1. define the problem

must know what information is needed, by whom, for what purpose, and what type of sample is to be analyzed

2. select a method

identify the sample type, size of sample, its cost, etc.

3. obtain a representative sample

get the sample type and its sampling statistics

4. prepare the sample for analysis

any preparations such as chemical separation and/or concentration for the sample

5. prepare any necessary chemical separations

such as distillation, precipitation, extraction etc.

6. perform the measurement

calibrate, validate, and replicate

7. calculate the results and report

using statistical analysis, the results are interpreted and evaluated carefully

contamination, loss, decomposition, matrix change

certain precautions should be taken in handling and storing samples to prevent or minimize

the container, atmosphere, heat, temperature, or light

prevent contamination or alteration of the sample by

method of standard additions

calibration technique wherein if there is any interference or spike in the sample, a known amount of substance helps compensate it

internal standard calibration

adding a known quantity of a substance that behaves the same way as the analyte, but is not the analyte or present in the sample naturally.

two validations of a method

random and systematic

random

measurement has some imprecision associated with it, which results in random distribution of results, for example, a Gaussian distribution

systematic

one that biases a result consistently in one direction (analytical balance is skewed high or low)

analyze

a sample is analyzed for all its constituents and the substance measured are the analytes

determination

process of measuring the analyte