Shihn-Sheng Wu

Chemically removable derivatization reagent for liquid chromatography : 2-(2-naphthoxy)ethyl 2-[1-(4-benzyl)piperazyl]ethanesulfonate

Abstract A new sulfonate reagent, 2-(2-naphthoxy)ethyl 2-[1-(4-benzyl)-piperazyl]ethanesulfonate, was synthesized for analytical derivatization in liquid chromatography. The reagent consists of two main moieties, i.e., one with a fluorophore (naphthoxy) for sensitive detection after being tagged to an analyte; and the other with a tertiary amino function (a substituted piperazine) that can be removed after derivatization by acid treatment. The reagent was applied to the derivatization of caproic acid as a model analyte. The resulting derivative was analyzed by high-performance liquid chromatography with fluorometric detection. The linear range of the method for the determination of caproic acid was over 0.01–0.5 nmol, with a detection limit (signal-to-noise ratio=3) of about 0.1 pmol. The excess reagent was readily removed from organic solvent after treatment with an aqueous acid solution.

Chiral separation of acebutolol by derivatization and high-performance liquid chromatography

Abstract A simple and specific high performance liquid chromatographic (HPLC) method is described for the determination of R-(+)- and S-(−)acebutolols. The method is based on the derivatization of the hydroxyl and amino functions of acebutolol with N-benzyloxycarbonyl-L-phenyl-alanine and acetic anhydride, respectively. The resulting derivatives were separated on a reversed phase C-18 column and monitored with a UV detector, leading to a base line resolution of the diastereomeric derivatives of S-(−) and R-(+) acebutolols.

A Bayesian Approach to Identifying New Risk Factors for Dementia: A Nationwide Population-Based Study.

AbstractDementia is one of the most disabling and burdensome health conditions worldwide. In this study, we identified new potential risk factors for dementia from nationwide longitudinal population-based data by using Bayesian statistics.We first tested the consistency of the results obtained using Bayesian statistics with those obtained using classical frequentist probability for 4 recognized risk factors for dementia, namely severe head injury, depression, diabetes mellitus, and vascular diseases. Then, we used Bayesian statistics to verify 2 new potential risk factors for dementia, namely hearing loss and senile cataract, determined from the Taiwans National Health Insurance Research Database.We included a total of 6546 (6.0%) patients diagnosed with dementia. We observed older age, female sex, and lower income as independent risk factors for dementia. Moreover, we verified the 4 recognized risk factors for dementia in the older Taiwanese population; their odds ratios (ORs) ranged from 3.469 to 1.207. Furthermore, we observed that hearing loss (OR = 1.577) and senile cataract (OR = 1.549) were associated with an increased risk of dementia.We found that the results obtained using Bayesian statistics for assessing risk factors for dementia, such as head injury, depression, DM, and vascular diseases, were consistent with those obtained using classical frequentist probability. Moreover, hearing loss and senile cataract were found to be potential risk factors for dementia in the older Taiwanese population. Bayesian statistics could help clinicians explore other potential risk factors for dementia and for developing appropriate treatment strategies for these patients.

Determination of Methanol by 4-[N-Methyl, N-(1-naphthylmethyl)]-amino-4-oxo-butanoic Acid in Presence of 4-Dimethylaminopyridine and 1-Ethyl-3-(3-dimethylaminopropyl) Carbodiimide Hydrochloride as Catalysts

Abstract High performance liquid chromatography (HPLC) with chemically removable derivatizing reagents for the analysis of methanol has been developed. Methanol was derivatized with 4-[N-methyl, N-(1-naphthylmethyl)]-amino-4-oxo-butanoic acid (NAOB), using 4-dimethylaminopyridine (DMAP) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) as activators. NAOB and the activators are chemically removable and can be removed by aqueous base and acid treatment after derivatization to minimize reagent interference in chromatography. The method can simultaneously determine methanol, ethanol and 1-propanol. The proposed HPLC method was validated for linearity, specificity, accuracy and reproducibility. The method was applied to the analysis of methanol spiked in Ipecac fluid extract with a satisfactory recovery (>95%).

Trace analysis of acetaldehyde as fluorogenic derivative by high performance liquid chromatography.

A sensitive method is described for the determination of acetaldehyde as a fluorogenic derivative of decahydroacridin-1,8-dione by high performance liquid chromatography. The analytical derivatization is based on the reaction of acetaldehyde in an acidic aqueous system with 1,3-cyclohexanedione and ammonium acetate. The resulting derivative was separated by a reversed-phase C-18 column and monitored with a fluorescent detector (lambda ex, 375nm; lambda em, 512nm). Several parameters affecting the derivatization of acetaldehyde were studied. The linear range of the method for the quantitation of acetaldehyde was between 20 and 800 pmol in aqueous sample (0.5 mL). Application of the method to the analysis of acetaldehyde in plasma was performed.