What is a preservative, and why is it important? According to the EPA, methods of preservation are relatively limited and are intended generally to (1) retard biological action, (2) retard hydrolysis of chemical compounds and complexes, (3) reduce volatility of constituents, and (4) reduce absorption effects.
In other words, the purpose of a preservative is to “freeze” the sample chemistry at the point of sampling so that what gets analyzed at the lab is as similar to the source as possible, despite the unavoidable delay between the sampling and analysis.
Some common preservatives include:
However, the most important, but often overlooked, preservative is ice. Keeping a sample cold (between 2-6C) is a requirement for nearly every analytical test we perform EXCEPT for metals analysis. It is generally preferable to use wet ice instead of ice packs when possible.
Sample containers, just like preservatives, are designed to inhibit the natural chemical changes which will occur in a sample as time passes. In addition to that, sample containers also serve a few other purposes:
But how do I know which sample bottle and preservative to use? Simple, you ask the lab! By contacting WETLAB before you begin your sampling process, you will help ensure that you use the correct bottle and preservative. Our staff can also help you review your permit making sure the correct samples are taken at the correct time of the year (DPBs, LCR, SOCs), and making sure the correct methods are used for your sample matrix (drinking water, waste water, haz waste). We can even help with sampling requirements making sure your samples are collected as intended by your permit (LCR first draw, grab vs. composite), saving you valuable time that can be lost from unintended mistakes.
Be aware, preservatives and hold times are dictated by the analytical method and enforced by state/federal agencies and the laboratory. Cyanide species, Volatile Organics, Dissolved Oxygen, Bacteria, SOCs, DBPs, and many other tests absolutely require correct bottles and preservatives to analyze for compliance.
Contact WETLAB at (775)355-0202 to discuss your sampling needs. Our seasoned staff can help you determine which samples you need, how they need to be collected, and provide you with all the right bottles and preservatives to make sure your procedures remain in compliance.
In our blog posts Lessons From the Lab we answer frequently asked questions from clients. Find all installments of Lessons From the Lab here.
Cyanide sampling requirements have become stricter over the years. The Nevada Division of Environmental Protection (NDEP) issued guidance in October of 2015 that cyanide analysis must be collected correctly in the field so as not to have samples rejected by the analytical laboratory, or by the state due to incorrect sampling procedures.
NDEP stated, “If you are analyzing Cyanide samples for compliance with a Nevada program, (SDWA, CWA, RCRA, Mining) samples must be collected as described below (ASTM D-7365-09). Data obtained from samples not collected as described in ASTM D-7365-09 will be rejected.”
“ASTM D-7365-09 8.2.1 states that sample containers shall be made of materials that will not contaminate the sample, cleaned thoroughly to remove all extraneous surface contamination prior to use. Chemically resistant glass containers as well as rigid plastic containers made of high density polyethylene (HDPE) are suitable. Samples should be collected and stored in amber gas tight vials or narrow mouth bottles to minimize exposure to ultraviolet radiation and to minimize headspace in the sample containers (for example, amber open top VOA vials, amber Boston round bottles, or amber narrow-mouth HDPE bottles).”
“All certified Laboratories must reject samples not collected in suitable containers.”
What does this mean? All samples, regardless of matrix (drinking water, wastewater, ground water, surface water, aqueous, soil, sludge, etc.), must be collected in an amber narrow mouth container to minimize UV radiation exposure and to minimize headspace in sample containers. Samples not collected in the correct containers must be rejected by the laboratory and the sample should be collected in the correct containers, as described above. Furthermore, as dictated by the method cited by NDEP, chemical preservation is also required for aqueous samples. Aqueous samples must be preserved with sodium hydroxide (NaOH) to pH >10 at the time of collection, and then chilled on ice.
At WETLAB, we provide the appropriate bottles and preservative (NaOH) needed for your cyanide analysis, and are happy to answer any questions you may have regarding cyanide sampling containers.
Please call us at any at 775-355-0202 to request sample containers.
Lithium Brine Testing- Methods for Analysis
In part one of this two part series, we provided an overview of WETLAB’s industry leading practices for Lithium Brine Testing. In part two, we will explore the strengths and limitations associated with each of the four testing methods, including ICP-OES- the preferred method of brine characterization.
WETLAB is an industry leader for lithium brine testing, and has excelled at characterization using ICP-OES. The four main methods of lithium brine testing each have its own strengths and limitations, which we explore below.
FAAS (Flame Atomic Absorption Spectroscopy) involves a nebulized sample being passed through an acetylene flame and the light absorbance of a specific wavelength is then measured. Some of the potential limitations involved with FAAS characterization include low sensitivity, relatively low ionization temperature (3000°C), and only one analyte can be run at a time. Phosphates and Sulfates can also form flame-stable metal salts, which can complicate analysis.
GFAAS (Graphite Furnace Atomic Absorption Spectroscopy) involves the sample being heated in a graphite tube, and then atomized light is passed through the tube and measured at a specific wavelength. Due to heating programming and specificity, GFAAS analyses are typically done for one element at a time. GFAAS also has long sampling times, low temperature, and a limited dynamic range.
