Determination of Rhenium in Geological Samples by Isotope Dilution–Multicollector–Inductively Coupled Plasma-Mass Spectrometry with Novel Chromatographic Separation

A method was developed to determine rhenium contents in geological samples using multicollector–inductively coupled plasma-mass spectrometry (MC–ICP-MS) and extraction with an ion-exchange resin. Samples were digested in Carius tubes and osmium was converted into volatile OsO₄, which was purified by distillation and microdistillation. The purified Os contents and isotopic ratios were determined using negative thermal ionization mass spectrometry. After the distillation of Os, the samples were treated with HF, then 1.2?M HCl, and loaded on ion-exchange resin columns. Re was eluted using 0.75?M HNO₃ and directly determined by MC–ICP-MS. This method was validated using a series of reference materials and the analytical Re data are consistent with the literature values. This method precision (relative standard deviation) ranged from 0.8 to 6%. The procedural blank and detection limit (3σ) of Re were 1.1 pg and 0.5 pg/g (for a sample size of 2g), respectively. These results indicate that the proposed method can be applied to determine trace Re in geological samples. Using Carius tube digestion combined with HF desilicification and redissolution, the Re and Os contents found in the soluble and insoluble phases of several reference materials indicated that the distributions of Re and Os were homogeneous and heterogeneous, respectively.     

Trace Determination of Manganese in Urine by Graphite Furnace Atomic Absorption Spectrometry and Inductively Coupled Plasma–Mass Spectrometry

This paper describes a simple and sensitive method for the determination of manganese in human urine by graphite furnace atomic absorption spectroscopy (GFAAS), which includes sample preparation by microwave digestion. Matrix modifier combinations, the digestion power, pyrolysis, and atomization temperatures were optimized. A mixture of 5.0 µg Pd(NO₃)₂ and 3.2 µg Mg(NO₃)₂ modifier presented the best performance. The optimal temperatures for pyrolysis and atomization were 1500°C and 1950°C, respectively. The GFAAS method was compared to inductively coupled plasma–mass spectrometry (ICP–MS) for the determination of manganese in urine. Analytical figures of merit for GFAAS and ICP–MS were: accuracy (3.46%, 2.19%), precision (3.61%, 5.84%), LOD (0.109 µg · L^?1, 0.015 µg · L^?1), LOQ (0.327 µg · L^?1, 0.045 µg · L^?1), and recovery (80–100%, 74–89%). Both methods were employed for the determination of Mn in urine and the results were compared statistically.     

High-Sensitivity and High-Performance Determination of Trace Aluminum in Water for Pharmaceutical Purposes by Microwave Plasma and Inductively Coupled Plasma–Atomic Emission Spectrometry

Procedures for the determination of aluminum in water for injections (Aqua ad iniectabilia) and high-purity water (Aqua valde purificata) at a level of several µg?L^?1 using atomic-emission spectrometry with a novel microwave plasma (MP–AES) and inductively coupled plasma (ICP–AES) are proposed. Regardless of the atomic-emission technique used, the procedure for aluminum needs no sample preparation (acidification only), no preconcentration, shows high sensitivity (limits of detection of 0.4 and 0.7?µg?L^?1 for ICP–AES and MP–AES with a polymeric inert concentric nebulizer, respectively, and 0.03?µg?L^?1 for ICP–AES with an ultrasonic nebulizer), high precision (repeatability, relative standard deviation, <5%), and high throughput (25 samples per hour), and is considerably simpler and more expedient from the viewpoint of the analysis cost and time compared with the standard spectrofluorimetric procedure of the US and the European Pharmacopoeia.     

Rapid Speciation of Lead in Water by High-Performance Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry

The rapid speciation of lead is reported by high performance liquid chromatography and inductively coupled plasma – mass spectrometry. The separation of inorganic lead, trimethyllead, triethyllead and triphenyllead was achieved within 3.5 minutes on a C₁₈ column using a gradient program of methanol and water containing 5 milligrams per liter sodium 1-pentanesulfonate at pH 5. The limits of detection for inorganic lead, trimethyllead, triethyllead, and triphenyllead were 0.01, 0.02, 0.02, and 0.02 micrograms per liter, respectively. The accuracy of the method was verified by the analysis of water (GSBZ 50009-88) and seawater (GBW (E) 080040) certified reference materials. The method was also employed for the analysis of water samples; inorganic lead was measured in river water.     

Determination of Indicator Congeners of Polychlorinated Biphenyls in Water at Ultratrace Levels by Gas Chromatography–Tandem Mass Spectrometry

Journal of Analytical Chemistry - We validated a procedure for the determination of indicator congeners (ICs) of polychlorinated biphenyls (PCBs) (IUPAC nos. 28, 52, 101, 118, 138, 153, and 180) in...     

