Quantitative Determination Of Trace Amounts Research Articles

Quantitative determination of trace amounts of Diethylhexyl phthalate content in Dextrose injection proficiently by a simplistic Gas Chromatography Technique

The objective of present study was to analyze Diethylhexyl phthalate content in 5% Dextrose injection and other reconstituting diluents for pharmaceutical injectable formulations. Reconstituting diluents for pharmaceutical injectable formulations are mainly stored and supplied in polyvinyl chloride bags. This may lead to leaching of Diethylhexyl phthalate, a toxic content from polyvinyl chloride bags into reconstituting formulations. In the current study, a proficient and simple method by using a Gas Chromatograph was developed and validated for the quantitation of trace amounts of Diethylhexyl phthalate in 5% Dextrose injection. The method was optimized by using silica fused short capillary column (DB-1; USP G2 phase) with dimensions 5 m length x 0.53 mm inner diameter and 2.65µm film thickness. The method involves a simple extraction procedure for sample preparation by means of extraction with n-Hexane solvent and evaporation with a stream of nitrogen gas. An Internal standard (1-Phenydodecane) was added to standard and sample preparations by using n-Hexane as diluent. The method was validated as per the current regulatory guidance for analytical method validation.The projected methodology was found to be selective, accurate, precise, and linear in the test concentration range from 0.004 µg/mL to 5.065µg/mL for Diethylhexyl phthalate. The method was effectively used to analyze the Diethylhexyl phthalate content in 5% Dextrose Injection and other reconstituting diluents for pharmaceutical injectable formulations.

Single optical sensor to multiple functions: Ratiometric sensing for SO32− and dual signal determination for copper (II)

Polymer dots possess superior emissive features, but most of them give rise to luminescence bands in the blue region. In addition, blue or green emissions have difficulty in penetrating tissue deeply. Therefore, long wavelength emissive signals are welcome for the development and application of polymeric dots towards sensing and bio-analysis. Herein, the color-tunable fluorescence polymer nanoparticles (F-PNPs) have been synthesized via one-step strategy based on the employment of hydroquinone and polyethyleneimine as precursors at low temperature. Moreover, its emission peak can be shifted from 523 nm to 612 nm by varying the excitation wavelength in the range of 380 nm to 480 nm. In view of sensing assessment, F-PNPs enable the quantitative determination of trace amount of SO32− and Cu2+. In the presence of SO32−, the polymer dots exhibit ratiometric fluorescence signals in deionized water and the color change from green to blue has been clearly observed by naked eyes (detection limit = 59 nM). In addition, two emission bands at 545 nm (green) and 601 nm (red) are observed to be responsive to the exposure of Cu2+. The entire dual sensing system for the detection of Cu2+ will be more accurate and reliable. The evaluation results reveal their optical signals are improved linearly due to the addition of Cu2+ at increasing concentrations and the detection limits are calculated to be 76 nM (green) and 41 nM (red), respectively. Such polymeric network will provide a new dynamic platform for sensing purposes in biomedicine study, environmental protection, and food safety.

Precise Evaluation of the Effects of a Small Amount of D-histidine in L-histidine Crystal Form B Using High-Frequency-Accurate Terahertz Spectroscopy

The effects of small amounts of enantiomeric impurities on the vibrational modes of polycrystalline L-histidine (His) were examined using high-frequency-accurate terahertz (THz) spectroscopy. Samples of polycrystalline L-His in its monoclinic form (form B) were grown from an ethanol-rich solvent. D-histidine, ranging from 0.05 to 10.0% in content, was added to the L-His/ethanol-rich solution prior to recrystallization. The crystal forms of all recrystallized samples were first confirmed by high-frequency-accurate THz spectra recorded at 70 K and room-temperature powder X-ray diffraction spectra. A detailed analysis of two spectral features (1.54 and 1.80 THz) measured at 10 K showed that the absorption lines had a narrow linewidth, as well as broad spectral components that could be fitted by Gaussian curves corresponding to defects within the crystals. The shifts in peak frequency with varying amounts of D-His additive in the polycrystalline L-His samples were examined in detail. It was observed that the peak frequency shifted to lower frequencies when small amounts of D-histidine were present and then to higher frequencies when relatively large amounts were present. At low concentrations, D-His molecules are thought to act as impurities that disturb the normal mode vibrations of L-His crystals; however, above certain concentrations, D-His contributes to the formation of a DL racemic crystal. Although the effects of small amounts of D-His molecules in L-His crystals were detectable, quantitative determination of trace amounts of impurity was limited by the complex crystallography of L-His, which includes defects and racemic compounds.

