Clinical Chemistry Terminology:
Clinical Chemistry: a quantitative science and branch of laboratory medicine that involves the measurement and accurate assessment of concentration levels of analytes found in body fluids and is centered on molecules, including
Analytes: biologically critical substances present in patient serum, plasma, whole blood, or in QC or calibration matrix (being tested or detected)
Reference Intervals: RI's; results of chemistry tests that diagnostic and clinical meaning to values and are also referred to as "ranges"
- ions (biologically charged particles)
- cations (positively charged particles)
- potassium (K+)
- sodium (Na+)
- calcium (Ca++)
- Magnesium (Mg+)
- anions (negatively charged particles)
- chloride (Cl-)
- CO2
- Iron (Fe)
- Phosphorus
- Lead
- salts
- NaCl
- minerals
- cations (positively charged particles)
- small organic molecules
- metabolites
- glucose
- cholesterol
- urea
- lactic acid
- bilirubin
- creatinine
- triglycerides
- ammonia
- cystatin C
- therapeutic drugs
- vancomycin
- theophylline
- digoxin
- phenytoin
- valproic acid
- toxicology
- alcohol
- salicylate
- acetaminophen
- drugs of abuse
- cocaine
- barbiturates
- amphetamines
- opiates
- cannbinoids
- metabolites
- large macromolecules
- proteins
- transport: albumin, transferrin, haptoglobin, ferritin, total protein
- specific: IgA, IgG, IgM, complement C3, complement C4, C-reactive protein
- lipoproteins: HDL, LDL, Lipoprotein A
- enzymes: lipase, amylase, ALT, AST, AlkP, LD, CK/CKMB
- immunoglobulins
- IgA
- IgG
- IgE
- IgM
- diabetes marker: hemoglobin A1C (HbA1c or GHGB)
- proteins
Analytes: biologically critical substances present in patient serum, plasma, whole blood, or in QC or calibration matrix (being tested or detected)
Reference Intervals: RI's; results of chemistry tests that diagnostic and clinical meaning to values and are also referred to as "ranges"
- numbers with units
- amount of an anlyte in a known volume of fluid, which is the concentration
- patient sample results are compated to the reference interval, or range
- set by a consensus of healthcare professionals (peer data) and also set by individual labs based on this information
Assay: an analytical procedure/test to qualitatively assess or quantitatively measure an analyte (target, which may be a biochemical substance a drug a biomarker a cell)
Stability: how long an assay, test, matrix or reagent is good for before it starts to degrade (break down)
Panel or Profile: a set or group of tests needed to assess or aid in the diagnosis of a medical condition
Matrix or Matrices: biological fluids or substances containing the analyte(s) of interest:
Reagent: a substance/solution added to the specimen to see if a chemical reaction occurs; Daily QC (quality control) is performed on reagents prior to patient testing and are treated exactly as patient testing
Calibrators:
Dead Volume: Many sample cups have a 50 microliter dead volume. This volume remains in the sample cup so that the probe does not hit the bottom of the cup or tube, which would cause it to break, become damaged, moved, or need to be recalibrated.
Algorithm: An algorithm is a specification or specific instructions on how to solve a problem. It may include a flow chart or a series of steps to follow or questions to ask in order to resolve a problem or know how to handle a sample and what to do next. It involves logic and reasoning. It may include rules, calculations, dilutions, processing data, a series of tasks (sequence), or tips to help you follow the next step in order to come to a logical conclusion. It is based on a model and aids the tech in solving common problems in the laboratory, particularly in regards to patient samples.
