Simultaneous Determination of Ultra Trace of Uranium and Cadmium by Adsorptive Cathodic Stripping Voltammetry Using H‐Point Standard Addition Method

A sensitive adsorptive cathodic stripping voltammetry with H‐point standard addition method for simultaneous determination of uranium and cadmium has been developed. The trace amounts of these metal ions can be simultaneously determined using the Levodpa as complexing agent. Optimal conditions were: accumulation time 50 s, accumulation potential 0.0 mV, scan rate 40 mV s^?1, supporting electrolyte 0.1 M ammonium buffer pH 9.6, and 1×10^?5 M of Levodopa. The results revealed that the cadmium and uranium could be simultaneously determined by H‐point standard addition method with different concentration ratios of uranium to cadmium. The method was successfully applied in a several of real samples.     

Simultaneous Spectrophotometric Determination of Aluminum and Iron in Micellar Media by Using the H‐Point Standard Addition Method

A very simple spectrophotometric method for simultaneous determination of aluminum(III) and iron(III) based on formation of their complexes with pyrocatechol violet (PCV) in micellar media, using the H‐point standard addition method (HPSAM), is described. In micellar media, the metal complexes of Al‐PCV and Fe‐PCV are formed very fast. Formation of both of the complexes was complete within 5 min at pH 8.5. The linear ranges for aluminum and iron were 0.05‐2.50 and 0.10‐4.00 μg mL^?1, respectively. The relative standard deviation (R.S.D.) for the simultaneous determination 0.40 μg mL^?1 of Al(III) and 0.20 μg mL^?1 of Fe(III) were 3.24% and 4.22%, respectively. Interference effects of common anions and cations were studied. The method was applied to simultaneous determination of Al(III) and Fe(III) in standard reference material and alloy samples.     

Simultaneous Kinetic Determination of Phosphate and Silicate by Spectrophotometric H‐Point Standard Addition Method

The H‐point standard addition method (HPSAM), based on spectrophotometric measurements for simultaneous determination of phosphate and silicate, has been established. The method is based on the difference between their reactions rates with molybdenum in the presence of ascorbic acid. The results revealed that phosphate and silicate could be determined simultaneously with the concentration ratios of phosphate to silicate varying from 1:10 to 12:1 in the binary mixtures. The effects of chelating agent nature, time, interferents and experimental variables are also investigated. Under working conditions, the proposed method was successfully applied to the simultaneous determination of phosphate and silicate in synthetic detergents.     

Simultaneous Determination of Copper and Bismuth by Anodic Stripping Voltammetry Using H‐Point Standard Addition Method with Simultaneous Addition of Analytes

Simultaneous determination of bismuth and copper by anodic stripping voltammetry using H‐point standard addition method (HPSAM) with simultaneous addition of analytes is described. The effect of various parameters including acid concentration, accumulation time, accumulation potential and concentration ratio of analytes in the standard solution on the sensitivity and accuracy of method were investigated. The results of applying the H‐point standard addition method showed that Cu²⁺ and Bi³⁺ could be determined simultaneously with the concentration ratios of Cu²⁺ to Bi³⁺ varying from 1 : 15 to 16 : 1 in the mixed sample. The method was successfully applied to the simultaneous determination of copper and bismuth in some synthetic mixtures.     

Simultaneous Kinetic‐Spectrophotometric Determination of Nb(V) and Ta(V) Using H‐Point Standard Addition Method

A simple, rapid, precise and accurate kinetic method for simultaneous spectrophotometric determination of Nb(V) and Ta(V) is described. This method is based on the difference between the rate of the reaction of Nb(V) and Ta(V) with 4‐(2‐pyridylazo)resorcinol (PAR) in the presence of tartaric acid. H‐point standard addition method (HPSAM) was used to resolve the mixtures. The results showed that Nb(V) and Ta(V) can be determined simultaneously in the ranges of 0.10–5.0 and 0.50–12.0 μg mL^?;1, respectively. The proposed method was successfully applied to the simultaneous determination of Nb(V) and Ta(V) in several alloy samples.     

