Single Ion Monitoring Mode Research Articles

Determination of lactose in milk products: a comparison of three-enzyme amperometric biosensor and gas chromatography/tandem mass spectrometry

Two completely different analytical methods for lactose determination are presented. Three-enzyme biosensor involving β-galactosidase, glucose oxidase, and horseradish peroxidase was constructed with successive steps of optimization. Primary experiments were carried out with horseradish peroxidase biosensor in solution of hydrogen peroxide. Addition of poly(ethylene glycol) diglycidyl ether was examined and the best constant potential for chronoamperometric experiments was selected at −0.05 V using cyclic voltammetry. Ferrocene was chosen as the best from three tested mediators and optimum concentration of ferrocene was found out at 2 g dm−3. Two electrode materials were compared. Spectroscopic graphite electrode proved better electrochemical response for its twice larger electro-active surface than screen-printed carbon electrode. Phosphate buffer solution of pH 7.5, at which the three-enzyme system provided the highest current signal, was used for lactose determination in milk, milk powder, curd cheese, and yogurt. Gas chromatography with tandem mass spectrometric detection was used for determination of lactose, glucose, and galactose in the real samples with internal standard salicine using single ion monitoring mode. Determined content of lactose in the milk products was compared with declared values. Gas chromatography with tandem mass spectrometric detection offers higher sensitivity and orthogonal selectivity in comparison to enzyme biosensor.

An assessment of different extraction and quantification methods of penta- and hexa-chlorobenzene from SRF fly-ash

Highly chlorinated benzenes, produced in the presence of organic matter and chlorine, are considered PCDD/Fs precursors, and are used as cost and time convenient substitute indicators for the indirect measurement of the latter. In this study penta- and hexa-chlorobenzene are quantified for the determination of the organochloride load of fly ash from solid recovered fuel incineration. Some of the chlorobenzenes are formed under ‘de novo’ conditions, through heterogeneous (ash particles/flue gases) reactions and are therefore deeply incorporated within fly ash. Accelerated solvent extraction (ASE) and ultrasonic solvent extraction (USE), along with the equivalent clean-up methods suggested by literature were compared to traditional Soxhlet. The extraction efficiencies achieved were 83 ± 7.5% for Soxhlet, 111 ± 19% for PFE, and 67 ± 17% for ultrasonication. Soxhlet extraction and clean-up through a multilayer silica gel column gave more precise results compared to the other sample preparation methods. Furthermore, performance comparison of gas chromatography fitted with either a mass spectrometer operated in single ion monitoring mode (GC-MS-SIM), or electron capture detector (GC- ECD) highlighted that ECD can be used for measuring chlorobenzenes traces down to 0.21 ng g−1, when the equivalent LOQ for MS-SIM was 3.26 ng g−1. The results further suggest that ECD can provide better peak integration than MS-SIM in the detection of chlorobenzenes in fly ash extracts, due to the detector's sensitivity to halogenated compounds.

Optimization of QuEChERS sample preparation method for acrylamide level determination in coffee and coffee substitutes

Modification of QuEChERS sample preparation method for the determination of acrylamide (2-propeneamide, AA) in coffee (roasted and instant) and coffee substitutes via silylation has been reported. The AA level after conversion to N,O-bis-(trimethylsilyl)acrylamide (BTMSA) was determined with gas chromatography/ion-trap mass spectrometry in a single ion monitoring mode (GC-SIM-MS). A sample of instant coffee was used to develop an analytical method in the optimisation experiment, which involved the selection of the most suitable sorbents for the dispersive solid phase extraction (d-SPE) clean-up. The usefulness of the method has been verified based on the recovery ratio of acrylamide (fortified samples analysis). Seven variants of the method were tested. The obtained results showed that the best recovery of 95% was obtained using a combination of PSA and SAX sorbents with the addition of hexane in the initial step of extraction. The chosen method was applied for the AA determination in 17 roasted, 10 instant and 8 coffee substitutes samples. The results of acrylamide content ranged from 17.7±1.4 to 776.1±8.8μgkg−1 in roasted coffee, from 96.4±1.7 to 346.5±10.9μgkg−1 in the case of instant coffee, and finally from 70.0±6.0 to 188.9±0.1μgkg−1 in the samples of coffee substitutes. The obtained results are in good agreement with previous literature reports.