Determination of Quinoxalines and Their Two Main Metabolites in Environmental Water Samples by Liquid Chromatography–Tandem Mass Spectrometry

A sensitive high performance liquid chromatography–tandem mass spectrometry method was developed for the determination of residues of carbadox, mequindox, olaquindox, quinocetone, cyadox, quinoxaline-2-carboxylic acid, and 3-methylquinoxaline-2-carboxylic acid in environmental water samples. The samples were freeze-dried at ?80°C, re-dissolved in 1.0 mL methanol-water (5:95), then purified with N-propyl ethylenediamine. The separation of the analytes was performed on a column (150 × 2.1 mm i.d., 5.0 µm) using acetonitrile and 0.1% formic acid as mobile phases. The target compounds were confirmed and quantified by tandem mass spectrometry in multiple reaction monitoring mode. The results showed that there were linear relationships between peak area and concentrations of these compounds with correlation coefficients exceeding 0.99. The average recoveries at the spiked levels of 0.25, 0.5, 1.0, and 2.0 µ g L^?1 ranged from 68.7% to 109% with relative standard deviations less than 14% except cyadox. The limits of detection of the analytes were between 2.0 and 6.0 ng L^?1. This method meets the requirements for the determination of drug residues in environmental water samples.     

Determination of Organotin Compounds in Wine by Microwave-Assisted Extraction and High Performance Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry

A new analytical procedure for the determination of five organotin compounds in several matrix wine samples is reported. The organotin compounds were extracted by microwave-assisted extraction with n-hexane. Extraction conditions, such as volume of n-hexane required, extraction temperature, and extraction time, were investigated and optimized by an orthogonal array experimental design. The determination of organotin compounds in the final extracts was carried out by liquid chromatography–inductively coupled plasma mass spectrometry. The procedure showed limits of detection between 0.029–0.049 µg · L^?1. The linearity was in the range of 0.5 to 100 µg · L^?1. The precision expressed as relative standard deviation (RSD) was below 9.43%. The developed method was successfully employed to analyze different matrix wine samples, and some analytes were detected at the level of 0.053 to 1.14 µg · L^?1.     

Simultaneous Determination of Flonicamid and its Metabolites in Tea by Liquid Chromatography–Tandem Mass Spectrometry

An analytical method was established to simultaneously quantify flonicamid and its metabolites 4-trifluoromethylnicotinic acid (TFNA), N-(4-trifluoromethylnicotinoyl) glycine (TFNG), and 4-trifluoromethylnicotinamide (TFNA-AM) in tea using orthogonal experimental design and liquid chromatography–tandem mass spectrometry (LC–MS/MS). Residues were extracted from the samples with acetonitrile containing 1% acetic acid and were purified with graphitized carbon black. The linearity of the method was excellent in the concentration range of 0.01–10?µg/mL, producing correlation coefficients greater than 0.996 for the target compounds. The limits of detection and quantification of all analytes in tea were 0.0013–0.013?mg/kg and 0.004–0.040?mg/kg, respectively. The average recoveries of flonicamid, TFNA, TFNG, and TFNA-AM ranged from 75.14 to 92.72%, with intra- and interday relative standard deviations of 1.07–9.75%. The proposed method was successfully applied to the terminal residue determination of flonicamid and its metabolites in dry tea processed from three field trials’ fresh samples. The determined total terminal residue concentrations of flonicamid 10?days after the last application at all three sites were below the maximum residue limit (MRL) set by the European Union (0.1?mg/kg) and the residues in all samples were lower than the MRL established by the United States Environmental Protection Agency (EPA) (8?mg/kg). This method may be used to meet the requirements for the determination of flonicamid and its metabolites that could provide guidance for establishing a MRL for flonicamid in tea in China.     

Determination of Five Arsenic Species in Porphyra by Microwave-Assisted Water Extraction and High Performance Liquid Chromatography–Atomic Fluorescence Spectrometry

Arsenic (As) speciation in edible seaweed has received a considerable research interest due to its impact on the food safety and human health. In this paper, we developed a simple and cost-effective methodology to extract, separate, and analyze As species in Porphyra samples collected from Jiangsu, Zhejiang, and Shandong provinces of China. Four extraction methods were compared in terms of extraction efficiency and resolution of As species. Microwave-assisted water extraction was chosen due to its short time (5 min) and high efficiency (93% of total As extracted). Total As concentration in the Porphyra samples varied within 14.0–42.1 µg g^?1, determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES) after acid digestion. Five As species were determined by high performance liquid chromatography—ultraviolet photo-oxidation—hydride generation—atomic fluorescence spectrometry (HPLC–(UV)–HG–AFS). DMA was found only in one sample with the concentration of 0.67 µg g^?1. No As(III), As(V), MMA, and AsB were detected. Taken together, the As speciation results suggest that the risk associated with As in Porphyra to human health may be negligible.     

