Mass spectrometric identification of polychlorinated dibenzothiophenes (PCDBTs) in surface sediments of the River Elbe

HRGC/MS was applied to six sediment samples from River Elbe for the determination of polychlorinated dibenzothiophenes (PCDBTs). Among the studied tri-, tetra- and octa-chlorinated isomers, trichlorinated species were found to be the dominating ones. The estimated concentration levels of the compounds were in the range of approximately 0.02–2 μg/kg dry weight for trichlorinated and 0.1–0.3 μg/kg for octachlorinated species. Tetrachlorinated dibenzothiophenes could not be detected.     

Arsenic metabolism in seaweed-eating sheep from Northern Scotland

Cation exchange and anion exchange liquid chromatography were coupled to an ICP-MS and optimised for the separation of 13 different arsenic species in body fluids (arsenite, arsenate, dimethylarsinic acid (DMAA), monomethylarsonic acid (MMAA), trimethylarsine oxide (TMAO), tetramethylarsonium ion (TMA), arsenobetaine (AsB), arsenocholine (AsC), dimethylarsinoyl ethanol (DMAE) and four common dimethylarsinoylribosides (arsenosugars). The arsenic species were determined in seaweed extracts and in the urine and blood serum of seaweed-eating sheep from Northern Scotland. The sheep eat 2–4 kg of seaweed daily which is washed ashore on the most northern Island of Orkney. The urine, blood and wool of 20 North Ronaldsay sheep and kidney, liver and muscle from 11 sheep were sampled and analysed for their arsenic species. In addition five Dorset Finn sheep, which lived entirely on grass, were used as a control group. The sheep have a body burden of approximately 45–90 mg arsenic daily. Since the metabolism of arsenic species varies with the arsenite and arsenate being the most toxic, and organoarsenic compounds such as arsenobetaine the least toxic compounds, the determination of the arsenic species in the diet and their body fluids are important. The major arsenic species in their diet are arsenoribosides. The major metabolite excreted into urine and blood is DMAA (95 ± 4.1%) with minor amounts of MMAA, riboside X, TMA and an unidentified species. The occurrence of MMAA is assumed to be a precursor of the exposure to inorganic arsenic, since demethylation of dimethylated or trimethylated organoarsenic compounds is not known (max. MMAA concentration 259 μg/L). The concentrations in the urine (3179 ± 2667 μg/L) and blood (44 ± 19 μg/kg) are at least two orders of magnitude higher than the level of arsenic in the urine of the control sheep or literature levels of blood for the unexposed sheep. The tissue samples (liver: 292 ± 99 μg/kg, kidney: 565 ± 193 μg/kg, muscle: 680 ± 224 μg/kg) and wool samples (10 470 ± 5690 μg/kg) show elevated levels which are also 100 times higher than the levels for the unexposed sheep. Received: 29 February 2000 / Revised: 26 April 2000 / Accepted: 1 May 2000     

Determination of carbaryl in foods by solid-phase room-temperature phosphorimetry

A phosphorimetric solid phase assay is proposed for the determination of the pesticide carbaryl (CBL) at room temperature. CBL was spotted on filter paper together with Tl(I) as heavy metal, and dried for 3 min, after which the diffuse transmitted phosphorescence was measured using two quartz plates to avoid the quenching effect produced by atmospheric oxygen. The linear dynamic range was 0.5–4.0 μg/mL and the detection and quantification limits were 0.09 and 0.31 μg/mL, respectively. The precision of the method, expressed as relative standard deviation, was 2.3% for a sample containing 2.0 μg/mL of CBL. The method was applied to the determination of CBL residues in cereals, potatoes and waters, obtaining recoveries ranging between 92 and 105%. Received: 10 October 1997 / Revised: 2 February 1998 / Accepted: 7 February 1998     

Highly sensitive semi-quantitative field test for the determination of chromium (VI) in aqueous samples

