Simple and reliable method to simultaneously determine urinary 1- and 2-naphthol using in situ derivatization and gas chromatography-mass spectrometry for biological monitoring of naphthalene exposure in occupational health practice.

OBJECTIVES: The aim of this study was to develop and validate a simple and reliable gas chromatography-mass spectrometry (GC-MS) method to simultaneously determine urinary 1-naphthol (1-NAP) and 2-naphthol (2-NAP) for biological monitoring of occupational exposure to naphthalene. METHODS: NAPs were derivatized in situ with acetic anhydride after enzymatic hydrolysis, extracted with n-hexane, and analyzed using GC-MS. Validation of the proposed method was conducted in accordance with US Food and Drug Administration guidance. A final validation was performed by analyzing a ClinChek® -Control for phenolic compounds. RESULTS: The linearity of calibration curves was indicated by a high correlation coefficient (>0.999) in the concentration range 1-100 µg/L for each NAP. The limits of detection and quantification for each NAP were 0.30 and 1.00 µg/L, respectively. The recovery was 90.8%-98.1%. The intraday and interday accuracies, expressed as the deviation from the nominal value, were 92.2%-99.9% and 93.4%-99.9%, respectively. The intraday and interday precision, expressed as the relative standard deviation, was 0.3%-3.9% and 0.4%-4.1%, respectively. The ClinChek® values obtained using our method were sufficiently accurate. CONCLUSIONS: The proposed method is simple, reliable, and appropriate for routine analyses, and is useful for biological monitoring of naphthalene exposure in occupational health practice.

A Simple and Robust Method for Determination of Alkylmercury in Seawater and Industrial Wastewater by Phenylation Pretreatment Combined with GC-MS.

For determination of methylmercury (MeHg) and ethylmercury (EtHg) in seawater and industrial wastewater, a simple and robust analytical method was developed based on phenylation and solvent extraction followed by GC-MS measurement. Alkylmercury compounds were directly phenylated with sodium tetraphenylborate in water and extracted into toluene. The method detection limits obtained for MeHg and EtHg in pure water were 53.3 and 33.5 ng Hg L-1, respectively, which are almost 10 times lower than the environmental quality standards for water pollution in Japan (EQSJ): 0.5 µg Hg L-1. The recoveries of alkylmercury compounds from seawater and four kinds of industrial wastewater except for EtHg from treated wastewater of an optic lens factory were satisfactory (>90%) at 1- or 4-fold concentrations of the EQSJ. Contrarily, the low recovery of EtHg from the treated wastewater (75.4 ± 4.7%) was found to be caused by the rapid decomposition of EtHg into inorganic mercury.

Stereocontrolled synthesis of oligoribonucleoside phosphorothioates by an oxazaphospholidine approach.

Oligoribonucleoside phosphorothioates (PS-ORNs) stereodefined at the phosphorus atoms were synthesized on solid support. Thermal denaturating experiments of the resultant PS-ORNs showed that a backbone consisting of (Sp)-PS-linkages as well as stereorandom PS-linkages had an unexpectedly large destabilizing effect on a PS-ORN-ORN duplex, whereas a backbone consisting of (Rp)-PS-linkages slightly stabilized a duplex.

Chemical synthesis and properties of stereoregulated phosphorothioate RNAs.

Stereoregulated oligoribonucleoside phosphorothioates were synthesized by the use of 2'-O-TBDMS-protected ribonucleoside 3'-O-oxazaphospholidine derivatives as monomers and N-(cyanomethyl)ammonium salts as activators. Diastereoselectivity of the condensation reaction was found to be highly dependent on the substituent groups of the oxazaphospholidine ring as well as the structure of the activators. By the use of the optimized oxazaphospholidine monomers and activators, stereoregulated oligoribonucleoside phosphorothioates containing four kinds of nucleobases were synthesized in good yields. Hybridization properties of thus obtained oligomers with the complementary RNAs were evaluated by the UV melting experiments.