scholarly journals Analytical Study of Comprehensive and Targeted Multidimensional Gas Chromatography Incorporating Modulated Cryogenic Trapping

2001 ◽  
Vol 84 (2) ◽  
pp. 323-336 ◽  
Author(s):  
Thy T Truong ◽  
Philip J Marriott ◽  
Nichola A Porter
Keyword(s):  
Gas Chromatography ◽  
Normal Mode ◽  
Analytical Study ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Complete Separation ◽  
Pollution Monitoring ◽  
Detection Sensitivity ◽  
Constant Frequency ◽  
Relative Standard

Abstract This paper reports the results of an analytical study comparing capillary gas chromatography (GC) operated in the normal mode with 2 new GC techniques, comprehensive GC (GC × GC) and targeted (or selective) multidimensional GC, which use a longitudinally modulated cryogenic system (LMCS), recently developed in our laboratory. A high-temperature application of derivatized sterols, of interest in fecal pollution monitoring, was chosen for this work. A directly connected coupled-column ensemble was used, comprising a nonpolar column and a moderately polar column. With LMCS, effluent from the first column is zone-compressed in a cryogenic trap and then pulsed to a short second column, producing narrower peaks with sharp, tall peak responses at the detector. The modulator is operated at a constant frequency, e.g., 0.25 s−1, to produce the GC × GC result, or is moved in a predefined manner so that whole peaks are selectively trapped and subsequently pulsed through to the second column in the targeted mode. Standard solutions containing a mixture of 7 sterols and 5-α-cholestane internal standard were used. Detection sensitivity is increased by a factor of ≥25 with the use of LMCS. The estimated limit of detection was about 0.1 μg/mL when normal GC with flame ionization detection (GC/FID) and a 1.0 μL splitless injection volume were used, compared with 0.02 and 0.004 μg/mL for the LMCS operated in GC × GC and selective modes, respectively. Calibration curves for GC/FID were linear over the 0.1–2.0 μg/mL range tested. Reproducibilities for the GC × GC and normal GC modes were comparable; generally, relative standard deviations (RSD) were on the order of 3–4%, based on raw peak responses. Improved reproducibility was found for selective LMCS operation, at an RSD of around 2%; with internal standardization, better results were achieved. The coupled-column arrangement allowed complete separation of sterol peaks from overlapping impurity peaks in a number of instances with LMCS modes, and its use should improve data quality over that of normal GC operation, in which the overlapping peaks interfere with measurement of peak response in the normal mode.

scholarly journals Determination of Gliclazide in Pharmaceutical Preparations by Capillary Gas Chromatography with Cool On-Column Injection and Elimination of the Matrix Effect

2001 ◽  
Vol 84 (6) ◽  
pp. 1695-1702 ◽  
Author(s):  
Jan Krzek ◽  
Janusz Czekaj ◽  
Maria Moniczewska ◽  
Włodzimierz Rzeszutko
Keyword(s):  
Gas Chromatography ◽  
Capillary Gas Chromatography ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Pharmaceutical Preparations ◽  
Fused Silica ◽  
Uv Spectrophotometry ◽  
Relative Standard ◽  
Wide Range ◽  
The Matrix

Abstract Conditions were established for the identification and quantitation of gliclazide in pharmaceutical preparations by capillary gas chromatography with flame ionization detection and cool on-column injection. Gliclazide was extracted with methanol and, after filtration, assayed on a (25 m × 0.25 mm id, 0.2 μm film thickness) CP-WAX 58 (FFAP)–CB WCOT fused silica column. Because the available preparations were of various origins and, therefore, could differ in auxiliary substances and their qualitative parameters, the influence of the matrix constituents on the analytical results was taken into account. Good separation conditions were established for the developed method. The retention time of gliclazide is about 36 min and differs from the retention times of the internal standard (approximately 29 min) and additional peaks present in chromatograms (20–26 min), which were assigned to matrix constituents. The recoveries of gliclozide were high and reached 96.5%. The developed method is characterized by selectivity and precision (relative standard deviation 0.38–1.26%), a wide range of linearity (0.1–10.0 mg/mL), and a limit of detection of 30 ng. In addition, the results of chromatographic analyses calculated in 3 ways were compared with those obtained by UV spectrophotometry. The suggested technique of cool on-column injection, in contrast with split-splitless injection (used in preliminary investigations), reduces to a minimum the possibility of thermal decomposition of gliclazide.

