Procedures
1. Sample preparation
1.1 Preparation of drying container
Place container in the drying oven at 100 ± 5°C until constant weight (1 - 2 h). Cool
in a desiccator for about 30 min and weigh (W1). For liquid or semisolid sample, prepare drying
container with 15 - 20 g acid washed sand and a stirring rod.
1.2 Preparation of sample
Grind or blend sample until homogenous. Analyse sample immediately after
preparation. If sample cannot be analysed on the same day, keep in screw-cap bottle in a
freezer. For samples intended for analysis of vitamins or other labile nutrients, flush sample with
nitrogen before storing.
2. Analysis
2.1 For dry sample: Thaw sample to room temperature. Mix sample thoroughly by
turning the tightly closed bottle up and down three times. Weigh accurately 3 – 4 g sample, in
duplicate, into a preweighed drying container (W2).
2.2 For liquid/wet/slurried sample: Mix sample thoroughly and weigh 5–15 g
slurried sample and 20 g for liquid sample into a pre-weighed drying container with acid washed
sand and stirring rod (W2). For liquid samples, dry to a consistency of a thick paste over a boiling
water bath before drying in an oven.
2.3 Place container with sample in the air oven pre-heated to 100 ± 5°C for 2 – 3
hours.
2.4 Transfer the container with the dried sample into a desiccator, cool for 30 min
and weigh (W3). Repeat the heating procedure until constant weight is obtained. Different in
weight between two consecutive weighing should not be more than 5mg.
2.5 Calculation
Moisture (g/100g) = (W2 –W3) x 100
(W2 –W1)
Total solid (%) = 100 - % moisture (w/w)
Where W1 = weight of container or empty dish (g)
W2 = weight of container + sample before drying (g)
W3 = weight of container + sample after drying (g)