0000000000294327
AUTHOR
André F. Lavorante
showing 4 related works from this author
Micropumping multicommutation turbidimetric analysis of waters
2007
Abstract A micropumping multicommutation manifold to perform turbidity determinations in waters is described. The procedure is based on the use of a combination of hydrazine sulfate and hexamethylenetetramine, to obtain an external standard of nephelometric turbidity units (NTU), which could compare the absorbance measurements at high wavelengths for samples with a calibration line obtained from a concentrated formazine standard diluted on-line. To minimize sample and reagent consumption and waste generation, the flow system was designed with two solenoid micro-pumps, one of them for the alternative introduction of the formazine standard and samples and the other one for the water carrier. …
A spectrophotometric flow procedure for the determination of cationic surfactants in natural waters using a solenoid micro-pump for fluid propulsion
2006
An automatic flow-analysis procedure for spectrophotometric determination of cationic surfactants in surface water using a solenoid micro-pump for propelling solutions of reagents and sample is des...
A multicommuted stop-flow system employing LEDs-based photometer for the sequential determination of anionic and cationic surfactants in water
2006
It has been developed an automatic stop-flow procedure for sequential photometric determination of anionic and cationic surfactants in a same sample of water. The flow system was based on multicommutation process that was designed employing two solenoid micro-pumps and six solenoid pinch valves, which under microcomputer control carry out fluid propelling and reagent solutions handling. A homemade photometer using a photodiode as detector and two light emitting diodes (LEDs) with emission at 470 nm (blue) and 650 nm (red) as radiation sources, which was tailored to allow the determination of anionic and cationic surfactants in waters. The procedure for anionic surfactant determination was b…
Monitoring of the smoking process by multicommutation Fourier Transform Infrared spectroscopy
2007
Abstract Nicotine was selected as the target molecule for monitoring of the smoking process by multicommutation Fourier Transform Infrared spectroscopy (FTIR). The method involved the use of CHCl3 for on-line extraction of nicotine from tobacco, cigarette filters and tobacco ash from NH4OH alkalinized samples, and absorbance measurement of the characteristic band at 1316 cm−1 in the stopped-flow mode, by obtaining the peak area in the range between 1334 and 1300 cm−1. Under the best operational conditions, the procedure developed provided a detection limit of 0.05 mg mL−1 nicotine, corresponding to 0.5 mg g−1 in the solid sample, a relative standard deviation less than 2.5%, and a sampling …