Pre-Analytical:
Stability: how long an assay, test, matrix or reagent is good for before it starts to degrade (break down)
Panel or Profile: a set or group of tests needed to assess or aid in the diagnosis of a medical condition
- Basic Metabolic Panel (8 Tests):
- Na+
- K+
- Cl-
- CO2
- Glucose
- Creatinine
- Cl-
- Urea (BUN or blood urea nitrogen)
- Comprehensive Metabolic Panel (14 Tests):
- Na+
- K+
- Cl-
- CO2
- Glucose
- Creatinine
- Urea
- Calcium
- Total Protein
- Albumin
- ALT
- AST
- AlkP
- Total Bilirubin
- Lipid Profile (4 Tests):
- Total cholesterol
- LDL
- HDL
- Triglycerides
- Hepatic Panel (Liver Profile) (7 Tests):
- Albumin
- Total Protein
- Alkaline Phosphatase
- ALT
- AST
- Total Bilirubin
- Direct Bilirubin
- Electrolyte Panel (3-4 tests):
- Na+
- K+
- Cl-
- CO2
Matrix or Matrices: biological fluids or substances containing the analyte(s) of interest:
- whole blood
- serum
- plasma
- urine
- CSF
- pleural fluid
- peritoneal fluid
- pericardial fluid
- amniotic fluid
- saliva
- synovial fluid
- QC material (similar to biological fluids)
Reagent: a substance/solution added to the specimen to see if a chemical reaction occurs; Daily QC (quality control) is performed on reagents prior to patient testing and are treated exactly as patient testing
- Some are refrigerated solutions
- Some are lyophilized powders that need to be reconstituted with deionized water, saline or other liquid materials designated by the package
- Some are frozen and need to be thawed
- Some are stored at room temperature
- All have an expiration date, which often changes once opened
- Must be observed for transport and storage conditions
- Some must be protected from light
- Some must not tip over because they are susceptible to formation of bubbles
- Observe for color changes, leaks, dents, punctures, spills, crystal or precipitate formation or microbial contamination
- Daily, Weekly, Quarterly, Annual and As-needed
- Includes washes, tubing and probe flushes, cleaning, draining and filling of alkaline and acidic washes and buffers and saline solutions, filling, and changing of the water bath water
- Acid washes: pH 0-7
- Alkaline washes: pH 7-14 (basic)
- Buffers: neutral pH (around 0)
- Detergents (contain surfactants to lift and remove dirt and particles
- Bleach (sodium chloride)
- Cleaning the instrument
- Changing bulk fluids and washes to keep the instrument functioning as well as it can
- Cleaning and maintaining probes/pipettors
- Changing probes/pipettors
- Calibrating probes/pipettors
- Changing parts like ICT modules, pumps, tubing, etc...
- Adding and removing reagents
- Reconstituting fluids and reagents
- Bleaching certain instrument parts
- Materials are kept refrigerated, frozen, at room temperature, or are powders that need to be reconstituted with deionized water or other solutions prior to testing
- All have expiration dates on the bottles and some change once opened
- Most come in amber glass vials to protect them from light
- Some need to be parafilmed after opening to prevent evaporation or rapid breakdown
- All need to be closed, resealed properly after opening, and stored at the correct temperature for the designated amount of days
- Set points and ranges and matrix may change with new lots/batches, so this is carefully monitored and entered into the analyzer/instrumentation if need be
- Check for bubbles prior to testing
- Some QC testing is performed daily, some tests are performed multiple times per day, some are with each individual test
- If QC is out of range and fails, it must be repeated until it comes back in and troubleshooting steps must be performed before patient tests can be performed and results released
- Sometimes failed QC requires recalibration
- QC is performed every time a new lot replaces an old lot
- New lots require 20 tests or consecutive days of testing prior to incorporating as the new lot default
- After major instrument maintenance or repair, QC often needs to be repeated
Calibrators:
- Materials are kept refrigerated, frozen, at room temperature, or are powders that need to be reconstituted with deionized water or other solutions prior to testing
- All have expiration dates on the bottles and some change once opened
- Most come in amber glass vials to protect them from light
- Some need to be parafilmed after opening to prevent evaporation or rapid breakdown
- Some need to be refrozen after use and can only be thawed several times then need to be discarded
- All need to be closed, resealed properly after opening, and stored at the correct temperature for the designated amount of days
- Set points, curves and matrix may change with new lots/batches, so this is carefully monitored and entered into the analyzer/instrumentation if need be
- Check for bubbles prior to testing
- Some calibrations only need to be performed monthly or as needed
- If calibration fails, it must be repeated until it comes in and troubleshooting steps need to be taken
- If QC is out of range and fails, sometimes calibration must be repeated until QC comes back in and troubleshooting steps must be performed before patient tests can be performed and results released
- Sometimes failed QC requires recalibration
- Calibration is performed every time a new lot replaces an old lot
- New lots of calibrators and QC materials require calibration prior to QC
Dead Volume: Many sample cups have a 50 microliter dead volume. This volume remains in the sample cup so that the probe does not hit the bottom of the cup or tube, which would cause it to break, become damaged, moved, or need to be recalibrated.