Simultaneous Determination of Tyrosine and Histidine by Differential Pulse Cathodic Stripping Voltammetry Using H‐point Standard Addition Method in Tap and Seawater

H‐point standard addition method (HPSAM) has been applied for simultaneous determination of tyrosine and histidine in trace levels using copper ions by adsorptive cathodic stripping voltammetry. The amino acids‐Cu(II) complexes were accumulated onto the surface of a hanging mercury drop electrode for 40 s. The reduction peaks of preconcentrated complexes were used for simultaneous determination of amino acids in the range 8.0–180 and 30–1100 nM for tyrosine and histidine respectively. The effect of various parameters such as pH, concentration of copper, accumulation time and scan rate on the selectivity were studied. Under the optimized conditions the method was successfully applied for determination of tyrosine and histidine in synthetic and real samples.     

Simultaneous Kinetic‐Potentiometric Determination of Hydrazine and Thiosemicarbazide by Partial Least Squares and Principle Component Regression Methods

Simultaneous determination of hydrazine (HZ) and thiosemicarbazide (TSC) by partial least squares (PLS) and principle component regression (PCR) was carried out based on kinetic data of novel potentiometry. The rate of chloride ion production in reaction of HZ and TSC with N‐chlorosuccinimide (NCS) was monitored by a chloride ion‐selective electrode. The experimental dada shows not only the good ability of ion‐selective electrodes (ISEs) as detectors for the direct determination of chloride ions but also for simultaneous kinetic‐potentiometric analysis using chemometrics methods. The methods are based on the difference observed in the production rate of chloride ions. The results show that simultaneous determination of HZ and TSC can be performed in their concentration ranges of 0.7‐20.0 and 0.5‐20.0 μg mL^?1, respectively. The total relative standard error for applying PLS and PCR methods to 9 synthetic samples in the concentration ranges of 0.8‐10 μg mL^?1 of TSC and 1.0‐12.0 μg mL^?1 of HZ was 4.62 and 4.98, respectively. The effects of certain foreign ions upon the reaction rate were determined for the assessment of the selectivity of the method. Both methods (PLS and PCR) were validated using a set of synthetic sample mixtures and then applied for simultaneous determination of HZ and TSC in water samples.     

Simultaneous Kinetic Spectrophotometric Determination of Ascorbic Acid and L-Cysteine by H-Point Standard Addition Method

The H-point standard addition method (HPSAM) is applied to kinetic data for the simultaneous determination of ascorbic acid (AA) and L-cysteine (Cys). If present in excess amounts, iron(III) is quantitatively reduced to iron(II) by AA or Cys which in turn, in the presence of phenanthroline (phen), produces a colored iron(II)-phen complex showing maximum absorbance at 510nm. HPSAM is based on the difference of the reaction rates between AA and Cys with Fe(III). The linear dynamic ranges for the two analytes AA and Cys are 0.50–4.00ppm and 1.00–8.00ppm, respectively. The RSD% for 6 replications of AA and Cys at 3.00ppm is 2.30 and 2.70, respectively. The predictability of the method is checked by determining the two analytes in real samples. The various effects of several similar reducing agents are investigated.     

H‐Point Standard Addition Method Applied to Voltammetry of Microparticles. Quantitation of Dyes in Pictorial Samples

A solid‐state electrochemical application of the H‐point standard addition method (HPSAM) for quantifying two electroactive compounds, A, B, that produce strongly overlapped voltammetric peaks is described. It is based on peak current measurement in square‐wave voltammograms recorded for solid samples containing a reference compound R, upon additions of a A‐ (or B‐) containing standard compound. The method allows to the determination of the mass fraction of A and B by applying the H‐point standard addition method to solid state voltammetry. The quotients between the currents measured at two selected potentials and the peak current of R vary linearly with the mass ratio of the added standard and the reference compound, thus providing an electrochemical method for determining the content of A and B in the sample avoiding matrix effects. The method is applied to the simultaneous determination of alizarin and purpurin in madder pigments and pictorial specimens using morin as a reference material.     