A method for the semi-quantitative colorimetric determination of chromium(VI) at sub μg/L levels after sorptive preconcentration is presented. The method is based on the retention of the reaction product (preformed in liquid phase) between Cr(VI) and diphenylcarbazide on membrane embedded cation exchange material. The color intensity of the membrane can be correlated to Cr(VI) concentrations in the range 0.05–50 μg/L (i.e. almost three orders of magnitude lower than the conventional spectrophotometric procedure) with a detection limit of about 10 ng/L (using 50 mL of sample volume). Due to the visual inspection mode and comparative color detection the precision is only 30–80% rsd which, however, is regarded as sufficient for screening purposes. Analysis of real samples including different kinds of waters and extracts of soil and filter collected airborne particulate matter demonstrated the applicability of the method for fast and species selective screening. Recovery experiments generally gave reasonably good results, yet also revealed the risk of the conversion of chromium species during sample pretreatment procedures due to redox reactions. Received: 1 December 1997 / Revised: 23 February 1998 / Accepted: 10 March 1998     

Spectrophotometric Determination of Some Phenolic Antibiotics in Dosage Forms

 A simple and sensitive spectrophotometric method is described for the determination of some phenolic antibiotics namely: cefadroxil, amoxicillin and vancomycin. The method is based on the measurement of the orange yellow species produced when the drugs are coupled with diazotized benzocaine in triethylamine medium. The method is applicable over the range of 0.8–12 μg/ml for cefadroxil, 2–16 μg/ml for amoxicillin and 2–18 μg/ml for vancomycin. The formed compounds absorb at 455 nm for both cefadroxil and amoxicillin and at 442 nm for vancomycin. The proposed method has detection limits of 0.018 μg for cefadroxil, 0.0034 μg for amoxicillin and 0.0156 μg for vancomycin. The stoichiometric ratio for the studied compounds was found to be 1:1 and a proposal of the reaction pathway was made. The proposed method was applied for the analysis of the cited drugs in their pharmaceutical preparations. The results are in good agreement with those obtained by the official methods. Received February 7, 2000. Revision June 14, 2000.     

Determination of aluminium in the edible part of fish by GFAAS after sample pretreatment with microwave activated oxygen plasma

An analytical method for the determination of aluminium in the edible part of fish was developed using a new pre-treatment method in a microwave activated oxygen plasma and graphite furnace atomic absorption spectrometry. The linearity of the calibration line as well as of different standard addition lines were very good within the measurement area of 0–60 μg Al/L. The recovery with spiked ocean perch fillet was good. The unsatisfactory recovery of aluminium with the reference-material (mussel tissue) may be due to high quantities of insoluble aluminium-silicates. An installed quality-control-card indicated that the method showed no significant fluctuation as well as contamination over the complete analysis time. The limit of detection calculated as 3 times the standard deviation of the blank absorbance divided by the slope of the calibration line was 1 μg Al/L. Received: 7 December 1998 / Revised: 14 February 1999 / Accepted: 24 February 1999     

Determination of aluminium in the edible part of fish by GFAAS after sample pretreatment with microwave activated oxygen plasma

An analytical method for the determination of aluminium in the edible part of fish was developed using a new pre-treatment method in a microwave activated oxygen plasma and graphite furnace atomic absorption spectrometry. The linearity of the calibration line as well as of different standard addition lines were very good within the measurement area of 0–60 μg Al/L. The recovery with spiked ocean perch fillet was good. The unsatisfactory recovery of aluminium with the reference-material (mussel tissue) may be due to high quantities of insoluble aluminium-silicates. An installed quality-control-card indicated that the method showed no significant fluctuation as well as contamination over the complete analysis time. The limit of detection calculated as 3 times the standard deviation of the blank absorbance divided by the slope of the calibration line was 1 μg Al/L. Received: 7 December 1998 / Revised: 14 February 1999 / Accepted: 24 February 1999     

A PVC-based cryptand C2B22 membrane potentiometric sensor for zinc(II)

