Laboratory Areas
The feed and fertilizer lab is responsible for
the analysis of manufactured fertilizers and animal feeds in North Dakota to verify that
the stated claims on the package are accurate and meet the regulatory
specifications--essentially that the consumer is getting what they pay for. Analyses
include protein, moisture, fat, and minerals such as calcium and salt in feeds; and
Nitrogen, Phosphorus, potassium, and micro nutrients such as copper and zinc.
Products in both areas are picked up by
inspectors that are employed by the Department of Agriculture. The inspectors go to
elevators around the state and collect samples either as they are manufactured for sale or
from bags stored in the warehouse. Inspectors also go to local stores in their areas and
buy products that are packaged. These packages range in size from small, such as fish food
packages that contain only a few ounces, to that of the larger pet food bags.
Instrumentation in this laboratory includes
balances, computers and a combustion analyzer. The combustion analyzer is used to test
products for their nitrogen content. This nitrogen content is either used as a strict
percentage in the case of fertilizers, or is converted to equivalent protein through the
use of a conversion factor for feed analysis.
In the feed area, a wide variety of samples are
tested. These range from cattle feed to turtle food. The manufacturer of the product
guarantees certain levels of protein, fat, fiber, moisture, ash, and various minerals.
This lab checks the products for these
guaranteed levels, also referred to as claims. These claims either appear on the label
that is given to the consumer at the manufactured site, such as elevators or feed stores,
or are stated on the bags, such as pet foods.
The analysis performed in this lab is used by
the North Dakota Department of Agriculture for the regulation of these products to ensure
that the consumer is getting what they pay for.
Some of the techniques used in this lab range
from the simplest, such as gravimetric analysis for claims such as moisture, fat and ash
to the more complex, such as Inductively Coupled Plasma Atomic Emission Spectroscopy
(ICP-AES) analysis for minerals such as calcium and salt.
The fertilizer section of this lab follows the
same criteria as does the feeds, however, they look for other types of claims such as
nitrogen, phosphorus, and potash, also known as potassium. There are also micro nutrients
that are tested for. An example of these micro nutrients are copper and zinc.
Again, the analysis techniques used in here
range from the more pedestrian gravimetric techniques or titrations to the more advanced
atomic absorption. As an example of the types of tests and their uses, gravimetric tests
are used to determine phosphorus levels, titrations to determine potash levels and atomic
absorption is used to determine micronutrient levels.
While as the feed section receives samples year
round, the fertilizer section has two main heavy seasons: midwinter and early spring.
Midwinter is when the elevators are filling bins with straight fertilizers that will be
used to make blended fertilizer in early spring. These blends are then tested for
accuracy. Straight fertilizers are made up of one constituent while blended fertilizers
are made up of more than one constituent. The blended products are sampled as they are
loaded into the farmers truck. The inspector takes the farmers name and address so that he
may receive a copy of the analysis. This ensures that the farmer knows whether or not he
received the product he purchased.
The mineral lab tests samples such as drinking
water, ground water, surface water and sediments. In most instances the samples are
collected by department personnel who are trying to determine such things as environmental
impact, fitness of water supply, general water quality, and possible sources of
contamination. Examples include hardness/softness of water, sodium level, calcium,
nitrates, sulfates, etc.
Depending on the parameter of interest, the
laboratory will utilize differing instrumentation. Instrumentation in the laboratory
consists of:
Flow injection analysis which is utilized for the analysis of water and prepared
sediments. Parameters specific to this instrument include: phosphorus, total Kjeldahl
nitrogen, nitrate, ammonia.
Ion specific electrode automated instrument used exclusively for fluoride.
Ion chromatograph for chloride and sulfate analysis. This instrument can also be
used to monitor for fluoride.
Autotitrator used to analyze for alkalinity and pH.
Spectrometer used to measure for chemical oxygen demand.
Conductivity meter used to measure conductance.
Some special projects which have been performed in the mineral lab include:
Samples of soils taken from turkey farm barns were analyzed for total Kjeldahl nitrogen,
total phosphorus, ammonia and nitrate to determine whether or not hazardous pollutants
were infiltrating the ground water below the barns.
Samples were run to help the Mandan wastewater treatment facility determine sources of
elevated pollutants, particularly ammonia.
After the flood of 1993 this laboratory ran hundreds of ground water samples for nitrate
content to determine the extent of ground water contamination from poorly constructed
wells.
Continuing analysis of sulfate content on air filters which are collected at various sites
around the state to determine the air quality of North Dakota. Sulfate level in air is an
indicator of acid rain potential.
