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1

Optimization of a dual-slot waveguide for a refractive index biosensor

Sahu S., Ali J., Singh G.

Optica Applicata

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2018

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Vol. 48, nr 1

161--167

EN

The present article illustrates the modeling and optimization of a dual-slot waveguide for the application of a refractive index biosensor. The nanometer scale waveguide structure uses the silicon-on-insulator platform for the consideration of higher sensitivity and compactness of a resonator biosensor. The modal analysis is performed using the finite difference method based on full vector eigenmode calculation. The maximum field penetration in the lower index region is found for the quasi-TE mode. The sensitivity is maximized through the optimization of the waveguide dimension by relating effective refractive index with the dispersion of a waveguide. The biosensor showed the maximum calculated sensitivity of 461.327 nm/RIU and a limit-of-detection of 2.601 × 10–6 RIU (where RIU denotes refractive index unit).

2

Phytoextraction of Cr by maize (Zea mays L.) : the role of plant growth promoting endophyte and citric acid under polluted soil

Ali J., Mahmood T., Hayat K., Afridi M. S., Ali F., Chaudhary H. J.

Archives of Environmental Protection

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2018

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Vol. 44, no. 2

73--82

EN

High chromium (Cr) toxicity has turned into a serious environmental concern. Cr contaminated agronomic soils negatively affect the growth and yield of crops. Current research was conducted to enhance the phytoextraction potential of maize by using Burkholderia vietnamiensis and citric acid (CA). Plants were subjected to three concentrations of Cr (0.86, 350, and 500 ppm). A pot experiment was conducted under greenhouse conditions with completely randomized design (CRD). After 72 days of experiment, plants were harvested to analyze the morphological and biochemical attributes of soil, bacteria and plant. Results revealed that plant fresh, dry biomass, root, shoot length and chlorophyll contents significantly increased by 56%, 50%, 58%, 78% and 60%, respectively, at 500 ppm Cr concentration in combine treatment of B. vietnamiensis and CA. Maize plants treated with both B. vietnamiensis and CA significantly increased the bioaccumulation (BA) of Cr up to 50% and translocation factor (TF) by 31%. Furthermore, superoxide dismutase (SOD), proline and peroxidase dismutase (POD) activities in leaves were markedly increased by 30%, 42% and 15%, respectively, when treated with CA. Current study reveals that exogenous co-application of B. vietnamiensis + CA enhance plant growth by alleviating heavy metal stress and accelerate the phytoextraction of Cr. Taking into account the heavy metal tolerance and accumulation capacity, Zea mays is suitable for phytoremediation of contaminated soils in combination with B. vietnamiensis and CA.

3

High-Performance Thin-Layer Chromatographic Analysis of Eugenol in Developed Nanoemulsion Gel and Nanoparticles: Validation of a Stability-Indicating Method

Pramod K., Ilyas U. K., Singh M., Kamal Y. T., Ahmad S., Ansari S. H., Ali J.

Acta Chromatographica

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2015

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Vol. 27, no. 3

571--582

EN

High-performance thin-layer chromatography (HPTLC) method for the quantification of eugenol from nanostructured drug delivery systems was successfully developed and validated. The mobile phase consisted of n-hexane:acetone (7:3, v/v), and the densitometric scanning was performed in the absorbance mode at 280 nm. The method was valid with respect to linearity and range, accuracy, precision, specificity, detection limit (DL), and quantitation limit (QL). The linearity of the method was established by a correlation coefficient value of 0.9930 ± 0.0013. The precision was tested by checking intra-day (repeatability) and inter-day (intermediate precision) variations. The method was established to be precise by low relative standard deviation (RSD) values for different concentration of eugenol. The results of the recovery studies of eugenol from preanalyzed samples demonstrated the accuracy of the method. The specificity of the developed method for the analysis of eugenol in the nanoemulsion gel and nanoparticles samples was confirmed by comparing the spectra obtained in standard and sample analysis. The DL and QL were determined to be 31.41 and 95.17 ng band−1, respectively, for the HPTLC method. The forced degradation studies revealed on eugenol established the effectiveness of the developed and validated method. The developed and validated HPTLC method was found to be a stability-indicating one, as indicated by the results of forced degradation studies, for its use during the accelerated stability studies of the nanoemulsion gels and nanoparticles of eugenol.

