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1.
Benzylpiperazine (BZP) is an amphetamine-type stimulant, which was legally available in New Zealand and widely used in “Party
Pills” until reclassification as a Class C drug in April 2008. BZP was included as part of a multi-analyte method developed
for hair screening using high-performance liquid chromatography triple quadrupole mass spectrometry (LC-MS/MS). A 20-mg sample
of hair is extracted and partially purified using mixed-mode solid-phase extraction cartridges prior to analysis by LC-MS/MS.
The method was developed as a broad screen for drugs of abuse (including amphetamines, opiates, and benzodiazepines), with
only the BZP results being presented here. The assay was validated and found to be linear over the range of 0.085 to 8.65 ng/mg
with correlation coefficient of r
2 ≥ 0.99. Blank hair samples spiked with BZP at 0.22 and 2.16 ng/mg gave intra- and inter-day precision coefficients of variation
of ≤10% (n = 6 per day, 3 days) at both levels and calculated extraction efficiencies of 78% and 91%, respectively. The results from
the samples submitted to the laboratory for BZP analysis showed 11% were positive (n = 126). The mean BZP level was 3.9 ng/mg (range, 0.4–33 ng/mg; the result was extrapolated when above the calibration). These
data are the first available showing the levels expected from users of BZP. 相似文献
2.
Microwave digestion and isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-SFMS) has been applied to the
determination of Pb in rice flour. In order to achieve highly precise determination of low concentrations of Pb, the digestion
blank for Pb was reduced to 0.21 ng g−1 after optimization of the digestion conditions, in which 20 mL analysis solution was obtained after digestion of 0.5 g rice
flour. The observed value of Pb in a non-fat milk powder certified reference material (CRM), NIST SRM 1549, was 16.8 ± 0.8 ng
g−1 (mean ± expanded uncertainty, k = 2; n = 5), which agreed with the certified value of 19 ± 3 ng g−1 and indicated the effectiveness of the method. Analytical results for Pb in three brown rice flour CRMs, NIST SRM 1568a,
NIES CRM 10-a, and NIES CRM 10-b, were 7.32 ± 0.24 ng g−1 (n = 5), 1010 ± 10 ng g−1 (n = 5), and 1250 ± 20 ng g−1 (n = 5), respectively. The concentration of Pb in a candidate white rice flour reference material (RM) sample prepared by the
National Metrology Institute of Japan (NMIJ) was observed to be 4.36 ± 0.28 ng g−1 (n = 10 bottles).
Figure Digestion blank of Pb was carefully reduced to approximately 0.2 ng g-1 which permitted the highly precise determination of Pb at low ng g-1 level in foodstuff samples by ID-SFMS 相似文献
3.
A fast and sensitive liquid chromatography–mass spectrometry method was developed for the determination of ursolic acid (UA)
in rat plasma and tissues. Glycyrrhetinic acid was used as the internal standard (IS). Chromatographic separation was performed
on a 3.5 μm Zorbax SB-C18 column (30 mm × 2.1 mm) with a mobile phase consisting of methanol and aqueous 10 mM ammonium acetate
using gradient elution. Quantification was performed by selected ion monitoring with (m/z)− 455 for UA and (m/z)− 469 for the IS. The method was validated in the concentration range of 2.5 − 1470 ng mL−1 for plasma samples and 20 − 11760 ng g−1 for tissue homogenates. The intra- and inter-day assay of precision in plasma and tissues ranged from 1.6% to 7.1% and 3.7%
to 9.0%, respectively, and the intra- and inter-day assay accuracy was 84.2 − 106.9% and 82.1 − 108.1%, respectively. Recoveries
in plasma and tissues ranged from 83.2% to 106.2%. The limits of detections were 0.5 ng mL−1 or 4.0 ng g−1. The recoveries for all samples were >90%, except for liver, which indicated that ursolic acid may metabolize in liver. The
main pharmacokinetic parameters obtained were T
max = 0.42 ± 0.11 h, C
max = 1.10 ± 0.31 μg mL−1, AUC = 1.45 ± 0.21 μg h mL−1 and K
a = 5.64 ± 1.89 h−1. The concentrations of UA in rat lung, spleen, liver, heart, and cerebellum were studied for the first time. This method
is validated and could be applicable to the investigation of the pharmacokinetics and tissue distribution of UA in rats. 相似文献
4.
