HYDROGEOCHEMISTRY

In recent years, advances in analytical technology have allowed hydrogeochemical surveys to become a very powerful exploration technique.

The high-resolution method Actlabs has developed has become the new benchmark in exploring for gold, base metals, uranium, REE and other metals using water. Actlabs is unique in that we are the only commercial lab in the world serving the mineral industry with this Technology.

Sample Preservation Instructions

The conventional method of preservation of water for analysis is 0.2% (2 mL/L) of concentrated ultra-pure nitric acid for inorganic parameters. This may be inadequate in alkaline environments. The acid should be added only after the sample has been collected, and not as pre-charged acid in bottles which may leach metals from the bottle. When filling the bottle, it should be rinsed with the sample water twice before retaining the sample. It should then be acidified. A test of pH using pH paper will indicate if the pH after acidification is adequate (pH 2). Depending on the sample composition, preservation with nitric may invalidate Ag, As, Br and I analyses. Preservation with acetic acid should be used in that case; however, acetic acid can invalidate results for Cr. Some customers do not add any stabilizing agents, since this has the potential for adding trace contaminants to the samples and causing analytical problems. A study conducted by the Geological Survey of Canada (GSC) has indicated that low cost, high-density screw cap polyethylene bottles (rinsed with water) are best. We require 30 mL of water for analysis for inorganic parameters. Conventional wisdom recommends storage at 4ºC. Studies by the GSC indicate that this may not be necessary where samples are acidified < pH 2. Do not freeze water as it will cause precipitation of some elements. Samples should be shipped to the lab as soon as possible for analysis. Stability tests indicate most samples are stable for at least 30 days and can be stable for a year or more (British Columbia Geological Survey) even when stored at room temperature. Gold unfortunately is not stable and will be adsorbed onto the sides of the bottle within a short period of time (hours). Addition of activated charcoal sachets can collect the gold which can then be analyzed by INAA. Further information is available from Actlabs on request. Code 6 HR-ICP/MS method removes these metals from the plastic bottle and puts it back into solution for analysis directly by HR-ICP/MS. For hydrogeochemical samples being analyzed by ICP-MS or by Ion Chromatography, please include TDS/conductivity measurements if available.

Samples must be acidified prior to analysis. Water samples are analyzed by Perkin Elmer Sciex ELAN 9000 ICP/MS, Perkin Elmer Nexion, Thermo icapQ or Agilent 7700. A blank and two water standards are run at the beginning and end of each group of 32 samples. A reagent blank is run at the beginning of the group and every 10th sample is run in duplicate. If instrument suppression occurs, sample(s) affected are re-run at appropriate dilutions until response is normal. Dilution factors will increase by the same factor that samples were diluted.
For analysis of marine waters or brines, detection limits will be correspondingly elevated depending on the dilution necessary to run the water samples.

If % RSDs are required, choose option Code 6 EXPER (detection limits listed below) for 1-4 elements only.

Elements and Detection Limits (µg/L)

ElementDetection LimitUpper Limit
Ag0.25,000
Al2100,000
As0.035000
Ba0.15000
Be0.15000
Bi0.32,000
Ca700200,000
Cd0.015000
Ce0.0015000
Co0.0055000
Cr0.55000
Cs0.0015000
Cu0.25000
Dy0.001100
Er0.001100
Eu0.001100
Fe1050,000
Ga0.012000
Gd0.001100
Ge0.015000
ElementDetection LimitUpper Limit
Hf0.0011000
Hg0.2
Ho0.001100
In0.0015000
K30200,000
La0.0015000
Li15000
Lu0.001100
Mg2200,000
Mn0.15000
Mo0.15000
Na5100,000
Nb0.0055000
Nd0.0015000
Ni0.35000
Pb0.012000
Pr0.0015000
Rb0.0055000
Sb0.015000
Sc15,000
ElementDetection LimitUpper Limit
Se0.25000
Si200200,000
Sm0.001100
Sn0.15000
Sr0.045000
Ta0.0011000
Tb0.0011000
Te0.15,000
Th0.001100
Ti0.15000
Tl0.0015000
Tm0.001100
U0.001200
V0.12000
W0.021000
Y0.0035000
Yb0.001100
Zn0.55000
Zr0.015000

6 ICP-MS options:

6 Hg (Hg on a separate sample)

ElementDetection Limit ( ng/L )
Hg6

6 B (Boron Add-On)

ElementDetection Limit ( µg/L )
B3

6 EXPER Elements and Detection Limits (µg/L)

ElementDetection LimitUpper Limit
Ag0.22,000
Al22,000
As0.03200
Au0.002-
B3-
Hf0.00120
Ho0.001100
I14,000
In0.001200
Ir0.002-
Rh0.02-
Ru0.01-
Sb0.01100
Sc120,000
Se0.2250

