Arikaree Environmental Laboratory

Overview

I) Quality Assurance

A) Water Quality

Deionized water with a specific conductance at or below 1.0 microsemens per centimeter is used for all analytical work. The 18.2 megohm/cm deionized water with a 0.2 micron filter is produced by an Aries Filter Works GEMINI Ultra High Purity Water System with an organic free cartridge. The Multi-Pass Ultraviolet system irradiates the water at three separate passes in the recirculation loop. The dispensing port is continuously exposed to UV for complete sterility at the outlet This system is attached to a Water and Power Technologies Water System with an 42 Activated Carbon Unit # 2, a 1 micron 10'' filter, and 42 Mixed Bed #2 Deionizer.  The GEMINI Ultra High Purity Water System provides up to 3.7 liters per minute of 18.2 megohm, 0.2 micron filtered water. The Multi-Pass Ultraviolet system irradiates the water at three separate passes in the recirculation loop. The dispensing port is continuously exposed to UV for complete sterility at the outlet.

Previous Method (system discontinued February 2008): Deionized water with a specific conductance at or below 1.0 microsemens per centimeter is used for all analytical work. The 18.2 megohm/cm deionized water is produced by a Barnstead Type D4700 Nanopure Analytical Deionization System with an organic free cartridge. This system is attached to a Siemens Water Technology/US Filter Corporation Water System with an Activated Carbon Unit # 2937, a 10'' Ametek filtering system, and #2936 mixed bed Deionizers.

Previous Method (system discontinued July 1994): Deionized water with a specific conductance at or below 2.0 microsemens per centimeter is used for all analytical work. The deionized water is produced by a Continental Water System Activated Carbon Unit #2937, 10'' Ametek filtering system and #2936 mixed bed Deionizers with a Millipore Model 8500 Ultrafiltration System.

B) Electrical Power Quality

Clean, conditioned power is delivered to the instrumentation with uninterrupted power supplies.

C) Chemical Quality

If available, chemicals are analytical reagent grade conforming to specifications of the Committee of Analytical Reagents of the American Chemical Society.

D) Cleaning of Labware (effective 950215)

1) Labware to be reused is rinsed well with deionized water before soaking.

2) New and reused labware that comes in contact with the samples and standards is soaked for at least 24 hours in deionized water. All other labware is soaked at least overnight in a covered container containing a 10% Concentrated Hydrochloric Acid solution.

NOTE: Goggles or safety glasses, acid gloves, and lab coats are worn at all times when working with 10% Concentrated Hydrochloric Acid.

NOTE: Chloride, pH, ANC, and Specific Conductivity results may be affected by labware soaked in 10% Concentrated Hydrochloric Acid.

Previous Method: Labware is soaked overnight in a covered container containing a 10% Hydrochloric Acid solution.

3) Rinse labware copiously five times with deionized water.

4) Dry glassware overnight.

5) Seal labware and store in cabinet space to minimize unnecessary exposure.

6) Rinse labware three times with deionized water immediately before use. Rinse labware that is to contain sample with a small amount of the sample whenever possible.

E) Gloves

Powder-free vinyl gloves are worn whenever handling samples or standards to avoid unnecessary contamination.

F) Sample Handling

1)      Samples for major anions, cations, silica, conductivity, and total phosphorus are collected in new, washed Nalgene High Density Polyethylene bottles.

2)      A portion of the sample is filtered within one week of receipt of sample. A 47 mm 1.0-um binder free, glass fiber filter is used for non-low ionic concentration water samples.  Glass fiber filter is rinsed with 200 mL of deionized water and then 25 mL of sample before filtrate collection. A 47-mm Nuclepore 1.0-um membrane is used to filter snow samples and water samples with low ionic concentrations. Nuclepore membrane is rinsed with at least 50 mL of deionized water and then 25 mL of sample before filtrate collection. Between samples, filters are rinsed with at least 100 mL of deionized water and 25 mL of next sample.

3)      A 100 mL aliquot of filtered sample is refrigerated at 2-8oC in an HDPE bottle for the analysis of NH4+, Mn, Ca2+, Mg2+, Na+, K+, Li+, Cl-, NO2-, NO3-, SO42-, Br-, F-. PO43-, Silica and Total Dissolved Phosphorus.  NH4+ is run immediately upon receipt of sample. If this is not possible, an aliquot of the sample is frozen until analysis.

4)      A 25 mL aliquot of filtered sample is stored frozen at or below 0oC in an HDPE bottle for archival purposes.

