Design and evaluation of a multi-detection system composed of ultraviolet, evaporative light scattering and inductively coupled plasma mass spectrometry detection for the analysis of pharmaceuticals by liquid chromatography

Reversed-phase liquid chromatography was coupled to a multi-detection system composed of ultraviolet (UV) detection, evaporative laser scattering detection (ELSD) and inductively coupled plasma mass spectrometry (ICP-MS). By applying the principle of post-column solvent compensation, the organic modifier content was kept constant in ELSD and ICP-MS under gradient elution. Chlorine ((35)Cl), bromine ((79)Br and (81)Br) and sulfur ((34)S) were monitored in several pharmaceutical compounds. The limit of quantitation (LOQ) was 80 ng/mL for chlorine (chlorpropamide) and 2 ng/mL for bromine (bromazepam). Calibration graphs were linear from 1.0 microg/mL to 100 microg/mL for chlorpropamide (r(2) 0.990) and from 10 ng/mL to 500 ng/mL for bromazepam (r(2) 0.996). The low LOQ value for bromine allows to quantify bromine in pharmaceutical samples below the 0.05% level of the active pharmaceutical ingredient.     

Determination of bromine in organic compounds by high-performance liquid chromatography

A method is proposed for the determination of bromine in organic compounds (which may also contain chlorine and iodine) by oxygen-flask combustion of the compound followed by pre-column reaction of bromide with acetanilide and 2-iodosobenzoic acid to form 4-bromoacetanilide which is then chromatographed on an ODS column with a mobile phase of methanol: water, 65:35 v/v, detection at 240 nm, and 4-N-acetylaminotoluene as internal standard. The method is rapid and precise (RSD 相似文献   

Determination of non-metallic elements by capacitively coupled helium microwave plasma atomic emission spectrometry with capillary gas chromatography

A capacitively coupled microwave helium plasma with a tubular tantalum electrode was evaluated as an element selective detector for gas chromatography (GC). The end of a 10-m bonded fused capillary column was directly inserted into the tubular electrode without any switching system. A heated copper tube was used to house the part of the GC column that protruded from the oven. The optimisation of operating parameters, line selection, background emission and horizontal and vertical observation position is described. Analytical figures of merit including sensitivity, reproducibility, signal to background ratio, selectivity, dynamic range and limit of detection (LOD), were evaluated for carbon, hydrogen, chlorine and bromine emission. Limits of detection in the low ng range (20 pmol) were obtained for halogenated compounds using carbon emission, whereas LODs in the 0.1 micrograms range (2 nmol) were obtained using chlorine or bromine emission lines.     

Flame-retardant modification of UV-curable resins with monomers containing bromine and phosphorus

UV-curable urethane acrylate resin and oligoester acrylate resin have been effectively flame retarded with vinyl-type flame-retardant monomers containing both bromine and phosphorus atoms. Thermogravimetric analysis indicates that the decomposition temperature of flame-retardant monomer is more closely matched to the decomposition temperature of cured oligoester acrylate resin than to that of cured urethane acrylate resin. The efficiency of each flame-retardant monomer in oligoester acrylate resin is higher than in urethane acrylate resin by a factor of ～ 2.2. The individual and the combined effects of tribromophenyl acrylate and triphenyl phosphate on the oxygen index of UV curable urethane acrylate resin have been studied. The bromine phosphorus synergistic action of the two flame-retardant components is evaluated quantitatively, and a maximum intermolecular bromine phosphorus synergism was observed in a flame-retarded formulation containing a Br/P atom ratio of 2. In the three acrylic monomers containing both bromine and phosphorus atoms, the optimum intramolecular bromine phosphorus synergism was observed at a monomer also containing a Br/P atom ratio of 2.     

