GC Device Research Articles

Isolation and Identification of Endophytic Fungi from Aloe vera Leaves and Chemical Analysis of the Alcoholic Extract of the Leaves Using HPLC, GC, and GC-Mass Devices

The study's goals were to separate and identify endophytic fungi from Aloe vera leaves by looking at their morphology and molecules, as well as to find the chemical compounds in the leaf extract by using HPLC, GC, and GC-Mass instruments. The results showed that 53 endophytic fungi were isolated from a total of 120 pieces of A. vera leaves, with a total colonization rate of 44.16%. The fungus Aspergillus terreus had a colonization rate of 14.16%; Aspergillus niger had a colonization rate of 13.33%; Penicillium chermesinum demonstrated a colonization rate of 6.66%; Paecilomyces variotii had a colonization rate of 2.5%; Talaromyces radicus; and Aspergillus flavus achieved a colonization rate of 1.66%. Finally, the fungi Aspergillus quadrilineatus, Talaromyces verruculosus, Neoscytalidium dimidiatum, Alternaria solani, and Aspergillus niveus achieved a colonization rate of 0.83%. The results of examining the alcoholic extract of the leaves using the HPLC device showed the presence of the chemical compounds aloin at a concentration of 125.39 ppm and aloe emodin at a concentration of 66.59 ppm. We looked at the leaf alcoholic extract with a GC machine and found a group of fatty acids. These included linoleic, oleic, palmitic, and stearic. The GC-MS test revealed a group of active compounds, including Heptane, 1-(ethenylthio), Ethanedicarboxamide, N-allyl-N'-(2,5-dimethylphenyl), 2H-Pyran, 2-(3-butynyloxy) tetrahydro, 1,2-Cyclobutanedicarboxylic acid, 3-methyl-dimethyl ester and 4 (1H)-Pyrimidinone, 2-(propylthio). The presence of endophytic fungi from which effective enzymes or compounds can be isolated could probably have an important role in future medical and therapeutic uses. Also, the leaves of the A. vera plant have medicinal and therapeutic uses for many diseases.

Responses of Saccharomyces cerevisiae Cells Grown in Cultures Prepared from Different Tea Infusions to Oxidative Stress

Tea is one of the most consumed beverages. Saccharomyces cerevisiae, a model organism in studies on oxidative stress and toxicology, was used to investigate the effects of tea on oxidative stress induced by H2O2. S. cerevisiae cultures were prepared from black, green and white tea infusions and incubated at 30°C for 72 hours. Glutathione-S-transferase enzyme activity and total protein spectrophotometric, malondialdehyde, glutathione and alpha-tocopherol and ergosterol analyses from cell pellets obtained from cultures were performed by HPLC, and fatty acids were performed by GC device. Although protein level in tea infusion groups was higher (p

Isolation and molecular identification of endophytic fungi associated with Ziziphora tenuior L. and their biological potential

Endophytic fungi are microorganisms found in the inter- or intracellular compartments of plant tissue and can improve plant performance through a variety of mechanisms. They are considered a potential source of biological compounds such as terpenoids, phenols, alkaloids, and fatty acids, which are extensively used in various industries. The present study was conducted to investigate the molecular identification, fatty acid profile analysis, and antibacterial properties of endophytic fungi isolated from the aerial parts of Ziziphora tenuior (L.). Phylogenetic analysis was performed based on the Internal Transcribed Spacer (ITS) region and seven fungal isolates were classified into six genera as follows: Acremonium, Aspergillus, Cladosporium, Neocamarosporium, Alternaria, and Stemphylium. The analysis of fatty acids in the n-hexane extracts of Z. tenuior and mycelia of endophytic fungi with GC device showed that the amount of fatty acids is between 32.7-55.5%. A. infectoria (55.5%) and A. ochraceus (54.3%) had the highest amount of fatty acids among studied isolated. γ–Linolenic acid (C18:3), linoleic acid (C18:2), palmitic acid (C16:0), stearic acid (C18:0), and oleic acid (C18:1) were the main fatty acids. Also, the n-hexane extract of A. ochraceus showed antibacterial activity against Bacillus cereus, B. subtilis, Escherichia coli, and Pseudomonas aeruginosa. The results reveal that endophytic fungi are a source of natural bioactive metabolites, which could be applied in different industries. This is the first report of endophytic fungi diversity in Z. tenuior, which provides knowledge on their future use on biotechnological processes.