Algorithm: An algorithm is a specification or specific instructions on how to solve a problem. It may include a flow chart or a series of steps to follow or questions to ask in order to resolve a problem or know how to handle a sample and what to do next. It involves logic and reasoning. It may include rules, calculations, dilutions, processing data, a series of tasks (sequence), or tips to help you follow the next step in order to come to a logical conclusion. It is based on a model and aids the tech in solving common problems in the laboratory, particularly in regards to patient samples.
Pre-Analytical:
- Things to check prior to testing the sample
- Test orders
- Location (hospital, floor, clinic, etc...)
- Time and date of collection
- Time of receipt
- Name of collector
- Medical Record Number #
- Financial # or SSN or other identifier
- Patient demographics: Name, D.O.B. (date of birth)
- Location of collection
- Name of ID number of person performing the collection
- Time of collection
- Test tube type and expiration date
- Proper fill
- Label placement
- Label intact and straight, no smeared ink, no rips or tears
- Patient preparation for collection (Fasting? Line Draw? Infusion? Was IV turned off for proper amount of time prior to testing? Did patient have any hematomas?)
- Centrifugation timing
- Transport (conditions, temperature, tracking, stayed upright, parafilmed if need be)
- Time sent
- Time in transit
- Time received
- Time testing began
- Condition of the specimen
- Spun?
- Unspun?
- Separated?
- Correct temperature?
- On ice?
- Refrigerated?
- Frozen?
- Thawed?
- Protected from light/heat?
- Viscosity?
- Any clots, clumps or fibrin strands?
- Color? Clear? Amber? Icteric?
- Any hemolysis?
- Any lipemia?
- Any suspect contamination with EDTA or with IV fluids?
- Collected in proper Vacutainer or container? Do you need to call for a recollection of another type of tube for the test ordered?
- Correct amount needed for testing?
- Lid on properly and not removed?
- Any bubbles?
- Serum Separator Gel intact?
- Correct orders?
- Any add-ons?
- Do you need to make an aliquot prior to testing?
- Do you need to centrifuge or ultrafuge the specimen?
- Analytic:
- Things directly affecting patient sample testing:
- QC was performed and is in/good
- Calibration was performed and is in/good
- Interferences during testing?
- Bubbles/Aspiration errors
- Clots
- Microclots/fibrin strands
- Hemolysis
- Lipemia
- Icterus
- Particles
- Proteins
- Antibodies
- Dilutions (auto, manual)
- Concentration
- Thickness of the serum
- Short samples
- Does the sample need a dilution? (Automatic or Manual)
- Instrumentation functioning correctly
- Pipettors working properly
- Machine maintenance complete and passed
- Instrument fluids and reagents replaced and full
- Tests enabled and not disabled
- Instrument track functioning properly, along with all its parts (belts, sensors, centrifuge, decapper, desealer, aliquoter, gates, routing, IOM, resealer, recapper, storage, racks, etc...)
- During a panel of tests, has one of them come up with a critical value that needs to be called and documented?
- Does the test need to be rerun due to a DELTA check or a < (less than) value or > (greater than) value?
- Does the test need to rerun undiluted?
- Is the specimen suspected of being contaminated with IV fluid, saline, glucose or EDTA?
