Tritium concentration in foods and human tissues: Estimation of mean residence times of organically-bound tritium in costal cartilage and sternum

Tritium (³H) concentrations in diet samples from Akita City, northern Japan, and in human tissue samples from the general population of Akita Prefecture were analyzed to study fallout³H transfer.³H concentrations in human soft-tissue samples have been previously found to be similar to those in diet samples. In this study, higher organically-bound³H (OBT) concentrations were found in human costal cartilage and sternum samples than in the soft-tissues. Mean residence times of OBT in the cartilage and sternum were estimated to be 57 years and <6 years, respectively, with a single compartment model which took into account compartment growth.     

Development of A Dual Channel Chemiluminescence FIA System for Rapid Measurement of Fish Freshness

Abstract

A dual channel chemiluminescence FIA system for the rapid measurement of the fish freshness index KI $$ where [IMP], [HxR] and [Hx] are, respectively, the inosine 5′-monophosphate, inosine and hypoxanthine contents of fish meat was developed. The system consisted of a pair of chemiluminescence FIAs (CL-FIA); one for the measurement of [IMP] + [HxR] + [Hx], and the other for [HxR] + [Hx]. IMP, HxR or Hx were measured using a reactor comprising immobilized alkaline phosphatase, purine nucleoside phosphorylase (PNP) and xanthine oxidase (XOD). The calibration curves for IMP, HxR or Hx were linear from 0.06 μM to 100 μM for a sample volume of 20 μl. The time for a single KI measurement was less than 1 min. This fish freshness FIA system is rapid, convenient and applicable for fish freshness measurements in real fish samples.     

Removal of Arsenazo-III from liquid radioactive waste by cloud point extraction

Optimization of a method, based on thermal oxidation using a tube furnace system (Pyrolyser), for the separation of organically bound tritium (OBT) from environmental matrices is discussed. Results show that a maximum of ~?4 g of the vegetation sample, typical wild plant leaves of tropical regions, and ~?8 g of sediment sample can be combusted efficiently in the pyrolyser system. The recovery of OBT from wheat sample was observed to be ~?92% and that for sediment sample was ~?88%. The minimum detectable activity (MDA) at 95% confidence level was 3.4 Bq kg^?1 for a sample weight?=?4 g, counting time?=?30,000 s, and detection efficiency?=?23%.

     

Variation of tritium concentration in the course of the degradation of fresh pine needles on a forest floor

Variation of tritium concentration was examined for 100 days in the course of degradation of fresh pine needles, which were left on a pine forest floor. No difference was observed on free water tritium (FWT) and organically bound tritium (OBT) concentrations of sterilized samples by gamma-ray irradiation or fumigation and control samples, attributable to incomplete sterilization. The OBT concentrations did not increase within the experimental period as the level of humus collected from the forest floor. The results suggest that a longer degradation time, more than 100 days, is necessary to elevate OBT up to the level, which is observed in the general environment.     

Ion chromatographic precision measurement procedure for electrolytes in human serum: validation with the aid of primary measurement procedures

In order to make analytical measurement results traceable to the SI units in the field of clinical chemistry, an ion chromatographic (IC) measurement procedure has been developed which allows the amount of substance of the four so-called electrolytes Na, K, Mg and Ca as well as that of Li to be determined efficiently in human serum and with high accuracy. The IC measurement procedure was validated using primary measurement procedures confirmed by international comparison measurements and is proposed for use as a transfer standard when comparing measurements with clinical reference laboratories. The solutions used for calibration were gravimetrically prepared from pure substances (salts). Their chemical compositions had been iteratively fitted to those of the samples. The serum samples were mineralized by microwave-assisted digestion. The following relative expanded uncertainties for the average elemental contents were obtained: Li 0.4%, Na 0.14%, K 0.6%, Mg 0.8% and Ca 0.4%.

