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1.
Lottmann A Cadé E Geagea ML Delhomme O Grand C Veilleraud C Rizet AL Mirabel P Millet M 《Analytical and bioanalytical chemistry》2007,387(5):1855-1861
In to order increase sensitivity and to reduce the background induced by matrix effects, a method was developed that uses
flash chromatography to separate various compounds present in atmospheric aerosol samples prior to their analysis with different
analytical techniques (GC–MS, GC–FID, HPLC). For this purpose, flash chromatography using a 4 g silica gel column crossed
by eluent at a flow rate of 20 mL min−1 was used. An eluent with enhanced polarity is needed to separate nonpolar (linear and branched alkanes), semipolar (PAH,
nitro-PAH and cholesterol) and polar (methoxyphenols, alkanoic acids, and levoglucosan) compounds. Three combinations of solvents
were used: hexane for the nonpolar fraction (F1), toluene/hexane for the semipolar fraction (F2) and dimethylformamide for
the polar fraction (F3). The use of different eluents for each fraction allows separation of the sample to be accomplished
with good repeatability and satisfying yields [85 ± 5% for F1, 81 ± 8% (PAHs), 89 ± 6% (nitro-PAHs) and 74 ± 7% (cholesterol)
for F2 and 79 ± 7% (n-alkanoic acids), 40 ± 11% (methoxyphenols) and 77 ± 6% (levoglucosan) for F3]. The methoxyphenol yields were low due to losses
during the concentration/evaporation step. This method was then applied to analyse the organic composition of particles collected
at an urban site in Strasbourg (France). 相似文献
2.
The alterations of organic acids citrate, α-ketoglutarate, succinate, fumarate, malate production together with isocitrate
lyase activity as a glyoxalate shunt enzyme, and antibiotic production of Streptomyces sp M4018 were investigated in relation to changes in the glucose, glycerol and starch concentrations (5–20 g/L) after identification
as a strain of Streptomyces hiroshimensis based on phenotypic and genotypic characteristics. The highest intracellular citrate and α-ketoglutarate levels in 20 g/l
of glucose, glycerol, and starch mediums were 399.47 ± 4.78, 426.93 ± 6.40, 355.84 ± 5.38 ppm and 444.81 ± 5.12, 192.96 ± 2.26,
115.20 ± 2.87 ppm, respectively. The highest succinate, malate, and fumarate levels were also determined in 20 g/l of glucose
medium as 548.9 ± 11.21, 596.15 ± 8.26, and 406.42 ± 6.59 ppm and the levels were significantly higher than the levels in
glycerol and starch. Extracellular organic acid levels measured also showed significant correlation with carbon source concentrations
by showing negative correlation with pH levels of the growth medium. The antibiotic production of Streptomyces sp. M4018 was also higher in glucose medium as was the case also for organic acids when compared with glycerol. On the other
hand, there is no production in starch. 相似文献
3.
Valiollah Babaeipour Seyed Abbas Shojaosadati Rasoul Khalilzadeh Nader Maghsoudi Amir Mohammad Farnoud 《Applied biochemistry and biotechnology》2010,160(8):2366-2376
Development of inexpensive and simple culture media and appropriate induction conditions are always favorable for industry.
In this research, chemical composition and stoichiometric data for γ-interferon production and recombinant Escherichia coli growth were used in order to achieve a simple medium and favorable induction conditions. To achieve this goal, the effects
of medium composition and induction conditions on the production of γ-interferon were investigated in batch culture of E. coli BL21 (DE3) [pET3a-ifnγ]. These conditions were considered as suitable conditions for the production of γ-interferon: 2.5× M9 medium, supplemented
with a mixture of amino acids (milligram per liter), including glutamic acid 215, aspartic acid 250, lysine 160, and phenylalanine
90, and induction at late-log phase (OD600 = 4.5). Under these conditions, dry cell weight of 6 ± 0.2 g/l and γ-interferon concentration of 2.15 ± 0.1 g/l were obtained.
Later, without changing the concentration ratio of amino acids and glucose, the effect of increase in the primary glucose
concentration on productivity of γ-interferon was investigated. It was found that 25 g/l glucose will result in maximum attainable
biomass and recombinant human γ-interferon. At improved conditions, a dry cell weight of 14 ± 0.2 g/l, concentration and overall
productivity of γ-interferon 4.2 ± 0.1 g/l and 420 ± 10 mg/l h, respectively, were obtained. 相似文献
4.
