Introduction to Analytical Chemistry and Chemical Analysis

Vocabulary practice flashcards covering fundamental concepts, classifications of analysis, chemical grades, balances, laboratory glassware, error types, accuracy, precision, and basic statistical evaluation in analytical chemistry.

Qualitative analysis

The identification of elements, species, and/or compounds present in a sample.

Quantitative analysis

The determination of the absolute or relative amounts of elements, species, or compounds present in a sample.

Structural analysis

The determination of the spatial arrangement of atoms in an element or molecule, or the identification of characteristic groups of atoms (functional groups).

Gravimetry

An analytical technique in which the property measured is the weight of pure analyte or compound of known stoichiometry.

Titrimetry

An analytical technique in which the property measured is the volume of standard reagent solution reacting with the analyte.

Volumetric methods

Quantitative chemical analysis methods in which the quantity of desired constituent is computed based on the volume of reagent needed for the reaction with the sample.

Gravimetric methods

Quantitative chemical analysis methods in which the quantity of desired constituent is computed based on the mass of pure compound to which the analyte is chemically related.

Macro analysis

A classification of analysis based on sample size in which more than $0.1\,\text{g}$ of sample is available.

Semi-micro analysis

A classification of analysis based on sample size in which $10\text{--}100\,\text{mg}$ of sample is available.

Micro analysis

A classification of analysis based on sample size in which $1\text{--}10\,\text{mg}$ of sample is available.

Ultra-micro analysis

A classification of analysis based on sample size in which samples are on the order of micrograms ($\mu\text{g}$).

Ultimate analysis

An analysis extent that covers the determination of the elemental composition of coal (such as carbon, hydrogen, sulfur, nitrogen) together with ash in the material as a whole.

Proximate analysis

An analysis extent that comprises the mass percentages of moisture, ash, volatile matter, and fixed carbon, obtained from a series of three standardized tests.

Major constituent

A constituent present in an amount ranging from $1\%$ to $100\%$ of the sample.

Minor constituent

A constituent present in an amount ranging from $0.01\%$ ($100\,\text{ppm}$) to $1\%$ of the sample.

Trace constituent

A constituent present in an amount ranging from $1\,\text{ppb}$ to $100\,\text{ppm}$ of the sample.

Ultratrace constituent

A constituent present in an amount of less than $1\,\text{ppb}$ of the sample.

Analyte

The constituent of interest in a sample.

Matrix

All other constituents in a sample except for the analytes.

Determination

An analysis of a sample to find the identity, concentration, or properties of the analyte.

Measurement

An experimental determination of an analyte's chemical or physical properties.

Technique

A chemical or physical principle that can be used to analyze a sample.

Method

A means for analyzing a sample for a specific analyte in a specific matrix.

Procedure

Written directions outlining how to analyze a sample.

Protocol

A set of written guidelines for analyzing a sample specified by an agency.

Reagent grade

Chemicals that meet established purity and specification requirements set forth by the Reagent Chemical Committee of the American Chemical Society (ACS) for general laboratory and analytical use.

Primary standard grade

An exceptionally well-characterized material with purity greater than $99.95\%$ suitable for accurate standard preparation and standardizing volumetric solutions.

Special-purpose reagent chemicals

Chemicals that have been specifically purified or controlled for a particular application, such as HPLC, histology, or tissue culture.

Technical grade

Chemicals of general or industrial quality subjected to only superficial purification, useful for manufacturing or cleaning solutions but seldom used in analytical work.

USP grade

Materials that meet applicable United States Pharmacopeia requirements, primarily used in pharmaceutical and medicinal applications.

Chemically Pure (CP) grade

Chemicals of a high degree of purity where impurities are too small to cause interference, though specifications depend on the supplier; used for general laboratory work.

Analytical Reagent (AR) grade

High-purity reagents suited for analytical procedures where trace impurities are restricted to the lowest possible limits for high-precision work.

ACS grade

High-purity chemical reagents meeting or exceeding American Chemical Society specifications ($\ge 95\%$), typically supplied with a certificate of analysis.

Macrobalance

The most common type of analytical balance, featuring a maximum load of $160\text{--}200\,\text{g}$ and a precision of $0.1\,\text{mg}$.

Semimicroanalytical balance

An analytical balance with a maximum load of $10\text{--}30\,\text{g}$ and a precision of $0.01\,\text{mg}$.

Microanalytical balance

An analytical balance with a maximum load of $1\text{--}3\,\text{g}$ and a precision of $0.001\,\text{mg}$ ($1\,\mu\text{g}$).

Tare

The mass of an empty sample container.

Taring

The process of setting a balance to read zero in the presence of the tare.

Buoyancy error

A weighing error that develops when the object being weighed has a significantly different density than the calibration masses.

Buret

A volumetric instrument used to accurately deliver an indeterminate amount of liquid.

Desiccator

A sealed vessel containing a drying agent (such as silica, calcium sulfate, calcium chloride, or sulfuric acid) used to dry solids and keep them dry.

Precision

The closeness of results to others obtained in exactly the same way, representing reproducibility.

Accuracy

The closeness of a measured value to the true or accepted value, representing nearness to the truth.

Absolute error

The difference between a measured value ($x_i$) and the true or accepted value ($x_t$), expressed as $E = x_i - x_t$.

Relative error

The absolute error divided by the true value, expressed as a percentage: $E_r = \frac{x_i - x_t}{x_t} \times 100\%$.

Gross error

An occasional error, neither random nor systematic, that results in the occurrence of a questionable outlier result.

Random (indeterminate) error

Uncertainties resulting from the operation of small uncontrolled variables that affect precision and cause replicate results to fall on either side of a mean value.

Systematic (determinate) error

Errors from a known source that produce bias by affecting measurements in one sense only (all too high or all too low) and can, in principle, be accounted for.

Instrumental errors

Systematic errors caused by nonideal instrument behavior, faulty calibrations, or use under inappropriate conditions.

Method errors

Systematic errors arising from nonideal chemical or physical behavior of analytical systems.

Personal errors

Systematic errors resulting from carelessness, inattention, or personal limitations of the experimenter.

Confidence interval

A statistical range defining bounds about the experimental mean within which—with a given probability—the true mean should be located.

Significance test

A statistical test used to decide whether the difference between analytical results is significant or can be accounted for merely by random errors.