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C B'Hymer

Publications and source records attributed to C B'Hymer.

9 recordsLinked to original sources
PubMed2006

Selenium speciation analysis using inductively coupled plasma-mass spectrometry.

Selenium exists in several oxidation states and a variety of inorganic and organic compounds, and the chemistry of selenium is complex in both the environment and living systems. Selenium is an essential element at trace levels and toxic at greater levels. Interest in speciation analysis for selenium has grown rapidly in this last decade, especially in the use of chromatographic separation coupled with inductively coupled plasma-mass spectrometry (ICP-MS). Complete characterization of selenium compounds is necessary to understand selenium's significance in metabolic processes, clinical chemistry, biology, toxicology, nutrition and the environment. This review describes some of the essential background of selenium, and more importantly, some of the currently used separation methodologies, both chromatographic and electrophoretic, with emphasis on applications of selenium speciation analysis using ICP-MS detection.

Chromatography, Gas↗
PubMed2006

A gradient HPLC test procedure for the determination of impurities and the synthetic precursors in 2-[4-(1-hydroxy-4-[4-(hydroxydiphenylmethyl)-1-piperidinyl]-butyl)-phenyl]-2-methylpropionic acid.

A gradient high-performance liquid chromatographic (HPLC) test procedure is developed and evaluated for its ability to establish the levels of impurities and remaining synthetic precursors in 2-[4-(1-hydroxy-4-[4-(hydroxydiphenylmethyl)-1-piperidinyl]-butyl)-phenyl]-2-methylpropionic acid. A gradient program with a mobile phase of 0.02 M sodium phosphate buffer and 0.004 M sodium perchlorate in acetonitrile-water (approximately pH 2.5) is used with a Spherisorb C6 column. The acetonitrile composition is increased linearly from 40% to 65% over a 45-min period and held at 65% for 20 min. UV detection at 210 nm is used to quantitate all components. The procedure is validated for accuracy using spiked levels (0.1% to 1.5%, w/w) with two suspected impurities, the synthetic precursors. A multiday repeatability study using two different Spherisorb C6 columns and HPLC systems shows consistent impurity quantitation results with one production lot of the bulk compound.

Chromatography, High Pressure Liquid↗
PubMed2005

Development of a headspace gas chromatographic test for the quantification of 1- and 2-bromopropane in human urine.

A test procedure was developed for the detection and quantification of 1- and 2-bromopropane in human urine. 1-Bromopropane (1-BP) is a commonly used industrial solvent, and 2-bromopropane (2-BP) is often found as an impurity component in industrial grade 1-BP. Both compounds are a health concern for exposed workers due to their chronic toxicity. Bromopropanes have been associated with neurological disorders in both animals and humans. Sample preparation consisted of diluting urine with water and fortification with 1-bromobutane (1-BB), which was used as an internal standard; then each sample was sealed in a headspace vial. A static-headspace sampler (Teledyne-Tekmar Model 7000) was used to heat each sample at 75 degrees C for a 35-min equilibrium time. Quantification was by means of a gas chromatograph (GC) equipped with an electron capture detector (ECD) and a dimethylpolysiloxane (DB-1) capillary column. A recovery study using fortified urine samples at multiple concentrations (0.5-8 microg/ml) demonstrated full recovery; 104-121% recovery was obtained. Precision ranged from 5 to 17% for the 15-20 spiked samples used at each concentration, which were analyzed over multiple experimental trial days. The limit of detection (LOD) for this test procedure was approximately 2 ng/ml 1-BP and 7 ng/ml 2-BP in urine. A recovery study of 1- and 2-BP from fortified urine stored in vials appropriate for field collection was also completed. These results and other factors of the development and validation of this test procedure will be discussed.

Chromatography, Gas↗
PubMed2004

Arsenic and its speciation analysis using high-performance liquid chromatography and inductively coupled plasma mass spectrometry.

It is known that arsenic has different toxicological properties dependent upon both its oxidation state for inorganic compounds, as well as the different toxicity levels exhibited for organic arsenic compounds. The field of arsenic speciation analysis has grown rapidly in recent years, especially with the utilization of high-performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS), a highly sensitive and robust detector system. Complete characterization of arsenic compounds is necessary to understand intake, accumulation, transport, storage, detoxification and activation of this element in the natural environment and living systems. This review describes the essential background and toxicity of arsenic in the environment, and more importantly, some currently used chromatographic applications and sample handling procedures necessary to accurately detect and quantify arsenic in its various chemical forms. Applications and work using only HPLC-ICP-MS for arsenic speciation of environmental and biological samples are presented in this review.