- Does the sample need to be recollected for a test?
- Do any tests that are or were running need to be canceled?
- Post-Analytical:
- After the testing:
- Reporting of results
- Autoverification
- Manual entry of results
- Calculations (GFR, DLDL, AGAP, TP, etc...)
- Resulting and verifying
- Calling critical results
- Documentation
- Corrections or corrected reports and calls
- Location
- Delayed results
- Incomplete/Pending (check for completion)
- Storage/Storage conditions
- Any add-ons?
- Does the specimen need to be sent out for further testing?
- Does the specimen need to go to another department for further testing?
- Does the specimen need to be stored in another area?
- Does the specimen need to be refrigerated or frozen?
- Is anything held up that needs to be released?
- Do you need to call for a recollect?
- Is something going on with the instrument, reagents, assays or QC?
- After the testing:
- Things directly affecting patient sample testing:
Procedure:
- Method or way of following steps to achieve a specific task or goal
- Instructions that tell you exactly what to do to perform a task, including step-by-step orders and sometimes visuals or examples to help you achieve the task
- The method designed by your lab that contains the steps you must follow when performing any task in your laboratory area or bench area, including machine maintenance, QC, calibration, troubleshooting steps, testing, resulting, tracking specimens, ordering and receiving samples, storing samples and reagents, safety, waste management, PPE, etc...
Aspirate/Aspiration:
- The drawing in of a fluid with suction (pipette)
- Aspiration errors in chemistry typically occur if there is a bubble, clot, the liquid is too high in the sample cup, or something is blocking the pipettor or probe
- Turn upside-down or gently shake to mix thoroughly or to coat something
Clinical Chemistry Methods:
Photometric/Photometry: the measurement of light (luminance and luminous flux and luminous intensity) , based on photodetectors, or special sensors that produce an electric signal when they are exposed to light. Solutes are dissolved in a solvent, forming a solution in which light may be transmitted/reflected/emitted, scattered/refracted or absorbed.
UV: Ultraviolet Light: This method uses visible spectroscopy, fluorochromes, uses the spectrophotometer and is a quantitative test. Monochromator: This is a device that can be used to select the desired wavelength of light produced by a light source. It disperses the light like a prism. A narrow band of wavelengths can be selected and directed through the sample cuvette. This is used with photometry. Turbidimetric/Turbidimetry/Immunoturbidimetric: When light is transmitted through a solution, it hits insoluble particles, which cause the light to scatter or reflect in different directions. Turbidimetry is the measurement of the scattering of light or the absorption of light as it passes through the cuvette containing a solution. The measurement is given as the amount of absorbed light/loss of light. This method is used to detect analytes, proteins, cells, antibodies, antigens, or antibody-antigen complexes found within a liquid, including urine, body fluids, blood, plasma, serum, or water. Examples include total protein, albumin, microalbumin, or transferrin, which are transport proteins found in the blood and are large complex molecules. Drug screens are also examples that use this method, as drugs are large particles that cause changes in turbidity. Nephelometry: This is the measurement of suspended particles in a liquid, such as water. We use special filters to create reagent grade analytical water in the clinical laboratory. Nephelometry measures pre-filtered and filtered water to determine the amount or concentration of suspended particles in water. A light beam and a light detector are utilized to transmit light through the liquid and detect the suspended colloidal particles in the liquid. Potentiometric: A potentiometer is used to measure electric potential or the activity of an ion or ions. Ions interact both with each other and with water molecules, due to positive and negative charges attracting one another. Ionic strength and concentration, heat, and pH all affect the measurement of potentiometry. A potentiometric sensor is a chemical sensor used to detect analytes in a solution or gas, particularly electrolytes (Na+, K+, Cl-, Mg+, Ca++). Ionized calcium assays are an example of one of the tests that utilizes this method. Osmometers used to test electrolytes in urine and serum are also examples of such technology. Spectrophotometry