Graphene Oxide-Wrapped Gold Nanorods for Direct Plasmon-Enhanced Electrocatalysis to Detect Hydrogen Peroxide and in the Hydrogen Evaluation Reaction

The modulation of electronic characteristics of a two-dimensional (2-D) graphene oxide (GO) nanosheet with plasmonic hot charge carrier doping is of great scientific prominence for improving and expanding its diverse applications in health and energy fields. Herein, we report a nanohybrid system of reduced GO-wrapped gold nanorods (GNRs) for plasmon acceleration under localized surface plasmon resonance (LSPR) excitation photoelectrochemical (PEC) biosensing of hydrogen peroxide (H2O2), followed by the early-stage detection of human cancer cells as well as hydrogen evolution reaction (HER) for energy production. A tremendously sensitive H2O2 biosensor device is constructed (GNRs@rGO/GC), which exhibits ∼4-fold enhanced electrocatalytic activity under 808 nm LSPR excitation (2 W/cm2), with a wide linear range from 5 μM to 10 mM, along with a lower limit of detection and sensitivity of 2.35 μM and 30.26 μA mM–1 cm–2, respectively. It is now proposed that the enhanced generation of hot charge carriers followed by their effective transportation and separation and an attentive electromagnetic field with a photothermal effect mainly contribute to the superior photoelectrocatalysis reaction, which is also directly related to the pH of a medium, light wavelength, and light intensity. The electrode device is finally applied for the PEC biosensing of cancer cells (HeLa) by measuring the current response of a released cancer biomarker (H2O2). Herein, we also report the plasmon-accelerated superior HER catalytic performance by the GNRs@rGO/GC device, where we found the decreased onset potential of 90 mV with an overpotential (η) of −0.386 V at 10 mV cm–2 and a Tafel slope of ∼81 mV dec–1 under LSPR excitation. This study reveals the plasmon-enhanced electrochemical performances of a plasmonic@2-D SC heterostructure nanohybrid material and henceforth makes it a potential candidate for electroanalysis, electrochemical energy conversion, electrochemical devices, and biomedical applications.

Antibacterial effect of Bacillus subtilis extract on the growth of pathogenic bacteria and analyzed by GC-MS

The antibacterial effect of three selected isolates of Bacillus subtilis (Sar1, Sar2, Sar3) was tested by the agar diffusion method, and the results showed that there was no inhibitory effect of these bacteria against the growth of pathogenic bacteria; Staphylococcus aureus, Staphylococcus haemolyticus Escherichia coli, and Pseudomonas aeruginosa, while the undiluted and half-diluted (200, 100, 50) mg/ml extracts, of the three cultures which are tested by the Agar Well Diffusion method, had varying inhibitory effects towards the growth of these five pathogenic bacteria and more effect on gram-positive compared to its effect on gram-negative bacteria. Through GC-MS detection of secondary metabolites of Bacillus subtilis (Sar1) extract, which were selected because they are identical to Bacillus subtilis bacteria contained in the standard GeneBank with a percentage of (95)%, it was found that they consist of (33) chemical substances according to the number of peaks produced. After injecting the extract into the GC device, and when this information was entered into the MS device, it was diagnosed by its names with the calculation of its molecular weight and the amount of area it occupies as a percentage within the used extract understudy.

Determination the Fatty Acid Composition of the Rumex patientia L. Leaves and in vitro Antimicrobial Activity of their Different Extracts

Rumex patientia L. is from Polygonaceae family and there are 25 species of it in Turkey. Rumex patientia L. has antifebrile, laxative, diuretic, and pain killer properties. In this study, the extraction of the Rumex patientia L. leaf were done and determination the fat content and fatty acid composition by using GC device and to determinate in vitro antimicrobial activity of their different extracts were aimed. On the purpose of detection of antimicrobial activity; Rumex patientia L. leaf was extracted with ethanol, methanol, acetone, petroleum ether and water. Rumex patientia L. leaves was tested their different extracts using Bacillus subtilis, Bacillus cereus, Escherichia coli, Pseudomonas aeroginosa, Pasteurella multocida, Yersinia enterocolitica, Klebsiella pneumoniae, Staphylococcus aureus bacteria and Candida albicans yeast by agar-well diffusion technique. As a result of the study, 26 fatty acid components were detected on Rumex patientia L. leaf. In addition, among obtained extracts the highest antimicrobial activity was formed by methyl alcohol extract on K. pneumoniae bacteria (32mm).

