A rapid colorimetric method for measuring arsenic concentrations in groundwater

Removal of iron, arsenic and coliform bacteria from water by novel constructed soil filter system

“…The residual arsenic in water sample was determined using rapid colorimetric method (Dhar et al, 2004) with detection limit 1 g l −1 . The method was used to estimate As(III) and As(V) concentrations in treated water samples.…”

Effect of ferrous on the adsorption of As(V) from aqueous solution on activated carbons

“…The dissolved arsenic concentrations in solutions were measured by molybdenum blue method (Dhar et al 2004). …”

A novel colorimetric method for field arsenic speciation analysis

“…A linear regression (R 2 = 0.9979) was achieved in four orders of magnitude concentration range (total As, 0.01-10 mg/L). The wider linear range increased from 2-220 (Johnson and Pilson, 1972) and 10-1000 μg/L (Dhar et al, 2004) to 10 mg/L enabled direct measurements of groundwater As concentrations in several mg/L level (Nordstrom, 2002) without sample dilution.…”

“…Researchers optimized the method to reach a detection limit of 7 μg/L with a mean recovery of total As of 97% ± 5% in a total As range 10-1000 μg/L (Dhar et al, 2004). However, the reducing reagent used in previous studies (14% Na 2 S 2 O 5 + 1.4% Na 2 S 2 O 3 + 10% H 2 SO 4 ) generates highly toxic SO 2 gas (Johnson, 1971;Johnson and Pilson, 1972;Dhar et al, 2004). Tsang et al (2007) attempted to modify the reducing reagent and used sodium dithionite to reduce 7-75 μg/L As(V) in neutral samples.…”

“…Nevertheless, this narrow linear range and complication in operation limit its field application. The other limitation in previous molybdenum blue method is the usage of KIO 3 as oxidant which could inhibit molybdate reduction (Dhar et al, 2004).…”