4

High-performance thin-layer chromatographic analysis of psoralen in marketed formulations and manufactured solid lipid nanoparticles (SLNs): Validation of the method

Akhtar N., Faiyazuddin Md., Mustafa G., Sultana Y., Baboota S., Ali J.

Acta Chromatographica

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2012

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Vol. 24, no. 4

603--613

EN

A quantitative method using precoated silica gel-60 Lichrosphere high-performance thin-layer chromatography (HPTLC) plates, automated band wise sample application, and n-hexane:acetone:formic acid (2:1:0.025 υ/υ/υ) as mobile phase, has been developed and validated for the analysis of psoralen in marketed formulations and novel solid lipid nanoparticles (SLNs). Densitometric analysis was performed at 250 nm in absorbance mode. Compact bands of psoralen were obtained at Rf 0.32 ± 0.02. The method was validated for linearity, precision, robustness, sensitivity, specificity, and recovery. Linearity (r2 = 0.995), limit of detection (8.0 ng band-1), limit of quantification (18.1 ng band) -1, recovery (98.06–99.64%), and precision (≤0.74) were satisfactory. Statistical analysis established that the developed method for quantification of psoralen in marketed formulation and from solid lipid nanoparticles is reproducible and selective.

5

Quantitative estimation of mimosine in anti-psoriatic ayurvedic formulation containing whole plant extract of Mimosa pudica Linn. by validated isocratic RP-HPLC method

Musthaba S, Athar M. T, Kamal Y. T, Ahmad S., Ali J., Baboota S.

Acta Chromatographica

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2011

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Vol. 23, no. 3

531--538

EN

In this chapter, an isocratic reverse phase HPLC determination of mimosine was developed and validated in an anti-psoriatic topically applied formulation “Lajjalu”. The chromatography was performed on a C18 column with water-orthophosphoric acid (98.8:0.2, υ/υ) as a mobile phase with a pH of 3.0 at a flow rate of 1.0 mL min-1. Detection was performed at 284 nm, and a sharp peak was obtained for mimosine at a retention time of 2.62 ± 0.01 min. Linear regression analysis data for the calibration plot showed a good linear relationship between response curve and concentration in the range of 0.050–5000 ng mL-1 and the regression coefficient was 0.9998 with the linear regression equation y = 4766.8x−17726. The detection (LOD) and quantification (LOQ) limits were 10.3 and 35.6 ng mL-1, respectively. The wide linearity range, sensitivity, accuracy, short retention time, and simple mobile phase imply the method is suitable for routine quantification of mimosine with high precision and accuracy.

6

Simplified coupling power model for fibers fusion

Saktioto J., Ali J., Fadhali M.

Opto-Electronics Review

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2009

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Vol. 17, No. 3

193-199

EN

Fiber coupler fabrication used for an optical waveguide requires lossless power for an optimal application. The previous research coupled fibers were successfully fabricated by injecting hydrogen flow at 1 bar and fused slightly by unstable torch flame in the range of 800-1350°C. Optical parameters may vary significantly over wide range physical properties. Coupling coefficient and refractive index are estimated from the experimental result of the coupling ratio distribution from 1% to 75%. The change of geometrical fiber affects the normalized frequency V even for single mode fibers. V is derived and some parametric variations are performed on the left and right hand side of the coupling region. A partial power is modelled and derived using V, normalized lateral phase constant u, and normalized lateral attenuation constant, w through the second kind of modified Bessel function of the l order, which obeys the normal mode and normalized propagation constant b. Total power is maintained constant in order to comply with the energy conservation law. The power is integrated through V, u, and w over the pulling length of 7500 µm for 1-D. The core radius of a fiber significantly affects V and power partially at coupling region rather than wavelength and refractive index of core and cladding. This model has power phenomena in transmission and reflection for an optical switch and tunable filter.