scholarly journals Determination of 1,3-Dichloropropanol in Soy Sauce and Related Products by Headspace Gas Chromatography with Mass Spectrometric Detection: Interlaboratory Study

2005 ◽  
Vol 88 (5) ◽  
pp. 1404-1412 ◽  
Author(s):  
Sarah Hasnip ◽  
Colin Crews ◽  
Nicholas Potter ◽  
Paul Brereton ◽  
Henri Diserens ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Internal Standard ◽  
Mass Spectrometric ◽  
Soy Sauce ◽  
Headspace Gas Chromatography ◽  
Relative Standard ◽  
Headspace Gas

Abstract An interlaboratory study was performed to evaluate the effectiveness of a headspace gas chromatography (GC) method for the determination of 1,3-dichloro-propan-2-ol (1,3-DCP) in soy sauce and related products at levels above 5 ng/g. The test portion is mixed with an internal standard (d5-1,3-DCP) and ammonium sulfate in a sealed headspace vial. After achieving equilibrium, the headspace is sampled either by gas-tight syringe or solid-phase microextraction (SPME) and analyzed by GC with mass spectrometric detection. 1,3-DCP is detected in the selected-ion mode (monitoring m/z 79 and 81 for 1,3-DCP and m/z 82 for the deuterated internal standard) and quantified by measurement against standards. Test materials comprising soy, dark soy, mushroom soy, and teriyaki sauces, both spiked and naturally contaminated, were sent to 9 laboratories in Europe, Japan, and the United States; of these, 5 used SPME and 4 used syringe headspace analysis. Test portions were spiked at 5.0, 10.0, 20.0, 100.0, and 500.0 ng/g. The average recovery for spiked blank samples was 108% (ranging from 96–130%). Based on results for spiked samples (blind pairs at 5, 10, 20, 100, and 500 ng/g) as well as a naturally contaminated sample (split-level pair at 27 and 29 ng/g), the relative standard deviation for repeatability (RSDr) ranged from 2.9–23.2%. The relative standard deviation for reproducibility (RSDR) ranged from 20.9–35.3%, and HorRat values of between 1.0 and 1.6 were obtained.

scholarly journals Validation of a New Sensitive Method for the Detection and Quantification of R and S-Epimers of Ergot Alkaloids in Canadian Spring Wheat Utilizing Deuterated Lysergic Acid Diethylamide as an Internal Standard

Toxins ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 22
Author(s):  
Jensen Cherewyk ◽  
Taylor Grusie-Ogilvie ◽  
Barry Blakley ◽  
Ahmad Al-Dissi
Keyword(s):  
Spring Wheat ◽  
Matrix Effects ◽  
Limit Of Detection ◽  
Ergot Alkaloids ◽  
Internal Standard ◽  
Lysergic Acid ◽  
Lysergic Acid Diethylamide ◽  
Relative Standard ◽  
Validation Parameters ◽  
Sensitive Method

Ergot sclerotia effect cereal crops intended for consumption. Ergot alkaloids within ergot sclerotia are assessed to ensure contamination is below safety standards established for human and animal health. Ergot alkaloids exist in two configurations, the R and S-epimers. It is important to quantify both configurations. The objective of this study was to validate a new ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for quantification of six R and six S-epimers of ergot alkaloids in hard red spring wheat utilizing deuterated lysergic acid diethylamide (LSD-D3) as an internal standard. Validation parameters such as linearity, limit of detection (LOD), limit of quantification (LOQ), matrix effects, recovery and precision were investigated. For the 12 epimers analyzed, low LOD and LOQ values were observed, allowing for the sensitive detection of ergot epimers. Matrix effects ranged between 101–113% in a representative wheat matrix. Recovery was 68.3–119.1% with an inter-day precision of <24% relative standard deviation (RSD). The validation parameters conform with previous studies and exhibit differences between the R and S-epimers which has been rarely documented. This new sensitive method allows for the use of a new internal standard and can be incorporated and applied to research or diagnostic laboratories.

