Boeco Quantitative Filters

389 - white spot - medium fast filtering, medium wide pores, ashless hardened

quantitative ashless filter papers are recommended for quantitative analysis.
As quantitative analysis requires a high purity, these filters are being washed out with acid. 

Typical grade for quantitative tasks, coarser precipitates, such as

• lead-iron
• silver sulphide
• alcali carbonates
• food stuff and soil analysis

390 - green spot - slowly filtering, narrow pores, ashless hardened

quantitative ashless filter papers are recommended for quantitative analysis.
As quantitative analysis requires a high purity, these filters are being washed out with acid

Filtration of fine precipitates such as

• lead dioxide
• calcium fluoride
• nickel sulphide
• zinc sulphide

391 - blue spot - very slowly filtering, fine pores, ashless hardened

quantitative ashless filter papers are recommended for quantitative analysis.
As quantitative analysis requires a high purity, these filters are being washed out with acid. 

Fine-grained precipitates such as

• barium sulphate
• metannic acid
• cupros oxide

393 - purple spot - particulary slow filtering, especially fine pores, ashless hardened

quantitative ashless filter papers are recommended for quantitative analysis.
As quantitative analysis requires a high purity, these filters are being washed out with acid. 

For extremely difficult filtration conditions and particulary fine precipitates.