Fluorescence polarization immunoassay for rapid screening of ochratoxin A in red wine 总被引:1,自引:0,他引:1
Francesco Zezza Francesco Longobardi Michelangelo Pascale Sergei A. Eremin Angelo Visconti 《Analytical and bioanalytical chemistry》2009,395(5):1317-1323
A fluorescence polarization (FP) immunoassay, based on a monoclonal antibody and an ochratoxin A (OTA)-fluorescein tracer,
has been developed for rapid screening of OTA in red wine. Wine samples were diluted with methanol and passed through aminopropyl
solid-phase extraction columns prior to the FP assay. Average recoveries from samples spiked with OTA at levels of 2.0 and
5.0 ng/mL were 79% with RDS of 11% (n = 6). The limit of detection of the FP immunoassay was 0.7 ng/mL OTA, and the whole analysis was performed in less than 10 min.
The assay was tested on 154 red wine samples (naturally contaminated or spiked at level ranging from 0.1 to 5.0 ng/mL) and
compared with an high-performance liquid chromatography/immunoaffinity column clean-up method, showing a good correlation
(r = 0.9222). Their compliance with the European regulation (2.0 ng/mL OTA maximum permitted level) was correctly assessed for
70% of the analyzed samples of red wine, whereas confirmatory analyses were required for the remaining ones with OTA levels
close to the regulatory limit. No false-negative or positive results were observed using the FP immunoassay. The proposed
FP assay is a useful screening method for OTA in red wines, when high throughput is required, that could also be used for
white and rosé wines, which are known to contain less interfering compounds such as polyphenols. 相似文献
5.
The use of olaquindox (OLA) as an additive in animal feedstuffs has been prohibited in the European Union and many other countries.
In this study, a highly sensitive and specific indirect competitive enzyme-linked immunosorbent assay (ELISA) for determination
of OLA in animal feed samples was developed. OLA was activated by N′N-carbonyldiimidazole and coupled with bovine serum albumin (BSA) and ovalbumin (OVA). It was found that the sensitivity and
specificity of the two antisera were very similar, with the IC50 values of 16 ng mL−1 and 19 ng mL−1, respectively. Cross-reactivity was less than 35% for four structurally related compounds and no recognition of five other
antibiotics was observed. The better antiserum I was selected for further experiments, for example testing stability, solvent
effect, accuracy, and precision. The IC50 value for eight standard curves was in the range 12–18 ng mL−1 and the LOD at a signal-to-noise ratio of 3 (S/N = 3) was 0.31 ± 0.11 ng mL−1. The ELISA tolerated 5% methanol without significant influence on IC50 value. The recoveries of spiked OLA in five different animal feed types including auxin, pig complex feed, fish complex feed,
broiler concentrated feed, and pig premix feed were in the range 88.3–119.0% and the intra-assay relative standard deviation
(RSD) was within 4.7–33.5% (n = 3). The ELISA for unspiked feed samples was confirmed by high-performance liquid chromatography (HPLC), with a high correlation
coefficient of 0.9862 (n = 5). The proposed ELISA could be a feasible quantitative/screening method for OLA analysis in feed samples with the properties
of high sensitivity, specificity, simplicity of sample pretreatment, high sample throughput, and low expense.
Figure Polyclonal antibody based ELISA for detection of olaquindox 相似文献
6.
Khalid Hamad Abu-Shandi 《Analytical and bioanalytical chemistry》2009,395(2):527-532
A high-performance liquid chromatographic (HPLC) method with fluorescence detection for the quantification of vancomycin in
human plasma was developed and validated. The method includes an extraction of vancomycin by deproteinization with acetonitrile.