     

Use of isotopically labelled octanoic acid to assess the effect of meal size on gastric emptying

It has been proposed that the (13)C-octanoic acid breath test (OBT) provides a safe, non-radioactive means of measuring gastric emptying. However, deuterated octanoic acid provides a better marker when compared with scintigraphy, as the kinetics are less complex than those of the (13)C label. The appearance of (2)H in saliva is modelled as a two-compartment body water system, using an asymmetric triangular gastric emptying function. This study compared the (2)H-octanoic acid saliva test (OST) with the OBT in measuring altered states of gastric emptying in the nutritional context of diet manipulation. Gastric emptying was measured using the OST and OBT in a three-way crossover study involving 12 healthy male and female subjects (mean BMI = 23.4 kg/m(2), aged 24-57 years). Following an overnight fast, subjects were given an egg meal, labelled with 10 microL/kg body weight (2)H-octanoic acid and 100 microL (13)C-octanoic acid. The meal was nutritionally manipulated to provide a 1 MJ, 2 MJ or 3 MJ meal. Breath and saliva samples were collected at regular intervals for 6 h, with further saliva samples being collected over four subsequent days. (2)H isotopic enrichment in saliva and (13)C isotopic enrichment in breath were analysed using isotope ratio mass spectrometry and the data fitted to the respective gastric emptying models. The half excretion time (T(1/2) (D)), time to maximum emptying rate (T(1) (D)) and time when emptying is complete (T(2) (D)) were calculated from the (2)H saliva test data, and the lag time (T(lag) (C)), half excretion time (T(1/2) (C)), latency phase (T(lat) (C)) and ascension time (T(asc) (C)) were calculated from the (13)C breath test data. Overall, the OBT correlated well with the OST, with a significant relationship between T(1/2) (C) and T(1/2) (D), a significant relationship between T(lat) (C) and T(1) (D) and finally a significant relationship between T(asc) (C) and T(2) (D). Gastric emptying measured using the OST was significantly faster with the 1 MJ meal (DeltaT(1/2) (D) = -0.77 h vs. 2 MJ, p = 0.004). Increases were also seen when the meal size was increased from 2 MJ to 3 MJ (DeltaT(1/2) (D) = +0.44 h vs. 2 MJ), but these were not significant. These trends were mirrored in the OBT data, with significant differences between 1 MJ and 2 MJ (DeltaT(1/2) (C) = -0.63 h vs. 2 MJ, p = 0.013) and non-significant increases with the larger 3 MJ meal (DeltaT(1/2) (C) = +0.10 h vs. 2 MJ). Total meal calorie content was shown to have an effect on gastric emptying using both the OBT and the OST. The deuterium method allows the direct calculation of the gastric emptying function and could be used as an alternative to gamma scintigraphy, allowing further validation of the (13)C-octanoic acid breath test.     

Direct synthesis of o-bromobenzonitrile by catalytic and gas-phase ammoxidation of o-bromotoluene

The VCrPO/SiO₂ catalyst was obtained by doping a Cr element into VPO/SiO₂. Using this catalyst for the ammoxidation of o-bromotoluene (OBT) to o-bromobenzonitrile (OBBN), we studied the influence and effect of each single factor such as reaction temperature, the molar ratio air/OBT (air ratio), the molar ratio NH₃/OBT (NH₃ ratio), and the molar ratio H₂O/OBT (H₂O ratio) in the feed and feed load on the reaction. As the results show, the most appropriate reaction conditions of the catalyst are a temperature of 360°C, an air ratio of 30, a NH₃ ratio of 8, an H₂O ratio of 0.6, and a feed load of 57 g/(1 Cat h). With these parameters the conversion of OBT is 99.4 mol% and the mole productivity of OBBN is 77.9%. The function of the doped Cr element is mainly to increase the lattice defects in the catalyst and improve the quantity and activity of lattice oxygen [O^2?], which contributes to increasing the activity of the catalyst and to reducing the most appropriate reaction temperature.     