Highly selective adsorption of cadmium ions by water‐dispersible magnetic thioglycolic acid/graphene oxide composites

A new selective and fast procedure based on magnetic dispersive solid‐phase extraction and zeta potential analysis is proposed for the determination of Cd (II) in some food samples. In the developed method, novel magnetic nanoparticles modified with thioglycolic acid were synthesized/characterized and also applied for quantitative determination of trace amounts of Cd (II) in food samples. The prepared nanoparticles were characterized via infrared spectroscopy, electron microscopy and adsorption–desorption experiments. These magnetic nanocomposites carrying Cd (II) could be easily separated from real samples simply by applying an external magnetic field; no filtration or centrifugation was necessary. Several parameters affecting the analytical performance, such as sample pH, amounts of nanocomposite sample, desorption solution volumes and coexisting ions, were investigated in detail. The detection limit of the method was 0.1 μg l−1 while the relative standard deviation was 1.2% for a Cd (II) concentration of 0.5 mg l−1. The proposed method was successfully applied to food sample analysis and standard reference material samples with satisfactory results, and excellent recoveries were obtained in the range 95–99% even when the matrix, such as sea water, was complex.

Electrochemical method for quantitative determination of trace amounts of disperse dye in wastewater

The electrochemical behaviour of Disperse Red 13 dye at a glassy carbon electrode was investigated in both organic and aqueous organic mixtures. Best results were obtained in N,N-dimethylformamide/Britton–Robinson buffer (1:1, v/v), which displays a well-defined peak at -0.40 V (vs Ag/AgCl) owing to reduction of the protonated nitro group. This method can be successfully applied to the electroanalytical determination of Disperse Red 13 in a very simple and inexpensive way. All the differential pulse voltammetry parameters were optimised by using a glassy carbon electrode modified with poly(glutamic acid) films. The targeted analytical method presented a linear response from Disperse Red 13 concentrations between 2.5 × 10−7 and 3 × 10−6 mol l−1 (r = 0.997), with a detection limit of 1.5 × 10−8 mol l−1 and recoveries of 89.7–95.10% in water samples. Disperse Red 13 was successfully determined in textile industry wastewater by means of the proposed method after pre-extraction in a solid-phase extraction cartridge.

Indirect Spectrophotometric Determination of Oxymetazoline Hydrochloride

A simple and sensitive spectrophotometric method for the quantitative determination of trace amounts of oxymetazoline hydrochloride (OMZ) was developed .The method based on the reaction of (OMZ) with Fe(III) in acidic medium.The librated Fe(II) coupled with potassium ferricyanide, the reaction needs heating for 25 minutes at 50 o C, to form Prussian blue which is more stable by adding 1ml of 1% ethylendiaminetetraacetic acid. The maximum absorption of the product was measured at 766 nm .Beer's law is obeyed in the concentration range 5-125 µg/10ml with a molar absorptivity of 5.07x104 l. mol-1.cm-1,with a relative error of +1.74 to +2.34 % and a relative standard deviation (RSD%) of the of ±1.272 to ±1.982 %.The method was applied successfully for the assay of OMZ in pharmaceutical preparation.