A Sensitive Precolumn Derivatization Method for Determination of Piperazine in Vortioxetine Hydrobromide Using a C8 Column and High-Performance Liquid Chromatography-Mass Spectrometry.

A rapid and sensitive high-performance liquid chromatography-mass spectrometry method was established to determine the trace residues of piperazine in vortioxetine hydrobromide. The presence of piperazine was determined by precolumn derivatization with dansyl chloride. Chromatographic separation was performed on a Waters SunFire C8 column (150 × 4.6 mm, 3.5 μm) in gradient elution mode, using formic acid and acetonitrile as mobile phase. Detection was performed in a single quadrupole mass spectrometer in single ion monitoring mode using positive ionization. An m/z value of 553 was selected for monitoring disubstituted piperazine by DNS-Cl. Linearity, accuracy, and precision were found to be acceptable over the piperazine concentration range of 0.3525 - 2.35 ng mL-1. The limit of detection and limit of quantification of piperazine were 0.1175 and 0.3525 ng mL-1, respectively, which complied with the requirements of qualitative and quantitative analyses. The method was deemed sensitive and efficient.

Liquid chromatography-high-resolution mass spectrometry for regulated bioanalysis: bile acid and oligonucleotide quantitation as a reference.

Liquid chromatography-high-resolution mass spectrometry for regulated bioanalysis: bile acid and oligonucleotide quantitation as a reference.

Occurrence of 4‐methoxy‐2‐methyl‐2‐butanethiol in blackcurrant (Ribes nigrum L.) berries

Abstract4‐Methoxy‐2‐methyl‐2‐butanethiol is a powerful sulfur‐containing aroma compound identified several decades ago in blackcurrant buds (Ribes nigrum L.). However, an unambiguous identification in blackcurrant fruits has been lacking. In this study the occurrence of 4‐methoxy‐2‐methyl‐2‐butanethiol in blackcurrant berries has been demonstrated for the first time by the analysis of seven cultivars. After isolation of the volatiles by vacuum‐headspace‐extraction, the sulfur‐containing compound was enriched on mercurated agarose gel. Identification was performed via capillary gas chromatography/mass spectrometry. Quantitation was performed in the single ion monitoring mode using 4‐methyl‐4‐sulfanylpentan‐2‐one as internal standard. The concentration of 4‐methoxy‐2‐methyl‐2‐butanethiol in Andega (4.5 µg/kg) was significantly higher than those in the other cultivars investigated in this study (from 0.16 to 0.72 µg/kg). Calculation of the odour activity values indicated that this sulfur‐containing volatile contributes to the aroma of blackcurrant berries. Copyright © 2016 John Wiley & Sons, Ltd.

Absorption and pharmacokinetic study of two sulphated triterpenoid saponins in rat after oral and intravenous administration of saponin extracts of Pearsonothuria graeffei by HPLC-MS

Echinoside A (EA) and holothurin A (HA) are the major saponins found in sea cucumbers. Their pharmacokinetics were studied following intravenous and oral administration of saponin extracts in rats. The serum and liver of rat were pretreated by protein precipitation and performed on ENVI-18 SPE cartridges. The compounds were analyzed by using a high-performance liquid chromatography–mass spectrometry (HPLC-MS) method in the single ion monitoring (SIM) mode. The results demonstrated that serum EA concentration rapidly reduced in 5 min after intravenous administration. HA serum concentration reduced to its lowest level after 1 h. After oral administration, EA reached its peaks at 3 h and 7 h. The first peak of HA occurred at 3 h and reached a second peak at 9 h. In the liver, there were two peaks for EA at 2 h and 9 h, and only one peak for HA at 9 h.