The analyses were carried out at 258 nm as the emission wavelength while exciting at 225 nm on a reversed-phase column (30 cm × 4 mm
i.d. × 10 μm Waters Associates μBondapak C18) using a mobile phase composed of methanol and phosphate buffer at pH 6.3. Vancomycin
was quantitatively recovered from human plasma samples (>96%) with high values of precision. The separation was completed
within 27 min. The calibration curve was linear over the range from 5 to 1,000 ng/mL with the detection and quantification
limits of 2 ng/mL and 5 ng/mL, respectively. This method is suitable for the routine assay of plasma samples.
Figure The effect of the deproteinization solvent on the signal of the interference peak at retention time of 15.0 min. The peak
which interferes with the peaks of Erythromycin and Vancomycin has been disappeared by using 2 mL acetonitrile as the deproteinization
solvent. 相似文献
7.
This paper presents the development of a fast and sensitive analytical method for the simultaneous determination of UV filters
and degradation products having quite different polarities (log Kow 2.19–6.88) in sediment, by means of pressurized liquid
extraction (PLE) with in-cell purification and analysis by ultra-performance liquid chromatography (UPLC) coupled to tandem
mass spectrometry (MS/MS). Analytes were simultaneously concentrated and purified by placing aluminium oxide as clean-up sorbent
in the extraction cell for a faster sample pre-treatment. Under optimized conditions, quantitative recoveries (only one compound
below 80%) and satisfactory precision (RSD, 5–15%) were obtained. Low limits of detection were achieved of 0.5–15 ng/g dry
weight (dw). The use of PLE extraction and purification and UPLC technology enabled all the compounds to be separated chromatographically
in less than 9 min, and with a total chromatographic analysis time of 18 min. This method significantly decreased the overall
time of analysis as compared to those of previously developed. Finally, the optimized methodology was applied to investigate
the occurrence of the target UV filters in sediment samples collected along the Ebro river basin (Spain). UV filters were
detected in 95% of the sediment samples analysed. Results revealed a widespread presence of octocrylene (OC), reaching concentrations
up to 24 × 102 ng/g dw, the highest reported so far. Ethylhexyl dimethyl PABA (OD-PABA) and benzophenone-3 (BP3) were also frequently detected
(60–65%), but at lower concentrations (4.4–27 ng/g dw). 4DHB (an estrogenic degradation product of BP3) was present in three
samples at concentrations between 12 and 21 ng/g dw. These results constitute the first data on the occurrence of OD-PABA
and 4DHB in sediments. 相似文献
8.
Ahn KC Gee SJ Kim HJ Aronov PA Vega H Krieger RI Hammock BD 《Analytical and bioanalytical chemistry》2011,401(4):1285-1293
Pyrethroid insecticides widely used in forestry, agricultural, industrial, and residential applications have potential for
human exposure. Short sample preparation time and sensitive, economical high-throughput assays are needed for biomonitoring
studies that analyze a large number of samples. An enzyme-linked immunosorbent assay (ELISA) was used for determining 3-phenoxybenzoic
acid (3-PBA), a general urinary biomarker of exposure to some pyrethroid insecticides. A mixed-mode solid-phase extraction
reduced interferences from acid hydrolyzed urine and gave 110 ± 6% recoveries from spiked samples. The method limit of quantification
was 2 μg/L. Urine samples were collected from forestry workers that harvest pine cone seeds where pyrethroid insecticides
were applied at ten different orchards. At least four samples for each worker were collected in a 1-week period. The 3-PBA
in workers classified as high, low, or no exposure based on job analysis over all sampling days was 6.40 ± 9.60 (n = 200), 5.27 ± 5.39 (n = 52), and 3.56 ± 2.64 ng/mL (n = 34), respectively. Pair-wise comparison of the differences in least squares means of 3-PBA concentrations among groups
only showed a significant difference between high and no exposure. Although this difference was not significant when 3-PBA
excretion was normalized by creatinine excretion, the general trend was still apparent. No significant differences were observed
among days or orchards. This ELISA method using a 96-well plate was performed as a high-throughput tool for analyzing around
300 urine samples measured in triplicate to provide data for workers exposure assessment. 相似文献
9.