and UV light: When a wavelength of light is measured, spectrophotometry is a quantitative measurement of the reflection or transmission of light, as opposed to the absorption of light. This technology is based on the electromagnetic spectrum and the Beer-Lambert law, as shown in the images below. Chemiflex: Chemiflex is enhanced chemiluminescence. Immunoassays particularly use this technology via the measurement of magnetic or paramagnetic microparticles complexing with analytes in a solution. Examples include ATG, ATP, C-Peptide, iPTH, bHCG, Vitamin B12, Vitamin D, Ferritin, Folate, Iron, Cortisol, Estradiol, PSA, Testosterone, TSH, Total T3 and 4, Free T3 and 4, Insulin, HIV, Hepatitis panels, and more. Chemiluminescence: When a chemical reaction occurs, there is an emission of light or heat. Reagent A plus Reagent B plus an excited energy state intermediate result in a product, or products, plus light. The product and light are measured. A catalyst or an enzyme and/or coenzyme kick off a chemical reaction, resulting in the end product(s) plus light. The excited energy state decays into a lower energy state, resulting in the emission of light in the form of a photon for each molecule or reagent, or in the form of a biomolecule or protein in a minute quantity. Enzymatic assays, such as Liver Panels (AST, ALT, Alk-Phos), Cardiac Enzymes (Troponin, BNP, CKMB, CK) are examples that utilize such technology. Cuvette: This is the little plastic cup in which a solution is placed to detect a chemical reaction on the analyzer EIA: Enzyme Immunoassay or Enzyme-Linked Immunosorbant Assay; based on the linking of antibodies and antigens to form antibody-antigen complexes that can be detected in solution Enzymatic (see below): based on the use of enzymes and/or coenzymes as catalysts to kick off metabolic reactions; enzymes, substrates, and/or product(s) can be measured directly or indirectly
Colorimetric: detection of dye-complexes formed in solution as a result of an analyte-dye complex formation during a chemical reaction Diatotization: amines + acids result in diazonium salts, which serve as an intermediate for halides and azo complexes, resulting in a dye or pigment that can be detected; includes the Sandmeyer Reaction and Schiemann Reaction; Aromatic diaz. ions act as electrophiles, and this is dependent upon a mildly acidic to neutral pH
Phosphomolybdate method: inorganic salt of phosphomolybdate acid forms an ion complex resulting in a highly yellow precipitate Biuret Method: a dye complex forms when testing proteins, resulting in a lavender-purple solution ISE: Ion Selective Electrodes (Electrolytes); indirect Fermentation: breakdown of glucose into pyruvate and further into product(s) FPIA: fluorescent polarization immunoassay involving attachment of fluorophores to analytes, which form a detectable complex AMP Buffer: This provides electrical impedance for signal detection |
OTHER RELATED TERMINOLOGY:
- Absorbance: Visible light is absorbed when it passes through a solution which contains the analyte.
- Selective Absorbance: Certain wavelengths of visible light from the spectrum of white light give a solution a unique color.
- Example: Hemoglobin gives a solution a red color due to the pigment found in hemoglobin. Hemoglobin appears red but really the light in the green range of the electromagnetic spectrum is selectively absorbed.
- Green range of the electromagnetic spectrum falls under wavelengths of 500-600 nm
- A light source emits white light; Light passes through the cuvette, which acts as a prism, absorbing and reflecting/transmitting/emitting various wavelengths of light; A photodetector measures the amount of emitted or transmitted or absorbed or scattered or refracted light.
- Example: Hemoglobin gives a solution a red color due to the pigment found in hemoglobin. Hemoglobin appears red but really the light in the green range of the electromagnetic spectrum is selectively absorbed.
- Analyte: An analyte is a reaction product or products.
- Has an intrinsic color
- May generate or produce a color during a chemical reaction, which can then be detected
- Fluorescence: Chemicals that absorb one wavelength of light yet emit light of another wavelength are referred to a fluorescent. This can be observed in the image of the flask below containing a chemiluminescent reaction fluorescing in UV light. The shorter wavelength of light is absorbed, whereas the longer wavelength of light is emitted. A photodetector is placed at a 90 degree angle from the light so it detects the emitted light only and concentration of the compound can be detected.