Highly sensitive and selective spectrofluorimetric approach for the rapid determination of trace benzo[α]pyrene in drinking water and in solutions leached from disposable paper cups

Based on the excellent band narrowing and background suppressing features of second-derivative constant-energy synchronous spectrofluorimetry with a Δ⁻υ value of 1400 cm(-1) , the strong fluorescence intensity for benzo[α]pyrene (BaP) obtained in dichloromethane and the use of standard addition method, a highly sensitive and selective approach for the quantitative determination of trace amount of BaP in drinking water has been established in this study. The detection and quantification limits were 0.11 and 0.37 ng L(-1) , respectively, and the recoveries obtained from spiked Milli-Q water, bottled natural spring water, tank-purified water and tap water at different concentrations, ranged from 86.0 to 104.0%. This method has been applied for the determination of trace BaP in solution leached from disposable paper cups. The experimental results indicated that BaP was leached from paper cups when filled with hot water, but it was not detected when cool (unheated) water was used.

Electrochemical Method for Quantitative Determination of Trace Amounts of Lead

An ultrasensitive chronoamperometric method for quantitative determination of trace amounts of lead (down to 20 ppb) in acidic solutions is proposed in this paper. The method is based on observations that a complete underpotentially deposited (UPD) lead layer inhibits the electroreduction of nitrate on a bare Cu(111) electrode. To asses the limits of the method, both the electroreduction of nitrate and UPD of lead monolayer on copper single (111) and polycrystalline electrodes in perchloric acidic solution are studied by means of cyclic voltammetry, chronoamperometry, and rotating disk electrode (RDE) experiments. It is found that an inexpensive polycrystalline copper electrode is sensitive enough for analytical detection of lead traces in electrolytes down to 1 x 10(-8) M. Analytical results obtained by the proposed method in 2 orders of magnitude concentration range are compared to atomic absorption spectroscopy measurements to evaluate and assess the sensitivity of the employed experimental protocol. The excellent match between both analytical approaches validates the applicability of the proposed method.

Fluorescence Spectrometric Determination of Aluminum(III) Ion in Water Using 4-Chloro-2-phenyliminomethylphenol

Al(III) ion is usually found in spring water and ground water naturally. It is often found in tap water due to coagulation reagents, such as aluminum sulfate or poly aluminum chloride, used for the water cleaning process. It is also found in teas and kitchen vessels. The toxicity of Al(III) ion in human body has been a topic of interest over the past decades. It can damage various tissue cells in the central nervous system, and it has been suggested that accumulated aluminum in brain tissues is a cause of Alzheimer's disease. Therefore, considerable attention has been paid to the development of the quantitative determination of trace amount of Al(III) ion in water. Several methods have been established to detect the presence of Al(III) ion in water. It has been revealed that the absorption spectroscopic method has relatively low detection sensitivity. However, the fluorescence spectrometric method has been used for the quantitative determination of many organic and inorganic compounds due to its unique high sensitivity. Various organic compounds, such as salicylidene-o-aminophenol, N-salicylidene-2-amino-3-hydroxyflurene, N,N'-oxalylbis(salicylaldehydehydrazone), 2,6-bis[(o-hydroxy)phenyliminomethyl]-1-hydroxybenzene, and other Schiff base ligands, have been identified as useful fluorescent reagents for the quantitative determination of Al(III) in water. In this work, we synthesized a new bidentate Schiff base ligand, 4-chloro-2-phenyliminomethylphenol (Cl-PMP), as shown in Figure 1. Interestingly, Cl-PMP has been found to be useful for the quantitative determination of small amount of Al(III) ion dissolved in tap water, spring water or mineral water.

An electrochemical immunosensor based on agarose hydrogel films for rapid determination of ractopamine

A novel label-free electrochemical immunosensor for rapid determination of ractopamine was constructed by incorporating ractopamine–bovine thyroglobulin antigen in agarose hydrogel films modified on a glassy carbon electrode. Cyclic voltammetry and differential pulse voltammetry were employed to investigate the electrochemical character of the immunosensor during different modified stages using a redox probe system of K 3Fe(CN) 6/K 4Fe(CN) 6. In the presence of polyclonal antibody against ractopamine, K 3[Fe(CN) 6] electron transfer is inhibited, presumably due to that antibody in solution could adsorb on the electrode surface modified antigen. A competitive immunoreaction system was applied to determinate the free ractopamine in phosphate buffer solution. The selected polyclonal antibody showed very high sensitivity and specificity for ractopamine, and was used for the detection and quantitative determination of trace amounts of ractopamine in spiked animal feeds.

