Sensitive determination of methomyl in blood using gas chromatography-mass spectrometry as its oxime tert.-butyldimethylsilyl derivative

Determination of methomyl in the stomach contents of baited wildlife by gas chromatography–mass spectrometry

The poisoning of wildlife with fly-bait containing the active ingredient methomyl is an intentional and illegal act in many jurisdictions. A case of 2 animals poisoned by methomyl through consumption of tainted bait at multiple stations is described. Although thermally and ultraviolet-labile, methomyl can be identified by gas chromatography–mass spectrometry and is detected in abundance in bait samples; however, it is not readily observed in tissues, owing to its rapid metabolism and elimination. The application of derivatizing functionalities, such as trimethylsilyl groups, stabilizes the methomyl-oxime metabolite to facilitate its detectability during exposure to the relatively harsh conditions of gas chromatography. This brief communication reports on the analytical detection of methomyl in baits and biological samples from poisoned wildlife. Essential to the case were the added determination of a fly-bait coactive ingredient, ( Z)-9-tricosene, and identification of a chemical indicator, caffeine, to confirm both the type of pesticide product involved in the poisoning incident and the vehicle used to perpetrate its delivery.

Quantitative analysis of PD 0332991 in xenograft mouse tumor tissue by a 96-well supported liquid extraction format and liquid chromatography/mass spectrometry

Phase II attrition of clinical candidates in the drug development cycle is currently a major issue facing the pharmaceutical industry. To decrease phase II attrition, there is an increased emphasis on validation of mechanism of action, development of efficacy models and measurement of drug levels at the site of action. PD 0332991, a highly specific inhibitor of cyclin-dependent kinase 4 (CDK-4) is currently in clinical development for the treatment of solid tumor. A clinical presurgical study will be required to better understand how PD 0332991 affects signaling pathways and how the intratumoral concentration of PD 0332991 correlates with plasma PK parameters and molecular alterations in breast cancer tissues after PD 0332991 treatment. Before conducting such a clinical study, it is important to evaluate PD 0332991 levels in tumor tissue samples from a xenograft mouse model for the determination of drug exposure at the site of action. Therefore, the objectives of this study were (1) to develop and validate a sensitive LC-MS/MS method to quantify PD 0332991 in mouse tumor tissues from MDA-MB-231-Luc human breast tumor xenografts in SCID-beige mice; (2) to quantify PD 0332991 levels in mouse tumor tissues after oral administration of PD 0332991 at 10 and 100mg/kg using the validated LC-MS/MS method. Both liquid-liquid extraction (LLE) and supported liquid extraction (SLE) in a 96-well format were developed and evaluated to achieve optimal extraction recovery with minimal matrix effects. The newly developed SLE method is more efficient (speed and ease) and demonstrates comparable recovery (93.1-100% at three different concentrations) compared to the traditional LLE method. The validated LC-MS/MS for PD 032291 in mouse tumor tissue homogenate method exhibited a linear dynamic range of 0.1-100 ng/mL with inter-day accuracy and precision within 15%. The validated method was successfully applied to measure PD 0332991 levels in tumor tissues in MDA-MB-231-Luc human breast tumor xenografts in SCID beige mice. The mean tumor concentrations at 6h post-oral PD 0332991 administration at 10 and 100mg/kg were 1793 (+/-1008) and 25,163 (+/-3959) ng/g, respectively.

Simple and sensitive determination of free and total morphine in human liver and kidney using gas chromatography-mass spectrometry

We developed a reliable, simple and sensitive method to determine free and total morphine in human liver and kidney, using gas chromatography-mass spectrometry (GC-MS). Free morphine or total morphine obtained by acid hydrolysis from 0.2g tissue sample was extracted using an Extrelut NT column with an internal standard, dihydrocodeine, followed by trimethylsilylation. The derivatized extract was submitted to GC-MS analysis of EI-SIM mode. The calibration curves of morphine in both liver and kidney samples were linear in the concentration range from 0.005 to 5 microg/g. The lower limits of detection of morphine were 0.005 microg/g. This method proved successful when we determined free and total morphine in liver and kidney obtained from an autopsied man who was mis-ingested morphine compound in the hospital, which resulted in the cause of death being morphine intoxication.

Sensitive determination of alpha-methyltryptamine (AMT) and 5-methoxy-N,N-diisopropyltryptamine (5MeO-DIPT) in whole blood and urine using gas chromatography–mass spectrometry

We devised a sensitive and simple method to determine alpha-methyltryptamine (AMT) and 5-methoxy-N,N-diisopropyltryptamine (5MeO-DIPT) in whole blood and urine, using gas chromatography-mass spectrometry (GC-MS). AMT and 5MeO-DIPT were extracted using an Extrelut column with an internal standard, bupivacaine, followed by derivatization with acetic anhydride. The derivatized extract was used for GC-MS analysis of EI-SIM mode. The calibration curves of AMT and 5MeO-DIPT were linear in the concentration range from 10 to 750 ng/ml in both blood and urine samples. The method detection limit (MDL) of AMT and 5MeO-DIPT were 1 ng/ml each in whole blood and 5 ng/ml each in urine. This method should be most useful to accurately determine the presence of these drugs in blood and urine in clinical and forensic cases.

Review: derivatization in mass spectrometry--5. Specific derivatization of monofunctional compounds

The present paper is complementary to the foregoing reviews and describes some additional methods of the derivatization of particular functional groups mainly to enhance the structural information content of electron ionization and chemical ionization mass spectra. Derivatization approaches for the modification of unsaturated compounds, alcoholic, carboxylic, carbonyl, amine and other functional groups, are discussed. Derivatization for separation and quantitative determination of chiral enantiomeric compounds is also considered. Preliminary chemical and physicalchemical degradation for structure elucidation of high molecular weight compounds (biopolymers, synthetic polymers) is mentioned. Chemical aspects of derivatizations and characteristic mass spectral features of derivatives are described briefly. Some particular applications of chemical modification, in conjunction with mass spectral measurements for the analysis of various important bioorganic compounds and compounds in biological fluids, air, environmental etc., are considered.