Nicotine-free, nontransgenic tobacco (Nicotiana tabacum l.) edited by CRISPR-Cas9.

Nicotine-free, nontransgenic tobacco (Nicotiana tabacum l.) edited by CRISPR-Cas9.

Low-cost photoionization sensors as detectors in GC × GC systems designed for ambient VOC measurements

Conventional volatile organic compound (VOC) monitoring based on thermal desorption - gas chromatography–mass spectrometry (TD-GC–MS) or gas chromatography-flame ionization detector (TD-GC-FID) is relatively cumbersome and expensive. In this study commercial off the shelf low-cost and low-power photo-ionization detector (PID) sensors are used as simple detectors in VOC analysis systems based on GC, including a miniaturised GC × GC device with portable, low-cost, and low-energy-consumption features. PID sensors produce a voltage signal positively proportional to VOC concentration, which when incorporated into a TD-GC system gave limit of detection of 0.02 ppbV for isoprene. To test PID performance in real-world applications, PID sensors were deployed as (i) a second alternative detector in a GC-Quadruple Time Of Flight Mass spectrometry (GC-Q-TOF-MS), and (ii) the main detector in a compact two-dimensional gas chromatograph (GC × GC). PID sensors with 10.6 eV and 11.7 eV lamps were used to measure eight toxic chemicals including organic sulfide and organic phosphonates via GC; two species were ionized by a 10.6 eV lamp and four species by the 11.7 eV lamp. Commercially available low-cost PIDs designed for standalone could be straightforwardly and effectively re-used as detectors in compact GC × GC systems, in this work showing excellent VOC sensitivity, fast response and low operational demands compared to comparable field instruments based on GC-FID or MS.

The pharmacognostic study of the aerial part of Prangos ferulacea lindl. at the stage of the beginning of vegetation

Aim. To study the coumarin composition of salted Prangos ferulacea herb collected at the stage of vegetation and compare it with the coumarin composition of the freshly collected raw material.Materials and methods. The analysis was performed using Agilent 5977 GC and 7890B MS devices. The carrier gas was helium with a constant flow of 1 ml/min. The data of NIST library of standard mass-spectra were used to identify compounds.Results and discussion. The results of the study of coumarin derivatives in the food additive prepared from Prangos ferulacea herb collected at the beginning of the vegetation period are presented. The anatomical structure of the aerial part of Prangos ferulacea has been studied, and the diagnostic features of the plant raw material have been identified.Conclusions. The composition of coumarin derivatives in the food additive and in the freshly collected aerial part is identical. The diagnostic features of the structure of the plant raw material of Prangos ferulacea have been identified.

Chip-Based Multicapillary Column with Maximal Interconnectivity to Combine Maximum Efficiency and Maximum Loadability.

On the basis of our previous work on the design of pillar array columns for liquid chromatography, we report on a new pillar array design for high-efficiency, high volumetric loadability gas chromatography columns. The proposed pillar array configuration leads to a column design which can either be considered as a packed bed with perfectly ordered and uniform flow paths or as multicapillary columns (8 parallel tracks) with a maximal interconnectivity between the flow paths to avoid the so-called polydispersity effect (dispersion arising from the inevitable differences in migration velocity between parallel flow paths). Despite our relative inexperience with column coating, and most probably (not supported by data) suffering from the same problem of stationary phase pooling in the right-angled corners of the flow-through channels as other chip-based GC devices, the efficiencies obtained in a L = 70 cm long and 75 μm deep and 6.195 mm wide chip for, respectively, quasi-unretained and retained components (k = 7) went up to N = 60 000 and 12 500 under isothermal conditions using H2 as carrier gas and a downstream restriction. Under programmed temperature conditions (Ti = 80 °C, Tf = 175 °C at 30 °C/min, and a H2 flow of 0.4 mL/min), a peak capacity of 170 was obtained in 3.6 min. For retained compounds, the optimal flow rate is found to be on the order of 0.4 mL/min, achieved at an operating pressure of 2.3 bar. Intrinsically, the column combines the efficiency of a 75 μm capillary with the volumetric loadability of a 240 μm capillary.