5)       A 75mL aliquot of unfiltered sample is refrigerated at 2-8oC in an HDPE bottle for pH, Conductivity, Acidity, ANC, Total Phosphorus.  PH, Conductivity, Acidity and ANC are analyzed on unfiltered sample within one week of receipt of sample.

6)      Samples for Non-Purgable Organic Carbon, Total and Total Dissolved Nitrogen, Fluorescence Index and SUVA are collected in burned, amber glass bottle with Teflon lid. Filter sample with a 47mm Whatman GF/F filter ashed at 450oC for 4 hours into a burned amber, glass bottle. Unfiltered and filtered samples are stored refrigerated at 2-8oC.

7)      Unfiltered samples for pollen are collected in new, washed Nalgene High Density Polyethylene bottles and stored refrigerated at 2-8oC.

8)      Samples for d18O and d2H are collected in 30-mL clear Boston round glass bottles with poly-cone caps.  To minimize evaporation, ensure that each bottle is completely filled and no head space is visible.

G) Calibration Protocol

1) Calibration standard dilutions are discarded after one week. Calibration standard dilutions for NH4+ are used within two days.

2) Calibration standard dilutions are prepared that bracket the sample concentration range. Dilute any sample that has a nonlinear concentration range.

3) Calibration standard controls are distributed at 5% frequency throughout analytical runs as a check against calibration drift. Calibration is repeated if variation is greater than 10% of actual standard value.

H) Blank

A deionized water sample is analyzed with each run.

II) Quality Control

A) Analytical Bias

A synthetic charge balance control (CBC) consisting of six ions is prepared with CaCl2, MgSO4, and NaNO3. Unfiltered CBC's are included with each analytical run. Values are calculated from calibration standards of different origin than those used for CBC's.  The pH, ANC, and Conductivity of the CBC's are determined as well. Any persistent deviation in ion balance (sum of positive charge minus sum of negative charge/ sum of positive charge plus sum of negative charge) over the study period would suggest a bias. A value of zero implies no bias for the chemical methods that were employed.

B) Accuracy

1) Recovery of Synthetic Standards

Accuracy is assessed in each run by recovery of known addition of synthetic standards to deionized water. Mean percent recovery (R) is calculated as the ratio of measured value versus expected value. Synthetic standards are analyzed at the beginning of each run and after every 20 samples.

2) Interlaboratory Comparisons

Sample duplicates are submitted and analyzed in parallel with NADP/NTN Central Analytical Laboratory in an ongoing interlaboratory comparison study effort. Results are compared with other laboratories when parallel samples are available.C) Precision

1) Within Run Precision

Spiked samples are analyzed in duplicate with every 20 samples. Precision is measured by the standard deviation of means percent recovery (RSD).

2) Run to Run Precision

Run to run precision is assessed by including in each run a control of deionized water spiked with a known addition of synthetic standards. Precision is measured by the standard deviation of means percent recovery (RSD).3) Field Precision

Field replicates are collected to assess field precision. Precision is measured by the standard deviation of means percent recovery (RSD).

D) Detection Limits

Method detection limits are determined in accord with the Scientific Apparatus Makers Association (SAMA) definition for detection limit: that concentration which yields an absorbance equal to 3.143 times the standard deviation of seven measurements of a solution whose concentration is detectable above, but close to, the blank absorbance.

E) Filtration Effectiveness

To assess effectiveness of filtration followed by storage at 2-8oC as a means of preservation of chemical species, known additions of NH4+, Ca2+, Mg2+, Na+, K+, Cl-, NO3-, SO42-, and Silica are made to subportions of selected samples and laboratory deionized water blanks. Initial concentrations, pH, and conductivity for spiked and unspiked sample/blank set are analytically determined within one week. Final concentrations are analytically determined after 3 months storage at 2-8oC.

F) Ion Desorption from and Adsorption to Labware

To assess the effect of ion desorption from and adsorption to labware during storage, sample bottles are filled with deionized water and stored for one month. A subsample from each bottle is included in standard analysis suite to determine levels of desorption.  A known concentration of synthetic standard is added to remaining sample in each bottle and sample is stored again for one month. Spiked samples are included in standard analysis suite to determine levels of adsorption.

III) Analytical Methodology

A)    pH

The pH measurements, corrected to 25oC, are measured using an Accumet AR10 Laboratory pH Meter, an Accumet pH Electrode and an automatic temperature compensator. The electrode is calibrated with pH 4.00 and pH 7.00 or pH 7.00 and pH 10.00 NBS traceable reference buffer solutions, whichever buffer solutions bracket the samples. Prior to measurement; electrode, thermistor, and sample beaker are rinsed three times with deionized water. Sample beaker and electrode are then pre-rinsed with a small amount of sample. Sample is briefly swirled and meter reading is allowed to stabilize 5 minutes before being recorded.