Sushovan Chatterjee Lepakshi Barbora Swaranjit Singh Cameotra Pinakeswar Mahanta Pranab Goswami 《Applied biochemistry and biotechnology》2009,157(3):593-600
Lipase was immobilized in silk fibers through glutaraldehyde cross-linking to a maximum loading of 59 U/g silk-fiber and the
immobilized lipase was utilized for the hydrolysis of sunflower oil (Helianthus annuus). The hydrolytic activity of the lipase, which was poor in biphasic oil in water system, was increased significantly when
the sunflower oil was emulsified in aqueous medium. The hydrolytic activities of the immobilized lipase were 48.73 ± 1.26 U,
36.11 ± 0.96 U, and nil when the substrate sunflower oil was used as emulsion created by a rhamnolipid biosurfactant, Triton
X100, and ultrasonication, respectively. Although the efficiency of the immobilized lipase was less than 12% than the corresponding
free lipase, the immobilized lipase could be reused for the biosurfactant-mediated hydrolysis of sunflower oil up to third
cycle of the reaction. The yield of the fatty acids in the second, third, and fourth cycles were 49.45%, 22.91%, and 5.09%,
respectively, of the yield obtained in the first cycle. 相似文献
5.
Rodrigues TH Rocha MV de Macedo GR Gonçalves LR 《Applied biochemistry and biotechnology》2011,164(6):929-943
In this work, the potential of microwave-assisted alkali pretreatment in order to improve the rupture of the recalcitrant
structures of the cashew able bagasse (CAB), lignocellulosic by-product in Brazil with no commercial value, is obtained from
cashew apple process to juice production, was studied. First, biomass composition of CAB was determined, and the percentage
of glucan and lignin was 20.54 ± 0.70% and 33.80 ± 1.30%, respectively. CAB content in terms of cellulose, hemicelluloses,
and lignin, 19.21 ± 0.35%, 12.05 ± 0.37%, and 38.11 ± 0.08%, respectively, was also determined. Results showed that, after
enzymatic hydrolysis, alkali concentration exerted influence on glucose formation, after pretreatment with 0.2 and 1.0 mo L−1 of NaOH (372 ± 12 and 355 ± 37 mg gglucan−1) when 2% (w/v) of cashew apple bagasse pretreated by microwave-assisted alkali pretreatment (CAB-M) was used. On the other hand, pretreatment
time (15–30 min) and microwave power (600–900 W) exerted no significant effect on hydrolysis. On enzymatic hydrolysis step,
improvement on solid percentage (16% w/v) and enzyme load (30 FPU gCAB-M−1) increased glucose concentration to 15 g L−1. The fermentation of the hydrolyzate by Saccharomyces cerevesiae resulted in ethanol concentration and productivity of 5.6 g L−1 and 1.41 g L−1 h−1, respectively. 相似文献
6.
Pradnya Deshpande Sajitha Nair Shubhangi Khedkar 《Applied biochemistry and biotechnology》2009,158(3):552-560
Water hyacinth (Eichhornia crassipes), an aquatic weed common to the subtropic/tropical regions, was utilized as an inexpensive lignocellulosic substrate for
production of cellulase by Trichoderma reesei. The effects of process parameters like substrate pretreatment, substrate concentration, initial medium pH, mode of inoculation,
and incubation temperature on cellulase production were investigated. Under optimal conditions, a maximal cellulase activity
of 0.22 ± 0.04 IU/ml (approximately 73.3 IU/g cellulose) was recorded at the end of 15-day incubation period. Specific activity
of the enzyme was 6.25 IU/mg protein. Hydrolysis of 1% substrate (water hyacinth) using crude enzyme dosage of 1.2 IU/g water
hyacinth showed 28.7% saccharification in 1 h. The observations in present study indicate that saccharification of cellulose
from water hyacinth was significantly higher by laboratory-produced cellulase than the commercial blend. 相似文献
7.
