abstract The determination methods of the gold(III) and silver(I) with, 5-(4-hydroxy-3-methoxybenzylidene) rhodanine (3,4-MHBR) in the presence of benzyldimethyltetradecylammonium chloride (zephiramine), and 5(3,4-dihydroxybenzylidene) rhodanine (3,4-DHBR) in the presence of cetyltrimethylammonium bromide (CTAB) have been described. The application of first- and second-derivative spectrophotometry to simultaneous determination of gold(III) and silver(I) in their mixtures have been assayed using “zero-crossing” technique of measurement. In the pH ranges 8.8—9.8 and 9.0—10.2 the ternary 1 : 3 : 3 and 1 : 2 : 2 complexes gold(III)-3,4-MHBR-zephiramine and silver(I)-3,4-MHBR-zephiramine have been formed with molar absorptivities of 4.98 × 104 and 4.64 × 104 dm3 mol−1 cm−1 at 529 and 522 nm, respectively. The ternary 1 : 3 : 4 and 1 : 2 : 3 complexes gold(III)-3,4-DHBR-CTAB and silver(I)-3,4-DHBR-CTAB have been formed in the pH ranges 9.4—10.2 and 9.0—10.5 with molar absorptivities of 8.63 × 104 and 7.76 × 104 dm3 mol−1 cm−1 at 560 and 555 nm, respectively. The first- and second-derivative spectra of these complexes allow the determination of one metal in the presence an excess of the other. Gold(III) (0.21—3.6 μg cm−3) and silver(I) (0.12—2.63 μg cm−3) in different ratios have been determined simultaneously with good precision and accuracy using the proposed methods. The statistical analysis of the experimental results are presented. The methods have been applied to simultaneous determination of gold and silver in silicate rocks.

Application of UV absorbance and second-derivative spectrophotometry for analysing casein hydrolysates

UV absorbance and second-derivative spectrophotometry were used to analyse some tryptic and pancreatic casein hydrolysates. The decrease in absorptivities detected at the initial stage of protein hydrolysis indicated some similarities with the denaturation process, probably owing to the rupture of hydrophobic bonds. This technique was used to determine the degree of hydrolysis and the homogeneity of such preparations and was shown to be useful as a complementary method in characterizing casein hydrolysates. tryptophan addition, used to compensate for the losses during the fabrication of protein hydrolysates, could also be detected by this technique.

First- and second-derivative spectrophotometric determination of imipenem and cilastatin in injections.

First- and second-derivative spectrophotometry has been used for the quantitation of mixtures of imipenem and cilastatin sodium, compounds that have closely overlapping spectral bands. Beer's law was obeyed at concentrations up to 100 micrograms ml-1 of imipenem in both the first- and second-derivative modes and up to 75 micrograms ml-1 of cilastatin in the first-derivative mode. Detection limits at the P = 0.05 level of significance were calculated to be 0.40 and 0.52 micrograms ml-1 of imipenem and cilastatin sodium, respectively, in the first-derivative mode, and in a range from 0.45 to 0.68 micrograms ml-1 for imipenem in the second-derivative mode. The method, which is rapid, simple and does not require a separation step, has been successfully applied to the assay of commercial injections.

Tyrosine residues in unirradiated and gamma-irradiated dihydroorotate dehydrogenase: fluorimetric and second-derivative absorption spectrophotometric studies.

The effect of gamma-radiation on tyrosine residues of dihydroorotate dehydrogenase under different conditions was investigated by means of fluorescence spectroscopy and second-derivative spectrophotometry. No change in the fluorescence spectral distribution was observed when unirradiated and irradiated enzyme were denatured in guanidine hydrochloride. However, decreases in fluorescence intensity in irradiated samples indicates a radiation-induced modification of tyrosine residues. The fluorescence intensity at 340 nm decreased exponentially with radiation dose in aerated medium but non-exponentially under argon and nitrous oxide-saturated conditions. The percentage loss of tyrosine fluorescence under different conditions was determined. The number of tyrosine residues left intact following irradiation at a dose for 50% inactivation under different conditions was measured by second-derivative absorption spectrophotometry. The results obtained from both these methods show that the hydroxyl radical is less efficient in inducing radiation damage of tyrosine in aerated conditions compared with that under deoxygenated conditions. This lower efficiency of the hydroxyl radical in aerated medium has been attributed to the protective effect of oxygen and/or the superoxide radical anion.