Mutual Separation and Determination of Th(IV) and U(VI) Using Arsenazo III as a Dye Collector Reagent by Flotation‐Spectrophotometric Method

This paper reports a simple and highly selective method for the separation, preconcentration, and determination of trace amounts of thorium and uranium in some complex samples via staircase flotation. The method is based on the initial flotation of the Th(IV)‐arsenazo III complex in the presence of U(VI) from a solution of 5 mol dm^?3 HCl, then reduction of U(VI) to U(IV) and repetition of the flotation step. In both steps, the floated complex was dissolved in a 5‐mL portion of methanol and its absorbance was measured at 655 nm, spectrophotometrically. For a 30‐mL portion of the sample, Beer's law was obeyed over the concentration ranges of 3.40 × 10^?7to 3.06 × 10^?6 mol dm^?3 for Th(IV) and3.40 × 10^?7 to 3.40 × 10^?6 mol dm^?3 for U(IV) with the apparent molar absorptivity of 4.20 × 10⁵ dm³ mol^?1 cm^?1 and 3.59 × 10⁵ dm³ mol^?1 cm^?1, respectively. The RSDs (n = 7) corresponding to 1.7 × 10^?6 mol dm^?3 of Th(IV) and U(IV) were obtained as 1.7% and 1.87%. The detection limits (7 blanks) for both the metal ions were found to be 1.7 × 10^?7 mol dm^?3. The important benefit of the method is that the determinations are free from the interference of almost all cations and anions found in the complex matrixes, such as seawater samples. The proposed method was also applied to reference materials, and the determinations were shown to have good agreement with the certified values.     

偏最小二乘法及主组分回归法用于药物组分的测定

本文研究了多元校准方法——偏最小二乘法(PLS)和主组份回归法(PCR)在药物多组份光度分析中的应用,获得了较满意的结果。而且在系列校准样品的实验设计、交叉证实法确定最佳因子数以及空缺组份体系的分析等方面进行了探讨。     

Simultaneous Kinetic‐Spectrophotometric Determination of Hydrazine and its Derivatives by Partial Least Squares and Principle Component Regression Methods

Simultaneous kinetic‐spectrophotometric determination of a ternary mixture of hydrazine (HZ) and its derivatives by principal component regression (PCR) and partial least squares (PLS) calibration is described. The methods were based on the difference observed in the reduction rate of iron(III) with HZ, thiosemicarbazide (TSCZ) and phenylhydrazine (PHZ) in the presence of 2,2′‐bipyridine (Bpy). The colored complex of [Fe(Bpy)₃]²⁺ was formed in sodium dodecyl sulfate (SDS) as micellar media, and then monitored at 520 nm. The results showed that simultaneous determination of HZ, TSCZ and PHZ could be performed in their concentration ranges of 1.0–70.0, 0.2–6.0 and 0.1–10.0 μg mL^?1, respectively. The root mean squares errors of prediction (RMSEP) of HZ, TSCZ and PHZ were 0.719, 0.164 and 0.105 (for PLS) 0.788, 0.166 and 0.993 (for PCR), respectively. Both methods (PCR and PLS) were validated using a set of synthetic sample mixtures and then applied for simultaneous determination of HZ, TSCZ and PHZ in water samples.     

Comparison of Partial Least Squares Regression and H-Point Standard Addition Method for Simultaneous Spectrophotometric Determination of Zinc, Cobalt and Nickel by 1-(2-Pyridylazo)2-Naphthol in Micellar Media

Simultaneous spectrophotometric methods are described for the determination of Zn²⁺, Co²⁺ and Ni²⁺ by 1-(2-pyridylazo)2-naphthol (PAN) in micellar media, using absorbance correction-H-point standard addition method (HPSAM) and partial least squares (PLS) regression. The ligand and its metal complexes, i.e. Zn²⁺-PAN, Co²⁺-PAN and Ni²⁺-PAN, were made water-soluble by the neutral surfactant Triton X-100, and therefore extraction with organic solvents was no longer required. Formation of all of these complexes was complete within 10min at pH 9.2. The linear range was 0.1–1.5mgL^–1 for Zn²⁺, 0.1–2.0mgL^–1 for Co²⁺ and 0.1–2.0mgL^–1 for Ni²⁺. The relative standard deviation (RSD) for the simultaneous determination of 0.50mgL^–1 each of Zn²⁺, Ni²⁺ and Co²⁺ by applying the H-point standard addition method was 2.55%, 2.04% and 3.70%, respectively. The total relative standard error for applying the PLS method to 9 synthetic samples in the linear ranges of these metals was 1.8%. Interference effects of common anions and cations were studied, and both methods were applied to the simultaneous determination of Zn²⁺, Co²⁺ and Ni²⁺ in alloy samples.     