Erratum to: A High-Resolution LC–MS/MS Method for the Quantitative Determination of Artemether and Its Metabolite Dihydroartemisinin in Human Plasma and Its Application to Pharmacokinetic Studies

A highly sensitive and rapid liquid chromatography–tandem mass spectrometry method was developed and validated for the determination of artemether and its metabolite dihydroartemisinin in human plasma using artemisinin as an internal standard. Chromatographic separation was achieved on a Supelco Discovery HS C18 RP column (150 mm × 4.6 mm, 5 µm; Bellefonte, USA) using acetonitrile and water with 0.1 % formic acid (80:20, v/v) as a mobile phase in isocratic mode. A high-resolution Thermo Electron Corporation LTQ-Orbitrap mass spectrometer (San Jose, USA) was used in single ion monitoring (SIM) mode using atmospheric pressure chemical ionization (APCI) as an interface. The following extracted ion ranges ([M + H]+) were monitored: m/z 267.14–267.16 for artemether, m/z 221.16–221.18 for dihydroartemisinin and m/z 283.14–283.16 for internal standard. The limit of detection (LOD) and limit of quantification (LOQ) for artemether were 0.3 and 0.8 ng mL−1, while for dihydroartemisinin were 0.2 and 0.6 ng mL−1, respectively. The validated method was successfully applied to the quantification of artemether and dihydroartemisinin in plasma samples of healthy volunteers participating in pharmacokinetic drug–food interaction studies.

Determination of flumazenil in serum by liquid chromatography-mass spectrometry: Application to kinetics study in acute diazepam overdose.

Flumazenil is benzodiazepine receptor antagonist. It has been studied for a various indications, including reversal of sedation after surgery or diagnostic procedures, awakening of comatose patients in benzodiazepine overdose, or for symptomatic treatment of hepatic encephalopathy. Some drugs, like theophylline, may prolong its elimination half-life. Considering the long half-life of diazepam and its metabolites, concomitant use of theophylline may reduce the need for repeated dosing of flumazenil in patients with acute diazepam poisoning. The aim of this study was to introduce a reliable and accurate method for determining the concentration of flumazenil after therapeutic application in patients with acute poisoning, and using that method to assess whether the kinetics of flumazenil change in the presence of aminophylline (combination of theophylline and ethylenediamine in a 2:1 ratio) applied as concomitant therapy. Blood samples from patients with acute diazepam poisoning that received flumazenil at the dose of 0.5 mg, or the same dose with 3 mg/kg of body weight of aminophylline, were collected 1, 3, 10, 30, 60, 120 and 240 min after its intravenous administration. Samples were prepared by solid-phase extraction on Oasis HLB cartridges with ethylacetate as extracting agens. Flumazenil was determined by liquid chromatography with mass spectrometry (LC-MS) in single ionmonitoring mode at m/z 304. Separation of flumazenil from matrix compound was performed on Lichrospher RP-8 column usingthe mixture of acidic acetonitrile and 20 mM of ammonium acetatein water (55 : 45) as a mobile phase. The applied analitycal method showed excellent recovery (94.65%). The obtained extracts were much cleaner than the extracts obtained by the sameextractant in the process of liquid-liquid extraction. The limit ofdetection of the LC-MS method described in this paper was 0.5 ng/mL and the limit of quantitation was 1 ng/mL. In the patientstreated with both flumazenil and aminophylline, the eliminationconstant for flumazenil was significantly lower and the elimination half-life was longer (p < 0.05) in comparison with the same parameters in.the patients who received flumazenil alone. The applied LC-MS method for the determination of flumazenil in serum samples of patients with acute diazepam poisoning is rapid, sensitive, precise and specific. Concomitant use with theophylline significantly prolonged elimination of flumazenil during the treatment of acute poisonings with diazepam.