OBETICHOLIC ACID: AN INSIGHT INTO A QUANTITATIVE DETERMINATION AND METHODOLOGICAL VALIDATION THROUGH NUCLEAR MAGNETIC RESONANCE

2020 ◽  
pp. 179-190
Author(s):  
RAKESH SAHU ◽  
RAKHI MISHRA ◽  
CHANDANA MAJEE ◽  
AJAY KUMAR ◽  
RUPA MAZUMDER
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Quantitative Determination ◽  
Method Validation ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Proton Nuclear Magnetic Resonance ◽  
Obeticholic Acid ◽  
Relative Standard ◽  
Nuclear Magnetic

Objective: The research work unveils the use of nuclear magnetic resonance (NMR) technique for quantitative determination and method validation of obeticholic acid. As standard expository methodology for more up to date medications or formulations may not be available in pharmacopeias, hence it is fundamental need to create novel analytical procedures which should be precise and accurate. Methods: Proton (1H) and carbon (13C) NMR analysis were initially performed to confirm the preliminary authenticity of obeticholic acid API. Method validation was accomplished on the basis of standard guidelines for the parameters, in which tetramethylbenzene as an internal standard and deuterated dimethyl sulfoxide as a diluent were used to assess the obeticholic acid. Results: For the quantification of the drug, the proton nuclear magnetic resonance signals at 0.602 ppm and 6.86 ppm corresponding to the analyte proton of drug and internal standard respectively were used. The curve equation calculated from the regression method, the relative-standard-deviation and correlation-coefficient were found to be 0.743% and 0.9989 respectively, indicating good linearity. Consequently, the quantitative assay of the drug was found to be 99.91% in linearity with limit of detection and quantification values as 0.0773 mg and 0.2344 mg respectively, making successful the study of method validation for obeticholic acid. Conclusion: The advantage of the method was that no reference standard of analyte drug was required for quantification and method validation. The method is non-destructive and can be applied for quantification of drug in commercial pharmaceutical formulation products.

scholarly journals Determination of Tianeptine in Tablets by High-Performance Liquid Chromatography with Fluorescence Detection

2007 ◽  
Vol 90 (3) ◽  
pp. 720-724
Author(s):  
Sevgi Tatar Ulu
Keyword(s):  
Lower Limit ◽  
High Performance ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Linear Calibration ◽  
Fluorescence Detector ◽  
Relative Standard ◽  
Validation Parameters ◽  
Limit Of Quantitation

Abstract A sensitive and selective high-performance liquid chromatographic method has been developed for the determination of tianeptine (Tia) in tablets. The method is based on derivatization of Tia with 4-chloro-7-nitrobenzofurazan (NBD-Cl). A mobile phase consisting of acetonitrile10 mM orthophosphoric acid (pH 2.5; 77 + 23) was used at a flow rate of 1 mL/min on a C18 column. The Tia-NBD derivative was monitored using a fluorescence detector, with emission set at 520 nm and excitation at 458 nm. Gabapentin was selected as an internal standard. Linear calibration graphs were obtained in the concentration range of 45300 ng/mL. The lower limit of detection (LOD) was 10 ng/mL at a signal-to-noise ratio of 4. The lower limit of quantitation (LOQ) was 45 ng/mL. The relative standard values for intra- and interday precision were &lt;0.46 and &lt;0.57%, respectively. The recovery of the drug samples ranged between 98.89 and 99.85%. No chromatographic interference from the tablet excipients was found. The proposed method was validated in terms of precision, robustness, recovery, LOD, and LOQ. All the validation parameters were within the acceptance range. The proposed method was applied for the determination of Tia in commercially available tablets. The results were compared with those obtained by an ultraviolet spectrophotometric method using t- and F-tests.