Application of experimental design to the development of a multicomponent derivative spectrophotometric method: simultaneous determination of sulfamethoxazole and trimethoprim

A central composite design is used for the development of a spectrophotometric method for the simultaneous determination of sulfamethoxazole and trimethoprim. The method involves multicomponent second-derivative spectrophotometry in the ultraviolet range with a photodiode-array spectrophotometer. Accuracy, precision, linearity and other figures of merit are verified in connection with the application of the proposed method to pharmaceutical quality control. The influence of such variables as wavelength range, derivative order and solvent are discussed.

Second-Derivative Spectrophotometric Determination of the Binding Constant between Chlorpromazine and β-Cyclodextrin in Aqueous Solutions

Second-derivative spectrophotometry was applied to determine the binding constant (K) between chlorpromazine (CPZ) and β-cyclodextrin (CD) in aqueous solutions. An iterative calculation method which included a calculation of the free-ligand concentration was examined; two kinds of data were used in the calculation. One was the derivative intensity difference of CPZ at 03BBmax of CPZ between, before and after the addition of CD; the other was an increase in the derivative intensity induced by the CD addition at the zero-crossing point of the second-derivative spectrum of CPZ. Although both data gave similar lvalues, the latter data were highly scattered. The reason was considered to be that the small uncertainty in the wavelength reproducibility of the spectrophotometer would severely affect the derivative intensities at the zero-crossing point. The derivative intensity changes of CPZ induced by binding to CD were well reproduced by a calculation using the obtained K value. The results are useful for applications of derivative spectrophotometry to determine the binding constants between drugs and large molecules.

Simultaneous determination of uranium and thorium by second-derivative spectrophotometry

A second-derivative spectrophotometric method has been developed for the simultaneous determination of uranium and thorium using 4-(2′-thiazolylazo) resacetophenone oxime as the spectrophotometric reagent. The method allows the determination of uranium and thorium in the range 0–10.0 ppm. The relative error is less than 4%. Common anions and cations do not interfere in the determination even when present in large amounts. However, for transition metal ions, viz., Cu, Ni, Pd and Pt, the tolerance limit is less than 100 ppm.

On the hepatotoxicity of 1,1,2,2-tetrachloroethane

Intoxication of male and female mice with a single dose (300 or 600 mg/kg) of 1,1,2,2-tetrachloroethane (TTCE) resulted in significant decreases in cytochrome P-450 (to 58–73% of the control) and NADPH-cytochrome ( P-450) c-reductase (to 29–35% of the control) in hepatic microsomes. This was accompanied by an alteration of mixed function monooxygenases stemming from the marked reduction (to 20–64% of the control) of several oxidative activities to selected substrates towards different P-450 isozymes (classes IA1, IA2, IIB1, IIE1 and IIIA). As phase II markers, epoxide hydrolase (≈35% loss), UDP-glucuronosyl transferase (≈42% loss) and to a lesser extent glutathione S-transferase (≈17% loss) were all affected. Also, the activity of δ-aminolevulinic (ALA) synthetase was decreased (≈57% of the control). On the contrary, heme oxygenase activity was increased (up to 35%) at the maximal dose tested. The decrease of P-450-function may be explained in terms of an alteration in the rate of heme biosynthesis and degradation, provoking a loss of heme content (≈33%) as well as of the direct inactivation of both P-450 and reductase. Because of increasing evidence on the involvement of free radical intermediates in the case of toxicity of haloalkanes, electron spin resonance spectroscopy (ESR) spin-trapping in vivo techniques were used to characterize the possible free radical species involved in the observed liver damage. The results obtained with the spin-trap N-benzylidene-2-methylpropylamine N-oxide (phenyl t-butylnitrone, PBN) provide evidence for the formation and trapping of the CHCl 2CHCl free radicals. The detection of conjugated diene signals by means of second-derivative spectrophotometry, have enabled us to show that in vivo lipid peroxidation may be one of the main mechanisms responsible for TTCE hepatotoxicity.

