Stress testing in asymptomatic subjects with important coronary risk factors.
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Adult↗
Biomedical subjects
V K Gupta
Publications and source records attributed to V K Gupta.
Spectrophotometric method for determination of paraquat in food and biological samples.
A sensitive spectrophotometric method was developed for determination of paraquat, a widely used herbicide. Paraquat was reduced with glucose in an alkaline medium, and the blue radical ion obtained was measured at 600 nm. Beer's law was obeyed at 0.1-1.2 ppm paraquat. The molar absorptivity was 1.26 x 10(5) L mol-1 cm-1. The standard deviation and relative standard deviation were +/- 0.007 and 2.0%, respectively, for 5 micrograms paraquat/10 mL analyzed over 7 days. The method was free from interference by other commonly used pesticides and metal ions. The method may be used to the determine paraquat in plants, fruits, grains, water, blood, and urine.
Calibration↗
Sensitive spectrophotometric method for determining pentachlorophenol in various environmental samples.
A new, simple, and sensitive spectrophotometric method is described for determination of pentachlorophenol, a widely used insecticide and herbicide, in various environmental samples. The method is based on the reaction of pentachlorophenol with concentrated nitric acid to form chloranil, which liberates iodine from potassium iodide. The liberated iodine then selectively oxidizes leucocrystal violet to form crystal violet, which has an absorption maximum at 592 nm. Beer's law is obeyed over the concentration range of 0.1-1.6 micrograms pentachlorophenol/25 mL (0.004-0.064 ppm). The method was applied satisfactorily to determination of pentachlorophenol in air, water, plant material, textile effluent, and biological samples.
Air Pollution↗