• RAW MATERIALS:- The gelatin of the capsule shells should be assayed for various physical properties like bloom strength, viscosity , etc.
• MOISTURE PERMEATION TEST:- The degree & rate of moisture penetration is determined by packaging the dosage unit together with a color revealing dessicant pellet. Expose the packaged unit to known relative humidity over a specified time. Observe the dessicant pellet for color change. Any change in color indicates absorption of moisture. By measuring pretest weight & protest weight of pellet, amount can be calculated.
• CONTENT UNIFORMITY:- 10 capsules are taken and subjected to assay. 9 of 10 capsules should be in the range of ±15 %( 85-115%) and 10th Capsule in the range of 75-125%. If 2 Capsules are beyond ± 15% range. Then, 20 capsules are assayed. All capsules should be in the range of ± 25 %( 75%-125 %.)

·       WEIGHT VARIATION:-

1. FOR HARD CAPSULES:- Weigh 20 capsules individually, and determine the average weight. The individual weights should be within the limits of 90% and 110% of the average weight. If not all of the capsules fall within the limits, weigh the 20 capsules individually remove the contents of each capsule with the aid of a small brush. Weigh the emptied shells individually.

Net weight of contents (individual) = the weight of shell -respective gross weight.
Determine the average net content from the sum of the individual net weights. Then determine the difference between each individual net content and the average net content.
Limits:– Not more than 2 of the differences are greater than 10%of the average net content No case is the difference greater than 25% wt. range.
If more than 2, but not more than 6 capsules deviate from the average between 10%and 25%, determine the net contents of an additional 40 capsules, determine the average content of the entire 60 capsules Determine the 60 deviations from the new average.
Limits:– Not more than 6 of the 60 capsules does the difference exceed 10% of the average net content. No case does the difference exceed 25%

1. FOR SOFT CAPSULES:- Proceed as directed under Hard Capsules, but determine the net weight of the contents of individual capsules as follows. Weigh the capsules individually. Then cut & open the capsules remove the contents by washing with a suitable solvent. Allow the solvent to evaporate from the shells at room temperature. Weigh the individual shells calculate the net contents.

• BLOOM STRENGTH OF GELATIN:- Gelatin is weighed into water to typically create a 6.67% solution in standard Bloom bottles. The mix is then stirred and keep it for 3 hours at room temperature. Bottles are placed in a 65°C bath for 20 minutes. Allow the Bloom jars to cool for 15 minutes at room temperature. They are then conditioned for 16 hours in 10°C water bath. When conducting a gelatin bloom test. The bloom jar is centered with the probe just above the sample surface. The probe penetrates the gelatin to a target depth of 4 mm at a speed of 0.5 mm/s, and then retracts. The peak force is the gel strength in Grams. Bloom Chemical tests like purity, microbial properties, and limits for heavy metals like arsenic, ash content should be determined. The colorants should also be checked for purity, limits for heavy metals, color properties, dye content, subsidiary dye content and color value.

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Reference links
https://www.slideshare.net/mobile/Ramyapriya7/quality-control-of-capsules
http://www.pharmainfo.net/quality-control-capsules