- Fluorescent molecules called "fluorophores" are part of reagents that help to detect analytes
- Examples include tumor markers like CA-125 or CA15-3:
- Antibodies are attached to fluorescent molecules in the reagent
- Antibodies recognize and attach to tumor marker
- The unbound or excess antibodies are rinsed away
- The amount of the fluorescent light generated is directly proportional to the amount of tumor marker present in the sample
- Fluorescent molecules called "fluorophores" are part of reagents that help to detect analytes
Spectrophotometry/Spectometry/Colorimetric Methodology and UV Light:
Source Lamp:
The source lamp inside the chemistry analyzer detects wavelengths of 400-700 nanometers (nm). The UV lamp detects wavelengths of 200-400 nanometers (nm).
The source lamp inside the chemistry analyzer detects wavelengths of 400-700 nanometers (nm). The UV lamp detects wavelengths of 200-400 nanometers (nm).
Beer's Law:
Absorbance of light or a substance is directly proportional to the concentrations of the solute in the material solution (sample). According to the Beer-Lambert law, absorbance is affected by both the concentration of the solutes present in the solution, as well as the thickness of the solution. This is why chemistry samples are affected by hemolysis, icterus, lipemia (HIL reference), other analytes or interferences present in any given sample. Light is affected by the materials through which it is travelling. It can be absorbed or reflected/transmitted/scattered.
Beer's Law Formula:
A = elc (absorbance)
e = extinction coefficient
l = length of the cuvette
c = concentration of solute in standard solution (M in image below)
Absorbance of light or a substance is directly proportional to the concentrations of the solute in the material solution (sample). According to the Beer-Lambert law, absorbance is affected by both the concentration of the solutes present in the solution, as well as the thickness of the solution. This is why chemistry samples are affected by hemolysis, icterus, lipemia (HIL reference), other analytes or interferences present in any given sample. Light is affected by the materials through which it is travelling. It can be absorbed or reflected/transmitted/scattered.
Beer's Law Formula:
A = elc (absorbance)
e = extinction coefficient
l = length of the cuvette
c = concentration of solute in standard solution (M in image below)
Enzymes and Enzyme Denaturation:
Enzymes:
Enzymes are special 3 or 4-dimensional proteins that are catalysts that kick off chemical reactions or helpers that act as coenzymes for chemical reactions. They aid in either breaking things down or synthesizing (making) molecules. They are very specific and conditions must be just right in order for them to become activated. They are affected by temperature such as heat (speeds up reactions), cold (slows down reactions), pH (acidic or basic), moisture, light, and amount/concentration. A higher concentration means a speedier reaction, whereas a lower concentration means the reaction may take longer.
Enzyme Denaturation:
- Temperature increases are the main cause
- Changes in pH
- Radiation
- Chemicals
- Electricity
- Causes the protein to unfold (see image on left)
- Loses its potency or its ability to act upon a substrate
- Loses its ability to catalyze (kick off) or speed up a chemical reaction
Enzymatic Rate Reactions:
Endpoint Reactions:
- One of two ways in which to measure and detect an analyte using a chemical reaction
- Performed once the reaction is complete
- The total amount of analyte has been converted to a product
- Best performed for chemical reactions that are fairly rapid and produce just one product or complex for each molecule involved
- Albumin uses this type of reaction
- Albumin + Bromocresol Purple = colored complex (product)
- Albumin-BCP complex is what is measured
- Measure the synthesis of a product
- Measure the loss of a reactant
- Two Types:
- End-Up
- Synthesis of product is measured
- Absorbance is higher at the end point than at the starting point
- End-Down
- Loss of reactant is measured
- Absorbance is lower at the end point than at the starting point
- End-Up
- One of two ways in which to measure and detect an analyte using a chemical reaction
- Performed as the reaction is occurring
- Measures the rate of change in product that has formed over time
- An analyte may be an enzyme that catalyzes chemical reactions and acts on a substrate or substrates to produce a product or products, or it may be another type of analyte like a type of therapeutic drug or ammonia, a waste product of metabolism
- Measure the appearance of a product (synthesis)-anabolic
- Absorbance increases with time (rate-up reaction)
- or Measure the disappearance of a product (break down)-catabolic
- Absorbance decreases with time (rate-down reaction)
Precipitate:
Precipitate is the solid formed from a solution. After centrifugation, it tends to form a button or pellet on the bottom of the test tube. The liquid left above it is referred to as the supernatant.
