Simultaneous Determination of Palladium and Platinum by On‐Line Enrichment Followed by Rapid Column High Performance Liquid Chromatography

In this paper, a new method for the simultaneous determination of palladium and platinum ions was developed using a rapid column high performance liquid chromatograph equipped with an on‐line enrichment technique. The palladium and platinum ions were pre‐column derivatized with 5‐(p‐aminobenzylidene)‐thiorhodanine (ABTR) to form colored chelates. The Pd‐ABTR, Pt‐ABTR chelates can be absorbed onto the front of an enrichment column when they were injected into the injector and sent to the enrichment column [ZORBAX Stable Bound, 4.6 × 10 mm, 1.8 μm] with a buffer solution of 0.05 mol/L sodium acetate‐acetic acid buffer solution (pH 3.5) as mobile phase. After the enrichment had finished, by switching the six‐ports switching valve, the retained chelates were back‐flushed by mobile phase and traveled towards the analytical column. These chelates separation on the analytical column [ZORBAX Stable Bound, 4.6 × 50 mm, 1.8 μm] was satisfactory with 65% methanol (containing 0.05 mol/L of pH 3.5 sodium acetate‐acetic acid buffer salt and 0.01 mol/L of tritonX‐100) as mobile phase. The palladium and platinum were separated completely within 2 min. The detection limits (S/N = 3) of palladium and platinum are 1.4 ng/L and 1.6 ng/L, respectively. This method was applied to the determination of palladium and platinum in water and urine samples with good results.     

Study on Determination of Six Transition Metal Ions in Biological Samples by SPE and RP‐HPLC

This paper reports the utilization of solid phase extraction and the reversed‐phase high‐performance liquid chromatography (RP‐HPLC) for the determination of six transition metal ions (iron, cobalt, nickel, copper, zinc and manganese) in biological samples. The samples were digested by microwave digestion. The iron, cobalt, nickel, copper, zinc and manganese ions in the digested samples can react with 2‐(2‐quinolinylazo)‐5‐diethylaminophenol (QADEAP) to form colored chelates in pH 4.0 acetic acid‐sodium acetic buffer solutions and cetyl trimethylammonium bromide (CTMAB) medium. These chelates were enriched by solid phase extraction with C₁₈ cartridge. Then the chelates were separated on a Waters Nova‐Pak‐C₁₈ column (3.9 × 150 mm, 5 μm) by gradient elution with methanol (containing 0.5% of acetic acid and 0.1% of CTMAB) and 0.05 mol/L pH 4.0 acetic acid‐sodium acetic buffer solution (containing 0.1% of CTMAB) as mobile phase at a flow rate of 0.5 mL/min. The detection limits of iron, cobalt, nickel, copper, zinc and manganese are 3 ng/L, 4 ng/L, 2 ng/L, 4 ng/L, 8 ng/L, 10 ng/L, respectively. This method was applied to the determination of iron, cobalt, nickel, copper, zinc and manganese in biological samples with good results.     

Simultaneous Determination of Prazosin,Atorvastatin, Rosuvastatin and Simvastatin in API,Dosage Formulations and Human Serum by RP‐HPLC

Prazosin hydrochloride is the first developed selective antagonist for α₁ — adrenoceptors, which is used as antihypertensive agent. Statins are used in the treatment of various types of hypercholesterolemia. In the present paper a simple, specific an accurate RP‐HPLC method was developed and validated for the simultaneous determination of prazosin, atorvastatin, rosuvastatin and simvastatin in active and in dosage formulations. A nucleosil 100‐10, C‐18, 10μ column having 250 × 4.6 mm i.d. in isocratic mode, with mobile phase containing methanol:water:acetonitrile (70:20:10) adjusted to pH 2.5 ± 0.02 using orthophosphoric acid. The flow rate was 1 mLmin^?1 and effluents were monitored at 240 nm. The % recovery for all the drugs in formulations was found to be 94‐105%. The parameters such as accuracy (%RSD less than 2), precision (%RSD less than 2), linearity (>0.999) were found to be satisfactory. The presented method was applied without any interference of excepients for the determination of tablets. The proposed method due to its low LOQ, excellent accuracy, precision and selectivity could be used for routine quality control.     

