V. K. Dua

Application of ethyl chloroformate derivatization for solid-phase microextraction–gas chromatography–mass spectrometric determination of bisphenol-A in water and milk samples

AbstractA simple and rapid analytical method based on in-matrix ethyl chloroformate (ECF) derivatization has been developed for the quantitative determination of bisphenol-A (BPA) in milk and water samples. The samples containing BPA were derivatised with ECF in the presence of pyridine for 20xa0s at room temperature, and the non-polar derivative thus formed was extracted using polydimethylsiloxane solid-phase microextraction (SPME) fibres with thicknesses of 100xa0μm followed by analysis using gas chromatography–mass spectrometry. Three alkyl chloroformates (methyl, ethyl and isobutyl chloroformate) were tested for optimum derivatisation yields, and ECF has been found to be optimum for the derivatisation of BPA. Several parameters such as amount of ECF, pyridine and reaction time as well as SPME parameters were studied and optimised in the present work. The limit of detection for BPA in milk and water samples was found to be 0.1 and 0.01xa0μgxa0L−1, respectively, with a signal-to-noise ratio of 3:1. The limit of quantitation for BPA in milk and water was found to be 0.38 and 0.052xa0μgxa0L−1, respectively, with a signal-to-noise ratio of 10:1. In conclusion, the method developed was found to be rapid, reliable and cost-effective in comparison to silylation and highly suitable for the routine analysis of BPA by various food and environmental laboratories.n FigureSchematic diagram for the analysis of bisphenol-A using SPME/GC-MS after ECF derivatization in water and milk samples

INSECTICIDAL ACTIVITY OF VALERIANA JATAMANSI (VALERIANACEAE) AGAINST MOSQUITOES

ABSTRACT A root extract of Valeriana jatamansi (code BAL-O) exhibited larvicidal and adulticidal activity against different mosquito species. The median lethal concentration (LC50) of BAL-O against larvae of Anopheles stephensi, Anopheles culicifacies, Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus were 68.1, 42.8, 51.2, 53.8, and 80.6 mg/liter, respectively. The LC50 and the 90% lethal concentration against adult An. stephensi, An. culicifacies, Ae. aegypti, Ae. albopictus, and Cx. quinquefasciatus were 0.14, 0.16, 0.09, 0.08, and 0.17 and 0.24, 0.34, 0.25, 0.21, and 0.28 mg/cm2, respectively. The median knock-down time and 90% knock-down time of the fraction were 13, 13, 12, 13, and 18 and 24, 25, 21, 20, and 42 min against An. stephensi, An. culicifacies, Ae. aegypti, An. albopictus and Cx. quinquefasciatus, respectively, using 0.28 mg/cm2 impregnated papers. The median effective time and 90% effective time against An. stephensi at 4°C were 46.6 and 8.7 days, and at 29°C, 25.5 and 5.6 days, respectively. Gas chromatographic–mass spectrometric analysis of BAL-O showed 2-butanone,4-(2,6,6-trimethyl-2-cyclohexen-1-yl) (10.11%), patchouli alcohol (8.55%), cubenol (5.97%), caryophyllene oxide (5.46%), cadinol (5.23%), and aristolene (5.19%).

Determination of quinine in serum, plasma, red blood cells and whole blood in healthy and Plasmodium falciparum malaria cases by high-performance liquid chromatography

A normal-phase high-performance liquid chromatographic method using dichloromethane-methanol-1 M perchloric acid (100:9:0.4, v/v) at a flow-rate of 0.8 ml/min on a Zorbax-Sil column with fluorescence detection has been developed for the separation of quinine and quinidine from other antimalarials. Within-day and day-to-day coefficients of variation averaged 0.74 and 7.56%, respectively. The extraction recovery of quinine for plasma, serum, red blood cells and whole blood (filter paper) was 88.13, 87.12, 78.0 and 77.5%, respectively. The method is capable of separating quinine from dihydroquinine, a compound usually found as an impurity in authentic quinine samples. The method has been used for the determination of quinine in plasma, serum, red blood cells and whole blood (filter paper) of six healthy and twenty Plasmodium falciparum malaria cases. The average quinine concentration in P. falciparum malaria cases was three to four times higher than that in healthy volunteers. Quinine was absorbed much less in red blood cells than in plasma or serum.

Isolation of repellent ingredients from Lantana camara (Verbenaceae) flowers and their repellency against Aedes mosquitoes

The repellent properties of different fractions isolated from Lantana camara flowers by using steam distillation, solvent partition and chromatographic methods were evaluated against Aedes mosquitoes. Maximum protection time of one fraction eluted by chloroform from a silica gel column was 3.45u2003h. One application of this fraction gave 100% protection for 2u2003h and may protect 75.8% at 7u2003h (tu2003=u20037.00, Pu2003<u20030.001) against the bites of Aedes mosquitoes. Further purification of the most efficient fraction into pure compounds did not result in any increase in repellency.