ICP-MS (Inductively Coupled Plasma – Mass Spectrometry) involves a nebulized sample being passed through high temperature plasma to ionize atoms, which are then isolated by their mass/charge ratio and detected directly. ICP-MS can be an excellent option for some clients, but some of the limitations for lithium analysis are that lithium is very light and can be excluded by heavier atoms, and analysis is typically limited to <0.2% dissolved solids, which means that it is not great for brines. Equipment and technician training costs are also very high with this method.
ICP-OES (Inductively Coupled Plasma – Optical Emission Spectroscopy) involves a nebulized sample being passed through high temperature plasma to ionize atoms, which release light at specific wavelengths. This is the preferred analytical technique for most metals in any matrix, and all metals in a complex matrix such as brine solutions. ICP-OES can handle a high amount of dissolved solids, has little chemical interference, and has robust sample introduction with high-energy plasma (~10,000°C) plasma. ICP-OES can also perform multi-element analysis, easily determining concentrations of other metals (K, Mg, B, etc). Although ICP-OES is the preferred technique, it does have some limitations. These include moderate detection limits, typically lower than FAAS but higher than GFAAS and ICP-MS in a clean matrix. Complex matrices (such as brine) can often require dilutions from the other methods that may raise the overall Detection Limit. Also, spectral Interferences are common, but can typically be easily compensated to eliminate.
To determine how WETLAB can help you get the data you need with our industry leading practices, call WETLAB at (775) 355-0202 and speak with someone from our highly skilled customer and sample management team.
Matt Weikel, Inorganic Laboratory Manager, presented at a training hosted by Nevada Water Resources Association (NWRA) regarding WETLAB’s industry leading lithium brine testing methods. In this two part series, we will provide an overview of this presentation, and explore various methods of analysis.
Lithium Brine extraction and processing is gaining traction in Nevada. Lithium mining uses evaporation ponds, which produces a brine that lithium is then extracted from. With lithium brine gaining popularity, lithium brine testing has become an interesting and ever-changing topic.
WETLAB has always sought to develop products and practices that are in our clients’ best interest, which is why we have perfected the ideal method of lithium brine testing to meet various client needs. Lithium brine can be characterized on four different pieces of equipment, including:
WETLAB continues to excel at ICP-OES characterization, which is the preferred method of analysis for lithium brines. Each of these methods has its own strengths and limitations, and is coupled with a digestion method to place the metals into solution. WETLAB commonly uses a two-acid digestion, HNO3 + HCl, which include EPA methods 200.2, 3010, and 3050. After the sample is digested, it is ready for analysis. WETLAB commonly recommends using ICP-OES analysis, as it works best for the characteristics of brine, and obtaining other data metrics from the sample.
When you choose WETLAB for your lithium brine testing and characterization needs, you get a lot of benefits. WETLAB prioritizes customer service and accurate analysis, and we’re always here to help you get what you want. We ensure precise analysis through a robust QA/QC program coupled with several measures of internal data and accuracy checks.
Part two of this series, WETLAB Lithium Brine Testing, we will explore the strengths and limitations associated with each of the above testing methods, and determine why using WETLAB for ICP-OES analysis is ideal.
Effective March 6, 2014: The Bureau of Mining Regulation and Reclamation (BMRR) announces updated certified methods for mercury analysis required in Part I.D of the Water Pollution Control Permit.
WETLAB will no longer utilize the analytical method 200.8, Determination of Trace Elements in Waters and Wastes by Inductively Coupled Plasma using Mass Spectrometry, for testing non-potable water from Nevada mine sites.
The updated required EPA analysis is 245.1, Determination of Mercury in Water By Cold Vapor Atomic Absorption Spectrometry. Along with this change, the BMRR is requiring that all tests that occurred in January and February are updated, using the 245.1 analytical method.
WETLAB is currently certified by EPA 245.1 and has already begun to process samples that still remain within the EPA suggested hold time.
WETLAB has also contacted clients to inform them how this change has affected their 1st quarter samples.
Please contact the WETLAB Client Services Manager Kurt Clarkson at 775-355-0202 with any questions.
“Gold’s safe-haven allure has attracted investors fleeing the risk of debt crisis contagion in Europe and slowing global growth,” according the the Aug. 11 Reuters article. “Prices of cash gold have risen as much as 21 percent since the end of June.”
And that’s good news for Northern Nevada, where Elko has become the primary gold-producing region in the United States.
But all that demand on gold requires caution from an environmental standpoint.
Gold mining is an environmentally-challenging task, and both our state-of-the-art Sparks laboratory and Elko office work with our mining clients to make sure they stay in compliance with environmental regulations, operating in a clean and environmentally sound manner.
And that’s important, given what it takes to mine for gold.
According to mining watchdog group Earthworks, mining the gold for a standard 18-karat wedding band leaves behind 20 tons of ore and waste rock.
Disturbing that much earth can lead to toxic runoff from a mine if not properly controlled – long-buried chemicals and minerals exposed to air can produce acids and leach toxic metals like sulfuric acid and arsenic.
Extracting gold from the ore can release mercury as well, and some processes use cyanide to complete gold extraction. Cyanide is obviously very toxic on its own, but can also degrade into byproducts like nitrates that can contaminate groundwater.
If those toxins aren’t properly monitored and captured, that’s bad news for the environment and anybody using water down stream.
That’s why it’s critical for us at WETLAB to work with mines to track water and soil quality, to make sure that this new gold rush doesn’t leave any negative impact – just a positive impact on the economy of northern Nevada.
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