Simultaneous Determination of Paracetamol and Orphenadrine Citrate in Dosage Formulations and in Human Serum by RP‐HPLC

Rapid liquid chromatographic procedures are proposed for analysis of paracetamol and orphenadrine citrate in pharmaceutical preparations and human serum using acetonitrile: water (50:50) as a mobile phase, adjusting pH to 2.6, UV detection at 215 nm and propylparaben sodium as internal standard. The advantages of this method include good and rapid separation, well resolved peaks, and only a small amount of sample is required for assay and adequate precision. The method showed good linearity in the range of 6 to 10000 ng/mL for paracetamol serum concentrations with a correlation coefficient 0.9999 (inter and intra day CV < 3.15) and in the range 3–10000 ng/mL for orphenadrine citrate serum concentrations with a correlation coefficient of 0.9999 (inter and intra day CV < 3.58). The recovery of paracetamol and orphenadrine citrate was > 96.9% and > 96.7%, respectively. The proposed method may be used for the quantitative analysis of paracetamol and orphenadrine citrate alone or in combination from raw materials, in bulk drugs, dosage formulations and in serum.     

固相萃取富集高效液相色谱法测定烟草及烟草添加剂中的重金属元素

报道用固相萃取富集,高效液相色谱法测定烟草及烟草添加剂中镍、铜、锡、铅、镉、汞的方法。样品用微波消化,消化液中的镍、铜、锡、铅、镉、汞用四-(对甲氧基苯基)-卟啉(T4MPP)柱前衍生．用C18固相萃取小柱萃取富集镍、铜、锡、铅、镉、汞的T4MPP络合物,然后用甲醇和四氢呋喃为流动相梯度洗脱,Waters Xterra^TMRP18色谱柱分离二极管阵列检测器检测。镍、铜、锡、铅、隔、汞的捡出限在2～4ng／L之间,方法相对标准偏差为1．8％～2．4％,加标回收率为96％～103％。     

Determination of Se(IV) in On‐Line System by Cathodic Stripping Voltammetry

A sensitive and selective on‐line voltammetric procedure for determination of traces of Se(IV) is presented. The pulsed potential accumulation was proposed for minimization of interferences of surface active substances and foreign ions. The calibration plot was linear from 1×10^?9 mol L^?1 to 4×10^?8 mol L^?1 for accumulation time of 180 s. The relative standard deviation was 6.1% (n=5) for a Se(IV) concentration of 1×10^?8 mol L^?1. The detection limit estimated from (3 σ) for an accumulation time of 180 s was about 4×10^?10 mol L^?1. The validation of the procedure proposed was made by a recovery tests for tap and river water samples.     

Simultaneous Quantitation of Captopril and NSAID's in API,Dosage Formulations and Human Serum by RP‐HPLC

An accurate, sensitive and least time consuming reverse phase high performance liquid chromatographic (RP‐HPLC) method for the estimation of captopril in the presence of non steroidal anti‐inflammatory drugs in formulation and human serum has been developed and validated. Chromatographic separation was conducted on prepacked Purospher star C18 (5 μm, 25 × 0.46 cm) column at room temperature using methanol:water (80:20 v/v) as a mobile phase, pH adjusted at 2.8 with o‐phosphoric acid and at a flow rate of 1.0 mL min⁻¹, while UV detection was performed at 227 nm. The limit of detection and quantification for captopril were 1 and 0.35 ng mL⁻¹, while that for (NSAID's) i.e. flurbiprofen, ibuprofen, diclofenac sodium and mefenamic acid LOD were 0.2, 1, 2 and 0.4 ng mL⁻¹ respectively and LOQ were 0.9, 2.9, 8 and 1 ng mL⁻¹ Analytical recovery was > 98.1%. The method used for the quantitative analysis of commonly administered non steroidal anti‐inflammatory drugs (NSAID's) i.e. ibuprofen, flurbiprofen, diclofenac sodium and mefenamic acid alone or in combination with captopril from API (active pharmaceutical ingredients), dosage formulations and in human serum. The established method is rapid (RT < 12 min), accurate (recovery > 98.1%), selective (no interference of excepients and other commonly used drugs and food) and sensitive (LOQ 3.5 ng mL^;‐1) and reproducible (SD ± 0.003).     

逆最小二乘法-导数光谱同时测定锌、镉、汞和铅

本文研究了在碱性介质中,CPB存在下,meso-四(4-三甲铵基苯)卟啉与Zn(Ⅱ)、Cd(Ⅱ)、Hg(Ⅱ)和Pb(Ⅱ)络合物的导数光谱,提出了应用逆最小二乘法(或称CPA-矩阵法)原理对导数光谱进行解释,同时测定四组分的方法。应用本法对合成样品和水进行分析,结果满意。     

Validated Method for the Simultaneous Determination of Gemifloxacin and H2‐receptor Antagonists in Bulk,Pharmaceutical Formulations and Human Serum by RP‐HPLC; In‐vitro Applications