6 ICP-MS-Exper proposed Elements and Detection Limits (µg/L)

ElementDetection LimitUpper Limit
Ag0.25,000
Al2100,000
As0.035000
B35000
Ba0.15000
Be0.15000
Bi0.32,000
Ca700200,000
Cd0.015000
Ce0.0015000
Co0.0055000
Cr0.55000
Cs0.0015000
Cu0.25000
Dy0.001100
Er0.001100
Eu0.001100
Fe1050,000
Ga0.012000
Gd0.001100
Ge0.015000
ElementDetection LimitUpper Limit
Se0.25000
Si200200,000
Sm0.001100
Sn0.15000
Sr0.045000
Ta0.0011000
Tb0.0011000
Te0.15,000
Th0.001100
Ti0.15000
Tl0.0015000
Tm0.001100
U0.001200
V0.12000
W0.021000
Y0.0035000
Yb0.001100
Zn0.55000
Zr0.015000

Our research activities over the last few years have allowed us to link the capillary electrophoresis and HPLC techniques to conventional ICP/MS or High Resolution ICP/MS. Using as little as 5 µg/L of solution, we can conveniently speciate a number of metals for their inorganic or organic metal species. This allows determination of a number of metal species sequentially. ACTLABS can consult on the best ways to preserve samples for speciation analysis.

  • Pore Water Extraction (from sediment core)
  • As speciation (As3+, As5+, MMA, DMA)
  • Sn speciation (Tripropylpentyl; Tributylpentyl; Dibutyldipentyl; Monobutyl,tripentyl; Monophenyl,tripentyl; Diphenyl,tripentyl;
  • Triphenyl,tripentyl)
  • Fe Speciation (Fe3+, Fe2+)
  • Se Speciation (Se6+, Se4+, Se-Methionine, Se-Cystine)
  • Cr Speciation (Cr3+, Cr6+)

Note – Minimum of 10 samples

Samples must be preserved with AR. Water samples are analyzed using a High Resolution Magnetic Sector ICP-MS (Finnegan Mat ELEMENT 2).

6 Au HR-ICP-MS Elements and Detection Limits (ng/L)

ElementDetection Limit
Au0.1

Samples must be acidified prior to analysis. Water samples are analyzed using a High Resolution Magnetic Sector ICP-MS (Finnegan Mat ELEMENT 2). A blank and two water standards are run at the beginning and end of each group of 32 samples. A reagent blank is run at the beginning of the group and every 10th sample is run in duplicate. If instrument suppression occurs, sample(s) affected are re-run at appropriate dilutions until response is normal. Dilution factors will increase by the same factor that samples were diluted.

Elements and Detection Limits (µg/L)

ElementDetection Limit
Ag0.002
Al0.5
As0.02
B0.1
Ba0.01
Be0.001
Bi0.001
Ca5
Cd0.001
Ce0.001
Co0.001
Cr0.01
Cs0.001
Cu0.05
Dy0.0005
Er0.00005
Eu0.00005
Fe1
Ga0.001
Gd0.00005
ElementDetection Limit
Ge0.001
Hf0.0005
Hg0.05
Ho0.0001
In0.0001
K1
La0.001
Li0.05
Lu0.00005
Mg0.2
Mn0.05
Mo0.005
Na5
Nb0.0001
Nd0.0001
Ni0.05
Pb0.005
Pr0.00005
Rb0.005
Re0.0001
ElementDetection Limit
Sb0.001
Sc0.01
Se5
Sm0.005
Sn0.01
Sr0.01
Ta0.0005
Tb0.00002
Te0.001
Th0.00002
Ti0.01
Tl0.0001
Tm0.0001
U0.0001
V0.001
W0.001
Y0.0005
Yb0.00005
Zn0.5
Zr0.001

Water samples are analyzed using ICP-OES (Agilent Axial 730-ES) for the 36 element suite.

 Elements and Detection Limits (µg/L)

ElementDetection Limit
Ag5
Al0.1 mg/L
As30
Ba20
Be2
Bi20
Ca0.1 mg/L
Cd2
Ce30
Co2
Cr20
Cu2
ElementDetection Limit
Fe0.01 mg/L
K0.1 mg/L
Li0.05 mg/L
Mg0.1 mg/L
Mn0.01 mg/L
Mo5
Na0.1 mg/L
Ni5
P0.02 mg/L
Pb10
S1 mg/L
Sb10
ElementDetection Limit
Se20
Si0.1 mg/L
Sn10
Sr10
Te10
Ti10
Tl10
U0.05 mg/L
V10
W10
Y10
Zn5

Water samples are analyzed using a High Resolution Magnetic Sector ICP-MS (Finnegan Mat ELEMENT 2).

