Balances and volumetric glassware are examples of laboratory equipment. Laboratory
instrumentation also must be calibrated using a standard providing a
known response. For example, a spectrophotometer’s accuracy can be evaluated by
measuring the absorbance of a carefully prepared solution of 60.06 ppm K2Cr2O7 in
0.0050 M H2SO4, using 0.0050 M H2SO4 as a reagent blank.2 The spectrophotometer
is considered calibrated if the resulting absorbance at a wavelength of 350.0 nm
is 0.640 ± 0.010 absorbance units. Be sure to read and carefully follow the calibration
instructions provided with any instrument you use.