Analysis of a Digital Pipet
Mechanical micropipets are commonly used to dispense small (μL) volumes of reagents. A recent “Application Note” [Am. Lab. June 1999] contains the following data for 50 replicate deliveries of a reagent using […]
Calculation
Analysis of Basic Copper Carbonates
The %w/w Cu in a synthetic basic copper carbonate may be found by reducing and isolating the copper as Cu metal. To calculate the %w/w Cu we use the following formula The […]
Determination of Fat in a Snickers’ Bar
In a recent paper [J. Chem. Educ. 1997, 74, 1108-1111], Snow, Dunn and Patel describe the experimental determination of fat in a SnickersTM candy bar. The fat was removed by extraction with […]
Calculating HCl Molarity and Titration Error
In determining the concentration of HCl by titrating against the primary weak base TRIS, the molarity of HCL is calculated using the following equation where GFW is the gram formula weight of […]
Comparison of Glucometers
A glucometer is a portable device used to monitor glucose levels in blood. Of concern for users is repeatability between units of the same model, or between different models. The following data […]
Spike Recovery for Analysis of Ginkgolide
One concern in any analysis is the impact of the sample’s matrix. A method for an analyte that is known to work well in one matrix may yield problems when applied to […]
Uncertainity in Dispensing a Reagent
Concentrated HCl is 37.2% w/w HCl (±0.5% w/w) and has a density of 1.19 g/mL (±0.01 g/mL). Suppose that you need to dispense 0.0500 mol of HCl with an uncertainty of no […]
Propagation of Error in Preparing Solutions
Suppose you have a bottle of 53.4% w/w NaOH (the density of which is 1.52 g/mL) from which you are to prepare a 1.000-L solution of 0.534 M NaOH. Two obvious ways to […]
Preparing Solutions
During lab you need to prepare a solution that is 5.00 x 10-2 M Fe(CN)63- using K3Fe(CN)6. (a) Explain how to make 500 mL of this solution so that you know its […]
Concentration of Parathion Solutions
Parathion, C10H16NO5PS, is a toxic organophosphorous pesticide. A recently published method [Sacks, et al. Anal. Chem. 2000, 72, 2055-2058] for parathion reports a detection limit of 10 ng/mL. Express this concentration in […]
Concentrations
Gratzel et. al. [Anal. Chem. 1999, 71, 2751-2756] describe the use of a diffusional microburet to transfer solutions to very small droplets of solvent. The purpose of their work is to run […]
NIST Statistics Problem
Have you ever wondered how atomic weights are determined? The National Institute of Standards and Technology (NIST) is one of several research organizations that seeks to make accurate measurements of this sort. […]