High-performance liquid chromatographic determination of primaquine and carboxyprimaquine concentrations in plasma and blood cells in Plasmodium vivax malaria cases following chronic dosage with primaquine

A reversed-phase HPLC method using acetonitrile-methanol-1 M perchloric acid-water (30:9:1:95, v/v) at a flow-rate of 1.5 ml/min on a mu-Bondapak C18 column with UV detection at 254 nm was developed for the separation of primaquine, its major metabolite carboxyprimaquine and other metabolites such as N-acetylprimaquine, 4-hydroxyprimaquine, 5-hydroxyprimaquine, 5-hydroxy-6-methoxyprimaquine, demethylprimaquine and 6-methoxyprimaquine, and also other antimalarials. The calibration graphs were linear in the range 0.025-100 micrograms/ml for primaquine and 4-1000 micrograms/ml for carboxyprimaquine. The within-day and day-to-day coefficients of variation averaged 3.65 and 6.95%, respectively, for primaquine and 3.0 and 7.52%, respectively for carboxyprimaquine in plasma. The extraction recoveries for primaquine and carboxyprimaquine were 89 and 83%, respectively. The mean carboxyprimaquine concentration was much higher in plasma and blood cells of Plasmodium vivax patients than that in plasma from healthy subjects. The carboxyprimaquine level was also higher in blood cells than plasma whereas the primaquine concentration was the same in both cases.

Sulphadoxine concentrations in plasma, red blood cells and whole blood in healthy and Plasmodium falciparum malaria cases after treatment with Fansidar using high-performance liquid chromatography

A reversed-phase high-performance liquid chromatographic method using acetonitrile-methanol-(1M) perchloric acid-water (30:9:0.8:95, v/v/v/v) at a flow of 1.5 ml min-1 on mu-Bondapak C18 column with UV (254 nm) detection has been developed for the separation of sulphadoxine, sulphalene and sulphamethoxazole from other antimalarials. Calibration curves were linear in the range 0.5-100 micrograms ml-1. The limit of quantitation was 50 ng ml-1. Within-day and day-to-day coefficients of variation averaged 2.1 and 6.45%, respectively. The extraction recovery of sulphadoxine from plasma, red blood cells and whole blood was 90.28, 92.05 and 94.69%, respectively. The method has been used for the determination of sulphadoxine concentrations in plasma, red blood cells and whole blood of eight healthy and 50 Plasmodium falciparum malaria cases after administration of two tablets of Fansidar. Mean sulphadoxine concentration in plasma was higher than red blood cells or whole blood. Sulphadoxine concentration in plasma and whole blood of P. falciparum malaria cases was significantly higher as compared to healthy volunteers while it was the same in red blood cells. Sulphadoxine was absorbed much less in red blood cells than in plasma or whole blood.

Isolation and antimalarial activity of peroxydisulfate oxidation products of primaquine

Five compounds formed by peroxydisulfate oxidation of primaquine were isolated using chromatographic methods and evaluated for antimalarial activity in vitro. One compound 6-methoxy-5,8 bis(4-amino-1-methylbutylamino)quinoline [P(1)] was found to have good gametocytocidal activity against Plasmodium yoelli infected mice at 10mg kg(-1) dose in vivo.

Plasmodium vivax relapses after 5 days of primaquine treatment, in some industrial complexes of India

In an investigation of relapse patterns, 5541 cases of Plasmodium vivax malaria, from four major industrial complexes, each received at least one, 5-day course of primaquine (at 15 mg/day). Any subject relapsing was retreated with the same course. Overall, 511 (9.2%) of the P. vivax cases relapsed after the first course and 99 (1.78%), 25 (0.45) and three (0.05%) cases relapsed two, three and four times, respectively. Most cases of relapse occurred within 1 year of treatment. Clearly, a 5-day primaquine regimen is inadequate to control relapses among P. vivax cases and there is therefore an urgent need to review the treatment strategy. It may now be appropriate to implement the 14-day regimen recommended by the World Health Organization, although this is much less feasible under field conditions.

LARVIVOROUS ACTIVITY OF POECILIA RETICULATA AGAINST CULEX QUINQUEFASCIATUS LARVAE IN A POLLUTED WATER DRAIN IN HARDWAR, INDIA

ABSTRACT The efficacy of the larvivorous fish Poecilia reticulata against mosquito larvae was monitored in a drain at Bharat Heavy Electricals Limited, Hardwar, India. The water was polluted and the water flow was in some way impeded. Poecilia reticulata failed to feed on Culex quinquefasciatus larvae in this drain. Laboratory experiments also confirmed the inefficacy of P. reticulata as a predator of Cx. quinquefasciatus larvae during the first 24 h. Significant differences in the efficacy of P. reticulata against Cx. quinquefasciatus were recorded between polluted water and drinking water. Poecilia reticulata preferred to feed on other available food present in the polluted water rather than on Cx. quinquefasciatus larvae. This was verified by the identification of plankton in the gut content of the fish and by the high density of plankton present in the polluted water.

Chloroquine and desethylchloroquine concentrations in blood cells and plasma from Indian patients infected with sensitive or resistant Plasmodium falciparum.

The sensitivities of 61 Indian cases of Plasmodium falciparum malaria to chloroquine (CQ) were investigated using in-vitro and in-vivo methods. Concentrations of CQ and desethylchloroquine (DCQ) in blood cells and plasma from CQ-sensitive and -resistant cases were determined 2 and 7 days after initiation of treatment, by HPLC. On day 2, the mean CQ concentrations in the samples collected from the sensitive cases were higher than those in the samples from the resistant patients, in plasma (0.47 v. 0.32 µg/ml; P<0.02) and particularly in the blood cells (1.51 v. 0.46 µg/ml; P<0.001). By day 7, however, the CQ concentrations in the two groups were similar. Although, on day 2, the mean ratio of the CQ to DCQ concentrations was significantly higher in the blood cells from the sensitive group than in those from the resistant cases (P<0.01), the CQ/DCQ ratios for the plasma were similar for the two groups. Similarly, the mean ratio between the blood-cell concentration of CQ. on day 2 and the concurrent plasma concentration (BPr) was also relatively high in the sensitive group (P<0.001).