7

Stability-indicating HP TLC method for determination of donepezil hydrochloride in bulk drug and pharmaceutical dosage form

Ali J., Ali M., Ahmad S., Bhavna M.

Chemia Analityczna

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2009

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Vol. 54, No. 6

1501-1516

EN

A sensitive, selective, precise and stability-indicating high-performance thin layer chroma-tographic (HPTLC) method for analysis of donepezil hydrochloride (DH) as bulk drug and in formulations was developed and validated. TLC aluminum plates pre-coated with 60 F-254 silica gel (20 x 10 cm) were used as the stationary phase. The solvent system consisted of butanol-water-glacial acetic acid (5:4:1, v/v/v). Densitometric analysis of DH was carried out in the absorbance mode at 260 nm. This system was found to give compact spots for DH (RF= 0.53 š 0.03 for six replicates). DH was subjected to acidic and alkaline hydrolysis, oxidation, dry and wet heat treatment, and photodegradation; under all these conditions the drug underwent degradation. Degradation products had significantly different RF values and thus were well separated from the pure drug. The method was validated with respect to linearity, precision, robustness, limit of detection (LOD), limit of quantification (LOQ), ruggedness and accuracy. Linearity was observed in the range 50—1000 ng per spot with a significantly high value of the correlation coefficient r2 = 0.9979; 95% confidence interval of r2 was 0.9908-0.9995. The mean S.E. value of the slope was 0.1316 with respect to the peak area. LOD and LOQ were 15.40 and 50.90 ng per spot, respectively. Statistical analysis proved that the method was repeatable and specific for the estimation of the studied drug. As the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating procedure.

PL

Opracowano i zwalidowano czułą, selektywną i precyzyjną, metody wysokosprawnej TLC do analizy chlorku donezepilu (DH) jako substancji chemicznej i w preparatach. Metoda umożliwia również ocenę trwałości leku. Zastosowano płytki na podłożu aluminiowym o wymiarach 20 * l O cm, pokryte żelem krzemionkowym 60 F-254. Jako eluent zastosowano butanol-wodę-lodowaty kwas octowy (5:4:1, v/v/v). DH wykrywano densytometrycznie przy 260 nm. W tych warunkach otrzymano zwarte plamki DH z RF= 0,53 š 0,03 dla sześciu powtórzeń. DH poddawano hydrolizie kwasowej i zasadowej, utlenianiu, ogrzewaniu na mokro i na sucho oraz naświetlaniu. We wszystkich tych przypadkach lek ulegał degradacji. Produkty degradacji miały wyraźnie różne wartości RFi były dobrze oddzielone od wyjściowego leku. Metodę walidowano uwzględniając liniowość, precyzje, odporność, wykrywalność, oznaczalność i dokładność. Liniowość obserwowano w zakresie 50—1000 ng w plamce, ze współczynnikiem korelacji r2 = 0,9979. Średnia wartość nachylenia wynosiła 0,1316 w odniesieniu do powierzchni piku. Wykrywalność i oznaczalność wynosiła odpowiednio 15,40 i 50,90 ng w plamce. Za pomocą analizy statystycznej wykazano, że metoda oznaczania badanego związku jest powtarzalna i specyficzna, umożliwia też oddzielanie leku od produktów jego degradacji, dzięki czemu może być zastosowana do badania trwałości leku.

8

Thin-layer chromatographic analysis of psoralen in babchi ( Psoralea corylifolia ) oil

Ali J., Akhtar N., Sultana Y., Baboota S., Ahmad S.

