Specifications

Below are standard specifications for quantitative filter paper. Items marked Customizable are available upon request.

Grade	Ash (%)	Particle Retention	Thickness (mm)	Flow Rate	Typical Application
Grade 40	0.007	8µm	0.21	Medium	Routine gravimetric analysis, precipitate filtration (e.g., BaSO₄)
Grade 41	0.01	20-25µm	0.22	Fast	Coarse precipitate rapid filtration (e.g., CaCO₃)
Grade 42	0.007	2.5µm	0.20	Slow	Finest particles — BaSO₄ fine particles
Grade 589/1	0.01	12-15µm	0.19	Fast	Coarse precipitate fast filtration, "Black Ribbon"
Grade 589/2	0.01	8-12µm	0.20	Medium	Medium particle precipitate filtration
Grade 589/3	0.01	4-7µm	0.21	Slow	Fine particle precipitate filtration, "Blue Ribbon"

Ash content is residue after ignition, suitable for gravimetric analysis.

📌 Customization Notes:
• Custom sizes available (Round: φ 55/70/90/110/125/150/185mm; Square: various)
• Special ash requirements or grades available upon consultation

* Data are typical values, actual parameters may vary slightly by batch.

Product Description

I. Overview

Quantitative filter paper is an essential consumable for gravimetric analysis. Manufactured from 100% high-quality cotton linter cellulose with acid treatment to remove metal ions and impurities, ensuring ultra-low ash content (≤0.01%). Features high wet strength and stable filtration performance, specifically designed for gravimetric determination and precipitate filtration.

The key distinction between quantitative and qualitative filter paper lies in ash content and acid treatment. Minimal residue after ignition ensures no significant interference with analytical balance measurements, guaranteeing accuracy and reproducibility of gravimetric results.

🔬 Quantitative vs Qualitative:
Quantitative Filter Paper — Acid-treated, ash ≤0.01%, minimal ignition residue, suitable for gravimetric analysis.
Qualitative Filter Paper — Not acid-treated, higher ash (~0.1%), general filtration only, not for gravimetric determination.

II. Core Performance Parameters

Material: 100% Cotton Linter Cellulose, α-cellulose ≥ 92%
Ash Content: ≤ 0.01% (Ashless Grade), some grades ≤ 0.005%
Acid Treatment: HCl/HF treatment, removes metal ions (Fe, Cu, Pb, etc.)
Particle Retention Range: 2.5µm (Grade 42) ~ 20-25µm (Grade 41)
pH Range: 0-12
Max Operating Temperature: 120℃ (drying), Ignition ≤ 550℃
Wet Strength: High (acid treatment enhances fiber bonding)
Optical Brighteners: None

III. Material & Workmanship

Manufactured from imported high-quality cotton linter through alkalization, bleaching, and refining, followed by acid treatment to remove metal ions and trace impurities. Precision-formed using cylinder paper machines to ensure uniform fiber distribution and consistent thickness. All products undergo high-temperature ignition testing to verify ash content, ensuring batch-to-batch consistency.

All products are cut and packaged in cleanroom environments to prevent secondary contamination.

Applications

Typical Applications

Gravimetric Analysis

Precipitate filtration, ignition weighing (BaSO₄, CaCO₃, SiO₂, etc.)

Environmental Monitoring

TSS determination, TDS analysis

Pharmaceutical

API intermediate filtration, residue determination

Food Testing

Insoluble impurity determination in food

Mining & Metallurgy

Precipitate separation for elemental analysis

Industries

Environmental Monitoring Water quality analysis, wastewater testing, soil analysis
Pharmaceutical Quality control, R&D, residual solvent analysis
Food Industry Food safety testing, quality control
Research Institutions Basic research, material science, geological analysis

Precipitate	Recommended Grade	Notes
BaSO₄ (coarse)	Grade 40	Routine gravimetric
BaSO₄ (fine)	Grade 42	Finest particle retention
CaCO₃	Grade 41	Fast filtration
CaC₂O₄	Grade 41	Coarse particle fast filtration
Al(OH)₃	Grade 589/2	Medium particle
SiO₂·nH₂O	Grade 589/3	Fine particle