Christopher W. Heppel Anne-Kathrin Heling Elmar Richter 《Analytical and bioanalytical chemistry》2009,393(5):1525-1530
4-Hydroxy-1-(3-pyridyl)-1-butanone (HPB)-releasing DNA adducts are formed by metabolic activation of the tobacco-specific
nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N′-nitrosonornicotine (NNN). NNK and NNN are considered carcinogenic to humans by the International Agency for Research on
Cancer. Existing analytical methods for determination of HPB-releasing DNA adducts require 0.3–2.0 g of human target tissues
such as lung and esophagus. For adduct determination in milligram amounts of biopsy samples, an ultrasensitive and specific
method is presented using capillary gas chromatography coupled to a high-resolution mass spectrometer operated in the negative
chemical ionization mode (GC-NCI-HRMS). The method has a limit of detection of 4.6 fmol HPB, a limit of quantification of
14.9 fmol HBP and a recovery of 45 ± 15%. Intra- and inter-day imprecision for N = 6 samples were calculated with coefficients of variation of <3.1%. Method applicability was evaluated with biopsies of
esophageal mucosa (N = 14) yielding 5.6 ± 1.9 mg tissue and a mean adduct level of 6.13 ± 9.35 pmol HPB/mg DNA. 相似文献
8.
Maneerat Yodjun Aphichart Karnchanatat Polkit Sangvanich 《Applied biochemistry and biotechnology》2012,166(8):2037-2050
Ammonium sulphate cut protein extracts, and their pepsin hydrolysates, from the rhizomes of 15 plants in the Zingiberaceae
family were screened for their in vitro angiotensin I-converting enzyme inhibitory (ACEI) activity. The protein extract from
Zingiber ottensii had the highest ACEI activity (IC50 of 7.30 × 10−7 mg protein/mL) and was enriched for by SP Sepharose chromatography with five NaCl step gradients 0, 0.25, 0.50, 0.75 and
1 M NaCl collecting the corresponding five fractions. The highest ACEI activity was found in the F75 fraction, which appeared
to contain a single 20.7-kDa protein, suggesting enrichment to or near to homogeneity. The ACEI activity of the F75 fraction
was moderately thermostable (−20–60 °C), showed >80% activity across a broad pH range of 4–12 (optimal at pH 4–5) and appeared
as a competitive inhibitor of ACE (K
i of 9.1 × 10−5 mg protein/mL). For the pepsin hydrolysates, that from Zingiber cassumunar revealed the highest ACEI activity (IC50 of 0.38 ± 0.012 mg/mL), was enriched to a single active hexapeptide by RP-HPLC with a strong ACEI activity (IC50 of 0.011 ± 0.012 mg/mL) and acted as a competitive inhibitor of ACE (K
i of 1.25 × 10−6 mg protein/mL). 相似文献
9.
Chen Dong Xingfei Zheng Guolin Li Honglin Zhu Mingquan Zhou Zhongli Hu 《Applied biochemistry and biotechnology》2011,163(5):679-691
Two cytosolic copper–zinc superoxide dismutase (cytCuZnSOD) complementary deoxyribonucleic acid were achieved in Nelumbo nucifera (Elian). The active sites and common characteristics of cytCuZnSOD family were showed by homology modeling. The two recombinant
proteins expressed by PET-32a vector showed the similar SOD activity (89.94 ± 0.54 U/mg) and could maintain more than 90%
activity after incubation at 65°C. The subcellular location by green fluorescent protein revealed that these two isoforms
were all located in cytosol and nucleus. The cytCuZnSODs were expressed in various parts of N. nucifera, which were expressed highest in the leafstalks and young leaves and lowest in the roots. The cytCuZnSOD messenger ribonucleic acids isolated from wounded leaves significantly increased at 1.5 h after treatment (HAT) with the
highest expression at 3 HAT, after which the level decreased. 相似文献
10.