A PVC membrane electrode for zinc ions based on cryptand C2_B22 as membrane carrier was prepared. The electrode exhibits a linear stable response over a wide concentration range (5.0 × 10^–2– 5.0 × 10^–5 mol/L) with a slope of 24 mV/ decade and a limit of detection of 3.98 × 10^–5 mol/L (2.6 μg/g). It has a fast response time of about 30 s and can be used for at least 4 months without any divergence in potential. The proposed sensor revealed good selectivities for Zn²⁺ over a wide variety of other metal ions and could be used in a pH range of 4–7. It was used as an indicator electrode in potentiometric titration of zinc ion. Received: 26 February 1998 / Revised: 25 May 1998 / Accepted: 28 May 1998     

Determination of chlorophenols in urine of children and suggestion of reference values

During the course of a human biomonitoring project (Biebesheim in Hessen, Germany) we elaborated a simple but sensitive method for the determination of tri- (TCP), tetra- (TeCP) and pentachlorophenol (PCP) in human urine. Urine samples, spiked with internal standards, were treated by acid hydrolysis. After a steam bath distillation the distillates were extracted using solid phase extraction. Derivatization of the chlorophenols was not carried out. GC/ECD system was used for detection. Detection limits of the chlorophenols were found in the range of 0.02 μg/L urine (detection limits of the ECD: 0.52 to 2.76 μg/L). By this method mono- and dichlorophenols cannot be detected. We investigated 24h-urine samples of 339 pupils (age 10 to 12 years). The children live either in the surroundings of a hazardous waste incinerator (SVA) in Biebesheim (n = 193), or controls (i.e. regions without waste incinerator) in the non polluted areas of Odenwald (n = 90) and Rheintal (n = 56). Between these three groups we did not find statistically significant differences in chlorophenol concentrations of the urine samples. The 95-percentiles of the analyzed samples are 0.74 μg/L (2,3,4-TCP), 1.24 μg/L (2,3,5-TCP), 0.70 μg/L (2,3,6–TCP), 1.10 μg/L (2,4,5–TCP), 1.74 μg/L (2,4,6–TCP), 2.84 μg/L (3,4,5–TCP), 4.78 μg/L (2,3,4,5-TeCP), 1.86 μg/L (2,3,4,6-TeCP), 2.90 μg/L (2,3,5,6-TeCP) and 4.39 μg/L (PCP). Received: 24 February 1999 / Revised: 3 May 1999 / Accepted: 6 May 1999     

Determination of chlorophenols in urine of children and suggestion of reference values

During the course of a human biomonitoring project (Biebesheim in Hessen, Germany) we elaborated a simple but sensitive method for the determination of tri- (TCP), tetra- (TeCP) and pentachlorophenol (PCP) in human urine. Urine samples, spiked with internal standards, were treated by acid hydrolysis. After a steam bath distillation the distillates were extracted using solid phase extraction. Derivatization of the chlorophenols was not carried out. GC/ECD system was used for detection. Detection limits of the chlorophenols were found in the range of 0.02 μg/L urine (detection limits of the ECD: 0.52 to 2.76 μg/L). By this method mono- and dichlorophenols cannot be detected. We investigated 24h-urine samples of 339 pupils (age 10 to 12 years). The children live either in the surroundings of a hazardous waste incinerator (SVA) in Biebesheim (n = 193), or controls (i.e. regions without waste incinerator) in the non polluted areas of Odenwald (n = 90) and Rheintal (n = 56). Between these three groups we did not find statistically significant differences in chlorophenol concentrations of the urine samples. The 95-percentiles of the analyzed samples are 0.74 μg/L (2,3,4-TCP), 1.24 μg/L (2,3,5-TCP), 0.70 μg/L (2,3,6–TCP), 1.10 μg/L (2,4,5–TCP), 1.74 μg/L (2,4,6–TCP), 2.84 μg/L (3,4,5–TCP), 4.78 μg/L (2,3,4,5-TeCP), 1.86 μg/L (2,3,4,6-TeCP), 2.90 μg/L (2,3,5,6-TeCP) and 4.39 μg/L (PCP). Received: 24 February 1999 / Revised: 3 May 1999 / Accepted: 6 May 1999     