Skalka N Krol A Schlesinger H Altstein M 《Analytical and bioanalytical chemistry》2011,400(10):3491-3504
The present research focused on the development of an immunoassay and an immunochemical sol–gel-based immunoaffinity purification
(IAP) method for purification and detection of the non-steroid anti-inflammatory drug (NSAID) indomethacin (IMT). A polyclonal
antibody (Ab) for IMT was generated, and two sensitive microplate assays for the detection of IMT were developed (termed OV
and HRP formats), based on the enzyme-linked immunosorbent assay (ELISA) method. The limits of detection of the assays were
15 ± 1.25 ng mL−1 (n = 50) and 12 ± 0.17 ng mL−1 (n = 4) for the OVA and HRP formats, respectively. The Abs exhibited slight cross-reactivity with other NSAIDs. The Abs were
also used to develop a sol–gel-based IAP method for clean-up and concentration of IMT. Several sol–gel formats with various
amounts of antibodies were examined; the best and most reproducible format was at a TMOS:HCl molar ratio of 1:6 in which 120 μL
of IMT Abs was entrapped. The binding capacity under these conditions was ca. 100 to 250 ng of IMT with very low non-specific
binding (less than 5% of the applied amount). The sol–gel IAP method, combined with solid-phase extraction, successfully eliminated
serum interference to a degree that enabled analysis of spiked serum samples by ELISA. The method was also found to be fully
compatible with subsequent chemical analytical methods, such as liquid chromatography followed by mass spectrometry. The approaches
developed in this study form a basis for analysis of IMT in biological samples in order to monitor their pharmacokinetic properties,
and may be further used to study population exposure to IMT, and to monitor the occurrence of IMT contamination in water samples. 相似文献
10.
Kokot ZJ Matysiak J Urbaniak B Dereziński P 《Analytical and bioanalytical chemistry》2011,399(7):2487-2494
The aim of this study was to develop a new precise and accurate CZE-DAD method for honeybee venom analysis using cytochrome
c as an internal standard. The 64.5 cm total length, 56 cm effective length, 75 μm ID, and 360 μm OD uncoated fused-silica
capillary was used. The samples were injected into the capillary under a 50-mbar pressure for 7 s. There were 15 kV of electric
field across the capillary applied. The current intensity was 26 μA. The separation was carried out at 25 °C. The analysis
was run with the normal electrode polarity. The following steps and parameters were taken into account for the validation
of the developed method: selectivity, precision, accuracy, linearity, limit of detection and limit of quantitation. All steps
of the validation procedure proved that the developed analytical procedure was suitable for its intended purpose. Possibly
this was the first study in which several honeybee venom components were separated and five of them were identified by capillary
zone electrophoresis. In addition, the developed method was applied for quantitative analysis of 38 honeybee venom samples.
The content (relative to the dry venom mass) of analyzed peptides in honeybee venom samples collected in 2002–2007 was as
follows: apamine from 0.93% to 4.34% (mean, 2.85 ± 0.79%); mast cell degranulating peptide (MCDP) from 1.46% to 4.37% (mean,
2.82 ± 0.64%); phospholipase A2 from 7.41% to 20.25% (mean, 12.95 ± 3.09%); melittin from 25.40% to 60.27%, (mean, 45.91 ± 9.78%). The results were compared
with the experimental data obtained for the same venom samples analyzed earlier by the HPLC method. It was stated that HPCE
and HPLC data did not differ significantly and that the HPCE method was the alternative for the HPLC method. Moreover, using
the results obtained principal component analysis (PCA) was applied to clarify the general distribution patterns or similarities
of four major honeybee venom constituents collected from two different bee strains in various months and years. PCA has shown
that the strain of bee appears to be the only criteria for bee venom sample classification. Strong correlations between apamine,
MCDP, phospholipase A2, and melittin were confirmed. These correlations have to be taken into account in the honeybee venom standardization. The
developed method due to its simplicity can be easily automated and incorporated into routine operations both in the bee venom
identification, quality control, and standardization of the product. 相似文献
11.