Determination of nonmetals using ICP-AES-techniques

The determination of iodine, bromine, sulphur and phosphorus using different modes of sampling in ICP-AES is described. Detection limits in the range of some 10 gL^–1 have been obtained using directly aqueous solutions with pneumatic nebulization. The influence of several anions and metals has been investigated. The addition of methanol and ethanol have improved sensitivities but decreased signal-to-background ratios and detection limits due to extended blank values and increased standard deviations. Using ultrasonic nebulization the sensitivities and the detection limits could be enhanced for these elements in aqueous solutions, but a significant decrease in sensitivity has been observed using additives as methanol or ethanol. By coupling of pneumatic nebulization and gas generation of iodine by addition of oxidizing agents, the detection limits of iodine could be improved to 6 ngL^–1 at the 178.28 nm line. Electrothermal vaporization has sucessfully been applied for microsampling of nonmetals and ICP-AES determination. Using aqueous solutions without any modifier the following absolute detection limits at the S (180.73 nm), P (178.27 nm), I (178.28 nm) and Br (163.34 nm) lines have been obtained: 0.25 ng of S, 0.44 ng of P, 0.36 ng of I and 43 ng of Br.Dedicated to Professor Dr. K. Doerffel on the occasion of his 70th birthday     

Determination of the total amount of organically bound chlorine,bromine and iodine in environmental samples by instrumental neutron activation analysis

The determination of chlorine, bromine and iodine present as non-polar, hydrophobic hydrocarbons in environmental samples is reported. The organohalogen compounds are separated from water into an organic phase by on-site liquid—liquid extraction, and from biological material by procedures based on lipid phase extraction and codistillation. After removal of inorganic halides by washing with water and concentration of the sample by evaporation of the solvent, the resulting extracts are analyzed for their chlorine, bromine and iodine contents by instrumental neutron activation analysis. Strict attention is paid to the possibility of contamination in every step of the procedure. Background values in routine analysis are approximately 100–200 ng of chlorine, <5 ng of bromine and <3 ng of iodine.     

Germanium dioxide as internal standard for simplified trace determination of bromate, bromide, iodate and iodide by on-line coupling ion chromatography-inductively coupled plasma mass spectrometry

The use of elemental mass spectrometry as detection for ion chromatography allows sensitive determination of several bromine and iodine species at a reasonable time scale. Lowest concentrations observable are 66 ng L(-1) for bromate, 45 ng L(-1) for iodate, 74 ng L(-1) for bromide and 151 ng L(-1) for iodide. A major drawback of previous IC-ICP-MS applications is the high consumption of time and thus the running costs. The use of GeO2 as internal standard not only allows improved external calibration, but also semiquantitative determination of bromate, bromide, iodate and iodide without any calibration procedure. Furthermore, GeO2 can be used for all known types of anion exchange columns regardless of their construction principles. It is shown, that the analyte-to-GeO2 ratio of four bromine and iodine species was nearly constant over 4 months and almost independent from the ICP-MS instrumental settings. The quantification by means of the analyte-to-GeO2 ratio for samples taken from a bromate round robin test shows that the values obtained are in excellent agreement with calibration curve and isotope dilution results.     

Immunoaffinity column cleanup with liquid chromatography using post-column bromination for aflatoxins in medicinal herbs and plant extracts

A new and accurate method to quantitate aflatoxins in medicinal herbs is developed. This method consists of extraction of the sample with MeOH-H2O (70:30) followed by clean-up of the extracts with immunoaffinity columns and, finally, high-performance liquid chromatographic determination with fluorescence detection. Aflatoxins B1 and G1 are determined as their bromine derivatives, produced in an online post-column derivatization system. The overall average recoveries for three different medicinal herbs spiked at levels of 1.3 and 2.6 ng/g of total aflatoxins range from 93% to 97%. The detection limit is 0.15 ng/g for both G2 and B2 and 0.20 ng/g for both G1 and B1, based on a signal-to-noise ratio of 3:1 and a precision (within-laboratory relative standard deviation) ranging from 0.8% to 1.4%. The use of immunoaffinity columns provides excellent clean-up of these particular extracts, which are generally difficult to analyze. The method is applied successfully to 96 samples of natural drugs.     

Thermal degradation of flame-retardant compounds derived from castor oil

Castor oil is a non-edible plant oil produced in a large quantity annually. It is a triglyceride of primarily (approximately 90%) ricinoleic acid. The acid residues contain both a hydroxyl group and a double bond which permit ready functionalization. The hydroxyl group may be converted to phosphorus esters of varied structure while the unsaturation readily undergoes addition of bromine. Derivatives of castor oil containing phosphorus, bromine, or phosphorus and bromine have been prepared and fully characterized using spectroscopic and thermal methods. The thermal stability and mode of degradation for these compounds have been assessed using thermogravimetry and infrared spectroscopy. The primary mode of degradation for the phosphorus esters is elimination of the corresponding phosphorus acid (phosphates more readily than phosphonates). Brominated castor oil undergoes thermally induced dehydrobromination at relatively modest temperatures and this promotes dehydration (at temperatures well below that required for dehydration of unmodified castor oil). Brominated phosphorus esters of castor oil undergo degradation initiated by dehydrobromination.