Simple, isocratic and rapid RP‐HPLC method has been developed for the simultaneous analysis of gemifloxacin and H₂‐receptor antagonists i.e. Cimetidine, Famotidine and Ranitidine, in bulk, pharmaceutical formulation and human serum. Separation was achieved on the RP‐Mediterranea column [C18 (250 × 4.6 mm, 5 μ)] at ambient temperature using mobile phase consisting of acetonitrile: methanol: water (20:28:52 v/v/v pH 2.8 adjusted by phosphoric acid). Flow rate was 1.0 mL/min with an average operating pressure of 180 kg/cm². Gatifloxacin (GATI) was used as an internal standard (IS). Quantitation was achieved with UV detection at 221, 256 and 267 nm, respectively. Linear calibration curves, at concentration ranges of 0.05‐37.5 μgmL^‐L with a correlation coefficient of ±0.9994. The detection and quantification limits were in the ranges of 0.023‐0.250 μgmL^‐L and 0.071‐0.756 μgmL^‐L, respectively. Friedman's and Student's t‐test were applied to correlate these results. Method was validated in terms of selectivity, linearity, precision, robustness, recovery, limits of detection and quantitation and is applicable to the routine analysis of GFX and H₂‐receptor antagonists, alone or in combination.     

Simultaneous Determination of Ceftriaxone Sodium and Non Steroidal Anti‐Inflammatory Drugs in Pharmaceutical Formulations and Human Serum by RP‐HPLC

An accurate, sensitive and least time consuming reverse phase high performance liquid chromatographic (RP‐HPLC) method for the estimation of ceftriaxone in the presence of non steroidal anti‐inflammatory drugs in formulation and human serum has been developed and validated. Chromatographic separation was conducted on prepacked Purospher Star, C18 (5 μm, 250 × 4.6 mm) column at room temperature using methanol:water:acetonitrile (80:15:5 v/v/v) as a mobile phase, pH adjusted at 2.8 with ortho‐phosphoric acid and at a flow rate of 1.0 mL/minute, while UV detection was performed at 270 nm. The results obtained showed a good agreement with the declared content. The method shows good linearity in the range of 2.5‐25 μg/mL ceftriaxone serum concentrations with a correlation coefficient 0.999 (inter‐ and intra‐day RSD < 2.0%). The limit of detection and quantification for ceftriaxone and NSAID's in pharmaceutical formulation and serum were in the range 0.51‐1.54 μg/mL. Analytical recovery was >98.1%. The proposed method may be used for the quantitative analysis of commonly administered non steroidal anti‐inflammatory drugs i.e. tiaprofenic acid, naproxen sodium, flurbiprofen, diclofenac acid and mefenamic acid alone or in combination with ceftriaxone from raw materials, dosage formulations and in serum. The established HPLC method is rapid, accurate and selective, because of its sensitivity and reproducibility.     

Trace Enrichment and Atomic Absorption Spectrometric Determination of Lead,Copper, Cadmium and Nickel in Drinking Water Samples by Use of an Activated Carbon Column

Abstract

A simple method for atomic absorption spectrometric determination of lead, copper, cadmium and nickel in drinking water samples after preconcentration by sorbing 1-(2-pyridylazo) 2-naphthol (PAN) complex of these metals on an activated carbon column has been established. The metal/PAN complexes were quantitatively retained on the activated carbon in the pH range 6-8. Metals retained on the activated carbon column were completely eluted with 2M HCl in acetone. This method was applied to the determination of lead, copper, cadmium and nickel in drinking water samples and good results were obtained (Recoveries >95%, relative standard deviations <7%, relative error <3%).     

The Efficiency of a Microcolumn of Rice Bran for On‐line Trace Enrichment in FI‐AAS,a Highly Selective System for On‐line Preconcentration and Determination of Copper

A flow injection flame atomic absorption spectrometry system incorporating a microcolumn of rice bran was designed, and its capability for on‐line trace enrichment of copper, cadmium and lead was studied. Analytes were deposited on the microcolumn by processing a standard or solution of analytes on the column. Injection of 250 μL of nitric acid (1 mol/L) then served to elute the retained species to FAAS. The procedure was successfully applied for determination of copper in tap water, well water and multivitamin tablets. The accuracy was assessed through recovery experiments and independent analysis by furnace‐AAS. A sample volume of 20 mL of copper resulted in a preconcentration factor of 96; precision value at the 20 μg/L was 4.1%.     