Norbert Szoboszlai Erzsébet Andrási Zsolt Ajtony Ivett Császma 《Mikrochimica acta》2001,137(1-2):81-86
A method is reported for measuring Se and Sn in human brain tissue. The patients from whom the samples were taken had no
diseases in their central nervous system. Microwave energy was applied to digest the brain samples. The digested samples were
analyzed without dilution by transversely heated graphite atomizer for atomic absorption spectrometry with longitudinal Zeeman
background correction. The dependence of integrated absorbance on various chemical modifiers has been examined. The most appropriate
technique proved to be 5 μl sample injection using 20 μg prereduced palladium-nitrate for Se determination, and 20 μl sample
injection applying 10 μg palladium-nitrate + 3 μg magnesium-nitrate for the measurements of Sn. The optimal temperature program
was found to be 1200 °C pyrolysis and 2100 °C atomisation temperature for Se and 1500 °C pyrolysis and 2300 °C atomisation
temperature for Sn. Accuracy of the applied techniques was tested by the analysis of standard reference materials. The precision
was ±5% for Se and ±10% for Sn. The range of recovery values was 85–95% for Se and 95–105% for Sn. The mean Se concentrations
in the investigated brain parts ranged from 200 to 700 ng/g, while the Sn concentrations were between 20 and 300 ng/g dry
weight.
Received October 3, 2000. Revision February 1, 2001. 相似文献
12.
Sheng-da Qi Shun-lian Tian Hong-xi Xu Joseph J. Y. Sung Zhao-xiang Bian 《Analytical and bioanalytical chemistry》2009,393(8):2059-2066
Serotonin (5-hydroxytryptamine, 5-HT) plays vital roles in regulating gastrointestinal functions. Thus, the detection of 5-HT
in the gastrointestinal tract is of great importance for biomedical research, medical diagnosis, and pharmaceutical therapy.
This paper presents a simple, sensitive, and fast method for the quantification of luminally released serotonin in the feces
and tissues of the rat proximal colon by means of capillary electrophoresis with laser-induced fluorescence detection. 5-Carboxyfluorescein
N-succinimidyl ester was used for precolumn derivatization of serotonin. The optimal separation and detection conditions were
obtained with an electrophoretic buffer containing 60 mM borate (pH 8.90) and an air-cooled argon-ion laser (excitation at
488 nm, emission at 520 nm). The serotonin concentrations in the feces and tissues of proximal colons were analyzed with this
method, and the average values of serotonin in the feces samples were 1.951 ± 0.446 ng/mg (male) and 2.095 ± 0.533 ng/mg (female)
and 1.397 ± 0.267 ng/mg in rat proximal colon tissues. The results demonstrate that this method can accurately determine luminally
released 5-HT in rats. 相似文献
13.
András Székács Éva Lauber Eszter Takács Béla Darvas 《Analytical and bioanalytical chemistry》2010,396(6):2203-2211
The distribution of Cry1Ab toxin was detected in the leaves of genetically modified maize of genetic event MON 810 by enzyme-linked immunosorbent assay. Cry1Ab toxin contents in the leaves at reproductive (milk, R3) phenological stage were
measured to be between 3,878 and 11,148 ng Cry1Ab toxin/g fresh weight. Toxin content was significantly lesser (significant
difference (SD) = 1,823 ng Cry1Ab toxin/g fresh leaf weight, p < 0.01) in leaves at the lowest leaf level, than at higher leaf levels, probably due to partial leaf necrotisation. A substantial
(up to 22%) plant-to-plant variation in Cry1Ab contents in leaves was observed. When studying toxin distribution within the
cross and longitudinal sections of single leaves, lesser variability was detected diagonally, with approximately 20% higher
toxin concentrations at or near the leaf vein. More significant variability (SD = 2,220 ng Cry1Ab toxin/g fresh leaf weight,
p < 0.01) was seen lengthwise along the leaf, starting at 1,892 ng Cry1Ab toxin/g fresh weight at the sheath and rising to
maximum concentration at the middle of the lamella. Cry1Ab toxin content may suffer significant (SD = 2,230 ng Cry1Ab toxin/g
fresh leaf weight, p < 0.01) decreases in the leaf due to necrotisation. The results indicate that the longitudinal dimension of the leaf has
more significance for sampling purposes than the diagonal position. 相似文献
14.