OC-069 Non-invasive afferent vagus nerve stimulation (nvns) using gammacore (gc) in patients with treatment refractory gastroparesis awaiting enterra gastric neurostimulation

Introduction High frequency, low energy gastric neurostimulation (EnterraTM) is indicated for compassionate treatment of patients with refractory gastroparesis. Symptom improvement is reported in 50–60% of patients but not accompanied by improved gastric emptying. It is likely that gastric neurostimulation affects the gut-brain axis influencing autonomic afferents.1GammaCore (electroCore, LLC) is a non-invasive, afferent selective vagus nerve stimulator (nVNS) used for the treatment of migraine and cluster headache.2We report the first use of gammaCore (gC) in patients with refractory gastroparesis. Method 35 consecutive patients with intractable gastroparesis were invited to undergo a course of gC whilst awaiting funding for Enterra. The gC device delivers its stimulus to afferent vagus fibres as they cross the neck adjacent to the carotid arteries and it is programmed to deliver doses of 120 s. Patients were trained to deliver 2 doses (240 secs) to the left and right vagus nerve respectively. This dosing regimen was self-administered 8 hly (12 doses/day) for 2 weeks, increasing in week 3 to 3 doses 8 hly (18 doses/day). Patients were asked to grade their symptoms daily using the 9 item Gastroparesis Cardinal Symptom Index (GCSI) with a 5 point Likert scale. The GCSI was completed for 2 weeks prior and throughout the treatment period. At the end of the treatment period, the mean aggregated GSCI score at baseline was compared with the score of the final week of treatment. Clinically meaningful improvement was defined as a GCSI Likert scale reduction of ≥1. Results Twenty-three of the 35 patients (65.7%) used the gC as instructed and completed the diary. At 3 weeks, 8 patients (35%) had a ≥1 reduction in the aggregated GSCI score. Two patients who continued stimulation for more than three weeks had a delayed response, giving a total response rate of 43%. The response was evident within 1 week of commencing treatment in 8/10 responders (80%) and there was symptom recurrence within a week of stopping treatment in all the responders. There were no significant adverse events. Conclusion In this group of patients with treatment refractory gastroparesis, 1/3 failed to engage with short term nVNS. In compliant patients,43% recorded a fall of ≥1 in their aggregated GCSI score. As gC stimulates afferent vagus fibres, it is likely that the response is mediated at the level of the gut-brain axis. In refractory gastroparesis, gC might offer a new approach to symptom control. The dosing and duration of nVNS required to obtain an optimal response deserves further consideration. Disclosure of interest None Declared. References McCallum RW, et al. Neurogastroenterol Motil. 2010;22(2):161–7 Goadsby P, et al. Cephalgia 2014;34(12):986–93

A simplified Quick, Easy, Cheap, Effective, Rugged and Safe approach for the determination of trihalomethanes and benzene, toluene, ethylbenzene and xylenes in soil matrices by fast gas chromatography with mass spectrometry detection

A method based on simplified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction followed by large-injection volume-fast gas chromatography and mass spectrometry detection has been developed for the determination of trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane and bromoform) and BTEX (benzene, toluene, ethylbenzene and xylenes) in soil samples. The simplified version of QuEChERS used meets the requirements of the “green chemistry” and provides reliable results with high sample throughput, low solvent consumption, little labour and the use of materials commonly employed in laboratories. The GC device used is equipped with a programmable temperature vaporizer (PTV), with a liner packed with Tenax-TA ®. Using the solvent-vent mode, the PTV allows the injection of large volumes of sample, affording an improvement in the sensitivity of the method. The chromatographic conditions used here allowed the separation of the compounds in less than 5.50 min. Good linearity was obtained for all the target compounds, with highly satisfactory repeatability and reproducibility values. The limits of detection were in the 0.2 to 15 μg kg −1 range. The method was validated by the analysis of two certified reference materials.

Construction of a thermodesorption injector for gas chromatography

A detailed description for the do-it-yourself construction of a high-performance thermodesorption GC injector (HPTI) is presented. The injector consists of a heated desorption chamber, a cooled loop for focusing the desorbed volatiles as well as a heating control for sample injection into the separation column. The gas flow is controlled by valve switching during the steps of the operation. Two versions of the injector function either for the injection of highly volatile compounds or for compounds with extremely low volatility, e.g. lubricants. The sophisticated gas flow management allows injection of highly concentrated samples without memory effects in a sample gas split mode, while traces may be injected with virtually 1:1 sample transfer. A wide range of adsorbents appropriate for the compounds can be chosen due to homemade adsorbent tubes and the achievability of high desorption temperature. Solutions may be injected from a carrier material after solvent evaporation. The HPTI fulfills all multipurpose GC injector requirements and with the support of downloadable instruction files can be built by anyone working with conventional GC devices.