Determination of Trace Metals in Fish Tissue by Flame Atomic Absorption Spectrometry using a Discreet Nebulization Technique

Abstract

Flame atomic absorption spectrometry is applied to the analysis of trace metals in fish tissue after digestion of the sample with nitric acid in a decomposition vessel. The digested sample is analyzed directly using a discreet nebulization technique. Enhancement effects were observed for all elements studied. The method was applied to the analysis of copper, iron and zinc in several species of fish.     

Measurement of tritium with plastic scintillators in large vials of a low background liquid scintillation counter: an organic waste-less method

The tritium compounds, tritiated water as a volatile compound and ³H-methionine as a non-volatile compound, were measured with two types of plastic scintillators (PSs) using a low background liquid scintillation counter (LSC). It is advantage that minimal organic waste is generated when a plastic scintillator is used for LSC measurement. The effect of large vials on counting efficiency, plasma effects with three types of plasma devices for PS-sheets, the effect of UV-light on PS-pellets, the relationship between the activity and the count rate, and the detection limits of tritium were studied with respect to the development of large-scale measurement systems.

     

Identification of Acepromazine and Its Metabolites in Horse Plasma and Urine by LC–MS/MS and Accurate Mass Measurement

Acepromazine maleate (Sedalin^®) was administered orally to six thoroughbred horses at a dose of 0.15 mg kg⁻¹. Urine and blood samples were collected up to 412 h post-administration. Plasma and urine were hydrolysed; plasma samples were then processed using liquid–liquid extraction and urine samples using solid-phase extraction. A sensitive tandem mass spectrometric method was developed in this study, achieving a lower limit of quantification for acepromazine of 10 pg mL⁻¹ in plasma and 100 pg mL⁻¹ in urine. Acepromazine, hydroxyethylpromazine, hydroxyacepromazine, hydroxyethylpromazine sulphoxide, hydroxyethylhydroxypromazine, dihydroxyacepromazine and dihydroxyhydroxyethylpromazine were detected in the post-administration samples. The parent drug and its metabolites were identified using a combination of UPLC–MS/MS and accurate mass measurement. Separation of the structural isomers hydroxyethylpromazine sulphoxide and hydroxyethylhydroxypromazine was another significant outcome of this work and demonstrated the advantages to be gained from investing in chromatographic method development.

     

Magnetic solid-phase extraction of malachite green using soluble eggshell membrane protein doped with magnetic graphene oxide nanocomposite

ABSTRACT

This study describes a new magnetic solid-phase extraction (MSPE) technique based on Fe₃O₄/graphene oxide-soluble eggshell membrane protein (Fe₃O₄/GO-SEP) for accurate measurement of malachite green (MG) residue in various water samples residues by UV-Vis spectroscopy. The morphology of the prepared adsorbent has been studied by scanning electron microscopy and atomic force microscopy in details. Parameters affecting the MSPE were optimised and determined with UV-Vis spectrophotometry thoroughly. Under the optimised extraction circumstances, the introduced method represented a wide linearity over the concentration of 0.5–250 ng mL^?1, a high enrichment factor of 83.3 and low detection limit of 0.2 ng mL^?1. The prepared Fe₃O₄/GO-SEP was successfully used for preconcentration and determination of MG in river and fish farming water samples with suitable precision and accuracy.     

Determination of Biodegradation Process of Benzene,Toluene, Ethylbenzene and Xylenes in Seabed Sediment by Purge and Trap Gas Chromatography

Benzene, toluene, ethylbenzene, and xylenes (BTEX) are commonly found in crude oil and are used in geochemical investigations as direct indicators of the presence of oil and gas. BTEX are easily volatile and can be degraded by microorganisms, which affect their precise measurement seriously. A method for determining the biodegradation process of BTEX in seabed sediment using dynamic headspace (purge and trap) gas chromatography with a photoionization detector (PID) was developed, which had a detection limit of 7.3–13.2 ng L⁻¹ and a recovery rate of 91.6–95.0%. The decrease in the concentration of BTEX components was monitored in seabed sediment samples, which was caused by microorganism biodegradation. The results of BTEX biodegradation process were of great significance in the collection, transportation, preservation, and measurement of seabed sediment samples in the geochemical investigations of oil and gas.