First results on Fe solid-phase extraction from coastal seawater using anatase TiO2 nano-particles 总被引:1,自引:0,他引:1
Christophe R. Quétel Emilia Vassileva Ivan Petrov Kristina Chakarova Konstantin I. Hadjiivanov 《Analytical and bioanalytical chemistry》2010,396(6):2349-2361
This paper describes the application of TiO2 nano-particles (anatase form) for the solid-phase extraction of iron from coastal seawater samples. We investigated the adsorption
processes by infra-red spectroscopy. We compared in batch and on-(mini)column extraction approaches (0.1 and 0.05 g TiO2 per sample, respectively), combined to external calibration and detection by inductively coupled plasma mass spectrometry
at medium mass resolution. Globally, this titania phase was slightly more efficient with seawater than with ultra-pure water,
although between pH 2 and pH 7, the Fe retention efficiency progressed more in ultra-pure water than in seawater (6.9 versus
4.8 times improvement). Different reaction schemes are proposed between Fe(III) species and the two main categories of titania
sites at pH 2 (adsorption of [FeL
x
](3 − x)+ via possibly the mediation of chlorides) and at pH 7 (adsorption of [Fe(OH)2]+ and precipitation of [Fe(OH)3]0). Under optimised conditions, the inlet system was pre-cleaned by pumping 6% HCl for ∼2 h, and the column was conditioned
by aspirating ultra-pure water (1.7 g min−1) and 0.05% ammonia (0.6 g min−1) for 1 min. Then 3 g seawater sample was loaded at the same flow rate while being mixed on-line with 0.05% ammonia at 0.6 g
min−1 to adjust the pH to 7. The iron retained on the oxide powder was then eluted with 3 g 6% HCl (<0.002% residual salinity in
the separated samples). The overall procedural blank was 220 ± 46 (2 s, n = 16) ng Fe kg−1 (the titania was renewed in the column every 20 samples, with 2-min rinsing in between samples with 6% HCl at 1.5 g min−1). The recovery estimated from the Canadian certified reference material CASS-2 was 69.5 ± 7.6% (2 s, n = 4). Typically, the relative combined uncertainty (k = 2) estimated for the measurement of ∼1 μg Fe kg−1 (0.45 μm filtered and acidified to pH 1.5) of seawater was ∼12%. We applied our method to a similar sample, from the coastal
region of the North Sea. The agreement well within stated uncertainties of our result with the value obtained independently
by isotope dilution mass spectrometry further validated our method. 相似文献
15.
Rudolf Brenneisen Pascale Meyer Haithem Chtioui Martial Saugy Matthias Kamber 《Analytical and bioanalytical chemistry》2010,396(7):2493-2502
Since 2004, cannabis has been prohibited by the World Anti-Doping Agency for all sports competitions. In the years since then,
about half of all positive doping cases in Switzerland have been related to cannabis consumption. In doping urine analysis,
the target analyte is 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH), the cutoff being 15 ng/mL. However, the wide urinary detection window of the long-term metabolite
of Δ9-tetrahydrocannabinol (THC) does not allow a conclusion to be drawn regarding the time of consumption or the impact on the
physical performance. The purpose of the present study on light cannabis smokers was to evaluate target analytes with shorter
urinary excretion times. Twelve male volunteers smoked a cannabis cigarette standardized to 70 mg THC per cigarette. Plasma
and urine were collected up to 8 h and 11 days, respectively. Total THC, 11-hydroxy-Δ9-tetrahydrocannabinol (THC-OH), and THC-COOH were determined after hydrolysis followed by solid-phase extraction and gas chromatography/mass
spectrometry. The limits of quantitation were 0.1–1.0 ng/mL. Eight puffs delivered a mean THC dose of 45 mg. Plasma levels
of total THC, THC-OH, and THC-COOH were measured in the ranges 0.2–59.1, 0.1–3.9, and 0.4–16.4 ng/mL, respectively. Peak concentrations
were observed at 5, 5–20, and 20–180 min. Urine levels were measured in the ranges 0.1–1.3, 0.1–14.4, and 0.5–38.2 ng/mL,
peaking at 2, 2, and 6–24 h, respectively. The times of the last detectable levels were 2–8, 6–96, and 48–120 h. Besides high
to very high THC-COOH levels (245 ± 1,111 ng/mL), THC (3 ± 8 ng/mL) and THC-OH (51 ± 246 ng/mL) were found in 65 and 98% of
cannabis-positive athletes’ urine samples, respectively. In conclusion, in addition to THC-COOH, the pharmacologically active
THC and THC-OH should be used as target analytes for doping urine analysis. In the case of light cannabis use, this may allow
the estimation of more recent consumption, probably influencing performance during competitions. However, it is not possible
to discriminate the intention of cannabis use, i.e., for recreational or doping purposes. Additionally, pharmacokinetic data
of female volunteers are needed to interpret cannabis-positive doping cases of female athletes. 相似文献
16.