Determination of antioxidants in new and used lubricant oils by headspace-programmed temperature vaporization–gas chromatography–mass spectrometry

A sensitive method is presented to determine antioxidants (2-, 3-, and 4-tert-butylphenol, 2,6-di-tert-butylphenol, 3-tert-butyl-4-hydroxyanisol, 2,6-di-tert-butyl-4-methylphenol, 1-naphthol, and diphenylamine) in new and used lubricant oil samples. Research was carried out on a GC device equipped with a headspace sampler, a programmed temperature vaporizer, and an MS detector unit. The proposed method does not require sample treatment prior to analyses, hence eliminating possible errors occurring in this step. Sample preparation is reduced when placing the oil sample (2.0 g) in the vial and adding propyl acetate (20 μL). Solvent vent injection mode permits a pre-concentration of the compounds of interest in the liner filled with Tenax-TA®, while venting other species present in the headspace. Thereby, both the life of the liner and the capillary column is prolonged, and unnecessary contamination of the detector unit is avoided. Calibration was performed by adding different concentrations of analytes to a new oil which did not contain any of the studied compounds. Limits of detection as low as 0.57 μg/L (2-tert-butylphenol) with a precision lower or equal to 5.3% were achieved. Prediction of the antioxidants in new oil samples of different viscosities (5W40, 10W40, and 15W40) was accomplished with the previous calibration, and the results were highly satisfactory. To determine antioxidants in used engine oils, standard addition method was used due to the matrix effect.

Programmed temperature vaporizer based method for the sensitive determination of trihalomethanes and benzene, toluene, ethylbenzene and xylenes in soils

A methodology based on the coupling of a headspace autosampler with a GC and a MS detector operating in SIM mode has been developed for the determination of volatile organic compounds (THMs and BTEX) in soils. The GC device used is equipped with a programmable temperature vaporizer (PTV) packed with Tenax-TA ® to introduce the samples (the injection mode used was solvent vent), and a modular accelerated column heater (MACH™) to control column temperature. The proposed measurement procedure reduces the sample pretreatment step to a minimum. Combined use of solvent vent injection mode and mass spectrometry detection allows a highly sensitive method to be proposed, with limits of detection of the order of ng/kg for all the target compounds. Furthermore, the capillary column used allows rapid separations of compounds in less than 4.60 min, affording a very short total analysis cycle time of 9 min.

Determination of aromatic and polycyclic aromatic hydrocarbons in gasoline using programmed temperature vaporization-gas chromatography–mass spectrometry

A sensitive method is presented for the fast analysis of three aromatic and six polycyclic aromatic hydrocarbons (biphenyl, 3-methylbiphenyl, 4-methylbiphenyl, fluorene, phenanthrene, fluoranthene, pyrene, 1,2-benz( a)anthracene and chrysene) in gasoline samples. The applicability of a GC device equipped with a programmable temperature vaporizer (PTV) and an MS detector is explored. Additionally, a modular accelerated column heater (MACH™) was used to control the temperature of the capillary gas chromatography column. This module can be heated and cooled very rapidly, making total analysis cycle times very short. The proposed method does not require any previous analyte extraction and preconcentration step, as in most methods described to date. Sample preparation is reduced to simply diluting the gasoline samples in methanol. This reduces the experimental errors associated with this step of the analytical process. By using sampling injection in the solvent vent mode, and through choice of a suitable temperature, the lightest major components of the gasoline were removed. Moreover, use of a liner packed with Tenax-TA allowed the compounds of interest to be retained during the process. This working strategy could be extended to other groups of compounds through the choice of different venting temperatures. In this way, a large part of the gasoline components are eliminated, the life of the liner is prolonged, and it is possible to inject sample volumes that will not saturate the chromatographic column. The limits of detection ranged from 0.61 μg/L (pyrene) to 6.1 μg/L (biphenyl), and precision (measured as the relative standard deviation) was equal to or lower than 7.3%. The method was applied to the determination of analytes in gasoline samples and the results obtained can be considered highly satisfactory.