scholarly journals Development of Sensitive and Specific Analysis of Vildagliptin in Pharmaceutical Formulation by Gas Chromatography-Mass Spectrometry

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Ebru Uçaktürk
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Pharmaceutical Formulation ◽  
Gas Chromatography Mass Spectrometry ◽  
Selected Ion Monitoring ◽  
Chromatography Mass Spectrometry ◽  
Validation Parameters ◽  
Diagnostic Ions

A sensitive and selective gas chromatography-mass spectrometry (GC-MS) method was developed and fully validated for the determination of vildagliptin (VIL) in pharmaceutical formulation. Prior to GC-MS analysis, VIL was efficiently derivatized with MSTFA/NH4I/β-mercaptoethanol at 60°C for 30 min. The obtained O-TMS derivative of VIL was detected by selected ion monitoring mode using the diagnostic ionsm/z223 and 252. Nandrolone was chosen as internal standard. The GC-MS method was fully validated by the following validation parameters: limit of detection (LOD) and quantitation (LOQ), linearity, precision, accuracy, specificity, stability, robustness, and ruggedness. LOD and LOQ were found to be 1.5 and 3.5 ng mL−1, respectively. The GC-MS method is linear in the range of 3.5–300 ng mL−1. The intra- and interday precision values were less than ≤3.62%. The intra- and interday accuracy values were found in the range of-0.26–2.06%. Finally, the GC-MS method was successfully applied to determine VIL in pharmaceutical formulation.

Trace Analysis of Phenols in Water by Gas Chromatography

1975 ◽  
Vol 32 (2) ◽  
pp. 292-294 ◽  
Author(s):  
Derek A. J. Murray
Keyword(s):  
Gas Chromatography ◽  
Lower Limit ◽  
Water Samples ◽  
Trace Analysis ◽  
Organic Material ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Low Concentrations ◽  
Trimethylsilyl Derivatives ◽  
Derivatives Of

A method for analysis of low concentrations of phenols, cresols, and xylenols in water samples was developed. O-xylene was added to the sample as an internal standard and the sample was extracted once with chloroform to remove a portion of the total organic material present. The trimethylsilyl derivatives of the phenols were formed and analysis completed by gas chromatography. The method was rapid and required a minimum of sample manipulation. The lower limit of detection was 0.100 mg/liter for phenol, 0.025 mg/liter for cresols, and 0.050 mg/liter for xylenols.

scholarly journals Electroanalysis Of Paracetamol By A Carbon Paste Electrode Modified By Zinc: Analytical Application In Human Blood

2021 ◽  
Vol 16 (1) ◽  
pp. 25-31
Author(s):  
Hayat EL Ouafy ◽  
Tarik EL Ouafy ◽  
Mustapha Oubenali ◽  
Mohamed Mbarki ◽  
Malika Echajia ◽  
...  
Keyword(s):  
Human Blood ◽  
Carbon Paste Electrode ◽  
Catalytic Effect ◽  
Limit Of Detection ◽  
Detection Sensitivity ◽  
Modified Carbon Paste Electrode ◽  
Potential Range ◽  
Carbon Paste ◽  
Relative Standard ◽  
Paste Electrode

The present work describes the catalytic effect of zinc particles for electroanalysis the paracetamol (PAR). The working electrode was prepared by mixing the zinc with the carbon powder. The voltammetric behavior of paracetamol was studied when an anodic peak to appear at 0.35 V in 0.1 M Na2SO4 solution (pH 12). The peak resulting from the irreversible oxidation of paracetamol on the zinc modified carbon paste electrode (Zn/CPE). The catalytic effect was evaluated by cyclic voltammetry (CV) and square wave voltammetry (SWV). The electrocatalytic behavior of the zinc particles is allotted to its chemical and physical properties. This electrode has a good performance for the electroanalysis of paracetamol. To obtain an electrochemical analysis of paracetamol oxidation at the surface of Zn/CPE, the voltammograms are used in a potential range of - 1.5 V to 1.5 V. More, Zn/CPE can be utilized successfully to ameliorate the electroanalysis of paracetamol at very feeble concentration and with high detection sensitivity. The limit of detection (LD) and quantification (LQ) obtained are respectively 7.52·10-8 mol L-1 and 2.6·10-7 mol L-1. Then the relative standard deviation (RSD) at 2.0·10-5 mol L-1 PAR concentration was 2.88 % for nine repetitions. Afterward, the presented method was used to electroanalysis paracetamol in human blood samples with satisfying results.