EIA: Enzyme-Linked Immunosorbant Assay
Diazotization and Diazatonium coupling:
Phosphomolybdate:
Biuret Method:
Reconstitution:
Reconstituting means that you mix/dissolve a solvent (liquid) and solute (solid) to create a solution. Oftentimes this involves lyophilized material or powder (freeze-dried) that you mix with or dissolve into a solvent or with deionized water with a calculated pipette that delivers the exact amount to create a solution that can then be stored for a specific amount of time at a designated temperature (usually refrigeration). Certain reagents, QC material and calibrators need to be reconstituted. Follow the manufacturer's packaged instructions for techniques and amounts.
Solutions and Mixtures:
Constituents of a Solution:
Solvent: a substance that dissolves a solute to form a solution
Solute: the substance being dissolved by a solvent
Solution:
In chemistry, a solution is a homogenous mixture. It is made up of two or more substances. A solute is dissolved in a solvent to create a solution. This occurs due to chemical polarity (ions, or molecules that have positive or negative charges and are attracted to one another). You cannot always see the particles of solute in solution with the naked eye. With a solution, beams of light typically do not scatter. Solutions are stable. Liquid solutions are a phase.
Mixture:
Mixtures are heterogenous mixes of two or more substances, forming different phases. Properties include:
Solubility:
This is the ability of one substance or compound to dissolve in another.
Precipitate: the solid or crystals left behind when the liquid portion of a solution has evaporated
Solute: the substance being dissolved by a solvent
Solution:
In chemistry, a solution is a homogenous mixture. It is made up of two or more substances. A solute is dissolved in a solvent to create a solution. This occurs due to chemical polarity (ions, or molecules that have positive or negative charges and are attracted to one another). You cannot always see the particles of solute in solution with the naked eye. With a solution, beams of light typically do not scatter. Solutions are stable. Liquid solutions are a phase.
- Aqueous Solution: one in which the solvent is water
- Water is the ideal solvent
- Can be gases, liquids or solids
- Saturated: concentration at which no further solute will dissolve in solution
- Unsaturated:
Mixture:
Mixtures are heterogenous mixes of two or more substances, forming different phases. Properties include:
- Concentration: the amount of the substance or constituent divided by the total volume of the mixture; increases by adding more solute
- Dilution: decreases concentration by adding more solvent or removing more solute
- Suspension or phase separation: the two or more components in the mixture remain separated in layers, depending upon density; the more dense particles stay at the bottom, whereas the lighter particles remain on top
- Temperature
- Density: weight of the solute particles
Solubility:
This is the ability of one substance or compound to dissolve in another.
- Miscible: one liquid can totally dissolve in another one (example: sodium chloride solution)
- Immiscible: two substances that can never mix completely to form a homogenous solution (example: oil and water or oil and vinegar)
Precipitate: the solid or crystals left behind when the liquid portion of a solution has evaporated
- In chemistry, this is also the creation of a solid from a solution
- Settles at the bottom of the liquid solution
- The precipitant is the liquid that caused the solid to form
- Can remain in suspension without settling if there isn't enough gravity to separate them
- Centrifuges help separate the components of blood into different layers
- Examples: pigments, dyes, salts, paramagnetic particles, antibody-antigen complexes, components of blood, crystals, fluorochromes, etc...
