Pharmaceutical Analysis II HPLC Assay, System Suitability, Validation & Online Tutoring

Pharmaceutical Analysis II usually covers instrumental methods such as UV-visible, IR and fluorescence spectroscopy, flame photometry, atomic absorption, thin-layer, liquid and gas chromatography and electrophoresis, applied to drug assays, impurity testing, dissolution and analytical method validation. The exact list depends on the university syllabus.

Pharmaceutical Analysis I focuses on classical methods: errors, volumetric titrations, gravimetry and electrochemical techniques such as potentiometry and conductometry. Pharmaceutical Analysis II moves to instruments and quality control, including spectroscopy, chromatography, impurity testing, dissolution and the validation of analytical methods.

Compare the sample peak area with the standard peak area, then scale by the standard and sample weights and dilutions, the standard purity and, for tablets, the average tablet weight. This gives milligrams per tablet, which is divided by the label claim and multiplied by one hundred to give percent of label claim.

Percent of label claim compares the amount of drug actually found in a dosage unit with the amount stated on the label. A tablet labelled 50 milligrams that assays at 49.25 milligrams contains 98.5 percent of label claim. The monograph sets the acceptable range for each product.

An assay on the dried basis corrects the result for water or volatile matter lost on drying, so it reflects the dry substance. Divide the as-is result by one minus the fraction lost on drying: 98.0 percent with 1.5 percent loss on drying becomes about 99.49 percent on the dried basis.

System suitability is a set of checks run before samples to show the chromatographic system works properly on the day. Typical parameters are the relative standard deviation of replicate standard injections, theoretical plate count, tailing factor and resolution between critical peaks, each with limits set by the method.

One common formula is sixteen times the square of retention time divided by peak width at the base. A peak at 6.0 minutes with a base width of 0.30 minutes gives 6,400 plates. Some methods use the width at half height instead, with a factor of 5.54.

The tailing factor describes peak symmetry. It is the peak width at five percent of peak height divided by twice the distance from the leading edge to the peak maximum at that height. A perfectly symmetrical peak scores 1.0, and many methods require a value of not more than 2.0.

Relative retention time is an impurity peak's retention time divided by that of the main drug peak, used to recognise impurities between runs. Relative response factor compares how strongly an impurity and the drug respond at the detector, and is used to correct impurity percentages calculated against a drug standard.

Divide the impurity peak area by the area of a diluted drug standard, multiply by the ratio of standard to sample concentration, divide by the relative response factor if one applies, and multiply by one hundred. The result is the impurity as a percentage of the drug, compared with the specification.

The main parameters are specificity, linearity, range, accuracy, precision including repeatability and intermediate precision, detection limit, quantitation limit and robustness. Which ones are required depends on the type of test, for example an assay, an impurity test or an identification test.

One approach in ICH Q2 uses the standard deviation of the response and the slope of the calibration curve: the detection limit is 3.3 times the standard deviation divided by the slope, and the quantitation limit is ten times the standard deviation divided by the slope. Signal-to-noise ratios are another accepted approach.

Q is the amount of drug, as a percentage of label claim, that must dissolve within the stated time. In the stage-wise scheme, each unit tested at the first stage must reach at least Q plus five percent. If they do not, more units are tested at the second and third stages.

Content uniformity checks that individual tablets or capsules each contain close to the labelled amount, not just the batch average. In the harmonised pharmacopoeial method, ten units are assayed individually and an acceptance value is calculated; if it exceeds 15.0, twenty more units are tested against a wider limit.

Yes. A tutor can work through HPLC assay, impurity, system suitability, validation and dissolution calculations with your data and help you write up practicals and quality-control reports. You complete and submit your own assessed work in line with your college or university's academic integrity rules.