Determination of uric acid in human urine by capillary zone electrophoresis with indirect laser-induced fluorescence detection

A CZE with indirect LIF detection method was used for the determination of uric acid (UA) in human urine. UA and its coexisting analytes (i.e. hypoxanthine, xanthine and ascorbic acid) could be well separated within 4.5?min at a voltage of 25?kV with 25°C cartridge temperature in a running buffer composed of 5?mM sodium borate, 10% methanol (v/v) and 0.3?μM fluorescein sodium (apparent pH of the final mixed hydro-organic solution of sodium borate, methanol and fluorescein is 9.5). Under the optimum condition, the method has good linearity relationships (correlation coefficients: 0.9973-0.9987) with ranges of 25-500, 25-350, 25-250 and 25-300?μg/mL for hypoxanthine, ascorbic acid, xanthine and UA, respectively. The detection limits for the analytes were in the range of 0.29-0.90?μg/mL. The intra-day RSD values for migration times and peak areas were less than 0.43 and 3.27%, respectively. This method was applied to the quantitation of UA in human urine with recoveries in the range of 93.1-107.3%.     

Synthesis and crystal structures of two polymeric silver(I) complexes with polyamines and terephthalic acid

Two polymeric silver(I) complexes, [Ag₄(TAA)₂(TA)₂] · 2[Ag(TA)₂] (I) and [Ag₂(TA)(BA)] _n (II), where TAA is tris(2-aminoethyl)amine, TA is terephthalic acid, BA is butane-1,4-diamine, were synthesized and structurally characterized by elemental analyses and X-ray diffraction. Complex I consists of mononuclear [Ag(TA)₂] units and TA-bridged tetranuclear [Ag₄(TAA)₂(TA)₂] units, which are further linked via Ag…Ag interactions to form chains. In complex II, the silver atoms are linked by the TA and BA groups to form chains, which are further linked via Ag…Ag interactions to form layers. In both complexes, molecules are finally linked through intermolecular hydrogen bonds to form three-dimensional networks.     

Trace LC/MS/MS quantitation of 17β‐estradiol as a biomarker for selective estrogen receptor modulator activity in the rat brain

A sensitive LC/MS/MS method has been developed by derivatization of 17β‐estradiol (E2) with dansyl chloride to quantitate 17β‐E2 in female rat serum. The use of E2‐d₅ minimized interferences from endogenous 17β‐E2 in order to achieve a limit of quantitation (LOQ) of 2.5 pg/ml using 150 µl of female rat serum. The recovery of the dansyl derivative was 95% or greater in quality control samples. The intra and interday assay precision was better than 8.2 and 6.2%, respectively, with accuracies ranging from 97 to 101% in the quality control samples. The assay was used for the quantitation of serum E2 as a biomarker for the estrogen receptor (ER) antagonist activity of small molecule SERMs (selective estrogen receptor modulators) in the female rat brain. The study revealed that a statistically significant upregulation of serum 17β‐E2 occurred for rats dosed with SERMs that are known to penetrate the brain and disrupt the hypothalamic‐pituitary‐ovarian (HPO) axis. Variations in 17β‐E2 in ascending dose studies also correlated with the corresponding trends in CYP17a1 levels, an mRNA biomarker for ovarian hyperstimulation. This biomarker assay has provided a useful screen for medicinal chemistry optimization to produce SERMs that do not interfere with negative feedback of estrogens on the brain and for biological hypothesis testing. Copyright © 2009 John Wiley & Sons, Ltd.     

Characterization of an exception to the ‘even‐electron rule’ upon low‐energy collision induced decomposition in negative ion electrospray tandem mass spectrometry

Electrospray‐generated precursor ions usually follow the ‘even‐electron rule’ and yield ‘closed shell’ fragment ions. We characterize an exception to the ‘even‐electron rule.’ In negative ion electrospray mass spectrometry (ES‐MS), 2‐(ethoxymethoxy)‐3‐hydroxyphenol (2‐hydroxyl protected pyrogallol) easily formed a deprotonated molecular ion (M‐H)^? at m/z 183. Upon low‐energy collision induced decomposition (CID), the m/z 183 precursor yielded a radical ion at m/z 124 as the base peak. The radical anion at m/z 124 was still the major fragment at all tested collision energies between 0 and 50 eV (E_lab). Supported by computational studies, the appearance of the radical anion at m/z 124 as the major product ion can be attributed to the combination of a low reverse activation barrier and resonance stabilization of the product ions. Furthermore, our data lead to the proposal of a novel alternative radical formation pathway in the protection group removal of pyrogallol. Copyright © 2009 John Wiley & Sons, Ltd.     