scholarly journals Distribution of Pesticides in Different Commonly Grown Vegetables of Cameron Highlands, Pahang, Malaysia

2021 ◽  
Vol 50 (10) ◽  
pp. 2937-2944
Author(s):  
Nusrat Munawar ◽  
Yang Farina Yang Farina ◽  
Mohammad Yaqoob ◽  
Abdul Nabi Abdul Nabi ◽  
Syed Munawar Shah Syed Munawar Shah
Keyword(s):  
Gas Chromatography ◽  
Limit Of Detection ◽  
Organophosphorus Pesticides ◽  
Pca Analysis ◽  
Wet Season ◽  
Vegetable Samples ◽  
Detection Frequency ◽  
Relative Standard ◽  
Pyrethroid Pesticides ◽  
Cameron Highlands

Gas chromatography-electron capture detector (GC-ECD) is used to extract and analyse pesticides in vegetable samples collected from Cameron Highlands, Pahang, Malaysia. The limit of detection (LOD) for all pesticides was in the range of 0.03 to 4.5 ng g-1. Recoveries in cabbage, lettuce, and celery ranged from 61.8%-121%, 60-128% and 60%-114%, respectively. The relative standard deviation (RSD) ranged 0.2-15% in cabbage, 0.5-18% in lettuce and 3-19.8% in celery. Organochlorine pesticides (OCPs) concentrations increased down the valley with dichlorodiphenyldichloroethylene (DDE) having the highest concentration at 233 µg kg-1. Organophosphorus pesticides (OPPs) were found to be dispersed throughout the valley, with the highest concentration of parathion ethyl (133 µg kg-1) whereas the pyrethroid pesticides (PYRs) concentrations were comparatively less. The detection frequency in the wet season was highest (5 < - < 100 µg kg-1) for most pesticides. However, in the dry season the pesticides concentrations were higher, at < 5 µg kg-1. PCA analysis indicated that farmers were using a mixture of pesticides.

Determination of Linuron in Potatoes Using Capillary Column Gas Chromatography/Mass Spectrometry

1989 ◽  
Vol 72 (6) ◽  
pp. 970-974
Author(s):  
Gregory C Mattern ◽  
George M Singer ◽  
Judy Louis ◽  
Mark Robson ◽  
Joseph D Rosen
Keyword(s):  
Gas Chromatography ◽  
Ion Trap ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Gas Chromatography Mass Spectrometry ◽  
Phenylurea Herbicides ◽  
Ionization Mode ◽  
Capillary Column Gas Chromatography ◽  
Ppm Level

Abstract A convenient method for the determination of the JV-methyl,iVmethoxy- phenylurea herbicide (linuron) in potatoes has been developed. The herbicide is extracted from potatoes using a slightly modifled Luke multiresidue procedure. The extract is analyzed directly by gas chromatography with cold on-column injection, using an ion trap mass spectrometer in the chemical ionization mode as the detector. Quantitation is performed using p-bromonitrobenzene as the internal standard. The limit of detection is 0.1 ppm. Recoveries of linuron in potatoes averaged 112 ± 6% at the 0.5 ppm level, and 110 ± 2% at the 0.2 ppm level. No linuron residues were found in 25 potato samples that were analyzed by this method. Two other iV-methyl,iV-methoxyphenylurea herbicides, metobromuron and chlorbromuron, are also sufficiently stable to be determined by this method, but the N,Ndialkyl- phenylurea herbicides neburon, diuron, and monuron are too thermally unstable and degrade in the gas chromatograph.

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