Sample Preparation Solvent Research Articles

Method for the determination of dialkyl phosphates in urine by strong anion exchange disk extraction and in-vial derivatization.

A method for the determination of four dialkylphosphate metabolites in urine by strong anion exchange disk (SAX) was investigated. Calcium hydroxide was added to a 1-mL urine sample to reduce interference. The aliquot was passed through the SAX disk to accumulate dialkylphosphate metabolites on the disk. The retained dialkylphosphate metabolites were derivatized with methyl iodide in acetonitrile online, and the resulting methyl esters of dialkylphosphate metabolites were directly analyzed by capillary column gas chromatography with flame photometric detection. The recoveries of these dialkylphosphate metabolites were found to be stable. When the intact sample was diluted with deionized water at a 1:1 ratio, the recoveries were both increased and stabilized. The urine samples collected from eight fruit farmers showed that levels of dialkylphosphate metabolites in urine were significantly different before and after pesticide application, indicating the method established in this study is applicable for real sample analysis. Compared with previous studies, this method not only can greatly simplify sample preparation, but it can also significantly reduce the consumption of toxic solvents in sample preparation.

Degradation products generated by sonication of benzyl alcohol, a sample preparation solvent for the determination of residual solvents in pharmaceutical bulks, on capillary gas chromatography.

Benzyl alcohol used as the sample preparation solvent in the determination of residual solvents in pharmaceutical bulks yielded benzene, toluene, and benzaldehyde on capillary gas chromatography (GC) by sonication. The factors responsible for compounds generated are discussed. The quality of benzyl alcohol and the type of sonicator were not involved in the generation of benzene, toluene, and benzaldehyde, whereas matrix contributions were observed. The degradation profiles of benzyl alcohol and its analogous compounds obtained by pyrolysis-GC/mass spectrometric analysis were similar to those obtained by sonication, suggesting that benzyl alcohol is degraded by the high local heat generated by sonication. Consequently, no matter how long it may take to dissolve bulk substances in benzyl alcohol completely, we do not recommend the use of a sonicator in sample preparation for the determination of residual solvents in pharmaceutical bulks.

Separation of Chlorhexidine Breakdown Products Including 4-Chloroaniline in Surgical Scrubs Containing Chlorhexidine

Abstract Chlorhexidine is an effective antimicrobial agent used in surgical hand scrubs and patient pre-operative preps for skin disinfection. As these solutions age, chlorhexidine degrades to produce breakdown products including 4-chloroaniline. The determination of 4-chloroaniline is usually carried out by a cleanup protocol using chlorinated solvents for sample preparation and by gas chromatography for analysis. This procedure is tedious and requires special precautions.(2) Current HPLC methods(3–4) are unable to analyze the chlorhexidine breakdown products in surgical scrub solutions which contain surfactants, gelling agents, etc., that give rise to complications in the resolution of peaks. The method reported here overcomes these problems while preserving the overall simplicity of the current HPLC methods. The 4-chloroaniline peak is clearly resolved from the peaks of the other breakdown products.

A sensitive high performance liquid chromatography microassay for bemoradan, a novel cardiotonic agent, in plasma/serum using a semi‐automatic liquid/solid extraction sample preparation system—AASP®

A high performance liquid chromatographic method for the measurement of bemoradan levels in plasma/serum is described. This method uses Varian's AASP (Varian Associates, Sunnyvale, CA, USA), a semi-automatic liquid/solid extraction sample preparation system. It requires only small volumes of plasma/serum samples (0.2-1 mL) and needs no organic solvent for sample preparation. The mean recovery of bemoradan at plasma or serum concentrations of 0.5-100 ng/mL is 82%. The assay has a detection limit of 0.5 ng/mL (when 1 mL of plasma/serum is used) and is linear in the concentration range 0.5-500 ng/mL.

Validation of High-Performance Liquid Chromatographic Methods for Analysis of Sustained-Release Preparations Containing Nitroglycerin, Isosorbide Dinitrate, or Pentaerythritol Tetranitrate

□ The assay of sustained-release tablets or capsules containing nitroglycerin, isosorbide dinitrate, or pentaerythritol tetranitrate by high-performance liquid chromatography is described. Acetonitrile was found to be the sample preparation solvent with the most general applicability to these products. Anisole was used as an internal standard for nitroglycerin and pentaerythritol tetranitrate, while 4-chloroacetanilide was used for isosorbide dinitrate. The method, which uses a C18 bonded-phase column, a methanol–water mobile phase, and 214-nm detection, was shown to be accurate, linear, and reproducible.