Raúl A. Sánchez-Moreno M. Jesús Gismera M. Teresa Sevilla Jesús R. Procopio 《Analytical and bioanalytical chemistry》2010,397(1):331-338
A disposable screen-printed electrode was designed and evaluated for direct detection of chromium(VI) in batch and flow analysis.
The carbon screen-printed electrode was modified with a graphite–epoxy composite. The optimal graphite–epoxy matrix contains
37.5% graphite powder, 12.5% diphenylcarbohydrazide, a selective compound for chromium(VI), and 50% epoxy resin. The principal
analytical parameters of the potentiometric response in batch and flow analysis were optimized and calculated. The screen-printed
sensor exhibits a response time of 20 ± 1 s. In flow analysis, the analytical frequency of sampling is 70 injections per hour
using 0.1 M NaNO3 solution at pH 3 as the carrier, a flow rate of 2.5 mL·min−1, and an injection sample volume of 0.50 mL. The sensor shows potentiometric responses that are very selective for chromium(VI)
ions and optimal detection limits in both static mode (2.1 × 10−7 M) and online analysis (9.4 × 10−7 M). The disposable potentiometric sensor was employed to determine toxicity levels of chromium(VI) in mineral, tap, and river
waters by flow-injection potentiometry and batch potentiometry. Chromium(VI) determination was also carried out with successful
results in leachates from municipal solid waste landfills. 相似文献
17.
Evaluation of a novel ELISA for serotonin: urinary serotonin as a potential biomarker for depression
Nichkova MI Huisman H Wynveen PM Marc DT Olson KL Kellermann GH 《Analytical and bioanalytical chemistry》2012,402(4):1593-1600
Depression is a common disorder with physical and psychological manifestations often associated with low serotonin. Since
noninvasive diagnostic tools for depression are sparse, we evaluated the clinical utility of a novel ELISA for the measurement
of serotonin in urine from depressed subjects and from subjects under antidepressant therapy. We developed a competitive ELISA
for direct measurement of serotonin in derivatized urine samples. Assay performance was evaluated and applied to clinical
samples. The analytical range of the assay was from 6.7 to 425 μg serotonin/g creatinine (Cr). The limit of quantification
was 4.7 μg/g Cr. The average recovery for spiked urine samples was 104.4%. Average intra-assay variation was 4.4%, and inter-assay
variation was <20%. The serotonin analysis was very specific. No significant interferences were observed for 44 structurally
and nonstructurally related urinary substances. Very good correlation was observed between urinary serotonin levels measured
by ELISA and liquid chromatography tandem mass spectrometry (LC-MS/MS; ELISA = 1.16 × LC-MS/MS − 53.8; r = 0.965; mean % bias = 11%; n = 18). Serotonin was stable in acidified urine for 30 days at room temperature and at −20 °C. The established reference range
for serotonin was 54–366 μg/g Cr (n = 64). Serotonin levels detected in depressed patients (87.53 ± 4.89 μg/g Cr; n = 60) were significantly lower (p < 0.001) than in nondepressed subjects (153.38 ± 7.99 μg/g Cr). Urinary excretion of serotonin in depressed individuals significantly
increased after antidepressant treatment by 5-hydroxy-tryptophane and/or selective serotonin re-uptake inhibitor (p < 0.01). The present ELISA provides a convenient and robust method for monitoring urinary serotonin. It is suitable to monitor
serotonin imbalances and may be particularly helpful in evaluating antidepressant therapies. 相似文献
18.