Suspensions, Concentration, Precipitate, and Supernatant:
Blood Fractionation by Centrifugation:
Fractionation is the process of fractionating whole blood by separating it into its components so the various components can be tested. The components include the following:
- Plasma or serum (upper phase): the liquid portion of the blood (clear, straw-colored solution)
- The buffy coat (middle phase): the thin, middle layer consisting of leukocytes (white blood cells) and platelets
- The hematocrit (lower phase): the dense, tightly packed red blood cell layer at the bottom
Dilution:
In chemistry, a dilution means to add a buffer or saline solution to the sample to dilute it and retest it. The solute in the solution is decreased by adding more solvent.
Solvent: the liquid or material in which the solute is dissolved in order to create a solution
Solute: the material that is dissolved in the solvent to create a solution
Solvent: the liquid or material in which the solute is dissolved in order to create a solution
Solute: the material that is dissolved in the solvent to create a solution
Understanding Solutions:
A solution is a combination of solute dissolved or mixed in a solvent. Water is the most common universal solvent.
Tonicity is the measure of the osmotic pressure gradient. The cell membrane separates two water potentials, solutions which are trying to maintain equilibrium. Water is able to freely diffuse across the cell membrane by osmosis. Tonicity is basically the relative concentration of solute inside and outside the cell (on either side of the cellular membrane) dissolved in solution and the rate and amount of diffusion.
Tonicity is the measure of the osmotic pressure gradient. The cell membrane separates two water potentials, solutions which are trying to maintain equilibrium. Water is able to freely diffuse across the cell membrane by osmosis. Tonicity is basically the relative concentration of solute inside and outside the cell (on either side of the cellular membrane) dissolved in solution and the rate and amount of diffusion.
Isotonic Solution:
In an isotonic solution, the concentration of solutes is the same or equal inside the cell as it is on the outside of the cell on either side of the cell membrane. Because of the equal gradient, the cells will neither swell nor shrink. They are just right. Water can cross the cell membrane in both directions at a rate that is even or equal (diffusion). The cell will not gain nor lose water. This is equilibrium or homeostasis (balance).
In an IV solution, normal saline is nearly isotonic to blood solution. The osmolarity of normal saline is 9 grams of NaCl dissolved in water to form a solution of around 1 liter. NaCl in blood is approximately 290 mOsm/L.
The OSMO test in chemistry tests this concept. If the body is not in homeostasis, the solution may either shift to a hypotonic or hypertonic solution. This test aids nurses and physicians in treating patients and monitoring the administration of solutions and/or medications and diet.
In an IV solution, normal saline is nearly isotonic to blood solution. The osmolarity of normal saline is 9 grams of NaCl dissolved in water to form a solution of around 1 liter. NaCl in blood is approximately 290 mOsm/L.
The OSMO test in chemistry tests this concept. If the body is not in homeostasis, the solution may either shift to a hypotonic or hypertonic solution. This test aids nurses and physicians in treating patients and monitoring the administration of solutions and/or medications and diet.
Hypertonic Solutions:
A hypertonic solution is one in which the concentration of solute is greater outside the cell than inside the cell. Water molecules rush out of the cell to try to create equilibrium, causing the cell to crenate (shrink).
Hypotonic Solutions:
A hypotonic solution is one in which the concentration of solutes is greater inside the cell than outside the cell. Water molecules rush in by osmosis (osmotic pressure) to try to create equilibrium, causing the cell to swell. If it bursts, this is called "lysing" or "cytolysis" (rupture).
Potentiometry:
Potentiometry involves the measurement of electrical potential between two electrodes, one of which is in direct contact with ions in solution. Ions (electrolytes) such as K+, Na+ and Cl- are measured using this technology. A voltage change occurs based on the concentration of each ion, reflected in a logarithmic equation called the Nernst equation. Blood gas analyzers such as the NOVA pHox utilize this type ot technology to measure things like pH and ionized calcium (Ca++ ) in the blood.