Chromatographic determination of phenylarsenic compounds

Urinary arsenic speciation is considered to be an effective procedure to differentiate between toxic inorganic and less toxic organic arsenic exposure. The aim of the present work was to develop a new method for the simultaneous determination of the main arsenic species so far detected in urine: arsenite (As(III)), arsenate (As(V)), methylarsonic acid (MA), dimethylarsinic acid (DMA), and arsenobetaine (AsB). The method is based on anion exchange HPLC coupled on-line to an inductively coupled plasma mass spectrometer (ICP-MS) for element specific detection. Experimental parameters, such as column type and composition of the mobile phases were optimized in order to get best separation, little matrix interferences, lowest detection limits, and short total times of analyses. Best chromatographic conditions were obtained by using a Dionex AS14 anion exchange column and a gradient elution with tetramethylammonium hydroxide and ammonium carbonate as eluting compounds. The detection limits (3 σ) were found to be in the sub μg L^–1 range. The method was applied to analyze different urine samples from persons with and without consumption of seafood. To avoid significant matrix influences, samples (24 h urine) had to be diluted 1 : 5 with water and were filtered through a 0.45 μm filter prior to analyses. Special attention was focused on the validation of the method according to the regulations of the “Deutsche Forschungsgemeinschaft” (DFG) for the analyses of hazardous substances in biological materials. Received: 22 December 1997 / Revised: 18 February 1998 / Accepted: 22 February 1998     

Validation of a high-performance chromatographic method for determination of cefotaxime in biological samples

An analytical method for detecting and quantifying cefotaxime in plasma and several tissues is described. The method was developed and validated using plasma and tissues of rats. The samples were analyzed by reversed phase liquid chromatography (HPLC) with UV detection (254 nm). Calibration graphs showed a linear correlation (r > 0.999) over the concentration ranges of 0.5–200 μg/mL and 1.25–25 μg/g for plasma and tissues, respectively. The recovery of cefotaxime from plasma standards prepared at the concentrations of 25 μg/mL and 100 μg/mL was 98.5 ± 3.5% and 101.8 ± 2.2%, respectively. The recovery of cefotaxime from tissue standards of liver, fat and muscle, prepared at the concentration of 10 μg/g was: 89.8 ± 1.2% (liver), 103.9 ± 6.5% (fat) and 97.8 ± 2.1% (muscle). The detection (LOD) and quantitation (LOQ) limits for plasma samples were established at 0.11 μg/mL and 0.49 μg/mL, respectively. The values of these limits for tissues samples were approximately 2.5 times higher: 0.3 μg/g (LOD) and 1.25 μg/g (LOQ). For plasma samples, the deviation of the observed concentration from the nominal concentration was less than 5% and the coefficient of variation for within-day and between-day assays was less than 6% and 12%, respectively. The method was used in a pharmacokinetic study of cefotaxime in the rat and the mean values of the pharmacokinetic parameters are given. Received: 25 May 1998 / Revised: 27 July 1998 / Accepted: 1 August 1998     

Determination of trace impurities in high purity copper using sector-field ICP-MS: continuous nebulization, flow injection analysis and laser ablation

High resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) was applied for multielement-determination in high-purity copper (approx. 99.99%). The samples were introduced into the instrument by three different introduction systems, which were studied with respect to high accuracy, low detection limits and fast analysis: continuous nebulization (CN), flow injection analysis (FIA) and laser ablation (LA). The trueness of the applied method was checked by the analysis of high-purity copper reference material (BCR Cu074). All values obtained for this CRM using CN were in the range of the stated uncertainty for the 9 elements determined: Ag, As, Bi, Cr, Fe, Ni, Pb, Sb, and Sn with contents in the range of 0.5–13 μg/g. Another approach for checking the trueness of the method was to compare the results obtained by this method characterizing the purity of a 4N (99.99% copper content) copper material with those obtained by application of electrothermal atomic absorption spectrometry (ET-AAS) and inductively coupled plasma optical emission spectrometry (ICP-OES). For further characterizing, the concentrations of 49 elements were found in this material below detection limits of HR-ICP-MS in the range of low μg/kg and sub μg/kg. The combination of HR-ICP-MS and a flow injection analysis system (FIAS) improved the robustness of the system in regard to high matrix concentrations. Therefore, matrix concentrations up to 4 g/L could be used for liquid analysis and detection limits were lowered by a factor of 2–5. A calibration method for bulk analysis with laser ablation was developed with doped copper powder as pressed pellets for calibration standards. This method proved to be an excellent fast semi-quantitative method, which was less time consuming in comparison with the analysis of liquids. After application of correction factors the deviation between the results obtained by laser ablation and by analysis of liquids was ≈ 15% for most elements. The method offered the possibility to check for potential losses of analytes occurring during the wet chemical operations. Received: 23 November 1998 / Revised: 25 February 1999 / Accepted: 2 March 1999     

Determination of trace impurities in high purity copper using sector-field ICP-MS: continuous nebulization, flow injection analysis and laser ablation

High resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) was applied for multielement-determination in high-purity copper (approx. 99.99%). The samples were introduced into the instrument by three different introduction systems, which were studied with respect to high accuracy, low detection limits and fast analysis: continuous nebulization (CN), flow injection analysis (FIA) and laser ablation (LA). The trueness of the applied method was checked by the analysis of high-purity copper reference material (BCR Cu074). All values obtained for this CRM using CN were in the range of the stated uncertainty for the 9 elements determined: Ag, As, Bi, Cr, Fe, Ni, Pb, Sb, and Sn with contents in the range of 0.5–13 μg/g. Another approach for checking the trueness of the method was to compare the results obtained by this method characterizing the purity of a 4N (99.99% copper content) copper material with those obtained by application of electrothermal atomic absorption spectrometry (ET-AAS) and inductively coupled plasma optical emission spectrometry (ICP-OES). For further characterizing, the concentrations of 49 elements were found in this material below detection limits of HR-ICP-MS in the range of low μg/kg and sub μg/kg. The combination of HR-ICP-MS and a flow injection analysis system (FIAS) improved the robustness of the system in regard to high matrix concentrations. Therefore, matrix concentrations up to 4 g/L could be used for liquid analysis and detection limits were lowered by a factor of 2–5. A calibration method for bulk analysis with laser ablation was developed with doped copper powder as pressed pellets for calibration standards. This method proved to be an excellent fast semi-quantitative method, which was less time consuming in comparison with the analysis of liquids. After application of correction factors the deviation between the results obtained by laser ablation and by analysis of liquids was ≈ 15% for most elements. The method offered the possibility to check for potential losses of analytes occurring during the wet chemical operations. Received: 23 November 1998 / Revised: 25 February 1999 / Accepted: 2 March 1999     

Rapid and simple chromatographic separation of V(V) and V(IV) using KH-phthalate and their determination by flame atomic absorption spectrometry

A method was developed for the chromatographic separation of V(V) and V(IV) based on the different sorption forces of these vanadium species in C18 columns in presence of KH-phthalate. The vanadium species were detected with a flame atomic absorption spectrometer with acetylene/N₂O flame. The detection limits (3σ) of V(V) and V(IV) were 0.18 μg/mL and 0.15 μg/mL, respectively. The relative standard deviations (N = 5) are 4.2% and 3.4% for 20–20 μg/mL V(V) and V(IV), respectively. The sampling frequency is 75/h. Because of the special interaction occurring between phthalate and V(IV) on the C18 column and the acetylene/N₂O flame atomic absorption detection, practically no interferences can be detected even in large inorganic matrix. Received: 20 February 1997 / Revised: 2 June 1997 / Accepted: 7 June 1997     