Flotation‐Spectrophotometric Determination of Trace Amounts of Thorium

A simple, sensitive and reproducible flotation‐spectrophotometric method for the determination of thorium is reported. The method is based on the ion‐associate formation between thorium, xylenol orange (XO) and cethyltrimethyl ammonium bromide (CTAB) which is floated in the interface of the aqueous phase and n‐hexane by vigorous shaking. By discarding the aqueous solution and n‐hexane, the adsorbed ion‐associate (Th‐XO‐CTAB) on the wall of a separating funnel was dissolved in a small volume of ethanol solvent, and its absorbance was measured at 568 nm. The effects of different parameters such as pH, concentrations of HCl, XO, and CTAB, volume of n‐hexane, and standing and shaking time were studied. The calibration graph was linear in the concentration range of 2–200 ng mL^?1 of thorium(r = 0.9994). The limit of detection (LOD) is 1.4 ng mL^?1. The relative standard deviations (RSD) at 50 and 175 ng mL^?1 of thorium were 2.5% and 1.0% (n = 7), respectively. The method was successfully applied to the determination of thorium in gas mantel samples.     

偏最小二乘分光光度法同时测定扑热息痛等五组分含量

本文将偏最小二乘分光光度法应用于感冒液中扑热息痛、扑尔敏、咖啡因、对氨基酚和愈创木酚甘油醚五组分含量的分析研究，介绍了基本原理和具体的分析步骤。实验结果表明，偏最小二乘分光光度法对样品各组分的平均回收率在96．4％－105．0％之间，样品不经分离即可同时测定，取得了满意的分析结果。     

对乙酰基偶氮胂两波长标准加入法同时测定铁和镍

ｐＨ５．５的ＨＡｃ－ＮａＡｃ绶冲介质中，铁和镍与对乙酰基偶氮胂形成最大吸收波长分别为６２０ｎｍ和６３０ｎｍ的有色配合物，其吸收光谱严重重叠。本文用两波长标准加入法，同时光度测定微量铁和镍。该法灵敏度高、选择性好、操作简便、应用于铝合金中铁、镍的同时测定．结果满意。     

Cloud Point Extraction Simultaneous Spectrophotometric Determination of Zn(II), Co(II) and Ni(II) in Water and Urine Samples by 1-(2-Pyridylazo)2-Naphthol Using Partial Least Squares Regression

A cloud-point extraction (CPE) process using the nonionic surfactant Triton X-114 to simultaneous extraction and spectrophotometric determination of Zn(II), Co(II) and Ni(II) from aqueous solution using partial least squares (PLS) regression is investigated. The method is based on the color reaction of these cations with 1-(2-pyridylazo)2-naphthol and subsequent micelle-mediated extraction of products. The optimum extraction and reaction conditions such as pH, reagents concentration and effect of time have been studied. Linearity was obeyed in the range 2–150, 5–250 and 2–150 ng mL⁻¹ of Zn(II), Co(II) and Ni(II) respectively. The relative standard error (RSE) for the simultaneous determination of 15 test samples of different concentrations of Zn(II), Co(II) and Ni(II) was 4.38%;, 1.18% and 2.42%, respectively. The total relative standard error (RSE_t) for applying the PLS method to 15 synthetic samples in the linear ranges of these metals was 2.36%. The interference effect of some anions and cations was also tested. The method was applied to the simultaneous determination of Zn(II), Co(II) and Ni(II) in water and human urine samples.