Determination of Essential and Toxic Elements in Tropical Fruit by Microwave-Assisted Digestion and Inductively Coupled Plasma–Mass Spectrometry

The concentrations of eight essential (Co, Cr, Cu, Mn, Ni, Se, V, and Zn) and five toxic elements (Al, As, Cd, Hg, and Pb) were determined in 457 samples of commonly consumed fresh tropical fruit including bananas (Musa acuminata), kiwi (Actinidia deliciosa), mangos (Mangifera indica), and pineapple (Ananas comosus) from supermarkets from Seoul, Busan, Gangneung, Daegu, Daejeon, and Gwangju, South Korea. The samples were digested by microwave-assisted combustion using HNO₃ and H₂O₂ and determined by inductively coupled plasma mass spectrometry. The Hg concentrations were evaluated by furnace-gold amalgamation direct mercury analysis. The techniques were validated by linearity, limits of detection and quantification, precision, recovery, and the analysis of a NIST-1570a spinach leaves certified reference material. The concentrations of essential elements varied considerably among the tropical fruit. Overall, the tropical fruit was higher in Mn (0.027–13.2?µg/g) and Zn (0.514–2.20?µg/g), while lower in Co (0.002–0.005?µg/g) and V (0.001–0.002?µg/g). The concentrations (µg/g) of toxic elements were 0.001 (kiwi) to 0.003 (mango) for As and Cd, 0.0004 (pineapple) to 0.002 (banana) for Hg, and 0.005 (kiwi) to 0.013 (mango) for Pb. The calculated values of estimated dietary intake, target hazard quotients and hazard indices were lower than one and the safety limits established by World Health Organization. The tropical fruits were therefore safe and did not pose any threat to consumers.     

Speciation of Volatile Selenium Species in Plants Using Gas Chromatography/Inductively Coupled Plasma Mass Spectrometry

 Gas chromatography/inductively coupled plasma mass spectrometry (GC/ICP MS) coupled with solid phase micro extraction can provide a simple, extremely selective and sensitive technique for the analysis of volatile sulfur and selenium compounds in the hea     

Ion-Pairing Liquid Chromatography Coupled with Mass Spectrometry for the Simultaneous Determination of Nucleosides and Nucleotides

Adenosine and its corresponding nucleotides adenosine 5'-monophosphate (AMP), adenosine 5'-diphosphate ( ADP ) and adenosine 5'-triphos-phate (ATP) are important biomolecules that provide energy and substrates for various cellular bio-chemical processes. There have been strong     

Ion-Pairing Liquid Chromatography Coupled with Mass Spectrometry for the Simultaneous Determination of Nucleosides and Nucleotides

Adenosineanditscorrespondingnucleotidesadenosine 5′monophosphate (AMP) ,adenosine 5′diphosphate (ADP)andadenosine 5′triphosphate(ATP)areimportantbiomoleculesthatprovideen ergyandsubstratesforvariouscellularbiochemicalprocesses[1] .Therehavebeenstrongde…     

Determination of Phosphorus in Crude Oil and Middle Distillate Petroleum Products by Inductively Coupled Plasma–Optical Emission Spectrometry

A method for the precise and accurate determination of phosphorus in crude oil and middle distillate petroleum products was developed using inductively coupled plasma–optical emission spectrometry to rapidly determine phosphorus as a control method. The presence of phosphorus is undesirable in petrochemical products as it complexes with other metals generating residues that interrupt normal operation of refineries. The presence of phosphorus may be due to some anti-fouling additives or the crude oils processed. Consequently, it is necessary to control the phosphorus present at trace levels in the crude oil and in process streams that present various densities and viscosities. The instrumental power, nebulizer flow, pump rate, read time, and the sample preparation conditions were optimized. The desired level of quantification for the petrochemical industry was achieved allowing the simultaneous analysis of diverse liquid petroleum products.     

Determination of Pesticides in Carrots by Gas Chromatography–Mass Spectrometry

ABSTRACT

A sensitive and selective method was developed to determine pesticides in carrots by gas chromatography–mass spectrometry following the development of an optimized extraction procedure. The method was validated for 30 organochlorine pesticides for gas chromatography with electron capture detection obtaining limit of detection from 0.18 to 0.92?µg/kg except for cis- and trans-permenthrin. Twenty-six carrot samples were analyzed and six pesticides were detected. The results compared with the accepted maximum residue levels in correlation to crop origin.     