Comparing different gas chromatographic methods for the quantification of bisphenol A (BPA) trace levels in paper and cardboard products from the market

Bisphenol A (BPA; 4,4ʹ-(propane-2,2-diyl)diphenol), a suspected endocrine disruptor with weak estrogenic activity, is used in a variety of consumer products, including paper and cardboard products used as food contact materials. The present study compared four different gas chromatographic methods for the analysis of BPA in paper and cardboard food packages. Eighteen different food packages were extracted and BPA was determined using two different derivatisation reactions – trimethylsilylation with N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA) and halide alkylation with pentafluorobenzoyl chloride (PFBOCl) – and four different separation and detection techniques. The BSTFA derivatives were quantified with (1) GC-MS in single-ion monitoring (SIM) mode with electron ionisation (EI-GC-MS) and (2) GC-MS/MS in multiple reaction monitoring (MRM) mode using electron ionisation (EI-GC-MS/MS); while the PFBOCl derivatives were quantified with (3) GC-MS using electron ionisation (EI-GC-MS) as well as (4) GC-MS with negative chemical ionisation (NCI-GC-MS). All developed methods showed good linearity (R2 > 0.9938), precision (CV < 4.5% for reproducibility; CV < 2.2% for repeatability) and sensitivity, with limits of detection (LODs) between 0.02 µg kg−1 for the pentafluorobenzoyl derivatives measured with the NCI-GC-MS method and 6 µg kg−1 for the pentafluorobenzoyl derivatives determined with EI-GC-MS. Levels of BPA in the samples were in agreement for all methods, ranging from values below the limit of quantitation (LOQ) to 11.9 mg kg−1 paper. In a last step, the maximum potential migration into food products was calculated for all tested paper and cardboard samples, assuming a ‘worst case’ scenario of 100% migration.

Comparison of GC/time-of-flight MS with GC/quadrupole MS for halocarbon trace gas analysis

Abstract. We present the application of time-of-flight mass spectrometry (TOF MS) for the analysis of halocarbons in the atmosphere after cryogenic sample preconcentration and gas chromatographic separation. For the described field of application, the quadrupole mass spectrometer (QP MS) is a state-of-the-art detector. This work aims at comparing two commercially available instruments, a QP MS and a TOF MS, with respect to mass resolution, mass accuracy, stability of the mass axis and instrument sensitivity, detector sensitivity, measurement precision and detector linearity. Both mass spectrometers are operated on the same gas chromatographic system by splitting the column effluent to both detectors. The QP MS had to be operated in optimised single ion monitoring (SIM) mode to achieve a sensitivity which could compete with the TOF MS. The TOF MS provided full mass range information in any acquired mass spectrum without losing sensitivity. Whilst the QP MS showed the performance already achieved in earlier tests, the sensitivity of the TOF MS was on average higher than that of the QP MS in the "operational" SIM mode by a factor of up to 3, reaching detection limits of less than 0.2 pg. Measurement precision determined for the whole analytical system was up to 0.2% depending on substance and sampled volume. The TOF MS instrument used for this study displayed significant non-linearities of up to 10% for two-thirds of all analysed substances.

Simultaneous determination of glycine betaine and arsenobetaine in biological samples by HPLC/ICPMS/ESMS and the application to some marine and freshwater fish samples

We describe a HPLC/mass spectrometry method for the simultaneous determination of glycine betaine and arsenobetaine in biological samples. The sample preparation included a water/methanol extraction followed by clean-up of extracts on a strong cation-exchange resin; the HPLC system consisted of a cation-exchange column with an ammonium formate buffer solution as mobile phase. Glycine betaine and arsenobetaine were quantified in a single chromatographic run by splitting the HPLC flow with an adjustable flow splitter and detecting glycine betaine selectively by electrospray MS in the positive single ion monitoring mode at m/z 118, and arsenobetaine with the arsenic-selective detector ICPMS at m/z 75. The proposed method was validated for arsenobetaine by analysis of CRM Dorm-2, and for glycine betaine by spiking the CRM Dorm-2 with a defined amount of glycine betaine. Finally, the developed method was applied to determine glycine betaine/arsenobetaine ratios in single specimens of four species of marine fish and one species of freshwater fish.