Three-phase solvent bar microextraction and determination of trace amounts of clenbuterol in human urine by liquid chromatography and electrospray tandem mass spectrometry

Three-phase solvent bar microextraction (TPSBME) technique is described for the quantitative determination of trace amounts of clenbuterol (CB) in urine samples using liquid chromatography (LC) and electrospray tandem mass spectrometry (ES-TMS). CB was extracted from a basified urine sample (donor phase) into the organic solvent residing in the pores of a freely moving hollow fiber and then back extracted into an acidic solution (acceptor phase) inside the lumen of the hollow fiber. The ends of the fiber were pressure-sealed. Here, forward and back extraction took place spontaneously. We studied various parameters affecting the extraction efficiency viz. type of organic solvent (octanol, nonanol and dihexyl ether) used for immobilization in the pores of the hollow fiber, i.e. extraction time (10–40 min), stirring speed (0–1000 rpm), effect of sodium chloride (0–25%, w/v) and concentration of the donor (0.25–3 M NaOH) and the acceptor (0.5–5 M formic acid) phases. After extraction, CB was analyzed by injecting the analyte enriched acceptor phase into LC combined with ES-TMS. Enrichment factor (79), repeatability (R.S.D. = 5.1%), correlation coefficient (0.9972, for the range of 0.1–4 ng mL −1), detection limit (7 pg mL −1) were also investigated. The present technique is compared with the reported solid phase microextraction techniques in terms of selectivity, analysis time per extraction, cost of analysis per extraction, and precision. Among all microextraction techniques reported, this technique is the most economical sample preparation/preconcentration technique to our knowledge. The method was applied for the analysis of CB in human urine.

Influence of sample pre-treatment on the determination of trace silver and cadmium in geological and environmental samples by quadrupole inductively coupled plasma mass spectrometry

The suitability of three different digestion procedures has been evaluated with regard to the quantitative determination of trace amounts of silver and cadmium in geological and environmental samples. Procedure A: extraction with aqua regia in an open vessel system; Procedure B: extraction with aqua regia in a closed pressurized vessel system; Procedure C: digestion with HF + HNO3 in a closed pressurized vessel system. It was found that procedure A represented an effective way of extracting analytes from different types of geological samples while the effect of extracting interfering metals is low. Because it is interference-free, poses a low risk of contamination and is time-saving, sample treatment procedure A was preferred. For this digestion procedure, a series of Chinese geological reference materials was determined by ICP-MS, the results of which were found to be in reasonable agreement with the certified values.

APPLICATION OF CHEMICAL CHAOS TO ANALYTICAL CHEMISTRY

A simple theoretical consideration of the possibility of using deterministic chaos for a quantitative determination of trace amounts of chemical compounds is analyzed in terms of return maps. This allows the development of a general approach to find a calibration plot for a chemical compound determination, i.e. to find a one-to-one correspondence between a measured value and the concentration of a substance to be determined. As experimental verification of these theoretical results, we present a study of the effect of copper (II) ions on the transient chaotic regime in the BZ reaction catalyzed by ferroin in batch as well as of the effect of vanadium (IV) on the deterministic chaotic regime in the BZ reaction catalyzed by ferroin in a CSTR. These studies show that it is possible to quantify the response of transient chaotic regimes to chemical compounds, i.e. to construct a calibration plot for chemical compound determination using their effect on the chaotic dynamics in the BZ reaction. Moreover, these studies shown that vanadium (IV) affects the chaotic regimes at concentration levels of the order of 10-12g/mL , which gives the best detection limit for the kinetic methods of trace analysis.