Wanwisa Moon-ai Ploypat Niyomploy Ruethairat Boonsombat Polkit Sangvanich Aphichart Karnchanatat 《Applied biochemistry and biotechnology》2012,166(8):2138-2155
Superoxide dismutase (SOD, EC 1.15.1.1) is a metalloenzyme or antioxidant enzyme that catalyzes the disproportionation of
the harmful superoxide anionic radical to hydrogen peroxide and molecular oxygen. Due to its antioxidative effects, SOD has
long been applied in medicinal treatment, cosmetic, and other chemical industries. Fifteen Zingiberaceae plants were tested
for SOD activity in their rhizome extracts. The crude homogenate and ammonium sulfate cut fraction of Curcuma aeruginosa were found to contain a significant level of SOD activity. The SOD enzyme was enriched 16.7-fold by sequential ammonium sulfate
precipitation, diethylaminoethyl cellulose ion exchange, and Superdex 75 gel filtration column chromatography. An overall
SOD yield of 2.51 % with a specific activity of 812.20 U/mg was obtained. The enriched SOD had an apparent MW of 31.5 kDa,
as judged by sodium dodecyl sulfate polyacrylamide gel electrophoresis, and a pH and temperature optima of 4.0 and 50 °C.
With nitroblue tetrazolium and riboflavin as substrates, the K
m values were 57.31 ± 0.012 and 1.51 ± 0.014 M, respectively, with corresponding V
max values of 333.7 ± 0.034 and 254.1 ± 0.022 μmol min−1 mg protein−1. This SOD likely belongs to the Fe- or Mn-SOD category due to the fact that it was insensitive to potassium cyanide or hydrogen
peroxide inhibition, but was potentially weakly stimulated by hydrogen peroxide, and stimulated by Mn2+and Fe2+ ions. Moreover, this purified SOD also exhibited inhibitory effects on lipopolysaccharide-induced nitric oxide production
in cultured mouse macrophage cell RAW 264.7 in a dose-dependent manner (IC50 = 14.36 ± 0.15 μg protein/ml). 相似文献
11.
Jaisson S Gorisse L Pietrement C Gillery P 《Analytical and bioanalytical chemistry》2012,402(4):1635-1641
Homocitrulline (HCit), an amino acid formed by the carbamylation of ε-amino groups of lysine residues, is considered a promising
biomarker for monitoring diseases such as chronic renal failure and atherosclerosis. This paper describes a tandem mass spectrometric
method for total, protein-bound and free HCit measurement in plasma samples. HCit was separated from other plasma components
by hydrophilic interaction liquid chromatography. Detection was achieved by monitoring transitions of 190.1 > 127.1 and 190.1 > 173.1
for HCit, and 183.1 > 120.2 for d7-citrulline used as internal standard. This method allowed HCit quantification within 5.2 min and was precise (inter-assay
CV < 5.85%), accurate (mean recoveries ranging from 97% to 106%), and exhibited a good linearity from 10 nmol/L to 1.6 μmol/L.
Plasma samples from control and uremic mice (n = 10) were analyzed. In control mice, mean total plasma HCit concentration was 0.78 ± 0.12 μmol/mol amino acids, whereas
it was increased 2.7-fold in uremic mice plasma, reaching 2.10 ± 0.50 μmol/mol amino acids (p < 0.001). In conclusion, this method exhibits good analytical performances and meets the criteria of sensitivity suitable
for HCit concentration assessment in plasma samples. 相似文献
12.
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
13.
Reiter EV Cichna-Markl M Chung DH Shim WB Zentek J Razzazi-Fazeli E 《Analytical and bioanalytical chemistry》2011,400(8):2615-2622
The paper presents a new sample clean-up method based on immuno-ultrafiltration for the analysis of ochratoxin A in cereals.
In contrast to immunoaffinity chromatography, in immuno-ultrafiltration, the antibodies are used in non-immobilised form.
Ochratoxin A was extracted with ACN/water (60/40, v/v), and the extract was loaded onto the ultrafiltration device. After a washing step with phosphate-buffered saline, containing
0.05% Tween 20, ochratoxin A was eluted with MeOH/acetic acid (99/1, v/v). The detection of ochratoxin A was carried out with high-performance liquid chromatography and a fluorescence detector coupled
to an electrochemical cell (Coring cell). The electrochemical cell was used to eliminate matrix interferences by oxidising
matrix compounds. The method was validated by repeatedly analysing spiked barley and rye samples as well as a certified wheat
reference material. Recoveries and standard deviations (1 SD) were found to be 71 ± 9%, 77 ± 12% and 77 ± 8% in wheat, barley
and rye, respectively. The limit of detection (S/N = 3) and limit of quantitation (S/N = 10) were determined to be 0.4 μg kg-1 and 1 μg kg-1. The analysis of the certified reference material resulted in ochratoxin A concentrations which were in the range assigned
by the producer. Additionally, the effect of the electrochemical cell on other widely used clean-up techniques, namely the
immunoaffinity clean-up and multifunctional columns (Mycosep #229), was evaluated. In all clean-up methods, an improvement
of the chromatogram quality was registered. 相似文献
14.