     

On-line speciation of bromine and bromide using sequential injection analysis with spectrophotometric detection

An on-line procedure for the simultaneous determination of bromine and total bromine (bromine+bromide oxidised to bromine) is proposed, which lead to the determination of bromide by subtraction. Phenol red was used as chromogenic reagent for bromine and total bromine after bromide was oxidised to bromine by Chloramine T. The linear range found is 1-10 mg L(-1) with a detection limit of 0.6 mg L(-1) for bromine, and a linear range of 0.8-15 mg L(-1) with a detection limit of 0.4 mg L(-1) for total bromine. The calculated RSD for bromine is less than 0.8% and for total bromine less than 0.7%. The system is fully computerised and able to run 30 samples per hour with an automated rinsing step that eliminates sample carry-over. The results for both bromine and bromide from the proposed sequential injection analysis (SIA) system compare favourably with standard manual methods and statistical evaluation proves no significant difference between the results of the proposed SIA system and the standard method at the 95% confidence level. The presence of other halides was found not to interfere.     

Determination of chlorinated and brominated micropollutants by capillary gas chromatography coupled with on-column radio frequency plasma atomic emission detection

Capillary gas chromatography (GC) combined with on-column radio frequency plasma atomic emission detection was evaluated for the determination of polychlorinated and polybrominated biphenyls (PCBs and PBBs). Quantitation was possible utilizing a single chlorine or bromine calibration curve based on a randomly selected reference compound, because the signal per ng of halogen ranged within 17 % for 29 congeners. Combined with an internal standard to correct for potential plasma quenching from matrix components, this type of universal quantitation represented a sub-stantial simplification of current calibration procedures. In combi-nation with relatively low detection limits (1–5 pg/s of halogen), the present work suggested that GC, coupled with on-column atomic emission detection is a promising technique for the determination of halogenated micropollutants.     

Pesticide residue analysis in foodstuffs applying capillary gas chromatography with atomic emission detection State-of-the-art use of modified multimethod S19 of the Deutsche Forschungsgemeinschaft and automated large-volume injection with programmed-temperature vaporization and solvent venting

Atomic emission detection (AED) provides high element-specific detection of all compounds amenable to gas chromatography (GC). The heteroatoms nitrogen, chlorine, phosphorus, sulfur, bromine and fluorine, which are important elements in pesticide residue analysis, are of major interest. A main drawback of AED is its lower sensitivity with respect to other selective detection methods used in pesticide residue analysis such as electron-capture and nitrogen-phosphorus detection. This holds true especially for the important nitrogen trace. For this reason, more sensitive detection can be achieved by injection of larger volumes or higher concentrations of sample extracts, because matrix compounds were usually registered only in the carbon, hydrogen and oxygen traces. This paper focuses on recent developments from the authors' laboratory in order to demonstrate the feasibility of screening analyses with the identification of pesticide residues down to the 0.01 ppm concentration level in plant foodstuffs. This has been achieved by means of automated large volume injection with programmed-temperature vaporization and solvent venting as well as careful optimization of make-up and reactant gases with AED. Clean up follows the principle of multimethod S19 of the Deutsche Forschungsgemeinschaft in a reduced procedure. After elimination of lipids and waxes by gel permeation chromatography, extracts from 10 g of the food samples were concentrated to 200 μl, of which 12.5 μl were introduced into the GC-AED system. Two analyses were usually performed with the element traces of sulfur, phosphorus, nitrogen and carbon in the first run and chlorine and bromine in the second run. Fluorine and oxygen were not detected in any screening analyses. The method has proved to be of great value especially with “problem foodstuffs”. The limits of detection were determined for 385 pesticides and are presented together with their retention data.     

