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ISO 17025:2017 Methods

ISO 17025:2017 Methods

Inorganic Chemistry

Mercury in waters, effluents, impinger solutions and digests.
Substances determined Mercury
Type of sample Waters, effluents, extracts and digests.
Method reference H108
Basis of method Atomic fluorescence
Range of application Up to 0.001 mg/l (Low Level)
Up to 0.025 mg/l (High Level)
Limit of detection 0.000003 mg/l (Low Level) reporting
0.00006 mg/l (High Level) reporting
Principle
The conversion of all forms of mercury into inorganic mercury is achieved by treating the acidified sample with a solution containing potassium bromate and bromide. Excess bromine is removed by the addition of hydroxylammonium chloride. The inorganic mercury is then determined by reacting the sample with acidic stannous chloride (Tin II Chloride solution) to release elemental mercury. The mercury vapour is carried along in a stream of argon and detected by atomic fluorescence.

Suspended solids in water, wastewater and effluents.
Substances determined Organic and/or inorganic matter which can be removed from sample by filtration under reduced pressure using a glass-fibre paper.
Type of sample Waters, effluents, untreated sewage, treated sewage and trade effluent.
Method reference H035
Basis of method Filtration through a pre-weighed filter paper. The weight of recovered matter is determined by drying and re-weighing.
Range of application Dependant on volume used.
Limit of detection 1.98 mg/l LOD
3 mg/l reporting limit
Principle
Suspended matter is removed from a measured volume of sample by filtration under reduced pressure through a pre-treated, pre-weighed glass fibre filter paper and determined gravimetrically after washing, and drying at 105° ± 5°C.

Organic Chemistry

The determination of organochlorine pesticides in water by solid phase extraction and GC-MS detection.
Substances determined Dichlobenil, Isodrin, Pentachlorobenzene, Tecnazene, Aldrin, Trifluralin, alpha-Endosulphan, alpha-BHC, beta-Endosulphan, Hexachlorobenzene, Endrin, beta-BHC, Dieldrin, gamma-BHC, Heptachlor-EXO-Epoxide, Chlorthalonil, Heptachlor-ENDO-Epoxide, Alachlor, Heptachlor, p,p-DDT, Chlorthal-Dimethyl (DCPA).
Type of sample Potable and raw waters.
Method reference 241
Basis of method The organochlorine pesticides are extracted from the sample using Solid Phase Extraction (SPE) using ENV+ cartridges. The concentrated samples are analysed by capillary gas chromatography using Mass Spectrometry (MS) in Selective Ion Monitoring (SIM) mode.
Range of application From the Limit of Detection to 0.15µg/l; except for Heptachlor, Aldrin, Dieldrin, Heptachlor-exo-epoxide and Heptachlor-endo-epoxide which is up to 0.045 µg/l or greater with dilution
Limit of detection 0.0023 µg/l to 0.0043 µg/l (depending on determinand)
Principle
Extraction of organochlorine pesticides by solid phase extraction prior to concentration and analysis by Gas Chromatography with Mass Selective Detection.

Polyaromatic hydrocarbons in raw and potable waters.
Substances determined Fluoranthene, Benzo(b)fluoranthene, Benzo(k)fluoranthene, Benzo(a)pyrene, Benzo(ghi)perylene, Indeno(1,2,3-cd)pyrene.
Type of sample Potable and raw waters.
Method reference HY108
Basis of method The PAHs are extracted from the sample, concentrated and separated by reversed phase HPLC and fluorescence detection.
Range of application Fluoranthene: up to 0.125 µg/l
Benzo (b) fluoranthene: up to 0.025 µg/l
Benzo (k) fluoranthene: up to 0.025 µg/l
Benzo (a) pyrene: up to 0.025 µg/l
Benzo (ghi) perylene: up to 0.025 µg/l
Indeno (1,2,3-cd) pyrene: up to 0.025 µg/l
Limit of detection Fluoranthene: 0.00066 µg/l
Benzo(b)fluoranthene: 0.00066 µg/l
Benzo(k) fluoranthene: 0.00066 µg/l
Benzo(a) pyrene: 0.00062 µg/l
Benzo(ghi) perylene: 0.00054 µg/l
Indeno (1,2,3-cd) pyrene: 0.00062 µg/l
Principle
PAH′s, if present in potable waters, are a consequence of old cast-iron water mains being lined with coal tar pitch. The coal tar pitch contains many aromatic organic compounds and the World Health Organisation has defined six of the most likely to occur in water.
The PAH′s are extracted from the sample using solid phase extraction. The eluted solvent is concentrated to a small volume and the components separated by reversed phase HPLC using isocratic elution and fluorescence detection.

Microbiology

Pseudomonas Aeruginosa in water.
Substances determined Pseudomonas Aeruginosa bacteria.
Type of sample Drinking water (public and private supplies, bottled water), raw water, pool water and purified/process water.
Method reference HY072
Basis of method Membrane filtration and culture on selective media.
Range of application 0-100 cells per membrane.
Limit of detection 1 cell per 100 ml of sample.
Principle
Counts of presumptive Pseudomonas Aeruginosa are determined by filtration of water samples through membrane filters and incubation of these filters on Pseudomonas CN selective agar. Confirmation of Pseudomonas Aeruginosa is carried out by sub-culturing onto Milk Agar with Cetrimide to demonstrate casein hydrolysis and a positive reaction in the oxidase test.

Isolation and enumeration of Legionella organisms from water.
Substances determined Legionella spp.
Type of sample Water from public and private supplies, air conditioning systems and showers.
Method reference LEG01
Basis of method Concentration of organisms on a filter followed by elution and culture on selective media.
Range of application 0 - 300 cells per 20 ml of sample.
Limit of detection 1 cell per 20 ml of sample.
Principle
Bacteria including Legionella organisms in the water sample, are concentrated on a sterile membrane using filtration. After elution from the filter the organisms are subjected to heat and acid pre-treatment steps to reduce the growth of unwanted bacteria and are then cultured on a selective medium (GVPC Agar). Confirmation of colonies as Legionella spp. is carried out by subculturing onto both BCYE and Nutrient Agar and serological diagnosis is performed using antibody sensitised latex particles.