Labs

• Erlenmeyer Flask● Features slanted sides and narrow neck● Useful for mixing without spilling as well as boiling liquids

  • should not be used for precise measurements
• Glass beaker

  • same width at top and bottom
  • useful for holding liquids
  • should not be used for precise measurements
• Graduated cylinder

  • long and slender
  • not intended for mixing, stirring, or heating liquids
  • often used for measurements with accuracy
• To contain pipettes - (TC) quantity/volume of liquid contained in pipette is equal to the capacity printed on the pipette
• TD pipette - (TD) quantity/volume of liquid contained in the pipette is equal to the capacity printed on the pipette minus the drainage holdback
• Volume of TD pipette - volume of TC pipette + drainage holdback error
• Serological pipets● User can determined volume pipetted up to the maximum capacity of thepipet.● Common sizes are 1, 5, and 10 ml● May be TC or TD

  • Etched with graduated measurements
• Volumetric pipettes

  • are designed to only measure 1 designated volume
  • also called "bulb" or "belly" pipettes
  • may be TC or TD
• MLA pipette

  • commonly used in laboratory science
  • can dispense very small, but accurate volumes of liquid
  • MLA pipettes may have a designated volume or a changeable volume
• assays

  glucose oxidase

  • more specific than copper sulfate
  • read spectrophotometrically at the endpoint of reaction, measure absorbance, generally read in visible spectrum (400-700 nm); depends on chromagen used
  • interferences - acetaminophen, excess uric acid, bilirubin, and ascorbic acid
• QC run every 24 hours is most common
• lyophilized - usually comes with buffer to reconstitute; dehydrated and frozen
• types of QC mats: lyophilized, frozen, ready-to-use
• assayed: comes form the manufacturer with a set mean and standard deviation
• unassayed: your lab must perform test runs of this QC to establish a mean and standard deviation
• control vials should be labeled with open date, expiration date, and initials
• new control should be run in parallel with old control for 30 days
• percentile: the value below which a percentage of data falls
• standard deviation is a measure of how idspersed data is in relation to a mean
• low SD - data is close to the mean
• high SD - data is far from the mean
• random error - occurs because of unpredictable events; will probably correct if repeated
• systematic errors occur because of a problem with the system
• examples of systematic error include shift and trend
• shift - sudden change in values
• shifts occur due to switching to new lot # of reagent or control
• trend is a gradual increase or decrease in values
• trends occur due to deterioration of the controls/reagents or contamination
• troubleshooting - consideration of why errors occur and how to fix them
• coefficient of variation is used to compare variation of distributions with different units relative to their means
• generally, CV should be 5% or less
• CV of >10% may indicate poor method performance
• 1(2s) means that one data point is greater than 2 SD from teh mean
• 22s is when two consecutive data points are greater than 2 SD away from the mean
• 13S is when one data point is greater than 3SD away from the mean
• 41s is when four consecutive data points are greater than 1 SD away from the mean
• 10x is when ten consecutive data points fall to one side of the mean
• R4s is when there are more than 4SD between two consecutive data points
• ortho-toluidine is read at 630 nm
• ortho-toluidine

  A) ortho-toluidine

  B) glucose

  C) hot acetic acid

  D) blue-green