Analytical chemistry assignment 12 questions - Essay Example

In other cases, the matrix can constitute the interferent, which alters the results of the chemical analysis procedure. The accuracy of a chemical measurement explains how close the results obtained are to the true value. It is essential to establish the accuracy of a chemical measurement before interpreting the results obtained from the measurement. To determine the accuracy of an analytical measurement, one is required to calibrate it with a known standard. For instance, you can determine the accuracy of a weighing scale by comparing it with a fully functional one.

Calibration refers to the process of comparing two measurements or methods whereby one is of a known magnitude or accuracy, made using a standard device or procedure and the other made in as alike a way as possible using a second device or method. The second device or method is usually referred to as the unit under test. To calibrate an analytical method, one needs to compare the results of the measurement to a set standard and making adjustments as required. The steps involved in making a chemical measurement include: selection of an analytical method, sample collection, sample processing, elimination of interferences, measurement, and calculation of results and estimation of the reliability of the results.

To collect toxic fumes from a room, a known volume of the contaminated air is drawn through a glass fibre filter. The sample is then desorbed using the appropriate chemical substance and then analyzed by gas chromatography using a flame ionisation detector. Care should be observed to avoid inhalation of the fumes during the collection and analysis process. Urine collection methods vary depending on the analyte being tested. Drugs differ in the way in which they are metabolized in the body, including the components that are excreted through the urine.

Depending on the analyte being investigated, urine samples can be collected during different times to