Acta Chromatographica

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2008

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Vol. 20, no. 2

277-282

EN

A simple, selective, precise, accurate, and cost-effective thin-layer chromatographic (TLC) method for analysis of psoralen in different brands of babchi (Psoralea corylifolia) oil has been developed and validated. Aluminium TLC plates precoated with silica gel 60F254 were used as the stationary phase and n-hexane-acetone-formic acid 2:1:0.025 (v/v) as mobile phase. A compact, resolved psoralen peak (RFvalue 0.32 š 0.02) was observed by densitometric analysis in absorbance mode at 250 nm. Calibration data revealed a good linear relationship (r2 = 0.9956) between peak area and concentration in the range 20-200 ng per spot. Mean š SD values of slope and intercept were 11.35 š 0.36 and 14.64 š 0.31, respectively. Statistical analysis proved the method to be a repeatable, selective, and accurate means of estimation of psoralen in different brands of babchi oil.

9

Development and validation of a stability-indicating HPTLC method for analysis of antitubercular drugs

Ali J., Ali N., Sultana Y., Baboota S., Faiyaz S.

Acta Chromatographica

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2007

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No. 18

168-179

EN

A simple, selective, precise, and stability-indicating high-performance thin-layer chromatographic (HPTLC) method has been established and validated for analysis of isoniazid and rifampicin both as the bulk drugs and in formulations. The compounds were separated on aluminumbacked silica gel 60 F254 plates with n-hexane–2-propanol–acetone–ammonia–formic acid, 3:3.8:2.8:0.3:0.1 (v/v) as mobile phase. This system was found to give compact spots for isoniazid and rifampicin (RF values 0.59 ± 0.02 and 0.73 ± 0.04, respectively). Densitometric analysis of isoniazid and rifampicin was performed at 254 nm. Regression analysis data for the calibration plots were indicative of good linear relationships between response and concentration over the range 100–700 ng per spot. The correlation coefficients, r2, were 0.994 and 0.997 for isoniazid and rifampicin respectively. The values of slope and intercept of the calibration plots were 3.755 ± 0.22 and 3099.1 ± 51.21, respectively, for isoniazid and 4.0957 ± 0.25 and 3567.6 ± 61.11, respectively, for rifampicin. The method was validated for precision, recovery, and robustness. The limits of detection and quantification were 20 ± 0.51 and 60 ± 1.05 ng, respectively, for isoniazid and 25 ± 0.63 and 75 ± 1.12 ng, respectively, for rifampicin. Isoniazid and rifampicin were subjected to acid, base, peroxide, and UV-induced degradation. In stability tests the drugs were susceptible to acid and basic hydrolysis, oxidation and photodegradation. Statistical analysis proved the method is repeatable, selective, and accurate for estimation of isoniazid and rifampicin. Because the method could effectively separate the drugs from their degradation products, it can be used as a stabilityindicating method.

10

Development and validation of a stability-indicating HPLC method for analysis of celecoxib (CXB) in bulk drug and microemulsion formulations

Baboota S., Faiyaz S., Ahuja A., Ali J., Shafiq S., Ahmad S.

Acta Chromatographica

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2007

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No. 18

116-129

EN

A simple, economic, selective, precise, and stability-indicating HPLC method has been developed and validated for analysis of celecoxib (CXB), a selective COX-2 inhibitor, both in bulk drug and in microemulsions. Reversed-phase chromatography was performed on a C18 column with methanol–water, 75:25 (%, v/v), as mobile phase at a flow rate of 1.25 mL min-1. Detection was performed at 250 nm and a sharp peak was obtained for CXB at a retention time of 4.8 ± 0.01 min. Linear regression analysis data for the calibration plot showed there was a good linear relationship between response and concentration in the range 0.27–80 µg mL-1; the regression coefficient was 0.996 and the linear regression equation was y = 48415x + 54359. The detection (LOD) and quantification (LOQ) limits were 0.086 and 0.2625 µg mL-1 respectively. The method was validated for accuracy, precision, reproducibility, specificity, robustness, and detection and quantification limits, in accordance with ICH guidelines. Statistical analysis proved the method was precise, reproducible, selective, specific, and accurate for analysis of CXB. The wide linearity range, sensitivity, accuracy, short retention time, and simple mobile phase imply the method is suitable for routine quantification of CXB with high precision and accuracy.