The organic residue laboratory is responsible
for testing samples for trace amounts of organic compounds, usually insecticides and
herbicides. Samples include drinking water, lake and river waters, soil, sediment, fish,
milk, vegetation etc. Some of the residues we look for include Round-Up, Treflan, Tordon,
Far-Go, PCB's (polychlorinated biphenyl), and 2,4-D. Many of these coumpounds are
regulated by the Environmental Protection Agency (EPA). These chemicals are used by
farmers and you may have used them yourself in your garden or around your house.
Organic compounds are compounds that contain
carbon. Trace means that we look for very small amounts of the chemicals. For example, we
look at the part per million level for chemicals. That means that 1 part of 1 million
parts is what we look for. If we assume that North Dakota has about 600,000 residents,
then each of us is about 1.7 ppm of the North Dakota population.
Our samples are most commonly water, which means
that we look for the chemicals in water. We also get soils, sediments, foliage, and fish
as samples. We have in the past tested birds and one time got a t-shirt to analyze. No
matter what the sample is, there is usually some type of sample preparation to be done and
this usually means concentration of the chemicals that we are looking for. We extract most
of our samples by liquid/liquid extraction, starting with 1 liter of water in a seperatory
funnel/EP Tox jar. The extractions are performed by shaking the separatory funnels
or rotating the EPTox jars on the rotator with the water sample and a solvent, usually an
organic solvent called dichloromethane. The basis for extraction is that the chemicals we
look for would rather be in the organic solvent that in the water, so when the funnel is
shaken, the chemicals are pulled from the water to the dichloromethane. This step is
repeated twice and the extracts are collected. This takes care of the extraction part of
sample preparation. The next step is to concentrate the chemicals that we are looking for
and we do that by evaporation. Evaporation of organic solvents is much faster than
evaporation of water. By the time evaporation is done, the sample volume will be reduced
to 1 milliliter from 1 liter which is a thousand-fold concentration. At this point, the
samples are ready to be analyzed. There are other ways to extract samples that utilize
automation, but for now the EPA requires us to do the liquid/liquid extraction.
Most of our samples are analyzed by a technique
called gas chromatography, or GC for short. It's called gas chromatography because it uses
a gas, usually helium or hydrogen, to separate compounds. A gas chromatograph is basically
a fancy oven with a GC column inside. A GC column is a long, very narrow glass tube with a
special coating on the inside of the column. The autosampler will take a very small
portion of the sample and inject onto the GC. The sample is vaporized by high
temperatures. The gas (helium or hydrogen) then gets involved. The gas will start to move
the compounds down the column. The compounds have different affinities for the coating on
the inside of the column. Some compounds will stick to the column for a short time while
some will stick for longer times. At the end of a column is a device that can measure a
change in current caused by the release of electrons from the compounds of interest. These
devices are called detectors and the one just described is an electron capture detector.
The result is called a chromatogram where each peak is an individual compound and the time
it takes to come out can be used to identify and quantify the chemicals. We also inject
known chemicals at known amounts, called standards, and compare our samples to them. From
the standards, we can calculate how much is present in our samples. We also use a
technique called liquid chromatography, which uses liquids to separate chemicals. In this
case a metal column is filled with particles that have a special coating on them. The
liquid is pumped through the column and the chemicals alternate time between the liquid
phase and the solid phase(coating). The more time in the liquid phase, the faster the
chemical will come out of the column and be detected by UV absorbance or fluorescence.
The petroleum laboratory is responsible for
testing gasoline and diesel taken from the same pumps where you buy your petroleum
product. Basically we test the petroleum to guarantee that the consumer is buying a
product that will keep their vehicles running. The samples are tested to guarantee the
quality of the gas/diesel by nationally established criteria set forth by American
Standards Testing Methods. Examples of the testing in this laboratory include octane
rating of gasoline and ethanol percentage in the gasohol.
This is the petroleum laboratory, in the organic
chemistry section. This lab is a regulatory section. Inspectors go out to all the gas
stations in the state, and all the pipeline terminals. They randomly pick up samples of
gas and diesel throughout the state. The gas samples are processed on a gas chromatogram
through simulated distillation and if the sample fails the parameters allowed on this
instrument, a manual distillation is done on a manual distillation unit.. The
distillation determines the quality of the gasoline and diesel. It also indicates the
tendency for vapor lock in the engine. Two laboratory engines determine what the octane is
on each gas sample, one is the motor engine and the other is the research engine. The
octane is the number which is posted on the pump at the gas station. We make sure that the
simulated distillation and the octane on each sample are what the claim says they are
supposed to be. We also check for ethanol and water and sediment on each sample. In diesel
we again do a distillation, check for water and sediment, and do specific gravity. Again
these must meet state specifications. Sometimes samples are right along the border of the
state, meaning, some come from South Dakota, Minnesota, and even Canada. However, if they
sell them in North Dakota, they must meet our specifications.