Determination of midazolam in rabbit plasma by GC and LC following nasal and ocular administration

GC with nitrogen phosphorus detection and HPLC with UV detection were used to determine midazolam (MDZ) levels in rabbit plasma following ocular and nasal administration. For GC with nitrogen phosphorus detection, the analyte was extracted from the plasma using a three‐step liquid–liquid extraction including extraction with an isopropanol/butyl chloride mixture in an alkaline solution, followed by extractions with 1 M HCl, and finally with an alkaline solution of butyl chloride. The recovery of MDZ was dependent on the sample alkalization time prior to the final extraction. The procedure increased the recovery of MDZ up to 99.6%. Improved sample preparation led to a significant increase in the sensitivity of the determination by GC with nitrogen phosphorus detection. The achieved detection limit was 0.34 ng/mL, which is ten times lower than that obtained using HPLC with UV detection. The small plasma volume was another advantage of the GC with nitrogen phosphorus detection method (200 μL per assay). Both administration routes of the anesthetic (nasal and ocular) resulted in comparable plasma MDZ levels. Kinetic simulation of the MDZ plasma was performed for both administration routes.     

Determination of bromine and iodine in biological and environmental materials using epithermal neutron activation analysis

Epithermal neutron activation analysis (ENAA) was applied to the determination of the contents of bromine and iodine in 40 biological and environmental standard reference materials and Chinese diets. Boron nitride (BN) for solid samples and BN+Cd for liquid samples were adopted as shield material. Irradiation was carried out in inner and outer irradiation sites in a Miniature Source Reactor (MNSR) for solid and liquid samples, respectively. The 443 keV photopeak of ¹²⁸I and the 616 keV photopeak of ⁸⁰Br were used. The precision of measurement (relative standard deviation) is 2∼6% for contents of iodine of more than 100 ng/g and 8∼12% in the 20∼100 ng/g range in solid samples, and 12∼18% at less than 100 ng/ml in liquid samples. For bromine, the precision of measurement is 2–8% for solid samples and lower than 13% for liquid samples. The detection limits under experimental conditions varied between 10∼30 ng/g, 55∼95 ng/g and 25∼68 ng/g for iodine and 50∼150 ng/g, 200∼450 ng/g and 100∼300 ng/g for bromine in ENAA with BN shield in inner irradiation sites, with Cd shield and BN+Cd shield in outer irradiation sites, respectively. Received: 13 June 1996 / Revised: 2 September 1996 / Accepted: 19 September 1996     

Direct determination of bromine in plastics by electrothermal vaporization/inductively coupled plasma mass spectrometry using a tungsten boat furnace vaporizer and an exchangeable sample cuvette system

A tungsten boat furnace vaporization inductively coupled plasma mass spectrometry (TBF/ICP‐MS) method has been applied to the direct determination of bromine in plastic samples. In the pretreatment, the plastic sample is spread over a small sample cuvette made of tungsten by treating it with a strongly basic organic solution, e.g., octanol or diisobutyl ketone in the presence of potassium hydroxide. The cuvette is placed on a tungsten boat furnace, with which the electrothermal vaporizer is equipped. At the vaporization step, a widely spread thin layer of the sample facilitates its efficient evaporation and introduction into an ICP mass spectrometer. The most remarkable feature is that all the bromine species in plastic samples are decomposed to form a thermally stable inorganic salt during the pretreatment procedure. Therefore, the bromine content in plastic samples can be measured by a calibration curve method constructed with an aqueous standard solution of potassium bromate(V). The detection limit (3σ) was estimated to be 0.77 pg of bromine, which corresponds to a concentration of 0.31 ng g^?1 of bromine in plastic samples when a sample amount taken of 2.5 mg is studied. The relative standard deviation was calculated to be 2.2%. Analytical results of some plastic samples, which contained both inorganic bromide salts and also organic bromine species, are given. Copyright © 2010 John Wiley & Sons, Ltd.     

Detection of bromine in thermoplasts from consumer electronics by laser-induced plasma spectroscopy

Laser-induced plasma spectroscopy (LIPS) was utilized for the detection of bromine in thermoplasts with flame retardants. For detection of bromine in the VUV region and UV/Vis/NIR region, two different experimental set-ups were realized. A time-resolved study of the plasma emission indicated that the detection of atomic Br lines in the VUV was complicated by the formation of molecular oxygen in the plasma. However, the limit of detection for bromine in the VUV region at 130.99 nm was significantly improved compared to the detection limit determined in the NIR region. With an optical path purged with argon, VUV-LIPS is feasible for process analysis.     