Silvia Castrignanò Sheila J. Sadeghi Gianfranco Gilardi 《Analytical and bioanalytical chemistry》2010,398(3):1403-1409
Human flavin-containing monooxygenases are the second most important class of drug-metabolizing enzymes after cytochromes
P450. Here we report a simple but functional and stable enzyme-electrode system based on a glassy carbon (GC) electrode with
human flavin-containing monooxygenase isoform 3 (hFMO3) entrapped in a gel cross-linked with bovine serum albumin (BSA) by
glutaraldehyde. The enzymatic electrochemical responsiveness is characterised by using well-known substrates: trimethylamine
(TMA), ammonia (NH3), triethylamine (TEA), and benzydamine (BZD). The apparent Michaelis–Menten constant (K′M) and apparent maximum current (I′max) are calculated by fitting the current signal to the Michaelis–Menten equation for each substrate. The enzyme-electrode has
good characteristics: the calculated sensitivity was 40.9 ± 0.5 mA mol−1 L cm−2 for TMA, 43.3 ± 0.1 mA mol−1 L cm−2 for NH3, 45.2 ± 2.2 mA mol−1 L cm−2 for TEA, and 39.3 ± 0.6 mA mol−1 L cm−2 for BZD. The stability was constant for 3 days and the inter-electrode reproducibility was 12.5%. This is a novel electrochemical
tool that can be used to investigate new potential drugs against the catalytic activity of hFMO3. 相似文献
15.
The strontium content of serum, bone, marrow, and teeth was determined by inductively-coupled plasma mass spectrometry (ICP–MS).
Significant correlations were obtained after the data were subjected to quality assurance (QA) performed according to validated
procedures. After four weeks of treatment with strontium malonate, strontium levels increased from 76 ± 9 μg g−1 in placebo-treated dogs to levels of 7.2 ± 1.7 mg g−1, 9.5 ± 2.7 mg g−1, and 9.8 ± 2.7 mg g−1 in groups treated with 300, 1000, and 3000 mg kg−1 day−1, respectively. Strontium induced a highly significant increase in the bone formation marker, bone-specific alkaline phosphatase
(BSAP), and an excellent correlation was found with the bone-strontium content. In females, the placebo-treated group showed
a decrease in BSAP of 53%, whereas the three strontium malonate-treated groups showed an increase of 60, 276, and 278% for
the groups treated with 300, 1000, and 3000 mg kg−1 day−1, respectively. For males the corresponding values were −44%, +142%, +194%, and +247% increases in BSAP in the placebo, 300,
1000, and 3000 mg kg−1 day−1 groups respectively. 相似文献
16.
To obtain extracellular and high-level expression of the Dictyoglomus thermophilum Rt46B.1 xylanase B gene, this gene was integrated into the α-amylase gene site of a host strain of Bacillus subtilis WB800. The extreme thermophile xylanase gene was successfully integrated and expressed in the host, measured at 24 ± 0.4 XUs/mL
in the Luria broth medium supernatant. The recombinant enzyme was purified by ammonium sulfate precipitation, anion exchange
chromatography, and gel filtration. The molecular mass and pI value of xylanase were estimated to be 24 kDa and 4.3, respectively. The optimal pH level and temperature of the purified
enzyme were 6.5 and 85 °C, respectively. Xylanase showed reasonable activity at temperatures up to 95 °C and remained stable
at 4 °C for 1 week. The purified enzyme retained most of its activity in 1 mM ethylenediaminetetraacetic acid or dithiothreitol
and 0.1% Tween-20 or Triton X-100. However, strong inhibition was observed in the presence of 5 mM Mn2+, 0.5% sodium dodecyl sulfate, Tween-20, or Triton X-100; a strong stimulating effect was also observed in the presence of
Fe2+. The K
m and V
max values of the recombinant xylanase for birchwood xylan were calculated to be 2.417 ± 0.36 mg/mL and 325 ± 41 μmol/min mg,
respectively. Xylanase was found to be useful in the prebleaching process of paper pulps. 相似文献
17.
