SH/T 0678-1999 Determination of dropping point of petrolatum

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Card type: Test method

1. Method number / full title / English name / replacement relationship

• Standard number: SH/T 0678-1999
• Chinese name: Determination of dropping point of petrolatum
• English name: Vaseline-Determination of dropping point (original text as such, source-text extraction doubtful point: droppbg poi requires confirmation against the source standard (source-text extraction))
• Replacement relationship: not provided in the available source
• Adoption relationship: This standard is equivalent to the method If A "Determination of dropping point" in Appendix VA of the British Pharmacopoeia BP-1993 edition.

2. Scope of application and non-applicability

• This standard specifies the method for determining the dropping point of petrolatum.
• This standard applies to petrolatum.
• Non-applicable scope: not provided in the available source.

3. Method principle

Place petrolatum into the grease cup of the dropping point apparatus, and under specified heating conditions, measure the temperature at which the first drop of liquid from the sample in the grease cup falls.

4. Reagents and materials (purity / preparation)

• Heating medium: when the dropping point is lower than 80℃, use water as the heating medium; when the dropping point is higher than 80℃, use liquid paraffin, glycerol, or light-colored silicone oil with good thermal safety as the heating medium (see 3.4.3).
• Other reagents: not provided in the available source.

5. Apparatus and equipment

• 3.1 Dropping point thermometer: technical conditions see Appendix A.
• 3.2 Metal grease cup: as shown in Figure 1a. Made of chrome-plated brass, dimensions as follows: wide mouth inner diameter 7.35～7.65 mm, wide mouth outer diameter 9.95～9.99 mm, narrow mouth inner diameter 3.1～3.2 mm, narrow mouth outer diameter 5.5～5.6 mm, cup height 15.0～15.4 mm. Wide mouth internal depth: the bottom of the wide mouth is approximately hemispherical; if a small steel ball of diameter 7.00 mm is placed into the cup, the top of the ball is 12.05～12.35 mm from the bottom of the narrow mouth. The top of the cup and the bottom of the narrow mouth must be smooth, parallel, and perpendicular to the cup axis; the bottom edge of the narrow mouth must not have grooves or rounded corners.
• 3.3 Metal sleeve for dropping point thermometer: as shown in Figure 1b and Figure 1c, a cylindrical metal tube is coaxially bonded to the lower part of the thermometer; a metal sleeve is screwed onto the metal tube; the metal sleeve has 2 small holes, one at the front and one at the back, for ventilation; inside the sleeve there is a positioning frame; the guide piece at the lower part of the metal sleeve allows the grease cup to be inserted coaxially into the metal sleeve; its spring clip can make the grease cup firmly press against the positioning frame. When the metal sleeve is screwed onto the metal tube, the bottom of the thermometer mercury bulb is 7.9～8.2 mm from the positioning frame.
• 3.4 Dropping point determination apparatus: as shown in Figure 2, including the following parts.
  • 3.4.1 Glass test tube: total length 110 mm, inner diameter 25 mm (original text source-text extraction is "H0mm", requires confirmation against the source standard (source-text extraction)).
  • 3.4.2 Cork stopper: length 25 mm, with a hole in the center for the thermometer and a ventilation groove on the edge.
  • 3.4.3 Heating bath (glass beaker and heating medium): when installing the test apparatus, the glass test tube is vertically immersed in the liquid in the beaker to a depth of 2/3, and the bottom of the test tube is about 25 mm from the bottom of the beaker. When the dropping point is lower than 80℃, use water as the heating medium; when the dropping point is higher than 80℃, use liquid paraffin, glycerol, or light-colored silicone oil with good thermal safety as the heating medium.
  • 3.4.4 Stirrer: to make the temperature of the liquid in the heating bath uniform.
  • 3.4.5 Auxiliary thermometer: 0～150℃, scale division value 1℃ (the thermometer range and scale division are unclear in the source transcription; both require verification), used for measuring bath temperature.
  • 3.4.6 Stand: equipped with clamps for fixing the test tube and auxiliary thermometer, so that it can be conveniently placed in the beaker and can support the heating bath on the heat source.
  • 3.4.7 Heater: used to heat the liquid in the beaker.
• 3.5 Blade.
• 3.6 Stopwatch.
• 3.7 Oven: temperature control can reach 122℃ (original text source-text extraction is "12290", requires confirmation against the source standard (source-text extraction)).
• 3.8 Constant-temperature water bath: controlled temperature 25℃ (original text source-text extraction is "25`0-19C}", requires confirmation against the source standard (source-text extraction)).