Determination of dissociation constants of sparingly soluble phenothiazine derivatives by second-derivative spectrophotometry

The dissociation constants (p K a) for sparingly soluble phenothiazines (promazine, chlorpromazine, trifluoropromazine) in water were measured by second-derivative spectrophotometry. The intense background signals in the absorption spectra due to the turbidity caused by the precipitation of insoluble free base of the phenothiazine derivatives were eliminated in the second-derivative spectra, and the solubilities of the phenothiazine derivatives could be easily determined from the peak-to-trough lengths ( D values) of the second-derivative signals. The p K a values were calculated from the pH dependence of the D values. The p K a values obtained agreed well with reported values and the standard deviations for 6–10 determinations were ⩽ 0.02. The solubilities of the free bases of the phenothiazines were also determined.

Spectrophotometric studies on complexation reactions of some water-soluble 5-nitro-2-pyridylhydrazones with cobalt. Spectrophotometric and derivative spectrophotometric determination of trace cobalt with 2-benzimidazolyl-3-sulphophenylmethanone 5-nitro-2-pyridylhydrazone

The complexation reactions of four water-soluble hydrazones, 2-quinolyl-3-sulphophenylmethanone 5-nitro-2-pyridylhydrazone, 3-sulphophenyl-2-thiazolylmethanone 5-nitro-2-pyridylhydrazone (STNPH), 2-benzothiazolyl-3-sulphophenylmethanone 5-nitro-2-pyridylhydrazone and 2-benzimidazolyl-3-sulphophenylmethanone 5-nitro-2-pyridylhydrazone (BISNPH), with cobalt(II) were studied spectrophotometrically. These hydrazones react with cobalt(II) to form stable 1:2 (metal:ligand) complexes, except for STNPH, which forms a 1:1 complex, with high molar absorptivities. A sensitive and selective spectrophotometric method for the determination of cobalt with BISNPH has been developed. The cobalt(II)-BISNPH complex is formed quantitatively in the pH range 2.7–9.4 and oxidized rapidly to give the corresponding cobalt(III) complex with an absorption maximum at 517 nm. Beer's law is obeyed over the range 0.02–1.0 μg ml −1 and the apparent molar absorptivity of the cobalt(III) complex is 6.65 × 10 4 l mol −1 cm −1 at 517 nm. The method was applied to the determination of cobalt in iron and steel samples with satisfactory results. The sensitivity is increased 11-fold by use of second-derivative spectrophotometry.

Simultaneous determination of uranium and thorium with Arsenazo III by second-derivative spectrophotometry

A derivative spectrophotometric method has been developed for the simultaneous determination of microgram quantities of uranium and thorium with Arsenazo III in hydrochloric acid medium. The second-derivative absorbances of the uranium and thorium Arsenazo III complexes at 679.5 and 684.4 nm are used for their quantification. Uranium and thorium, both in the range 0.1–0.7 μg/ml have been determined simultaneously with good precision. The procedure does not require separation of uranium and thorium, and allows the determination of both metals in the presence of alkaline-earth metals and zirconium, but lanthanides interfere.

Simultaneous Derivative Spectrophotometric Determination of Aztreonam and L-Arginine in Injections

Mixtures of aztreonam, 2S-[2α, 3β(Z)]-2-[[[1-(2-amino-4-thiazolyl-2-[(2-methyl-4-oxo-1-sulfo-3-azetidinyl) amino]-2-oxo-ethylidine]amino]oxy]-2-methyl-propanoic acid, and L-arginine are assayed by peak-to-baseline, peak-to-peak, and zero-crossing second-derivative spectrophotometry. Aztreonam is the first of a new class of beta-lactam antibiotics (i.e., the mono-bactam antibiotics, highly effective against aerobic gram-negative bacteria). Beer's law is followed for up to 31 μg/mL of aztreonam and L-arginine in the presence of one another. Detection limits at the p = 0.05 level of significance range from 0.11 to 0.37 μg/mL. The method was successfully applied to laboratory mixtures and commercial injections containing these substances.