The spectroscopy laboratory consists of two
distinct areas, the demands area and the metals area. The demands area tests water from
lagoons or sewage treatment facilities for the biochemical oxygen demand and total
suspended solids. This information is used to determine whether the lagoon can be
discharged into the natural environment without contaminating or polluting the ecosystem.
The metals area tests samples for metals. Samples include drinking water, lake and river
waters, soils, sediments, fish, and paint. Some of the analyses include mercury in fish,
lead in paint, lead and copper in drinking water, metals such as chromium and cadmium in
landfill samples.
Instrumentation in this laboratory includes
balances, pH meters, and four different instruments which measure metals in varying
amounts and with varying amounts of productivity:
FlAAS: Flame Atomic Absorption Spectrometer
CVAAS: Cold Vapor Atomic Absorption Spectrometer
This instrument is used to analyze for micronutrients in fertilizers. The CVAAS instrument
utilizes the FlAAS instrument to analyze for mercury in drinking water, fish, sediments
and TCLP extracts.
The analytical working range of the FlAAS is generally the ppm range and the CVAAS is
generally the ppb range.
Most of the FlAAS' work has been supplanted by the ICP-AES.
ICP-AES: Inductively Coupled Plasma Atomic Emission Spectrometer
This instrument is used to analyze drinking water, river and lake water, sediments, fish,
TCLP extracts, and paints for metals including sodium, magnesium, calcium, potassium,
iron, manganese, barium, copper, zinc, silica, aluminum, lead and boron. It is capable of
analyzing for all of these metals on the same sample at one time. Typical analytical run
time is approximately 1 to 2 minutes per sample.
The analytical working range of this instrument is generally in the ppm range.
GFAAS: Graphite Furnace Atomic Absorption Spectrometer
This instrument is used to analyze drinking water, river and lake water, sediments, and
fish for trace metals such as arsenic, cadmium, chromium, lead, selenium and silver. It is
capable of analyzing only one of these parameters on a sample at a time. Typical
analytical run time is approximately 3-4 minutes per sample.
The analytical working range of this instrument is generally in the ppb range.
Most of its analytical work has been supplanted by the ICP-MS.
ICP-MS: Inductively Coupled Plasma-Mass Spectrometer
This instrument is used to analyze drinking water, river and lake water, sediments and
fish for metals including barium, copper, zinc, chromium, arsenic, selenium, cadmium,
lead, nickel, silver, etc. It is capable of analyzing for all of these metals on the same
sample at one time. Typical analytical run time is 4-5 minutes per sample.
The metals area receives samples for testing
from various sources, i.e. drinking water, river and lake water, sediments, fish, TCLP
extracts, and paints. In most instances the samples are collected by department personnel
who are trying to determine such things as environmental impact, fitness of water supply,
possible sources of contamination, etc.
Depending on the sample matrix and the expected
level of the parameter of interest, the laboratory will utilize differing instrumentation.
The uses of the varied instruments is outlined above.
Some special projects which have been performed
in the metals area include:
The analysis of game fish for mercury and other metals to form consumption advisories for
many of the state's fisheries.
The analysis of sawyer landfill samples to determine whether or not the received waste is
hazardous (the recent determination of elevated barium levels which required excavation of
the landfill to remove some of the barrels which were determined to contain hazardous
waste.)
The analysis of paint chip samples from the homes of children who have been found to have
elevated levels of lead in their bodies.
The demands area receives samples from various
municipalities around the state in addition to samples which were collected by department
staff. Typically the sample is taken from a sewage lagoon or other water treatment
facility. It is this area's responsibility to determine such parameters as biochemical
oxygen demand and total suspended solids. The results of these tests are used to determine
the effect on the environment if the water was to be discharged from the lagoon. If the
wastewater is determined to be at a safe level, the water may then be discharged to the
natural environment. This evaluation of whether or not to allow a municipality to
discharge is handled by the permits area of the Water Quality Division. Typically the
sample needs to be at or below a 5-day biochemical oxygen demand level of 25 mg/L.
Special projects in this area include the
analysis of both the Red River and the James River to determine the impact of water
treatment plant upgrades on the receiving stream. A test known as an ultimate biochemical
oxygen demand is utilized in these instances.