Fontana AR Rodríguez I Ramil M Altamirano JC Cela R 《Analytical and bioanalytical chemistry》2011,401(2):767-775
This work evaluates the suitability of sorptive microextraction, using disposable silicone sorbents, and liquid chromatography
time-of-flight mass spectrometry (LC-TOF-MS) for the determination of 15 fungicides in wine. Under optimized conditions, wine
samples (10 mL) were diluted with the same volume of ultrapure water and poured in a glass vessel containing a magnetic stirrer
and 4 g of sodium chloride. Extractions were performed at room temperature for 4 h, using an inexpensive silicone disk (12 μL
volume) exposed directly to the sample. Thereafter, analytes were recovered with 0.2 mL of acetonitrile. The electrospray
ionization (ESI) source was operated in the fast polarity switching mode obtaining, in the same injection, selective LC-MS
records (extracted with a mass window of 10 ppm) of compounds rendering [M + H]+ and [M-H]− ions. The method provided limits of quantification (LOQs) between 0.1 and 2.2 ng mL−1, linear response ranges up to 500 ng mL−1, relative recoveries from 75% to 117% and an inter-day variability below 15% for all analytes in red and white wine samples.
The feasibility of in situ sample enrichment followed by delayed desorption and analysis is also assessed. 相似文献
19.
Oluwatosin O. Dada Lauren M. Ramsay Jane A. Dickerson Nathan Cermak Rong Jiang Cuiru Zhu Norman J. Dovichi 《Analytical and bioanalytical chemistry》2010,397(8):3305-3310
We report a multiplexed capillary electrophoresis system employing an array of 32 capillaries with a micromachined sheath-flow
cuvette as the detection chamber. The sample streams were simultaneously excited with a 473-nm laser beam, and the fluorescence
emission was imaged on a CCD camera with a pair of doublet achromat lens. The instrument produced mass detection limits of
380 ± 120 yoctomoles for fluorescein in zone electrophoresis. Capillary isoelectric focusing of fluorescent standards produced
peaks with an average width of 0.0029 ± 0.0008 pH. Capillary coating stability limits the reproducibility of the analysis. 相似文献
20.
García-Ruiz S Petrov I Vassileva E Quétel CR 《Analytical and bioanalytical chemistry》2011,401(9):2785-2792
The cadmium content in surface water is regulated by the last European Water Framework Directive to a maximum between 0.08
and 0.25 μg L−1 depending on the water type and hardness. Direct measurement of cadmium at this low level is not straightforward in real
samples, and we hereby propose a validated method capable of addressing cadmium content below μg L−1 level in natural water. It is based on solid-phase extraction using TiO2 nanoparticles as solid sorbent (0.05 g packed in mini-columns) to allow the separation and preconcentration of cadmium from
the sample, combined to direct isotope dilution and detection by inductively coupled plasma mass spectrometry (ID-ICP-MS).
The extraction setup is miniaturised and semi-automated to reduce risks of sample contamination and improve reproducibility.
Procedural blanks for the whole measurement process were 5.3 ± 2.8 ng kg−1 (1 s) for 50 g of ultrapure water preconcentrated ten times. Experimental conditions influencing the separation (including
loading pH, sample flow rates, and acid concentration in the eluent) were evaluated. With isotope dilution the Cd recovery
rate does not have to be evaluated carefully. Moreover, the mathematical model associated to IDMS is known, and provides transparency
for the uncertainty propagation. Our validation protocol was in agreement with guidelines of the ISO/IEC 17025 standard (chapter
5.4.5). Firstly, we assessed the experimental factors influencing the final result. Secondly, we compared the isotope ratios
measured after our separation procedure to the reference values obtained with a different protocol for the digested test material
IMEP-111 (mineral feed). Thirdly, we analysed the certified reference material BCR-609 (groundwater). Finally, combined uncertainties
associated to our results were estimated according to ISO-GUM guidelines (typically, 3–4% k = 2 for a cadmium content of around 100 ng kg−1). We applied the developed method to the groundwater and wastewater samples ERM-CA615 and BCR-713, respectively, and results
agreed with certificate values within uncertainty statements. 相似文献