Langmuir Aggregation of Fluorescein Isothiocyanate (FITC) on Cetyl Trimethylammonium Bromide (CTAB) and Application to Determination of Anionic Detergent in Sewage

The microphase adsorption - spectral correction (MPASC) technique was described and applied to study the interaction of fluorescein isothiocyanate (FITC) with cetyl trimethylammonium bromide (CTAB). The synergism mechanism of micelle was analyzed and discussed. The aggregation of FITC on CTAB obeys the Langmuir monolayer adsorption. Results showed that the monomer and micellar aggregate is FITC-CTAB 3 and (FITC-CTAB 3 ) 2 9 , respectively at pH 9.62. The adsorption constant of the CTAB-FITC aggregate was determined to be 2.10 x 10 5 . Interestingly, it was observed for the addition of an anionic surfactant to desorb FITC from its CTAB aggregate and this has been applied to the quantitative determination of trace amounts of anionic detergent (AD) in sewage.

Quantitative determination of trace amounts of Al-citrate by anion-exchange FPLC-ETAAS

An anion-exchange fast protein liquid chromatographic-electrothermal atomic absorption spectrometric procedure (FPLC-ETAAS) was developed for determination of trace amounts of negatively charged Al-citrate in the pH range 3.5–8.0. Aqueous-4 mol dm −3 NH 4NO 3 linear gradient elution at a flow rate of 1 cm 3 min −1 was applied for 10 min to separate Al-citrate on a FPLC Mono Q HR 5/5 column. The separated aluminium species were determined ‘off line’ by ETAAS in 0.5 cm 3 fractions. After separation the column was regenerated for 5 min with 4 mol dm −3 NH 4NO 3 and equilibrated with water. All reagents used in the separation procedure were cleaned with a silica based LiChrosorb RP-18 HPLC column to remove traces of aluminium. The main advantage of NH 4NO 3 as eluent lies in its ability to decompose quantitatively in the graphite tube during the ashing step, which enables reproducible analysis of aluminium in the separated fractions. Using the procedure developed reproducible (RSD±2.0%) and quantitative determination of negatively charged Al-citrate at a retention time of 4.5 min was obtained. The LOD was found to be 2.0 ng cm −3 of Al-citrate. The technique was successfully applied for the determination of Al-citrate in human serum. Spiked samples (50–150 ng Al 3+ cm −3) were microultrafiltered through a membrane filter (cut-off 30 000 Da) to separate aluminium bound to transferrin from low molecular weight aluminium complexes. It was found that 15–19% of aluminium in spiked samples from healthy volunteers passed through the membrane. By applying FPLC separation it was proved that all the aluminium in the filtrate corresponded to Al-citrate. The analytical technique developed enabled quantitative and reproducible determination (RSD±3.0%) of Al-citrate in spiked human serum at levels which could be found in patients undergoing long term haemodialysis.

Determination Of Arsenic In Various Environmental And Oil Samples By Differential Pulse Polarography After Adsorption Of Its Morpholine-4-Carbodithioate On To Microcrystalline Naphthalene Or Morpholine-4-Dithio-Carbamate-Ctmab-Naphthalene Adsorbent

ABSTRACT A highly selective, sensitive, rapid and economical differential pulse-polarographic (DPP) method has been developed for the quantitative determination of trace amounts of arsenic in various environmental and crude oil samples. The morpholine-4-carbodithioate of arsenic was quantitatively adsorbed on microcystalline naphthalene in the pH range of 6.0–9.5. The metal complex alongwith naphthalene was shaken with 10 ml of 1 M HCl and arsenic determined with a differential pulse polarograph using HCl-pyridine-NaCl as the supporting electrolyte. Arsenic may also be adsorbed quantitatively under similar conditions on morpholine-4-dithiocarbamate-cetyltrimethylammonium bromide-naphthalene adsorbent packed in a column at a flow rate of 0.5–5.0 ml/min and determined similarly. The detection limit is 0.016 ppm at the minimum instrumental setting (signal to noise ratio=2). Arsenic is being determined in the concentration range of 0.08–9.0 ppm with a correlation factor of 0.9996 and a relative standard deviation of ±0.81% (n=8). Various parameters such as the effect of pH, volume of aqueous phase, and interference of a number of metal ions and anions on the estimation of arsenic have been evaluated to optimise the conditions for the estimation of arsenic in various environmental and crude oil samples.