Multiresidue determination of fluoroquinolones in poultry muscle and kidney according to the regulation 2002/657/EC. A systematic comparison of two different approaches: Liquid chromatography coupled to high-resolution mass spectrometry or tandem mass spectrometry

This work involved the optimization and validation of two methods according to the Commission Decision 2002/657/EC directives for determining fluoroquinolones residues in samples of poultry muscle and kidney: ciprofloxacin, danofloxacin, difloxacin, enrofloxacin, flumequine, marbofloxacin, nalidixic acid, norfloxacin, ofloxacin, oxolinic acid, pipemidic acid and sarafloxacin. The extraction procedure was based on a QuEChERS approach, whose optimization employed a Box–Behnken 33 factorial design. A liquid chromatography–tandem mass spectrometry method (LC–MS/MS) was developed for determining the twelve analytes using the multiple reaction monitoring mode (MRM). Accuracy, evaluated by recovery studies, varied from 88.8 to 112.2% for the selected levels with RSD values lower than 12.3%. The second validated method employed high resolution mass spectrometry (HRMS) performed in the single ion monitoring mode (SIM), determining nine among twelve analytes. The validation parameters were evaluated as satisfactory, with recoveries from 82.5 to 114.4% and RSD lower than 8.7%. Decision limits and detection capabilities for both methods were reported. The two methods were statistically compared using the Student's t test, at 95% confidence level, resulting in no significant difference.

Quantification of neurosteroids during pregnancy using selective ion monitoring mass spectrometry

Analytical techniques used to quantify neurosteroids in biological samples are often compromised by non-specificity and limited dynamic range which can result in erroneous results. A relatively rapid and inexpensive gas chromatography–mass spectrometry (GC–MS) was developed to simultaneously measure nine neurosteroids, including allopregnanolone, estradiol, and progesterone, as well as 25-hydroxy-vitamin D3 in plasma samples collected from adult women subjects during and after pregnancy. Sample preparation involved solid-phase extraction and derivatization, followed by automated injection on a GC equipped with a mass selective detector (MSD) operated in single ion monitoring (SIM) mode to yield a run time of less than 11min. Method detection limits for all neurosteroids ranged from 30 to 200pg/mL (parts per trillion), with coefficients of variation that ranged from 3% to 5% based on intra-assay comparisons run in triplicate. Although concentrations of estradiol measured by chemiluminescent immunoassay (CIA) were consistent with values determined by GC–MS values, CIA yielded considerable higher values of progesterone, suggesting antibody cross reactions resulting from low specificity. Mean neurosteroid levels and representative time-course data demonstrate the ability of the method to quantify changes in multiple neurosteroids during pregnancy, including rapid declines in neurosteroid levels associated with delivery. This simplified GC–MS method holds particular promise for research and clinical laboratories that require simultaneous quantification of multiple neurosteroids, but lack the resources and expertise to support advanced liquid chromatography–tandem mass spectrometry facilities.

Analysis of organo-chlorine pesticides residue in raw coffee with a modified “quick easy cheap effective rugged and safe” extraction/clean up procedure for reducing the impact of caffeine on the gas chromatography–mass spectrometry measurement

The control of pesticide residues on raw coffee is a task of great importance due to high consumption of this beverage in Italy and in many other countries. High caffeine content can hamper extraction and measurement of any pesticide residue. A tandem extraction protocol has been devised by exploiting the quick easy cheap effective rugged and safe (QuEChERS) scheme for extraction, coupled to a dispersive liquid–liquid micro-extraction (DLLME) in order to drastically reduce caffeine content in the final extract. Gas chromatography–mass spectrometry (GC–MS) has been used for quantification of organo-chlorine pesticides in single ion monitoring (SIM) mode. Method has been validated and performances meet the criteria prescribed by European Union regulations.

Guaiacol and 4-methylphenol as specific markers of torrefied malts. Fate of volatile phenols in special beers through aging.

