Hasibe Yilmaz

Fatty acid composition and chemotaxonomic evaluation of species of Stachys

The fatty acid composition of the seed oil of 23 Stachys taxa was analysed by GC/MS. The main compounds were found to be linoleic (27.1–64.3%), oleic (20.25–48.1%), palmitic (4.3–9.1%), stearic (trace to 5.2%) and 6-octadecynoic (2.2–34.1%) acids. The latter compound could be used as a chemotaxonomic marker of the genus Stachys. A cluster analysis was performed for comparison and characterisation of the seed oil from Stachys species.

Validation of a GC-IDMS method for the metrologically traceable quantification of selected FAMEs in biodiesel

AbstractCurrent methods for the analysis of fatty acid methyl esters (FAMEs) in rapeseed oil-based biodiesel refer to operationally defined measurands, which is a practical solution for routine analysis. In this paper, a new method for the SI-traceable quantification of selected FAMEs in biodiesel and its validation are described. This method has the potential to be a reference method for applications requiring structurally defined measurands and traceability to the SI as it allows direct comparisons to well-characterised calibrants through the use of isotopically labelled analogues of the analytes as well as establishing a full uncertainty budget. The method is based on gas chromatography–isotope dilution mass spectrometry. Its performance is demonstrated through its implementation and validation in two independent laboratories and is shown to provide reliable and traceable results for selected FAMEs in biodiesel test samples.

Determination of taxanes by validated LC-MS/MS method in hazelnut collected from different regions and altitudes in Turkey

In this study, mass fractions of paclitaxel, cephalomannine, 10-DAB III and baccatin III in hazelnut were measured with new and validated LC-MS/MS method. Green outer nut husk and nutshell of Turkish hazelnut (Corylus colurna L.) were collected from Düzce, Trabzon, Adapazarı and Samsun at several altitudes during August and September in 2014. The target analytes were prepared using solid-liquid extraction and analysed by LC-MS/MS. High amount of baccatin III, used for synthesizing semi-synthetic paclitaxel, was found in the nutshells collected at 250-500 m altitude in Cumayeri district of Duzce. In the husk samples from Vakfıkebir district of Trabzon, the highest amount of baccatin III was obtained. The mass fractions of baccatin III in nutshell and husks were between 164.38-1020.85 μgkg-1 and 166.12-923.64 μgkg-1, respectively.

CCQM-K104 key comparison (avermectin B(1)a) on the characterization of organic substances for chemical purity

Under the Comite Consultatif pour la Quantite de Matiere (CCQM), a key comparison, CCQM-K104, was coordinated by the National Institute of Metrology (NIM). The comparison was designed to demonstrate a laboratorys performance in determining the mass fraction of the main component in a complex high purity organic material. Nine NMIs or DIs participated in the comparison. Eight participants reported their results. An additional impurity was resolved from the avermectin B1a peak and was tentatively identified as an unknown impurity by NMIA (National Measurement Institute (Australia)). It was subsequently identified by NIM as a diastereoisomer of avermectin B1a at the C-26 position. Final reference value (KCRV) = 924.63 mg/g, with uncertainty (k=1) = 3.89 mg/g, and expanded uncertainty = 8.97 mg/g. The degrees of equivalence with the avermectin B1a KCRV for each participant were reported. The measurement results and degrees of equivalence should be indicative of the performance of a laboratorys measurement capability for the purity assignment of organic compounds of high structural complexity (relative molecular mass range of 500 Da -1000 Da and low polarity (-log KOW ≤ -2).

Determination of neurotoxic agents as markers of common vetch adulteration in lentil by LC-MS/MS

Vicia sativa (common vetch), which contains β-cyanoalanine (BCA) and γ-glutamyl β-cyanoalanine (γGBCA) is used for adulteration of lentil and have neuro toxic effects on people and animals. Therefore the determination of BCA and γGBCA analytes in accurate and reliable manner has high importance for human and animal health. LC-IDMS/MS method has been developed and validated for quantitative analyses of β-cyanoalanine and 13C labeled BCA is used as an internal standard in γGBCA analysis. In order to validate the method, linearity, recovery, precision (repeatability), intermediate precision, limit of detection, and limit of quantification parameters were investigated. The correlation coefficient was found to be greater than 0.99 for both analytes. The recoveriess were determined as 95.8% for BCA and 97.4% for γGBCA. The relative expanded measurement uncertainties of β-cyanoalanine and γ-glutamyl-β-cyanoalanine were obtained as 4.6% and 5.8%, respectively with the coverage factor, k, is 2 and at 95% confidence level.