Retention Time Locking in the Determination of Narcotic Drugs by Chromatography and Chromatography–Mass Spectrometry

The use of retention time locking (RTL) in the development of unified procedures for the detection and quantitative determination of drugs in biological fluids was considered. With consideration for the use of RTL, a chromatographic procedure with flame-ionization and mass-selective detection was developed for the detection and quantitative determination of opiates and their synthetic analogs; phenylalkylamine derivatives; cocaine; ketamine; and other narcotic drugs, their derivatives, and metabolites in urine. The analytical ranges for chromatography–mass spectrometry were 0.05–1000 and 0.005–1000 g/mL under the conditions of total ion current (TIC) scanning and selected ion monitoring (SIM), respectively. With flame-ionization detection (GC–FID), the analytical range was 0.5–1000 g/mL.     

Preconcentration and Determination of Trace Amounts of Heavy Metals in Water Samples Using Membrane Disk and Flame Atomic Absorption Spectrometry

A fast and simple method for preconcentration of Ni^2＋, Cd^2＋, Pb^2＋, Zn^2＋, Cu^2＋ and Co^2＋ from natural water samples was developed. The metal ions were complexed with sodium diethyldithiocarbamate （Na-DDTC）, then adsorbed onto octadecyl silica membrane disk, recovered and determined by FAAS. Extraction efficiency, influence of sample volume and eluent flow rates, effects of pH, amount of Na-DDTC, nature and amount of eluent for elution of metal ions from membrane disk, break through volume and limit of detection have been evaluated. The effect of foreign ions on the percent recovery of heavy metal ions has also been studied. The limit of detection of the proposed method for Ni^2＋, Cd^2＋, Pb^2＋, Zn^2＋, Cu^2＋ and Co^2＋was found to be 2.03, 0.47, 3.13, 0.44, 1.24 and 2.05 ng·mL^-1, respectively. The proposed （DDTC） method has been successfully applied to the recovery and determination of heavy metal ions in different water samples.     

Determination of Chlorophenols and Alkylphenols in Water and Juice by Solid Phase Derivative Extraction and Gas Chromatography–Mass Spectrometry

A solid phase derivative extraction method using acetic anhydride was developed for the determination of chlorophenols and alkylphenols in water and fruit juice by gas chromatography–mass spectrometry (GC–MS). The quantitative extraction was performed by passing 100 mL of sample prepared in 0.1 mol L^?1 sodium hydroxide through a column packed with 500 mg of a strong anion-exchange resin at a flow rate of 0.75 mL min^?1. The retained phenols were quantitatively derivatized in the column by the introduction of 0.25 mL of acetic anhydride. The derivatized phenols were eluted with 3.0 mL of hexane and the effluent was dried under nitrogen. The final volume was diluted to fifty microliters with hexane and analyzed by GC–MS. Under the optimum conditions, preconcentration factors of 2000, limits of detection between 0.005 and 1.796 µg L^?1, and relative standard deviations of 2.1% to 6.7% were obtained. The method was successfully applied to wastewater and fruit juice and the recoveries of phenols were between 76% and 111%.     

Speciation of Mercury in Terrestrial Plants Using Vapor Generation and Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry

A sensitive method for mercury speciation in biological samples is reported. A simple vapor generation apparatus was coupled to liquid chromatography and inductively coupled plasma–mass spectrometry (ICP–MS) to achieve a substantial increase in sensitivity. Mercury(II) and methylmercury were separated by reversed-phase chromatography as thiolate compounds with 2-mercaptoethanol. A short reverse phase column with an octylated stationary phase (75 × 4 millimeters) was used with a mobile phase containing 0.02 mole per liter ammonium acetate, 0.2 percent (v/v) 2-mercaptoethanol, and 1 percent methanol. The effluent was mixed with hydrochloric acid (0.06 mole per liter) containing platinum (40 micrograms per liter) as the internal standard and bismuth (30 micrograms per liter) as a modifying agent followed by sodium borohydride (0.016 mole per liter). The generated volatile species were introduced into the ICP–MS by conventional solution nebulization. In addition to the sensitivity enhancement induced by vapor generation, the addition of bismuth further increased the methylmercury signal with a reduced increase in the mercury(II) signal. As a result, comparable but unequal signals were achieved: the mercury(II) signal was approximately 1.6-fold higher than the methylmercury signal. Extraction with a hydrochloric acid-2-mercaptoethanol solution was used for sample preparation. The accuracy of determination was verified using two standard reference materials and an interlaboratory reference material based on barley grown hydroponically in mercury-contaminated solution. The method was employed for mercury speciation of plant samples from a polluted region.