Determination of Tetramethylsuccinonitrile in Foods by NPD-GC

A method for the quantitative determination of trace amounts of tetramethylsuccinonitrile (TMSN) released into foods from their plastic containers is described. TMSN is a decomposition product of 2, 2′-azobisisobutyronitrile used as a polymerization initiator for monomers in plastic production. TMSN in 50g (or ml) of food is steam-distilled. The distillate, to which nitrobenzene has been added as an internal standard, is shaken with 50, 30 and 30ml of methylene chloride for extraction of TMSN. The combined solvent layers are concentrated to 5-7ml by a rotary evaporator, and to 1ml with a nitrogen gas stream. The concentrate is washed 3 times with 1ml of 6N hydrochloric acid. The solvent layer is dried with 1g of anhydrous sodium sulfate. The final step consists of gas chromatography using a 180cm column of 5% Thermon 1000 and 0.5% phosphoric acid on Chromosorb W and a nitrogen-phosphorus detector. The limit of detection was 1μg/kg or μg/L. Recoveries of TMSN ranged from 94.0 to 104.2% at levels of 10-20μg/kg. The method was applied to 9 kinds of foods packed or bottled in containers made of plastics. No interfering substances were observed on the gas chromatograms.

Determination of cobalt in two glasses by atomic absorption spectrometry after flow injection ion-exchange preconcentration

A flow injection ion-exchange preconcentration scheme, using a minicolumn loaded with Chelex-100 coupled on-line with the atomic detector, is described for the simple and quantitative determination of trace amounts of Co by atomic absorption spectrometry. The detection limit obtained for Co was 20 ng ml–1 with a precision of ±1.5% at the 0.5 µg ml–1 level, by preconcentrating 1 ml of the sample solution. The applicability of the optimized procedure to real problems is demonstrated by determining Co in two commercially available soda-lime–magnesia silica glasses produced in a local factory. The results were satisfactory as indicated by the results of the analysis of the same two samples carried out by inductively coupled plasma atomic emission spectrometry.

Trace analysis of alkylphenol ethoxylates

A method for quantitative determination of trace amounts of alkylphenol ethoxylates (APE) in environmental water is described. Levels of 1 to 3 μg/L can be detected and resolved into their complete oligomer distribution (1EO to 18EO) while maintaining integrity of the oligomer distribution. This is a major improvement over previous methods; for the first time distortion of oligomer distribution due to work‐up conditions of earlier methods has been prevented.Isolation of the APE from water is achieved using a simple and rapid dual‐column procedure. The first column removes interfering ionic materials, the second traps the APE on alkyl‐bonded silica. Assay of the extract employs HPLC with a fluorescence detector.The method was used for analyzing treated waste‐water and river water. A much better picture of the biodegradation behavior of APE in the environment has emerged as a result of keeping APE oligomer distribution intact during sample extraction. There is no accumulation of alkylphenol and the low EO oligomers during wastewater treatment, although the oligomer distribution may become skewed toward these species. Concentrations in the receiving waters examined were very low, in the range of 1–2 μg/L total APE species (OEO to 18EO).

Semiquantitative and Quantitative Determination of Trace Amount of Phosphate Ion in Water Using Polyurethane Foam Thin -Layer Colorimetry

Abstract A simple, sensitive and fast method for the colorimetric determination of phosphate ion in water is described. The method is based on spectrophotometric measurement of the blue molybdoantimony phosphoric acid species sorbed in a polyurethane foam thin-layer for quantitative determination of phosphate ion, or the visual color comparison technique for rapid semiquantitative determination. The detection limit for the quantitative procedure is 5 μg/1 and for semiquantitative procedure 20 μg/1 for sample volumes of 100 ml and 25 ml, respectively.