Craig Goch Field Surveys Group

Slater, Frederick Maurice

Online Research @ Cardiff

Craig Goch Project – UWIST   Report No. 8  Methods of Chemical Analysis  Detection Limit* Accuracy* Parameter Method (mg.1-1 unless otherwise stated) Turbidity ARPWW 0.2 Formazin Units + 0.4   F.T.U. Colour ARPWW 5 Hazen Units + Hazen units Reactive silica ARPWW 0.05 + 0.05 Chloride ARPWW (Mercuric nitrate titn) 0.2 + 0.2 Sulphate ARPWW (Turbidimetric 0.3 + 0.3 Orthophosphate ARPWW 0.001 + 0.001 Total phosphorus ARPWW 0.001 + 0.001 Alkalinity Conductometric titn. (1) 0.2 + 1% Ammonia Modified Indophenol Method (2) 0.002 + 0.004 Nitrate Cu/hydra zinc reduction, determined as nitrate 0.4 + 0.01 Nitrate Griess-Ilavay reaction (3) 0.0003 + 0.0003 pH pH meter, corrected to river temperature (4) - + 0.01 pH Free CO2 Nomograph (4) ? ? Soluble organic carbon TOC analyser (5) 0.04 + 0.02 Particulate organic carbon Dry, oxidation of particulate matter, analysis of CO2 by TOC analyzer (6) ? ? Dissolved solids 250ml sample, filtered through CF/C filter, filtrate evaporated to dryness in weighed vessel, heated to constant weight at 180oC 0.4 + 0.8 Suspended solids 1 ltr. Sample filtered through weighed GF/C filter, dried at 105oC 0.1 + 0.2 Ash Filter paper ignited at 500oC for 30 mins. 0.1 + 0.2 Chlorophyll Sample filtered through CF/C filter, ? filter extracted with methanol, measured in 4cm cells at 665 & 750mm. ? ? Humic acid Precipitation method (7) ? ? Conductivity Conductivity meter 0.1 us. cm-1 + 1 us. cm-1Temperature Mercury-in-glass thermometer - + 0.5oc Pesticide screen GLC (8) ? ? Fish tissue analysis Atomic absorption (9) - - Filtered in situ (GF/C), 5ml 1 : 1 HNO3/1; as total metals   Heavy metals:  (soluble) (total) 250ml evaporated, 5ml conc. HNO3 added, evaporated to dryness, taken up in 5ml 1 : 1 HNO3, made up to 25ml.   Total hardness Calculations from concentrations of calcium and magnesium - -  -1- Metals  Metal Wavelength (nm) Band-pass (nm) D.L. Accuracy Ha  (Atomic emission)  589 2 0.1 + 0.1 K (Atomic emission) 766.5 2 0.1 + 0.1 Ca (Atomic emission) 422.7 2 0.1 + 0.1 Mg (Atomic absorbsion) 285.2 2 0.1 + 0.1 Fe (Atomic absorbsion) 248.3 0.2 0.1 + 0.1 Pb (Atomic absorbsion) 283.3 0.7 0.001 + 0.003 Cu (Atomic absorbsion) 324.7 0.7 0.001 + 0.003 Cd (Atomic absorbsion) 258.8 0.7 0.001 + 0.003 Ni (Atomic absorbsion) 232.0 0.2 0.05 + 0.05 Zn (Atomic absorbsion) 213.8 2 0.01 + 0.01 Mn (Atomic absorbsion) 280 0.7 0.001 + 0.003 Cr (Atomic absorbsion) 357.9 0.2 0.01 + 0.02 Air/acetylene flame used.  Methods  ARPWW – Analysis of Raw, Potable, and Waste Waters (H.M.S.O.)  1) 100 ml sample titrated with N/10 HNO.  Equivalence point found from graph of conductivity against volume of titrant as the interaction of two straight lines.  There is good agreement between this method and potentiometric titration.  2) This is a manual adaptation of the Autoanalyser method.  Ammonia reacts with phenol and sodium hypochlorite under alkaline conditions to form an indophenol type compound.  Sodium nitroprusside acts as a catalyst.  EDTA and sodium citrate are added to complex metal ions which might otherwise interfere.  Colour measured in 4 cm cells at 635 mm.  3) Two methods have been used:  a) Sulphanilamide was reacted with nitrate ion and the resulting diazonium compound coupled withN-1 naphthylenthylediamine dihydrochloride, the colour being read at 540nm in 4cm cells. b) As the latter reagent is carcinogenic, the ARPWW method using sulphonilic acid and Cleve’s acid has been used instead.  4) Dye, J.F., J. Am. Wat. Wks. Assoc. 44 356-372 (1952).  5) Filtered sample made pH 2 with HNO3, carbon dioxide removed by bubbling CO20free air into sample.  Sample introduced into Oxidation furnace containing copper oxide at 950oc via peristaltic pump.  Resultant CO2 mixed with hydrogen and passed over a nickel catalyst at 425oc.  CO2 reduced to methane which is measured by a flame-ioniation detector whose output is recorded by a potentiometric recorder.  Standards prepared from potassium hydrogen phthalate.  -2- 6) Solid heated at > 500oc in a stream of oxygen to oxidise carbon to CO2 which is mixed with hydrogen as above.  (This is only a tentative procedure which is yet to be set up).  7) 250ml sample evaporated to dryness and taken up in 5ml water.  Solution filtered on GD/C filter paper and washed.  Filtrate treated with land nitrate solution to precipitate load humate.  After 2 hours precipitate filtered on weighed CF/C filter paper, washed, dried at 105oc and weighed.  Lead content of precipitate found by destroying precipitate with potassium persulphate and titration of liberated lead ions by ?D/TA.  Weight of humic acid found by difference.  (This procedure has not been fully worked up as yet).  8) 500 ml samples will be collected in stoppered glass bottles and extracted by organic solvents.  After separation by GLC using suitable columns organo-chlorine compounds will be detested by electron-capture detector and organo-phosphorus compounds by flame-ionisation detector.  Detection limits and accuracies depend on compounds.  9) Dried and weighed fish tissue (individual organs of while fish, whichever is more convenient) will be heated in a muffle furnace to destroy organic matter.  The residue will be extracted with as small a volume of 1 : 1 nitric acid as possible and made up to a convenient volume with distilled water.  Heavy metals will then be determined by atomic absorption spectrometry.  Sample Preservation Samples are collected in 2½ 1 screw top, wide mouth, hard plastic bottles.  At the time of collection small sub-samples are taken for phosphorus and nitrogen analyses.  Phosphorus samples are held in 60ml hard plastic screw top bottles and 0.6ml 8N sulphuric acid is added as preservative.  Nitrogen samples are held in 150 ml glass screw top bottles.  Nitrogen and phosphorus samples are analysed as soon as possible.  On return to the laboratory 1 litre of sample is filtered through GF/C filter paper and the filtrate stored at 4oc in iodised plastic bottles for analysis of other parameters.  Samples for total metal analysis are preserved in plastic bottles with the addition of 5ml 1 : 1 nitric acid per litre.    A.C. OBORNE  7th July 1075    *Detection limits and accuracy estimated from calibration graphs, etc.  A statistical analysis of each method has not been performed as yet.  -3- 

Craig Goch Project – UWIST. Report No. 8.

Methods of chemical analysis

https://orca.cardiff.ac.uk/id/eprint/52453/1/Craig%20Goch%20Report%208.pdf

Craig Goch Project – UWIST. Report No. 8. Methods of chemical analysis

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