Ultra-trace analysis of nitrite in food samples by flow injection with spectrophotometric detection

A flow injection system with spectrophotometric detection is proposed for the determination of low levels of nitrite based on its catalytic effect on the oxidation of gallocyanine by bromate in acidic media. Various analytical parameters such as acidity, reagent concentration, flow rate, sample size, time, temperature, and interfering species were studied. The calibration graph was linear for 0.020–0.500 μg/mL of nitrite. The method is successfully applied to food samples. Up to 30 ± 5 samples can be analyzed per hour. Received: 8 April 1998 / Revised: 3 June 1998 / Accepted: 31 July 1998     

Ultra-trace analysis of nitrite in food samples by flow injection with spectrophotometric detection

A flow injection system with spectrophotometric detection is proposed for the determination of low levels of nitrite based on its catalytic effect on the oxidation of gallocyanine by bromate in acidic media. Various analytical parameters such as acidity, reagent concentration, flow rate, sample size, time, temperature, and interfering species were studied. The calibration graph was linear for 0.020–0.500 μg/mL of nitrite. The method is successfully applied to food samples. Up to 30 ± 5 samples can be analyzed per hour. Received: 8 April 1998 / Revised: 3 June 1998 / Accepted: 31 July 1998     

Sensitive reaction rate method for the determination of low levels of formaldehyde with photometric detection

A simple and rapid method is proposed for the determination of ultra trace amounts of formaldehyde. It is based on the catalytic effect of formaldehyde on the oxidation of Brilliant cresyl blue by bromate. The reaction is monitored photometrically by measuring the decrease in absorbance of the dye. Formaldehyde in the range of 0.005–2.300 μg/mL can be determined with a limit of detection of 0.003 μg/mL. The relative standard deviation for ten replicate measurements of 1.5 μg/mL formaldehyde is 0.1%. The method was used for the determination of formaldehyde in real samples with satisfactory results. Received: 26 May 1998 / Revised: 30 September 1998 / Accepted: 3 October 1998     

Microdetermination of proteins by enhanced Rayleigh light scattering spectroscopy with morin

Under acidic conditions, the reaction between 3,5,7,2′,4′-pentahydroxyflavone (morin) and proteins enhances the weak light scattering of morin drastically. The enhanced light scattering intensity is proportional to the content of proteins. This fact is the basis of a new method for the quantitative analysis of proteins. The linear range is 0.45–7.15 and 0.46–11.14 μg/mL for BSA and HSA, respectively. The relative standard deviation is 3.76% (n = 12) for BSA in the middle of the linear range. The results of this assay for human serum samples were comparable with those from the traditional method (CBB method). There is almost no interfere from amino acids and most of the metal ions. The scattering spectrum of morin was also discussed. Received: 11 October 1998 / Revised: 18 February 1999 / Accepted: 24 February 1999     

Automated continuous monitoring of drug dissolution process using a flow injection on-line dialysis sampling – solvent extraction separation spectrophotometric system

Inductively coupled plasma optical emission spectrometry (ICP-OES) was used for the element-specific determination of water-soluble organosilicon species separated by high-performance liquid chromatography (HPLC). Leachates from different waste deposit sites were investigated. The polydimethylsiloxane (PDMS) degradation product dimethylsilanediol (DMSD) could be detected in almost all samples in the low mg L^–1 range, and it was furthermore possible to determine trimethylsilanol (TMSOL) in some leachate samples in the μg L^–1 range. TMSOL was additionally analyzed by a method established before (LT-GC/ICP-OES). This study proved the occurrence of silanol compounds in leachates from locations were silicone material is deposited. Received: 10 July 1998 / Revised: 2 November 1998 / Accepted: 5 November 1998