Yi Wang Jian Zhao Jian-He Xu Li-Qiang Fan Su-Xia Li Li-Li Zhao Xiao-Bo Mao 《Applied biochemistry and biotechnology》2010,162(8):2387-2399
A lipase gene from Serratia marcescens ECU1010 was cloned into expression vector pET28a, sequenced, and overexpressed as an N terminus His-tag fusion protein in
Escherichia coli. Through the optimization of culture conditions in shake flask, the lipase activity was improved up to 1.09 × 105 U/l, which is a great improvement compared to our previous reports. It was purified to homogeneity by Ni-NTA affinity chromatography
with an overall yield of 59.4% and a purification factor of 2.4-fold. This recombinant lipase displayed excellent stability
below 30 °C and within the pH range of 5.0−6.8, giving temperature and pH optima at 40 °C and pH 9.0, respectively. The lipase
activity was found to increase in the presence of metal ions such as Ca2+, Cu2+, and some nonionic surfactants such as PEG series. In addition, among p-nitrophenyl esters of fatty acids with varied chain length, the recombinant lipase showed the maximum activity on p-nitrophenyl laurate (C12). Using racemic trans-3-(4′-methoxy-phenyl)-glycidyl methyl ester [(±)-MPGM] as substrate, which is a key chiral synthon for production of diltiazem,
a 50% conversion yield was achieved after 4 h in toluene–water (100 mM KPB phosphate buffer, pH 7.5) biphasic system (5:5 ml)
at 30 °C under shaking condition (160 rpm), affording (−)-MPGM in nearly 100% ee. The K
m and V
max values of the lipase for (±)-MPGM were 222 mM and 1.24 mmol min−1 mg−1, respectively. The above-mentioned features make the highly enantioselective lipase from Serratia marcescens ECU1010 a robust biocatalyst for practical use in large-scale production of diltiazem intermediate. 相似文献
18.
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
19.
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
20.
Herranz S Ramón-Azcón J Benito-Peña E Marazuela MD Marco MP Moreno-Bondi MC 《Analytical and bioanalytical chemistry》2008,391(5):1801-1812
Specific polyclonal antibodies against s-triazine herbicides were obtained by preparing immunogens coupling home-synthesized haptens derivatives of simazine (6-chloro-N-ethyl-N′-ethyl-1,3,5-triazine-2,4-diamine) to lysine groups of hemocyanin from keyhole limpets and bovine serum albumin carrier proteins.
Three highly sensitive rabbit antisera were obtained and evaluated with a battery of six enzyme tracers derived from triazine
structures in an optimized ELISA format. The antiserum As8 and the HRP-2f tracer, which yield the best assay sensitivity for
simazine (detection limit 0.11 ± 0.02 μg L−1, IC50 0.88 ± 0.04 μg L−1), were applied to the development of a sensitive flow-through immunoassay for the analysis of this herbicide. The automated
assay was based on a direct competitive immunosorbent assay and fluorescence detection. The optimized method presents an IC50 value of 0.35 ± 0.04 μg L−1 with a detection limit of 1.3 ± 0.9 ng L−1 and a dynamic range from 0.010 to 7.5 μg L−1 simazine. The generic nature of the antiserum was shown by good relative cross-reactivities with other triazines such as
atrazine (420%) or propazine (130%) and a lower response to terbutylazine (6.4%) and desethyl-atrazine (2.2%). No cross-reactivity
was obtained for nonrelated pesticides such as 2,4-dichlorophenoxyacetic acid or linuron and the assay could be applied as
a screening method for triazine herbicides. The total analysis time was 30 min per determination and the immunosensor could
be reused for more than 150 cycles without significant loss of activity. The immunosensor has been successfully applied to
the direct analysis of simazine in surface water samples at the nanogram per liter level. The results obtained by comparative
analysis of the immunosensor with a chromatographic procedure for triazines showed a close correspondence. 相似文献