Study on the Determination of Cobalt,Nickel, Copper,Zinc and Vanadium in Environmental Samples by a Rapid High‐Performance Liquid Chromatography

A new method for the simultaneous determination of five transition metal ions in water and food by rapid high‐performance liquid chromatography was developed. The cobalt, nickel, copper, zinc and vanadium ions were pre‐column derivatized with 2‐(2‐quinolinylazo)‐4‐methyl‐1,3‐dihydroxidebenzene (QAMDHB) to form colored chelates, then the Co‐QAMDHB, Ni‐QAMDHB, Cu‐QAMDHB, Zn‐QAMDHB and V‐QAMDHB chelates were enriched by solid phase extraction with a C18 cartridge. The enrichment factor of 50 was achieved by eluting the retained chelates from the cartridge with tetrahydrofuran (THF). These chelates were separated on a ZORBAX Stable Bound rapid analysis column (4.6 × 50 mm, 1.8 um) with 68% methanol (containing 0.1% of acetic acid and 0.1% of CTMAB) as mobile phase at a flow rate of 2.0 mL/min and detected with a photodiode array detector from 450?600 nm. The Co‐QAMDHB, Ni‐QAMDHB, Cu‐QAMDHB, Zn‐QAMDHB and V‐QAMDHB chelates were separated completely within 2.0 min. The detection limits of cobalt, nickel, copper, zinc and vanadium are 2 ng/L, 1.5 ng/L, 2 ng/L, 3 ng/L, and 3 ng/L, respectively, in the original samples. This method was applied to the determination of the five transition metal ions in water and food samples with good results.     

Improved RP‐HPLC method for determination of bovine lactoferrin and its proteolytic degradation in simulated gastrointestinal fluids

The objective of this study was to qualitatively and quantitatively evaluate bovine lactoferrin (bLf) and its stability using a rapid RP‐HPLC method. bLf could be rapidly detected within 20 min and quantitated at levels down to 5 µg/mL, and the equation of linearity was y = 86.10x + 178.31 with the correlation coefficient (r²) 0.9997. Quantitative data obtained in the present study proved the improved RP‐HPLC method to be a sensitive and accurate analytical tool for bLf determination. The proteolytic cleavage of bLf in simulated human gastrointestinal fluids was further analyzed by RP‐HPLC, and found to follow pseudo‐first‐order kinetics. The typical equation obtained by pepsin was log₁₀ [A_t]/[A₀] = ?0.03x (r² = 0.85), and log₁₀ [A_t]/[A₀] = ?0.01x (r² = 0.81) for trypsin and chymotrypsin combination. Pepsinolysis of bLf in simulated gastric fluid was relatively fast with the half‐life t_1/2 23.1 min. The digestion of bLf in simulated intestinal fluid was slower with about a 3‐fold increase in half‐life (69.3 min). After the complete proteolysis of bLf, small cleaved peptide fragments were fully separated and identified by RP‐HPLC. The proteolytic study indicated that this validated RP‐HPLC was able to evaluate bLf stability though monitoring the derivatization products. Copyright © 2012 John Wiley & Sons, Ltd.     

RP‐HPLC enantioseparation of β‐adrenolytics using micellar mobile phase without organic solvents

Enantioseparation of a few commonly administered racemic β‐adrenolytics (namely, carvedilol, betaxolol, salbutamol and bisoprolol) has been achieved using a water micellar mobile phase containing surfactants (sodium dodecyl sulphate and Brij‐35) without organic solvents as a new approach in RP‐HPLC. Two chiral derivatizing reagents based on enantiomerically pure (S )‐(−)‐levofloxacin were synthesized using N ‐hydroxysuccinimide and N ‐hydroxybenzotriazole as the activation auxiliaries. Diastereomeric derivatives of the chosen β‐adrenolytics were synthesized under microwave irradiation in a very short reaction time. The (S )‐(−)‐levofloxacin moiety enhanced molar absorbance of the diastereomeric derivatives resulting in very low limit of detection (1.618 and 4.902 ng/mL, respectively, for diastereomeric derivatives of (RS )‐betaxolol and better resolution with lower retention times (for all the analytes), in comparison to literature reports. There was 15–20 times less consumption of mobile phase because of lower retention time.     

