Methods of Analysis for Parameters of Interest
Methods of analysis for parameters of interest
The below stated methods were provided with permission and verbatim from the National Laboratory for Environmental Testing, Environment Canada. Note that these methods may be periodically subject to change.
Standard Method 1021Dissolved Inorganic
Carbon/Dissolved Organic
Carbon / Analysis is conducted for dissolved inorganic and organic carbon using a UV-persulfate TOC Analyzer (Pheonix 8000). The dissolved inorganic carbon, (DIC), (carbonate, bicarbonate, and dissolved carbon dioxide) in filtered water samples is measured by acidifying with phosphoric acid to pH of 3 or lower, and then sparged with a stream of inert nitrogen gas in the IC sparger. Acidification converts carbonate and bicarbonate to carbon dioxide, which is then transported along with the dissolved CO2 by the gas stream. The gas stream passes through the Gas/Liquid Separator, Mist Trap, Permeation Tube and finally through the Chlorine Scrubber to remove moisture and chlorine which may have been produced during the oxidation step. The concentration of CO2 is measured by a non-dispersive infrared (NDIR) detector. The detector is sensitive to the absorption frequency of CO2 and provides a signal proportional to the concentration of CO2 in the carrier gas. The detector output signal is linearized and is displayed on the video screen as a real time strip chart recording. The linearized signal is integrated and referred to stored calibration data [1]. The dissolved organic carbon, (DOC), is measured by first removing the inorganic carbon as described above and the liquid at the bottom of the IC sparger is immediately re-sampled and introduced in the UV reactor chamber. In the reactor chamber, the sample is mixed with sodium persulphate solution and phosphoric acid solution, such that the sample is simultaneously exposed to persulphate ions and to UV radiation, which produce a highly oxidizing condition to convert organic carbon to CO2. The CO2 produced isthen swept by a stream of gas which passes through the Gas/ Liquid Separator, Mist Trap, Permeation Tube, Chlorine Scrubber, and finally through the NDIR detector.
AnalyticalRange: concentrations of organic carbon from 0.1 to 10 mg/L and concentrations of inorganic carbon from 0.2 to 25 mg/L
1. Phoenix 8000 User Manual, Tekmar - Dohrmann, 7143 East Kemper Road, Cincinnati, Ohio45242-9576.
Standard Method 1062
Calcium, Magnesium,
Sodium, Potassium
Silica / Cations, Filtered,Direct Analysis, Inductively Coupled Plasma-Optical Emission Spectrometry Method:A whole water sample is filtered through a 0.45 um cellulose acetate membrane filter.The filtrate is placed in a 100 mL high density polyethylene bottle. An aliquot of the filtrate is analyzed by an Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES). The sample is introduced as a fine aerosol to the instrument plasma by pneumatic nebulisation where energy transfer processes causes desolvation, atomization and ionization. Excitation of the atoms and ions occurs within the plasma. They will then decay to their lower more stable states and an emission spectra characteristic of the elements is produced. A diffraction grating is used by the instrument to disperse the spectra and the intensities of the lines for the elements of interest are captured by a CCD detector. The emission of radiation is proportional to the analyte's concentration in the sample. Quantification is achieved by calibration of the spectrometer with known solutions of analyte(s) standards spread across the analytical range. Typical line wavelengths include 317.9 nm for Ca, 766.5 nm for K, 285.2 nm for Mg , 589.6 for Na, and 251.6 nm for silicon (as silica, SiO2). NLET Method 01-1162. Reference Method: Standard Methods for the Examination of Water and Wastewater, 21st Edition, 3120 B.
AnalyticalRange: sample concentrations which exceed 100 mg/L for Ca and Na and 50 mg/L Mg and K require dilution
Si - 0.01 to 21.4 mg/L
Standard Method 1081
Fluoride, Chloride,
Nitrate, Sulphate / A whole water sample is filtered through a 0.45 um cellulose acetate membrane filter. The analysis of the anions, fluoride, chloride, nitrate and sulphate on an aliquot of the filtrate is conducted by ion chromatography. This chromatographic separation method is based on an ion exchange process occurring between the mobile eluent phaseand ion-exchange group bonded to the support material. The potassium hydroxide, KOH, eluent is produced electrolytically , in situ, in a Eluent Generator (EG) system based on the addition of water to a KOH generator cartridge. Any anions, in particular, carbonate ions, introduced into the system by the deionized water are contaminants, and are removed by a continuous generating anion trap column (CR-ATC) placed before the sample injection valve. The water sample is ejected into the eluent stream.It is then pumped through a guard column and an analytical hydroxide-selective ion exchange columnwhere the ion separation occurs. The ions of interest are separated based on the affinity for the exchange sites of the resin bed. The sample is then pumped through the suppressor which reduces the background conductivity of the eluent to a negligible level, by removing the KOH from the analytical stream and converting the anions of the sample to their respective acid forms ( HF, HCl, HNO3,and H2SO4). Any carbonic acid produced due to the presence of carbonate in the sample, may interfere with analyte peaks, and is minimized by the use of a Carbonate Removal Device (CRD). The concentrations of these separated anions are determined by measuring their respective conductivities using a conductivity detector. Anions are identified chromatographically by their retention times and quantified by comparing their peak integrationswith known calibration standards.
AnalyticalRange: normal ranges in precipitation and surface waters; fluoride (0.01 - 3.0 mg/L), chloride (0.01 - 45 mg/L), nitrate (0.005 - 3.0 mg/L) and sulphate ( 0.01- 90 mg/L)
for the exchange sites of the resin bed. The suppressor column reduces the background conductivity of the eluent to a negligible level
Standard Method 1090
Particulate Organic
Carbon / Nitrogen / The volume of water required for filtration to determine the particulate organic carbon content depends on the type of sample. The following guidelines may be useful:
- If the sample contains 10 mg/L or more of suspended matter, use 500 mL of water sample.
- Similarly, if there is 5-10 mg/L, 2-5 mg/L or less than 2 mg/L of suspended matter, use 1 L, 1-2 L or more than 2 L, respectively, of the water sample.
The sample is first oxidized in a pure oxygen environment. The resulting gases are then controlled to exact conditions of pressure, temperature and volume. Finally, the product gases are separated under steady-state conditions and are measured as a function of thermal conductivity. Operating gases include oxygen for combustion of the sample materials and helium or argon as a carrier gas. Several catalysts are employed to ensure complete conversion of C, H and N components to CO2, H2O and N2. For instance, when the PE 2400 CHN analyzer is used, the combustion is performed in the presence of chromium/nickel oxide to oxidize the carbonaceous material to CO2 and H2O. Any carbon monoxide formed is oxidized further to CO2 by passing the gaseous products through copper and copper oxide.
Particulate inorganic carbon and nitrogen, obtained by filtering the suspended solids, is dissolved by washing the solid residue with 0.3 % (v/v) sulphuric acid. The dried residue remaining is particulate organic carbon and nitrogen and is ready for analysis.
AnalyticalRange: the normal range for carbon is: 0.005 to 1.78 mg, and for nitrogen: 0.002 to 0.26 mg
Standard Method
1100
Chlorophyll / The water sample is filtered and the residue extracted with acetone forspectrophotometric determinations at specified wavelengths of 663 nm, 645 nm, and 630 nm. Chlorophyll a, b and c values are calculated using SCOR/UNESCO equations[1].
AnalyticalRange: 0.1 to 100 µg/ L
1. UNESCO, Determination of Photosynthetic Pigments in Seawater, 1965.