NOTE: Samples with pH's above 7.00 may be standardized with 4.0 and 7.0 pH buffer solutions if the accuracy of the results are verified by repeating a few of the samples with a 7.0 and 10.0 pH buffer calibration. Repeats should be within 0.10 pH units.

B)    Conductivity

Conductivity is measured using a Mettler Toledo SevenEasy Conductivity Meter with a Mettler Toledo InLab 720 2-plate conductivity sensor with automatic temperature compensation, calibrated against 84.0 uS/cm KCl solution according to manufacturer's instructions. Prior to measurement, cell and sample beaker are rinsed three times with deionized water. Cell and sample beaker are then pre-rinsed with a small amount of sample. Sample is briefly swirled and result is recorded after the meter reading is stabilized.

C) ANC (effective with 1992 samples)

Acid Neutralization Capacity is measured using a manual pH titration using a 2.0-mL Buret micrometer. The pH measurements, corrected to 25oC, are measured using an Accumet AR10 Laboratory pH Meter, an Accumet pH Electrode for low ionic strength titrations and an automatic temperature compensator. The electrode is calibrated with pH 4.00 and pH 7.00 NBS traceable reference buffer solutions. Prior to measurement; electrode, thermistor, and sample beaker are rinsed three times with deionized water. Sample beaker is pre-rinsed with a small amount of sample. Sample is titrated to pH 3.5 endpoint with 0.1 N HCl.  Prior to each pH measurement, sample is stirred and allowed sufficient equilibration.  Ten pH values between pH 4.5 and 3.5 and their corresponding titrant volumes added are recorded. ANC is calculated using an equivalence point determined by linear regression on a Gran's Plot. Perform the acidity procedure if initial sample pH is less than 4.5.

Previous Method: The original sample pH is measured. The sample is then titrated to just below pH 4.5 with 0.1 N HCl. The original pH and the pH's just above and below pH 4.5 are recorded.

4.5 pH titrant volume=(4.5-bph)/ (aph-bph) X (atv-btv) + btv, and

pH 4.5 alkanity HCO3=[(4.5 pH titrant volume X 0.1 X 1000000)/sample volume]/ 0.01639 X 1.219

where pH above 4.5=aph, pH below 4.5=bphi, pH above 4.5 titrant volume=atv, and pH below 4.5 titrant volume=btv

D) Lachat QuikChem 8500 Flow Injection Analyzer  (effective 20100129)

Nitrite, nitrate+nitrite, silica, orthophosphate, total and total dissolved phosphorus are analyzed using a Lachat QuickChem 8500 System Flow Injection Analyzer (FIA), employing spectrophotometric detection.  Samples for total and total dissolved phosphorus are digested and oxidized prior to analysis with the orthophosphate method.

Previous Method (effective 20040301): Ammonium, nitrite, nitrate+nitrite, total nitrogen, total dissolved nitrogen and silica are analyzed using an OI Analytical Flow Solution IV Analyzer, employing spectrophotometric detection. Samples for total and total dissolved nitrogen are digested and oxidized prior to analysis with the nitrate+nitrite method.

Previous Method (effective 950313): Ammonium, nitrate+nitrite, orthophosphate, and silica are analyzed using a Lachat QuickChem 8000 System Flow Injection Analyzer (FIA), employing spectrophotometric detection. Samples for total and total dissolved nitrogen are digested and oxidized prior to analysis with the nitrate+nitrite method. Samples for total and total dissolved phosphorus are digested and oxidized prior to analysis with the orthophosphate method.

Previous Method: Ammonium, nitrate+nitrite, orthophosphate, and silica are analyzed using a Lachat QuickChem System IV Analyzer (FIA), employing spectrophotometric detection. Samples for total and total dissolved nitrogen are digested and oxidized prior to analysis with the nitrate+nitrite method. Samples for total and total dissolved phosphorus are digested and oxidized prior to analysis with the orthophosphate method.

E) Metrohm 761 Compact Ion Chromatography Analyzer (effective 20030121)

The inorganic anions fluoride, chloride, bromide, nitrate, and sulfate are analyzed by ion chromatography (IC) using a Metrohm 761 Compact Ion Chromatography Analyzer with a Metrosep A Supp 5 anion column. Chemical ion suppression and conductivity detection are employed.

Previous Method (effective 19931108):  The inorganic anions chloride, nitrate, and sulfate are analyzed by ion chromatography (IC) using a Dionex DX500 System.                             