Microwave‐assisted extraction with water for fast extraction and simultaneous RP‐HPLC determination of phenolic acids in Radix Salviae Miltiorrhizae

An optimized microwave‐assisted extraction method using water (MAE‐W) as the extractant and an efficient HPLC analysis method were first developed for the fast extraction and simultaneous determination of D (+)‐(3,4‐dihydroxyphenyl) lactic acid (Dla), salvianolic acid B (SaB), and lithospermic acid (La) in Radix Salviae Miltiorrhizae. The key parameters of MAE‐W were optimized. It was found that the degradation of SaB was inhibited when using the optimized MAE‐W and the stable content of Dla, La, and SaB in danshen was obtained. Furthermore, compared to the conventional extraction methods, the proposed MAE‐W is a more rapid method with higher yield and lower solvent consumption with a reproducibility (RSD <6%). In addition, using water as extractant is safe and helpful for environment protection, which could be referred to as green extraction. The separation and quantitative determination of the three compounds was carried out by a developed reverse‐phase high‐performance liquid chromatographic (RP‐HPLC) method with UV detection. Highly efficient separation was obtained using gradient solvent system. The optimized HPLC analysis method was validated to have specificity, linearity, precision, and accuracy. The results indicated that MAE‐W followed by HPLC–UV determination is an appropriate alternative to previously proposed method for quality control of Radix Salviae Miltiorrhizae.     

四-(对甲基苯基)-卟啉柱前衍生固相萃取富集高效液相色谱法测定烟草中痕量铅、镉、汞

研究了用四-(对甲基苯基)-卟啉柱前衍生、固相萃取富集、高效液相色谱法测定烟草中痕量Pb、Cd、Hg的方法。烟草样品用微波消化后，用四-(对甲基苯基)-卟啉(T4MPP)柱前衍生，用Waters Sep-Park-C18固相萃取微柱萃取富集Pb、Cd、Hg的T4MPP络合物，富集倍数为50倍；然后用甲醇(内含0．01mol/L四氢吡咯-醋酸缓冲盐(pH＝10))和四氢呋喃(内含0．01mol/L四氢吡咯-醋酸缓冲盐(pH＝10))梯度洗脱为流动相，Waters Xterra TM RP18(3．9(150)色谱柱为固定相分离，用二极管矩阵检测器检测；Pb、Cd、Hg的含量在1-120ug/L范围内与峰面积呈线性关系，根据信噪比(S/N＝3)，方法检测限为：Pd0.3ug/L,Cd0.5ug/L和Hg0.3ug/L，方法相对标准偏差为2．6％-4.1％，标准回收率为91％-107％，该方法用于测定烟草中的Pb、Cd、Hg，结果令人满意。     

Facile and Simultaneous Stripping Determination of Zinc,Cadmium and Lead on Disposable Multiwalled Carbon Nanotubes Modified Screen‐Printed Electrode

Screen‐printed electrodes (SPEs) are cheap and disposable. But their application for heavy metal detection is limited due to the low sensitivity and poor selectivity. Here we report the ultrasensitive and simultaneous determination of Zn²⁺, Cd²⁺ and Pb²⁺ on a multiwalled carbon nanotubes and Nafion composite modified SPE with in situ plated bismuth film (MWCNTs/NA/Bi/SPE). The linear curves range from 0.5–100 µg L^?1 for Zn²⁺ and 0.5–80 µg L^?1 for Cd²⁺. Uniquely, the linear curve for Pb²⁺ ranges from 0.05–100 µg L^?1 with a detection limit of 0.01 µg L^?1. The practical application was verified in real samples with satisfactory results.     

On‐line two‐dimensional LC: A rapid and efficient method for the determination of enantiomeric excess in reaction mixtures

A novel LC‐based method for the determination of enantiomeric excess (ee) in a sample mixture has been developed by employing on‐line 2D LC. The orthogonal separation system is composed of an NH₂ column as the first dimension to elute the target chiral compound from the crude mixture and a chiral column as the second dimension to determine the ee of the target chiral product. A series of crude mixtures from asymmetric reactions have been directly analyzed without prepurification. Good reproducibility (intra‐ and interday precisions were all under 1.33%) and good accuracy (deviations from ee values determined by 1D HPLC were all <1.03%) have been obtained. Compared with the traditional method for the determination of ee, on‐line 2D HPLC can be used in real time and holds great potential in the time‐saving determination of ee in asymmetric synthesis.     

Simultaneous Determination of Cadmium,Lead, Copper and Mercury Ions Using Organofunctionalized SBA‐15 Nanostructured Silica Modified Graphite–Polyurethane Composite Electrode

A new sensor has been developed for the simultaneous detection of cadmium, lead, copper and mercury, using differential pulse and square wave anodic stripping voltammetry (DPASV and SWASV) at a graphite–polyurethane composite electrode with SBA‐15 silica organofunctionalized with 2‐benzothiazolethiol as bulk modifier. The heavy metal ions were preconcentrated on the surface of the modified electrode at ?1.1 V vs. SCE where they complex with 2‐benzothiazolethiol and are reduced to the metals, and are then reoxidized. Optimum SWASV conditions lead to nanomolar detection limits and simultaneous determination of Cd²⁺, Pb²⁺, Cu²⁺ and Hg²⁺ in natural waters was achieved.