Metals analysis is a focus of the Laboratory; the primary instrument used is a SHIMADZU AA-6200 Hydride Generation Atomic Absorption Spectrometer (HG-AAS). If only one element in a sample is of interest, atomic absorption may be an alternative choice for analysis. Flame AA (FAA) is a well-established, low-cost for ppm-level detection limits for a number of elements.
Ion chromatography is a separation technology that uses an anion exchange column to separate anion moving through the column, which are then measured by a detector system at the column outlet. At our lab, routine measurements of nitrate (NO3-1), phosphate (PO4-3), sulfate (SO4-2), fluoride (F-1) and chloride (CI-I) can be made in aqueous systems such as stream and pore waters. Detection limits for these constituents are roughly 1 ppm (mg/L) in dilute solutions. Nitrite (NO2-1) and bromide (Br-1) analyses can also be included in the sample run for an additional cost. Ion chromatography is performed using a DIONEX IC-90 ion chromatography system with conductivity detectors. Common anions are separated using an Ion Pac AS12A column and detected by suppressed conductivity.
Working calibration standards are prepared each day from dilution of a 1000ppm mixed stock solution. A four point calibration is performed and an independent check QC sample is analyzed at every 10 samples. Because of the long-of nitrite in aqueous solution, this ion is not included in the routine analysis. However, if required, nitrite standards can be made up on the day of analysis and this anion subsequently quantified for an additional cost.
Hydrogen ion activity (pH), electrical conductivity (EC, in units of S [Siemens] per m) and redox potential (Eh in volts) are important characteristics of both solutions and extracts of solids that can be readily determined at the lab. pH is determined with a Hi-sensitive glass electrode calibrated against solutions of known (H+). Precision is typically only good to two decimal places. EC is determined with a conductivity cell monitored using a resistance/conductivity meter; EC in mS/cm is closely related to total dissolved salts in a solution. Redox it, an estimate of the oxidation-reduction status, indicative of dissolved oxygen and the potential for formation of reduced gas species such as hydrogen sulfide. It is measured potentiometrically using a standard platinum electrode, and reported to the nearest mV, For solids, a paste is typically mixed at a 2.5 (water) : 1 (solids) ratio, equilibrated and pH and EC determined in the supernatant; pH and Eh do not vary greatly with the chosen ratio but EC is sensitive to the volume of water and is thus a relative or comparative value.
Accreditations and Professionals Affiliations
- BETV SAM Project(OCETA)
- DPHE Central Laboratory
- Miyazaki Environmental Science Laboratory
The usual activities of the lab is to carry out sampling water sources, measurement, analysis, cross-check, research of safe water devices with the aim of supplying safe water to the community. It also provides training to Union Council members on arsenic test by field-kit.
Types of services are –
- Water Sample Collection
- Water Quality Analysis