 Elements and Detection Limits (ng/L)

ElementDetection Limit
Au0.1
Ir1
Pd1
Pt0.5
Rh0.5
Ru3 µg/L

Un-acidified water samples are analyzed using the DIONEX DX-120 Ion Chromatography System to determine and quantify a group of seven anions. This analysis is applicable to concentrations less than 75 mg/L for Cl, NO2 and NO3; less than 50 mg/L for F; less than 125 mg/L for PO4; less than 250 mg/L for Br and less than 375 mg/L for SO4. Samples exceeding this range (with high total dissolved solids) must be diluted to avoid over-saturation. Measurement uncertainty is evaluated and controlled by an appropriate quality assurance program, including the use of regular laboratory duplicates of samples and verification of the precision/calibration of the instrument through regular runs of various primary dilution standard solutions

Ion Chromatography

AnionDetection Limit (mg/L)
Fluoride (F)0.01
Chloride (Cl)0.03
Bromide (Br)0.03
Nitrite (NO2 )0.01
Nitrate (NO3 )0.01
Phosphate (PO4 )0.02
Sulphate (SO4 )0.03

Reference:

EPA Method 300.0

Analysis and Reporting Limits

AnalysisMethodReferenceReporting Limit
AcidityTitrimetryEPA 305.210 mg/L CaCO3
Alkalinity (CaCO3)
Includes: Carbonate (CO32-), Bicarbonate (HCO32-)
TitrimetryAOAC 11.1.052 mg/L CaCO3
NH3 + NH4ISESM 4500-ammonia0.02 mg/L NH3
0.01 mg/L NH4
Bi214Detector0.1 Bq/L
Bisphenol A (BPA)Organics (GC/MS)1  µg/L
BTEXOrganics (GC/MS)0.25-0.97  µg/L
Cyanide (SAD CN)Analyzer0.15  µg/L
Cyanide (Weak Acid Dissociable - WAD CN)SKALAR automated analyzer0.8  µg/L
Cyanide (Free CN)SKALAR automated analyzer0.8  µg/L
Cyanide (Total CN)SKALAR automated analyzer0.8  µg/L
ColourColour1 – 500
ConductivityISE0.01 µS
Dissolved Oxygen (DO)Analyzer0.01 mg/L
DOCAnalyzer0.01 mg/L
Glycols
(Proplyene & Ethylene)
Organics (GC/FID)0.01%
H2STITR0.1 mg/L
HardnessICP/OESmg/L CaCO3
Microbiology
(E.coli, Total Coliforms, Fecal Coliforms, Heterotrophic Plate Count)
MF> 0
Oil & Grease (Total)GRAVmg/L
PICP/OES> 0.02 mg/L
Pb210Detector0.01 Bq/L
Pb214Detector0.1 Bq/L
PBB/PBDEOrganics (GC/MS)1 mg/g
PCBs (Total)Organics (GC/MS)1  µg/L
pHpH> 0.1 pH units
PhthalatesOrganics (GC/MS)5  µg/L
Polyaromatic Hydrocarbons (PAHs or PNAs - 16 compounds)Organics (GC/MS)0.42-0.99  µg/L
Ra226Detector0.005 Bq/L
SalinitySAL> 2.00 g/L
SilicaSP1 mg/L
Sulphur (Elemental)Organics (GC/MS)0.5 mg/kg
Total Dissolved Solids (TDS)ISEASTM0.01 mg/L
Total Dissolved Solids (TDS)GravimetricStandard methods for the examination of Water and Wastewater2.5 mg/L
Total Suspended Solids (TSS)GravimetricEPA 160.24 mg/L
Total Volatile Solids (TVS)Gravimetric4 mg/L
Total Kjeldahl Nitrogen (TKN)Analyzer0.03 – 25 mg/L
Total Organic Carbon (TOC)Analyzer0.01 mg/L
Total Petroleum Hydrocarbon (TPH)
(gas/diesel)
Organics (GC/FID)0.5 mg/L
TrihalomethanesOrganics (GC/MS)0.33-0.71  µg/L
TurbidityTurbidimetric0.1 – 10,000 NTU
Water DensityGRAVg/ml