Solvent extraction-spectrophotometric determination of phosphate with molybdate and malachite green in river water and sea-water

Molybdophosphate, formed between orthophosphate and molybdate in sulphuric acid solution, is extracted into a mixture of toluene and 4-methylpentan-2-one (1:3 v v ) with Malachite Green as counter-ion. A single extraction with equal phase volumes gives an apparent molar absorptivity for phosphate of 2.3 x 10(5) l.mole(-1).cm(-1) at 630 nm; the absorbance of the reagent blank is 0.03. With an organic to aqueous phase-volume ratio of 1:10, the molar absorptivity is 2.5 x 10(5) l.mole(-1).cm(-1) and the absorbance of the reagent blank 0.08. By the proposed method, ng ml levels of phosphorus can be determined, and the detection limit is about 0.1 ng ml . The standard deviation and relative standard deviation for the determination of phosphorus in tap water (4.3 ng ml ) are 0.05 ng ml and 1.1%, respectively. The method can also be applied to the determination of phosphorus in river water and sea-water.     

High-resolution continuum source electrothermal absorption spectrometry of AlBr and CaBr for the determination of bromine

Molecular absorption spectra of AlBr and CaBr, produced in a graphite furnace, were investigated using a high-resolution echelle spectrometer equipped with a xenon short-arc lamp as continuum source. The analytical usability of the spectra for the determination of bromine was studied. To this end, the molecular absorptions of AlBr at 278.914 nm and CaBr at 625.315 nm were evaluated. Apart from strong absorption bands of CaF around 625.3 nm, which disturb the use of CaBr, no spectral interferences were observed for both AlBr and CaBr. Regarding chemical interference with matrix substances, the molecular absorption of AlBr and CaBr is influenced in a different way. While the sensitivity of the CaBr absorption is susceptible to chloride, aluminum, potassium and sodium ions, there is no significant effect on the AlBr absorption. In contrast, the inorganic acids (nitric, phosphoric, and sulfuric) have an influence on AlBr, but not on the CaBr molecular absorption. Therefore, the two methods complement each other and each has its own application area. Regarding real samples, a salt sample from the death sea and an organic pharmaceutical were evaluated. The results were in good agreement with those derived from two independent methods and with an existing reference value. Relative standard deviations were found in the range of 5%. The limit of detection for bromine was about 2 ng for both AlBr and CaBr molecular absorption; the dynamic range was linear at least up to 250 ng Br.     

Advantages of hydride generation interface for selenium speciation in waters by high performance liquid chromatography-inductively coupled plasma mass spectrometry coupling

This paper focuses on the analytical performance improvement of the coupled technique HPLC-ICPMS using on-line collision/reaction cell technology for selenium elemental and speciation analyses at the ng (Se) l(-1) level in aquatic environment. Collision/reaction cell operating parameters were optimised, resulting in selected conditions of 5.5 ml min(-1) H(2) and 0.5 ml min(-1) He mixture. The detection limits obtained were around 5 ng (Se) l(-1) for total analysis, and between 7 and 15 ng (Se) l(-1) depending on the species for speciation analysis. The capability of UV irradiation-hydride generation interfacing to increase detector sensitivity was also evaluated for speciation analysis. The detection limits obtained were in the range 2-8 ng (Se) l(-1) depending on the species. Moreover, such interface allowed to prevent bromine introduction to the ICPMS which is particularly convenient for selenium trace analysis in natural waters as (80)Se is preserved free from BrH interferences. The developed method was validated using certified water with low selenium content (TM Rain 95, NWRI, Canada) and applied to the analysis of different waters.     

Determination of Phosphorus by Inductively Coupled Plasma Atomic Emission Spectroscopy after Hydride Generation

Thehydridegenerationtechniquehascontributedmuchtotheimprovementofthesensitivityinatomicabsorption,emissionandfluorescencespectroscopyofAs.Sb.Bi.Se.Te.Ge.SnandPh"=.ManyworkershavesuccessfullyappliedthistechniquetodeterminationofCu.Zn.Cd3'4'5.KazukoMatsumotostudiedphosphinegenerationcoupledwithICPatomicemissionspectrometry,wherephosphateinaqueoussolutionwasfirstprecipitatedbyaddingCaCI,ascalciumphosphate,whichwasthenreducedtoCa,P,byheating(ca,1100'C)togetherwithaluminumpowder'.Thedetecti…