Quantitative Analysis Flashcards

Flashcards covering key vocabulary and concepts from the Quantitative Analysis lecture notes.

Dimensional Analysis

Just because things match doesn't mean they are correlated.

Uncertainty

The inherent variability in data; every measurement has some degree of uncertainty.

Parallax

Different viewing locations can cause variability in measurements.

Significant Figure

The last significant figure of a measurement is the digit of uncertainty.

Nonzero digits

Always significant figures.

Sandwiched Zeros

Significant figures between nonzero digits.

Trailing zeros

Significant when there is a decimal.

Error

A deviation from an arbitrary reference point or 'true' value.

Experimental Error

Problems in the process of making the measurement; based in actions.

Standard Deviation (s)

Expresses the 'spread' of a set of measurements around a sample average.

Confidence Interval (CI)

Defines the interval over which a measurement is expected to be repeatable.

Degrees of Freedom

The 'n-1' term in the standard deviation calculation.

Outlier

A data point with a statistically significant difference from other repeated measurements.

Grubbs Test

Statistical test to determine if a potential outlier is truly an outlier.

Accuracy

How close the measured value is to the 'true' value.

Precision

The spread of the measured values; the reproducibility of the measurement.

Analyte

The specific compound, element, or ion in question.

Sample

A discrete amount of a substance that may or may not contain the analyte.

Standard

A sample with a known amount of analyte used for comparative purposes.

Unknown

A sample containing an unknown amount of analyte.

Matrix

The background solvent.

Blank

A sample created from an analyte-free solution similar in matrix to the samples being collected.

Spike

A sample to which a known amount of analyte has been intentionally introduced.

Stock

A concentrated solution used to prepare other standards or spikes.

Molarity (M)

molsolute / L solution

Parts per million (ppm)

mysolute / L solution (aqueous) or mysolute / kg sample (solid)

Parts per billion (ppb)

Mgsolute / L solution (aqueous) or Mgsolute / kg sample (solid)

Mass Percent (% (w/w))

g solute / 100g sample

Percent, weight-to-volume (% (w/v))

g solute / 100mL solution

Percent, volume-to-volume (% (v/v))

mL solute / 100mL solution

Molality (m)

mol solute / kg solvent

Uncertainty

The inherent variability in data; affects precision.

Error

Deviation from an arbitrary reference point; affects accuracy; can result from uncertainty.

Random (or indeterminate) error

Directly caused by uncertainty in measurement; unpredictable and uncontrollable

Systematic error

One-sided and repeatable; avoidable and/or correctable; also known as Bias

Gross Error

Mistake, screw-up, or 'oops' that is big enough to make you consider starting over.

Absolute uncertainty (δX)

The margin of uncertainty associated with a measurement, has the same units as the associated measurement.

Relative Uncertainty (Ex)

The margin of uncertainty relative to the measurement itself, is unitless.

Quality Assurance (QA)

Process-based approach to planning experiments and completing analysis to minimize systematic error.

Standard Operating Procedure (SOP)

Step-by-step instructions compiled to carry out routine operations and ensure efficiency and quality.

Certification

Verification that an individual has the necessary credentials and training to perform tasks.

Accreditation

Verification that a laboratory has an appropriate quality management system and can properly perform test methods.

Quality Control (QC)

Monitors the experimentation and analysis to ensure that the analyst has done what was expected.

Validation

Thorough testing to ensure an instrument or method works as intended.

Verification

An abbreviated process to demonstrate the performance of an instrument or method is in substantial compliance with established values.

Detection Limit

A measure of the capacity to measure the analyte under specific instrument, statistical, or use-based limitations.

Instrument Detection Limit (IDL)

Lowest signal for an analyte that can be measured by the instrument.

Method Detection Limit (MDL)

Minimum measured concentration of a substance that can be reported with 99% confidence that the measured concentration is distinguishable from method blank results; only detection limit defined by Federal law.

Minimum Level (ML)

Lowest level at which the entire analytical system must give a recognizable signal and be used as an acceptable calibration point for the analyte.

Linear Dynamic Range

Defines the TOTAL range over which an instrument can be used.

Buffer

A solution that resists changes in solution pH by releasing or consuming H+.

Acid/Base Indicator

Weak organic acids or bases whose various protonated species have different colors.