Ultrasensitive nucleic acid detection using confocal laser scanning microscope with high crystalline silver dendrites

A new kind of silver micro-dendrites with no surfactants protected has been synthesized for the separation and detection of DNA merely by earth gravity as the density of silver is larger than that of water. Through this approach, the DNA of human T-lymphotropic virus type I (HTLV-I) can be detected down to 10 pM with the detection range from 10 pM to 100 nM.     

Near infrared spectroscopy of stearic acid adsorbed on montmorillonite

The adsorption of stearic acid on both sodium montmorillonites and calcium montmorillonites has been studied by near infrared spectroscopy complimented with infrared spectroscopy. Upon adsorption of stearic acid on Ca–Mt additional near infrared bands are observed at 8236 cm^?1 and is assigned to an interaction of stearic acid with the water of hydration. Upon adsorption of the stearic acid on Na–Mt, the NIR bands are now observed at 5671, 5778, 5848 and 5912 cm^?1 and are assigned to the overtone and combination bands of the CH fundamentals. Additional bands at 4177, 4250, 4324, 4337, 4689 and 4809 cm^?1 are attributed to CH combination bands resulting from the adsorption of the stearic acid. Stearic acid is used as a model molecule for adsorption studies. The application of near infrared spectroscopy to the study of this adsorption proved most useful.     

An effective sequence characterized amplified region‐PCR method derived from restriction site‐amplified polymorphism for the identification of female Schistosoma japonicum of zoonotic significance

In the present study, restriction site‐amplified polymorphism (RSAP) markers were used to examine the genetic variability of Schistosoma japonicum isolates from different endemic provinces in mainland China. Of the 45 pairs of primers screened, 10 RSAP markers showed a clear banding pattern with good resolution; however, only six exhibited a polymorphism among different isolates. Among six RSAP markers, one pair of primers (R8+R10) was able to differentiate male and female parasites, and amplified one constant specific band for female S. japonicum isolates. The specific band was recovered, re‐amplified and sequenced, and a sequence of 162 bp was obtained. Based on this sequence, a pair of specific primers was designed and used to develop sequence characterized amplified region (SCAR)‐PCR assay for identification and differentiation of female S. japonicum isolates. The SCAR‐PCR assay allowed the specific identification of female S. japonicum, with no amplicons being amplified from male S. japonicum, Fasciola hepatica, Clonorchis sinensis, S. mansoni (male and female parasite). DNA sequencing confirmed the identity of the amplified products. The minimum amount of DNA detectable using SCAR‐PCR assay was 0.3 ng for female S. japonicum. The SCAR‐PCR was able to differentiate effectively the male and female S. japonicum worms collected from 12 geographical origins in eight endemic provinces, the gender of which was known based on the morphological and biological features. These results showed that SCAR‐PCR provides an effective tool for the sex differentiation studies of S. japonicum, identification of female S. japonicum, diagnosis and epidemiological survey of S. japonicum infections in animals and human.     

An automated instrument for human STR identification: design, characterization, and experimental validation

The microfluidic integration of an entire DNA analysis workflow on a fully integrated miniaturized instrument is reported using lab‐on‐a‐chip automation to perform DNA fingerprinting compatible with CODIS standard relevant to the forensic community. The instrument aims to improve the cost, duration, and ease of use to perform a “sample‐to‐profile” analysis with no need for human intervention. The present publication describes the operation of the three major components of the system: the electronic control components, the microfluidic cartridge and CE microchip, and the optical excitation/detection module. Experimental details are given to characterize the level of performance, stability, reliability, accuracy, and sensitivity of the prototype system. A typical temperature profile from a PCR amplification process and an electropherogram of a commercial size standard (GeneScan 500?, Applied Biosystems) separation are shown to assess the relevance of the instrument to forensic applications. Finally, we present a profile from an automated integrated run where lysed cells from a buccal swab were introduced in the system and no further human intervention was required to complete the analysis.     

Efficient synthesis of natural polyphenolic stilbenes: resveratrol, piceatannol and oxyresveratrol

The practical synthesis of important natural polyphenolic stilbenes, including resveratrol, piceatannol and oxyresveratrol, through Perkin methodology is described. Starting from 3,5-dihydoxyacetophenone (1), the common intermediate 3,5-dimethoxyphenylacetic acid (3) can be obtained via methylation and Willgerodt-Kindler reaction. Perkin condensations between (3) and substituted phenylaldehydes 4 furnished E-2,3-diarylacrylic acids 5, followed by decarboxylation in Cu/quinoline giving stilbene intermediates 6 which bear the Z-configuration. Finally, through a simultaneous demethylation/isomerization process in AlI?/CH?CN system, the target compounds 7a-c can be obtained respectively in good to high overall yields. The synthetic method proved to be more concise, trans-specific, mild, economical and commonly applicable.