Selection Guide

I. By Precipitate Particle Size

Precipitate Type	Recommended Grade	Particle Retention	Typical Precipitate
Coarse particles	Grade 41 / 589/1	20-25µm / 12-15µm	CaCO₃, CaC₂O₄
Medium particles (Recommended)	Grade 40	8µm	BaSO₄ (medium)
Fine particles	Grade 589/2	8-12µm	Al(OH)₃
Finest particles	Grade 42 / 589/3	2.5µm / 4-7µm	BaSO₄ (fine), SiO₂

II. By Standard Methods

ISO Standard Methods: Grade 40 or Grade 42 recommended
ASTM Standards: Grade 40 or Grade 589/3 recommended
EPA Methods: Grade 40 or Grade 41 recommended
Pharmacopoeia methods: Grade 42 or Grade 589/2 recommended

III. By Ash Requirement

Ultra-high precision gravimetric: Grade 40 / 42 (ash 0.007%)
Routine gravimetric: Grade 589/1 / 589/2 / 589/3 (ash 0.01%)
General quantitative: Grade 41 (ash 0.01%)

💡 Selection Tip: Grade 40 is the most commonly used quantitative filter paper for most gravimetric applications. For fine particle precipitates, choose Grade 42 (finest retention) or Grade 589/3 ("Blue Ribbon"). For coarse particle rapid filtration, Grade 41 or Grade 589/1 ("Black Ribbon") are ideal choices.

Operation & Maintenance

User Guide

Below are standard operating guidelines for quantitative filter paper. Proper use is critical for accurate gravimetric results.

I. Pre-use Preparation

Inspect packaging integrity and paper surface for damage or contamination
Select appropriate diameter (20-30mm larger than funnel diameter)
Fold using the umbrella folding method and place in funnel
Pre-wet with the same solvent as the sample to ensure tight adhesion
Important: Dry at 105℃ to constant weight and record for ash correction

II. Filtration Operation

Place folded filter paper into the funnel, ensuring tight fit against the funnel wall
Position the funnel over a receiving container with stem tip touching the container wall
Slowly pour the sample along a glass rod
Liquid level must not exceed approximately 5mm above the filter paper edge
After filtration, rinse the precipitate multiple times with solvent for complete transfer
Carefully remove the filter paper with precipitate and place in a pre-weighed crucible

III. Ignition & Weighing

Place the crucible on a hot plate for low-temperature charring of the filter paper
After charring, transfer to a muffle furnace at 550-600℃ and ignite to constant weight (typically 1-2 hours)
Remove the crucible, cool in a desiccator to room temperature, and weigh
Repeat ignition-cooling-weighing cycles until constant weight is achieved

IV. Important Notes

Quantitative filter paper is single-use only
Store in a dry, cool, dark place to prevent moisture absorption affecting weight
Do not use quantitative paper for qualitative analysis (cost-ineffective)
Do not use qualitative paper for gravimetric analysis (ash content too high)
Dispose according to laboratory waste regulations after use

💡 From a Seasoned Lab Technician: "Char before ignition, prevent loss" — Always low-temperature char before high-temperature ignition to prevent violent burning and precipitate loss.
"Constant weight is key" — The gold standard is constant weight (consecutive weighings within ≤ 0.3mg). Weigh three times and average.
"Ash correction required" — Run a blank sample from the same batch to correct for filter paper ash content.

Care & Notes

Show care & notes

⚠️ Safety & Compliance Checklist

Thermal Safety

Use muffle furnace with heat-resistant gloves and safety goggles

Chemical Safety

Filter corrosive samples in a fume hood

Weighing Precision

Allow analytical balance to warm up for ≥ 30 minutes before use

Documentation

Record all weighing data immediately

Quantitative Filter Paper