     

Seasonal trend of Anisakidae infestation in South Mediterranean bluefish

Abstract

A total of 1104 fish samples from markets of Sicily were analysed for the detection and species identification of Anisakidae nematodes. The preliminary analysis of the fish samples showed the presence of 2459 larvae. All the fish species revealed different prevalence of infestation, with a maximum of 100% for Lepidopus caudatus and a minimum of 4.5% in Sardina pilchardus. The 80% of the larvae examined by PCR-RFLP analysis belonged to Anisakis pegreffii species. The seasonal infestation trend of Anisakis was evaluated in all the fish sample examined. The results of the seasonal infestation trend showed a marked connection with the ecological aspects of the fish species examined. As far as we know, this work report for the first time important ecological aspects of Lepidopus caudatus specimens of South Mediterranean. This work could be useful to plan a seasonal fishing strategy aimed at reducing the health risks related to Anisakis.     

Corticosteroid Analysis by HPLC-UV Facilitated byv Use of an Injector-Mounted Extraction Column

Abstract

A method for integrating solid phase extraction of corticosteroids from biological samples with normal operation of reversed-phase HPLC is described. This method uses an extraction column mounted in place of the sample loop of a conventional injection valve to separate corticosteroids from some interfering compounds, and to effectively concentrate steroids from dilute samples. Both manual and fully automated chromatographs using this principle are described. A specific application to measurement of corticosterone in a rabbit serum preparation allows routine measurement of as little as 300 pg corticosterone per sample.     

Method validation and verification in liquid scintillation counting using the long-term uncertainty method (LTUM) on two decades of proficiency test data

Results from proficiency tests gathered over the past two decades by the laboratory for low level radioactivity measurements for liquid scintillation counting of ³H (184 results) and ¹⁴C (74 results) are used to verify the validated measurement methods used by the laboratory, in particular the estimated uncertainty budget of the method and its reproducibility and stability. A linear regression approach is used for the analysis of the results, described in the literature as the long term uncertainty in measurement method. The present study clearly indicates the advantages of using proficiency test results in identifying possible constant or proportional bias effects as well as the possibility to compare the laboratory performance with the performance of peer laboratories.

     

Die empirische Matrixkorrektur intermediärer Proben in der Röntgenspektrometrie

Very thin samples show proportionality between the intensity and the weight per unit area of the analyte. Matrix effects do not exist. The matrix effects of very thick samples suitably can be corrected by multiple regression according to Eq. (1). Between these two kinds of samples the intermediate ones are situated with the intensity of the analyte as a function of the weight per unit area of the sample as an additional parameter of correction.

It was shown that these samples can also be corrected by multiple regression without knowing the weight per unit area of the samples by using the weight per unit area of the analyte instead of its concentration according to Eq. (5). This was demonstrated by calculation with simulated standards.

In addition to the described effects the correction program Eq. (5) is able to correct for the influences of dust particle sizes and their depth distribution in the filter.

     

Chemometric Resolution for Rapid Determination of Prometryn in Leek Samples Using GC–MS

Much effort has been made to analyze the pesticides in foods or vegetables due to the interferences in the sample matrix. In this work, taking the determination of prometryn in leek samples as an example, a simple method is proposed for fast analysis of the components in real samples using GC–MS and chemometric resolution. The purification step in preparing the samples was simplified, and a short capillary column and fast temperature program were employed in GC–MS measurement. Although the measured signal is composed of overlapped peaks with the interferences and background, the signal of prometryn can be extracted by chemometric resolution. Six leek samples from different markets were analyzed within an elution time of 6 min. Compared with the results by the standard method, the results by the proposed method were found to be reliable.