Arsenic↗
PubMed2004

Development of a gas chromatographic test for the quantification of the biomarker 3-bromopropionic acid in human urine.

An accurate and precise method was developed for the detection and quantification of 3-bromopropionic acid (3-BPA), a metabolite and biomarker for exposure to 1-bromopropane (1-BP). 1-BP is used as an industrial solvent and exposure is a health concern for industrial workers due to its toxicity. It has been associated with neurological disorders in both animals and humans. Urine sample preparation for the determination of 3-BPA consisted of liquid-liquid extraction (LLE) with ethyl acetate and silylation with N-methyl-N-[tert-butyldimethylsilyl]trifluoroacetamide (MTBSTFA). Quantification was by means of a gas chromatograph (GC) equipped with a mass selective detector (MSD) using a dimethylpolysiloxane (HP-1) capillary column and 3-chloropropionic acid was used as an internal standard in the procedure. Demonstrated accuracy and precision during this method's validation was good; recovery varied between 93 and 98% with relative standard deviations (R.D.S.) of 5.7% or less. The limit of detection (LOD) for the procedure was approximately 0.01microg/ml 3-BPA in urine. These data and other factors of the development and validation of this test method will be discussed.

Biomarkers↗
PubMed2003

Procedure for the quantification of the biomarker (2-methoxyethoxy)acetic acid in human urine samples.

An accurate and precise procedure was developed for the detection and quantification of (2-methoxyethoxy)acetic acid (MEAA), a metabolite and biomarker for human exposure to 2-(2-methoxyethoxy)ethanol. The compound 2-(2-methoxyethoxy)ethanol has a wide array of industrial applications including its use as an additive in military jet fuel. Exposure to 2-(2-methoxyethoxy)ethanol is a health concern owing to its toxicity which includes developmental and teratogenic properties. Sample preparation consisted of liquid-liquid extraction (LLE) and esterification of MEAA to produce the ethyl ester. Measurement was by a gas chromatograph (GC) equipped with a mass selective detector (MSD) using a HP-1 capillary column. Recovery studies of spiked blank urine demonstrated good accuracy and precision; recovery varied between 95 and 103% with relative standard deviations of 8.6% and less. The limit of detection (LOD) for this procedure was found to range from 0.02 to 0.08 microg/ml equivalent levels of MEAA in urine. These data and other aspects of the validation of this procedure will be discussed.

Acetates↗
PubMed2001

An evaluation of extraction techniques for arsenic species from freeze-dried apple samples.

The extraction of arsenic from freeze-dried apples and subsequent determination of individual arsenic species by HPLC-ICP-MS is described. Solvent extraction with sonication using various aqueous and aqueous/solvent mixtures was initially evaluated by measuring total arsenic extracted by ICP-MS. A two step procedure using overnight treatment with alpha-amylase enzyme followed by sonication for 6 h with 40:60 acetonitrile-water was found to provide good extraction efficiency. The concentration of arsenic extracted was compared with the concentration of total arsenic in the samples determined using ICP-MS after microwave digestion in order to calculate extraction efficiency. Individual arsenic species in the extracts were measured using HPLC-ICP-MS. The three most abundant arsenic species found were arsenite, arsenate and dimethylarsinic acid. Total arsenic concentrations in the freeze-dried apple samples ranged from 8.2 to 80.9 micrograms kg-1 As, dry mass. By HPLC-ICP-MS, the relative amount of inorganic arsenic in the samples ranged from 73 to 90% of the sum of the arsenic species detected in each sample.

Arsenicals↗
PubMedDate not supplied

Evaluation of a capillary gas chromatographic impurity test procedure for 4-hexylaniline.

A capillary gas chromatographic test procedure for the detection and quantitation of impurities in the bulk intermediate, 4-hexylaniline, is evaluated and found to be accurate and precise. 4-Hexylaniline is dissolved in methanol and chromatographed isothermally at a temperature of 195 degrees C on a 60-m x 0.32-mm 85% polyethylene glycol-15% dimethylsilicone blend (DX-4) film column. A flame ionization detector is used, and the impurities in the parent compound are estimated from peak areas on a percent basis compared with the area of the parent peak in the chromatogram. Response factors are determined for the known impurities. Validation of this test method includes a recovery study of known impurity spiked samples fortified in the range of 0.1-1% (w/w). A repeatability study is performed, consisting of the analysis of two different synthetic batch lots of 4-hexylaniline analyzed over three experimental run days using two chromatographic columns of different manufacturing lots. These data and other aspects of this test procedure are discussed.

Journal Article↗