An analytical threshold voltage model for graded channel asymmetric gate stack (GCASYMGAS) surrounding gate MOSFET

A new structural concept, graded channel asymmetric gate stack (GCASYMGAS) SGT has been proposed and a two-dimensional analytical model is developed to examine the impact of this structure in suppressing short channel effects and in enhancing the device performance. It is shown that incorporation of ASYMGAS and graded channel designs leads to improved short channel immunity and hot carrier reliability. It is also demonstrated that for GCASYMGAS the average electric field in the channel is enhanced which leads to an increase in the electron velocity thereby improving the carrier transport efficiency. Furthermore, the device characteristics have been studied over a wide range of parameters and bias conditions and it is found that GCASYMGAS offers superior characteristics as compared to UD and GC devices. The results so obtained have been compared with simulated data obtained from the device simulator ATLAS 3D and are found to be in good agreement.

Simultaneous determination of gasoline oxygenates and benzene, toluene, ethylbenzene and xylene in water samples using headspace-programmed temperature vaporization-fast gas chromatography–mass spectrometry

A sensitive method is presented for the fast analysis of seven fuel oxygenates (methanol, ethanol, tert-butyl alcohol (TBA), methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME) and diisopropyl ether (DIPE)) and benzene, toluene, ethylbenzene and p-xylene (BTEX) in water samples. The applicability of a headspace (HS) autosampler in combination with a GC device equipped with a programmable temperature vaporizer (PTV) and a MS detector is explored. The proposed method achieves a clear improvement in sensitivity with respect to conventional headspace methods due to the use of the PTV. Two different packed liners with materials of different trapping strengths (glass wool and Tenax-TA) were compared. The benefits of using Tenax-TA instead of glass wool as packed material for the measurement of the 11 compounds emerged as better signal-to-noise ratios and hence better detection limits. The proposed method is extremely sensitive. The limits of detection are of the order of ng/L for six of the compounds studied and of the order of μg/L for the rest, with the exception of the most polar and volatile compound: methanol. Precision (measured as the relative standard deviation for a level with an S/N ratio close to 3) was equal to or lower than 15% in all cases. The method was applied to the determination of the analytes in natural matrixes (tap, river and sea water) and the results obtained can be considered highly satisfactory. The methodology has much lower detection limits than the concentration limits proposed in drinking water by the US Environmental Protection Agency (EPA) and the European Union for compounds under regulation.

Halitosis associated volatiles in breath of healthy subjects

BackgroundHalitosis can have an intra- or extra-oral origin. In all cases, bad breath is caused by the presence of volatile organic compounds originating from the mouth or the expired air. They can be specific for certain diseases or infections. Study objectiveThis study explored the presence and concentration of these volatile compounds normally associated with halitosis in the breath of healthy symptomless volunteers. MethodsAlveolar and mouth air of 40 healthy volunteers as well as environmental air were analyzed by gas chromatography–mass spectrometry (GC–MS) and by a commercially available GC device (OralChroma®). Results14 compounds, associated with halitosis could be detected. All of them except carbon disulfide, appeared to be (partly) produced endogenously and/or in the mouth. Acetone, 2-butanone, 2-pentanone and 1-propanol were common to all volunteers in both alveolar and mouth air and indole and dimethyl selenide in alveolar air. ConclusionsGC–MS seems a promising tool for differential diagnosis of halitosis, with the possibility to detect extra-oral causes, which often remain undetected unless characterized by a specific smell.

An analytical drain current model for graded channel cylindrical/surrounding gate MOSFET

In the present paper, a comprehensive drain current model incorporating various effects such as drain-induced barrier lowering (DIBL), channel length modulation and impact ionization has been developed for graded channel cylindrical/surrounding gate MOSFET (GC CGT/SGT) and the expressions for transconductance and drain conductance have been obtained. It is shown that GC design leads to drain current enhancement, reduced output conductance and improved breakdown voltage. The effectiveness of GC design was examined by comparing uniformly doped (UD) devices with GC devices of various L1/L2 ratios and doping concentrations and it was found that GC devices offer superior characteristics as compared to the UD devices. The results so obtained have been compared with those obtained from 3D device simulator ATLAS and are found to be in good agreement.