Phenol-specific extracts of 12 Belgian special beers were analyzed by gas chromatography hyphenated to olfactometry (AEDA procedure) and mass spectrometry (single ion monitoring mode). As guaiacol and 4-methylphenol were revealed to be more concentrated in brown beers (>3.5 and >1.1 μg/L, respectively), they are proposed as specific markers of the utilization of dark malts. Analysis of five differently colored malts (5, 50, 500, 900, and 1500 °EBC) allowed confirmation of high levels of guaiacol (>180 μg/L; values given in wort, for 100% specialty malt) and 4-methylphenol (>7 μg/L) for chocolate and black malts only (versus respectively <3 μg/L and undetected in all other worts). Monitoring of beer aging highlighted major differences between phenols. Guaiacol and 4-methylphenol appeared even more concentrated in dark beers after 14 months of aging, reaching levels not far from their sensory thresholds. 4-Vinylphenols and 4-ethylphenols, on the contrary, proved to be gradually degraded in POF(+)-yeast-derived beers. Vanillin exhibited an interesting pattern: in beers initially containing <25 μg/L, the vanillin concentration increased over a 14 month aging period to levels exceeding its sensory threshold (up to 160 μg/L). Beers initially showing an above-threshold level of vanillin displayed a decrease during aging.

Mechanism and Sensitivity of Anion Detection Using Rationally Designed Unsymmetrical Dications in Paired Ion Electrospray Ionization Mass Spectrometry

Paired ion electrospray ionization (PIESI) mass spectrometry was developed as a useful technique that provides sensitive detection for anions in the positive ion mode. The ion-pairing reagent (IPR) utilized plays an essential role affecting the detection limits. This work describes the design and synthesis of two novel dications with unsymmetrical structures and their utilization for anion detection and mechanistic insights. The performance of dications was evaluated for seven selected anions in both single ion monitoring (SIM) mode and selected reaction monitoring (SRM) mode. The unsymmetrical dications allowed sensitive detection for these anions with down to subpicogram limits of detection (LOD) and an improved sensitivity from 1.5 to 12 times compared to the corresponding symmetrical dications. The enhanced sensitivity could be attributed to the surface activity of the unsymmetrical dications, which results in a concurrent strong partitioning of the anion to the aerosol droplet surface. Surface activity measurements of the anion/IPR complex were conducted, and a correlation between the observed ESI responses and the surface activity of the complex was found. The mechanism was further explored and explained based on the concepts of the equilibrium partitioning model (EPM).

Determination of cocaine and its major metabolite benzoylecgonine in several matrices obtained from deceased individuals with presumed drug consumption prior to death

In the field of forensic toxicology, femoral blood is the most useful sample for the determination and quantification of drugs; however, cases in which blood is unavailable are common. In such cases, validated methodologies for drug determination in alternative matrices can be decisive in the investigation of a case. In particular, when femoral blood is unavailable for analysis for the presence of systemic exposure to cocaine and its principal metabolite, benzoylecgonine, validated methodologies from matrices other than blood that can be obtained in the autopsy room would be useful to the forensic toxicologist in the evaluation of a specific forensic case. To address this issue, we implemented and compared in our study the systematic evaluation of extraction, chromatographic separation, and quantification of cocaine and benzoylecgonine in different biological matrices (right and left cardiac blood, femoral arterial and venous blood, urine, vitreous humor, cerebrospinal fluid, brain accumbens nucleus, brain ventral tegmental area, and liver). The studied matrices were those most likely to be obtained from different autopsy rooms at the time of forensic testing in deceased individuals who are presumed of antemortem drug consumption. Solid phase extraction of analytes from the different matrices was performed using C-8/SCX mixed-phase columns, and gas chromatographic mass spectrometry separation was performed using detection in single-ion monitoring mode. The methodological validation was performed for all the studied matrices, and the results showed similar sensitivity and recoveries without statistical differences between the studied matrices. The methods were applied to evaluate a thanatological case using all the study matrices, showing unequal postmortem distribution of cocaine and benzoylecgonine throughout the different matrices tested. The present work opens the option of applying appropriate methodologies in the analysis of matrices, other than the usual blood, to obtain reliable results that may help clarify a forensic case. In addition, we present findings from different studies. This work affirms not only the potentiality of obtaining reliable data but also reaffirms the challenge of applying these data and taking into account the complexity of interpreting results in matrices other than blood.

