sieving lactose

Introduction

This project is a continuation of initial experiments done by Sarah, Damian and Jihyun. The experiments that I will conduct are basic refinements from their initial experiments and will serve as a metric for more standardized tests that can be done with powders. The goal will be to investigate the gold standards for powder characterization for pharmaceutical excipients and compare them to our novel tapping apparatus.

Sieving

I received lactose powder from DFEPharma on 2013-04-25 and am in the process of sieving it. I received three types of powders:

where GR=granulated, SD=spray dried, and M=milled lactose types. My process for sieving consists of the following steps:

  1. Weigh the initial amount of powder received.
  2. Stack the following sieves from top (1) to bottom (6):
    1. Lid
    2. 250 µm sieve
    3. 125 µm sieve
    4. 75 µm sieve
    5. 45 µm sieve
    6. Collection bucket.
  3. Place all the powder in the top most sieve and let the sieving machine go for 30 minutes—this is the first sieving. The machine is a Tyler RX-24 Portable Sieve Shaker.
  4. Take each fraction and weigh the amount of powder in each sieve.
  5. Return the powder to its respective sieve and allow the machine to shake for 30 more minutes.
  6. Repeat until there is no appreciable weight change between sieves for each fraction.

The sieving machine can be seen in action in the below video. It’s a loud machine but, very effective at what it does.

SuperTab 30GR

I started with the SuperTab 30GR granulated lactose powder. The ambient climate here in Austin for 2013-04-29 and my initial powder weight conditions are:

  • Temperature = 23.5˚C
  • Relative humidity = 47%
  • Initial amount of powder = 498 g
  • Powder name: Monohydrate Lactose USP/NF, Ph. Eur., JP
  • Product code: 42320-6460
  • Product date: 04-2012
  • Charge Number: 10637764
  • ME/SU number: 5633687
  • Expiration date: 03-2015
  • Drum number: 854

I had some difficulty starting the machine due to not tightening the clamps that hold the sieve down enough, however, things are moving smoothly now. For my first sieve, I obtained the following fractions:

  • > 250 µm = 42 g
  • 125–250 µm = 246 g
  • 75–125 µm = 122 g
  • 45–75 µm < 1 g
  • < 45 µm = 84 g

where the weight measurements are ±1 g. My second sieve obtained the following fractions:

  • > 250 µm = 40 g
  • 125–250 µm = 239 g
  • 75–125 µm = 126 g
  • 45–75 µm < 1 g
  • < 45 µm = 88 g

My third sieving obtained the following:

  • > 250 µm = 39 g
  • 125–250 µm = 236 g
  • 75–125 µm = 127 g
  • 45–75 µm < 1 g
  • < 45 µm = 90 g

My fourth sieving obtained the following:

  • > 250 µm = 38 g
  • 125–250 µm = 234 g
  • 75–125 µm = 129 g
  • 45–75 µm < 1 g
  • < 45 µm = 91 g

It would appear that I’ve reached enough of a plateau to stop. The percent change between sieves is between 1–5% and I’m okay with this. On to the next powder.

SuperTab 11SD

My initial conditions are:

  • Temperature = 23.5˚C
  • Relative humidity = 47%
  • Initial amount of powder = 513 g
  • Powder name: Monohydrate Lactose USP/NF, Ph. Eur., JP
  • Product code: 42332-6456
  • Product date: 11-2012
  • Charge Number: 10678880
  • ME/SU number: 5727977
  • Expiration date: 10-2014
  • Drum number: 976

My first sieving obtained the following:

  • > 250 µm = 9 g
  • 125–250 µm = 477 g
  • 75–125 µm = 4 g
  • 45–75 µm = 1 g
  • < 45 µm = 17 g

This powder is much more uniform in its size distribution than the granulated lactose. It also seems to be more cohesive which, is a completely qualitative statement right now.

My second sieving obtained the following:

  • > 250 µm = 8 g
  • 125–250 µm = 470 g
  • 75–125 µm = 5 g
  • 45–75 µm = < 1 g
  • < 45 µm = 24 g

My third sieving obtained the following:

  • > 250 µm = 6 g
  • 125–250 µm = 462 g
  • 75–125 µm = 6 g
  • 45–75 µm = < 1 g
  • < 45 µm = 28 g

I think I may have to break up the 125–250 µm fraction. It looks like the siever may be overloaded and would benefit from only having half as much powder in the 125–250 sieve for a cycle.

 

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