     

Determination of Pentachlorophenol (PCP) in Samples of the Environmental Specimen Bank Using Isotope Dilution

Abstract

Within the program of the Environmental Specimen Bank a quick and efficient method for determination of pentachlorophenol (PCP) in various environmental matrices has been developed. The method includes alkaline hydrolysis of bound PCP, acidification, simultaneous steam distillation and extraction in one glass apparatus. After clean-up and derivatization with acetic anhydride the samples were analyzed by gas chromatography/mass spectrometry. Concentrations were calculated using ¹³C-labeled PCP as the internal standard. Validation was carried out with various environmental samples (soil, fish, conifer needles, kale).

The method can be used for various biological samples without any modification. The extracts are free of matrix components (lipids, chloropyll, terpenes, etc.) and other contaminants, which results in clear chromatograms with few peaks; therefore, correct integration is facilitated. Although the recoveries of PCP are in the range of 50–90%, due to losses during the several method steps, these losses can be corrected with the ¹³C-labeled internal standard, resulting in high precision (1.5–2.2% standard deviation).     

Evaluation of the Effects of Sample Dilution and Volume in Hydrophilic Interaction Liquid Chromatography

The effects of sample dilution and volume on the peak shapes in hydrophilic interaction liquid chromatography (HILIC) were evaluated using fluorescence-labeled thiols as model compounds and ZIC-HILIC as the HILIC column. The content of acetonitrile, which was selected as the diluent of the aqueous samples in this study, was varied 0−95 % in the injection samples, and the numbers of theoretical plates (NTPs) and retention times were compared using a mobile phase composed of ammonium formate buffer/acetonitrile (25:75, v/v). Although the NTPs and retention times decreased with decreasing acetonitrile content, the peak shapes were acceptable for samples with acetonitrile contents down to 50 % based on asymmetry factor. Furthermore, the sample volume had a serious effect for samples with low acetonitrile contents. Although a high content of acetonitrile in samples is still recommended, the capacity for the aqueous solution in the injection samples under HILIC conditions should vary with the composition of the mobile phase and may be larger than previously thought. These findings should be helpful in deciding the sample composition under HILIC conditions, particularly in bioanalysis, where aqueous solution is often contained in the injection samples and the sample dilution with an organic solvent may decrease the detection sensitivity.

     

Development of quantitative vitellogenin-ELISAs for fish test species used in endocrine disruptor screening

The yolk protein precursor vitellogenin (Vtg) in plasma has proved to be a simple and sensitive biomarker for assessing exposure of fish to environmental estrogens. Within international bodies such as the Organization for Economic Cooperation and Development (OECD) work is ongoing to develop screening and testing programmes for endocrine disrupting effects of new chemicals, and in the focus of this development are the fish test species common carp (Cyprinus carpio), fathead minnow (Pimephales promelas), zebrafish (Danio rerio) and Japanese medaka (Oryzias latipes). In this study we have developed quantitative enzyme linked immunosorbent assays (ELISAs) for Vtg in common carp/fathead minnow, zebrafish and Japanese medaka. The assays were developed using a combination of monoclonal and polyclonal fish Vtg antibodies in a sandwich format, using stabilized Vtg from the test species as a standard. The carp Vtg ELISA has a working range of 1–63 ng/mL, a minimal detection limit of 0.6 ng/mL, and may also be used for quantification of Vtg in fathead minnow. In fathead minnow whole-body homogenate samples, the practical detection limit is 400 ng/mL due to the matrix effect. The zebrafish Vtg ELISA has a working range of 0.5–63 ng/mL, a minimal detection limit of 0.4 ng/mL, and a practical detection limit of 200 ng/mL in whole-body homogenate samples. The medaka Vtg ELISA has a working range of 0.25–16 ng/mL, a minimal detection limit of 0.1 ng/mL, and a practical detection limit of 125 ng/mL in whole-body homogenate samples. The intra- and inter-assay variations were below 20% for all assays. The assays were evaluated with sets of representative samples spanning the wide dynamic range of Vtg-levels found in fish exposed to environmental estrogens, and all three assays are currently undergoing international inter-laboratory validation.