LC–MS method for the simultaneous determination of six glucocorticoids in pharmaceutical formulations and counterfeit cosmetic products

A screening method based on liquid chromatography–electrospray mass spectrometry for the simultaneous determination of six corticosteroids (betamethasone 17-valerate BM 17-V, beclomethasone BC, beclomethasone dipropionate BCDP, methylprednisolone MP, budesonide BD, flunisolide FN) was developed in order to control their illegal use in cosmetic and natural products. Indeed, despite corticosteroids are banned in cosmetics, counterfeit products might be present on the market, representing a health hazard. Therefore, effective analytical methods are required to rapidly screen over the counter products in health care shops for counterfeit corticosteroids.The analytical method involves the employment of a Waters Synergy C18 column (150mm×2.0mm I.D.) by using the following mobile phase: A (0.1% formic acid in acetonitrile), B (0.1% formic acid in water) in a linear gradient (from A–B 25:75, v/v to A–B 95:5, v/v in 30min) at the flow rate of 0.3mL/min. The detection was performed with an ion trap (IT) mass spectrometer in positive polarity, total ion current (TIC) and tandem mass modalities for qualitative purpose; single ion monitoring (SIM) mode was used for quantitative analysis on the ESI generated most abundant ion for each steroid.The method was fully validated in terms of precision, detection and quantification limits, linearity, recovery, and it was applied to the identification and quantification of corticosteroids in pharmaceutical formulations and cosmetic products. The mean recovery of BM 17-V, BC, BCDP, MP, BD and FN were found to be 101.3, 101.5, 98.8, 98.9, 98.1, 99.0%, respectively. Limits of quantitation (LOQ) were comprised in the range 29–95ng/mL.To the best of our knowledge, for the first time this mix of glucocorticoids were simultaneously determined in cosmetic products by using a fully validated method. BMV, in its two isomeric forms BM 17-V and BM 21-V, was found to be illegally present in one cream sample (A) with the total concentration level of 0.036% (w/w).

Efficient and sensitive method for the quantification of saturated monoacylglycerols in biodiesel by gas chromatography–mass spectrometry

The experimental approach of this work was to develop a new method for the quantification of saturated MAGs in biodiesel using GC–MS. The method was established on a 30 m 5% phenyl phase column and ensured satisfying separation of the target MAGs. The quantification of the saturated MAGs was carried out in single ion monitoring (SIM) mode using the quantitation ions for the target MAGs: m/z 218 (2‐C16:0), m/z 371 (1‐C16:0), m/z 385 (1‐C17:0), and 399 (1‐C18:0) as well as m/z 413 for 1‐C19:0, serving as an internal standard (IS). The analytical procedure involved mixing the biodiesel sample with the IS and a silylating agent before applying GC–MS analysis. Response factors for the individual target MAGs related to the IS were determined. Prior to the quantification of saturated MAGs in real biodiesel samples, derived from used cooking oil (UCO) and waste animal fats (WAF), the linearity (R2&gt;0.99) and the limits of detection and quantification (LOD: 8–20 ng/g, LOQ: 26–61 ng/g) of the method were determined.Practical applications: The European Committee for Standardization (CEN) contemplates to establish a limit value specifically for saturated MAGs in biodiesel, primarily requiring a specific analysis method. At present, there is no suitable test method for the determination of saturated monoglycerol content in FAME. Therefore, the approach of this work was to develop a new method for the quantification of saturated MAGs in biodiesel using GC–MS. In contrast to the currently valid European standard method EN 14105 for the determination of free glycerol, mono‐, di‐ (MAGs, DAGs), and triacylglycerols (TAGs), this new method features a very high sensitivity and enables the exclusion of interfering substances, both due to performing the analysis in single ion monitoring mode (SIM).