6. Recommended operating conditions

• Heating bath temperature rise rate: make the sample rise at a rate of 1℃/min (see 4.6).
• Heating medium selection: dropping point lower than 80℃ use water; dropping point higher than 80℃ use liquid paraffin, glycerol, or light-colored silicone oil (see 3.4.3).
• Other operating conditions see Section 8.

7. Sampling and sample preparation

• 4.2 Heat the sample to 118～122℃, stir uniformly, then cool to 103～107℃. Heat the metal grease cup in the oven to 103～107℃, take it out and place it on a clean flat plate or tile, quickly pour in sufficient melted sample to completely fill it.
• 4.3 The metal grease cup filled with sample is cooled on the flat plate for 30 min, then placed in a 24～26℃ water bath at constant temperature for 30～40 min.
• 4.4 Take the metal grease cup out of the water bath, use a blade to level the sample surface in one direction, avoiding movement of the sample, then push the metal grease cup into the metal sleeve up to the positioning frame, taking care to avoid lateral movement of the metal grease cup during this process. Wipe off excess sample squeezed out at the bottom of the cup, ensuring the ventilation holes are unobstructed.

8. Analytical procedure

• 4.1 Install the heating bath, as shown in Figure 2.
• 4.2 Heat the sample to 118～122℃, stir uniformly, then cool to 103～107℃. Heat the metal grease cup in the oven to 103～107℃, take it out and place it on a clean flat plate or tile, quickly pour in sufficient melted sample to completely fill it.
• 4.3 The metal grease cup filled with sample is cooled on the flat plate for 30 min, then placed in a 24～26℃ water bath at constant temperature for 30～40 min.
• 4.4 Take the metal grease cup out of the water bath, use a blade to level the sample surface in one direction, avoiding movement of the sample, then push the metal grease cup into the metal sleeve up to the positioning frame, taking care to avoid lateral movement of the metal grease cup during this process. Wipe off excess sample squeezed out at the bottom of the cup, ensuring the ventilation holes are unobstructed.
• 4.5 Fix the dropping point apparatus in the test tube with a cork stopper having a central hole (as shown in Figure 2), so that the bottom of the metal grease cup is 24～26 mm from the bottom of the test tube; install the test tube vertically in the beaker so that at least 2/3 of its length is immersed in the heating medium.
• 4.6 Adjust the heating bath temperature so that the sample rises at a rate of 1℃/min; when the first drop of melted sample falls from the bottom of the metal grease cup, record the reading of the dropping point thermometer at this time as the result of this determination. Repeat the determination three times, record to one decimal place, and use a fresh sample each time.

9. Qualitative and quantitative determination and calculation formula

• Take the reading of the dropping point thermometer when the first drop of melted sample falls from the bottom of the metal grease cup as the result of this determination (see 4.6).
• Take the arithmetic mean of three repeated determination results as the dropping point of the sample, rounded to the nearest integer (see Report section).
• Calculation formula: not provided in the available source.

10. Precision

• Repeatability: the difference between every two results of repeated determinations shall not exceed 3℃ (original text source-text extraction is "39C", requires confirmation against the source standard (source-text extraction)).
• Reproducibility: not provided in the available source.

11. Report

Take the arithmetic mean of three repeated determination results as the dropping point of the sample, rounded to the nearest integer.

12. Referenced documents

• Appendix A (appendix to the standard): technical conditions for the dropping point thermometer.
• Other referenced documents: not provided in the available source.

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick reference Q&A