Previous Method: The inorganic anions chloride, nitrate, and sulfate are analyzed by ion chromatography (IC) using a Dionex 2010i System. Chemical ion suppression and conductivity detection are employed.

F) Perkin Elmer AAnalyst 200 Atomic Absorption Spectrometer (effective 20071009)

The inorganic cations calcium, magnesium, sodium, potassium, lithium and manganese are analyzed by atomic absorption using a Perkin Elmer AAnalyst 200 Atomic Absorption Spectrometer. 0.5% lanthanum solution is added to each standard and sample to prevent chemical and ionization interference.

Previous Method (effective 19990426): The inorganic cations manganese, lithium, calcium, magnesium, sodium and potassium are analyzed by atomic absorption using a Perkin Elmer AAnalyst 100 Atomic Absorption Spectrometer. 0.5% lanthanum solution is added to each standard and sample to prevent chemical and ionization interference.

Previous Method: The inorganic cations calcium, magnesium, sodium and potassium are analyzed by atomic absorption using a Perkin Elmer Model 2280 Atomic Absorption Spectrometer. 0.5% lanthanum solution is added to each calcium and magnesium standard and sample to prevent chemical and ionization interference.

G) BioTek Synergy 2 Multi-detection Microplate Reader (effective 20080604)

The inorganic cation ammonium is analyzed using a BioTek Synergy2 Multi-detection Microplate Reader, employing absorbance detection.

H) Shimadzu TOC-V csn Total Organic Carbon Analyzer (effective 20080411)

Non-purgable organic carbon is analyzed using a Shimadzu TOC-V csn Total Organic Carbon Analyzer by acidification, sparging with CO2 free air, combustion and detection in a non-dispersive infrared gas analyzer (NDIR).  Total nitrogen is detected after combustion utilizing a chemiluminescence gas analyzer.

Previous Method (effective 19991204): Non-purgable organic carbon is analyzed using a Shimadzu 5050A Total Organic Carbon Analyzer by acidification, sparging with CO2 free air, combustion and detection in a non-dispersive infrared gas analyzer (NDIR).

I) Picarro L1102-I Isotopic Liquid Water Analyzer (effective 20090527)

The Picarro L1102-i Isotopic Liquid Water Analyzer uses time based, optical absorption spectroscopy of the target gasses to determine concentration. They are based on wavelength-scanned cavity ring down spectroscopy, a technology in which light re-circulates many times through the sample, creating a very long effective path length for the light to interact with the sample.

J) VirTis Genesis 35L Freeze Dryer (effective 20120509)

The VirTis Genesis 35L Freeze Dryer includes a variety of condenser capacities, multiple refrigeration systems, and a vacuum pump to freeze and then extract moisture from the product by sublimation.

K) Thermo Finnigan FLASH EA 1112 Series CHN Analyzer

The weight percent is calculated for nitrogen and carbon using a Thermo Finnigan FLASH EA 1112 Series CHN Analyzer. Solid samples are combusted in a furnace with a chromium (III) oxide column to oxidize carbon into carbon dioxide and nitrogen into nitrogen gas and nitrogen oxides.  A second furnace with copper wires reduces the nitrogen oxides to nitrogen gas.  A magnesium perchlorate column removes water.  The carbon dioxide and nitrogen gases are measured in a gas chromatograph column with a thermal conductivity detector (TCD).

L) ISA Jobin Yvon-SPEX Fluormax-2 Spectrofluorometer

An ISA Jobin Yvon-SPEX Fluoromax-2 is used for analysis of fluorescence index and chlorophyll-a.  A xenon lamp emits wavelengths of light through an excitation monochromator, which selects increments of specific excitation wavelengths. Electrons in a fluorescent compound will jump to an excited state. When the excited electrons regress to their ground state, energy is released as light at a specific emission wavelength. The emitted photons pass through an emission monochromator and are counted by a photomultiplier tube. The fluorescence index is calculated as the ratio of intensity at 470nm/520nm emission and 370nm excitation.  The concentration of chlorophyll-a is directly proportional to the intensity (S) of the fluorescence of an extracted filtrate. The phaeophytin concentration is determined by measuring the decrease in fluorescence intensity upon acidification.

M) Agilent 8453 UV-Visible Spectrophotometer

SUVA is analyzed using an Agilent 8453 UV-Visible Spectrophotometer. Specific UV absorbance (SUVA) is the UV absorbance of a water sample at 254nm normalized for dissolved organic carbon.

Revised 2013-06-17 Chris Seibold.

Contact Information

4001 Discovery Drive
SEEL 150
Boulder, CO 80303