Lab Skill Academy

Some commonly used analytical instrument names:

🧪 Chromatography & Mass Analysis

Gas Chromatograph (GC) – VOCs, solvents, residual monomers testing

Gas Chromatography–Mass Spectrometry (GC-MS) – phthalates, flame retardants, PAHs testing

Liquid Chromatography–Mass Spectrometry (LC-MS/MS) – PFAS, APEOs, dyes testing

High Performance Liquid Chromatography (HPLC) – formaldehyde, colorants testing

⚗️ Elemental & Heavy Metal Analysis

Inductively Coupled Plasma Mass Spectrometer (ICP-MS) – Pb, Cd, Hg (CPSIA, EN 71-3) testing

Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) – heavy metals screening

Atomic Absorption Spectrometer (AAS) – metals in textiles

🌈 Spectroscopy (Routine Lab)

UV-Visible Spectrophotometer – color, formaldehyde, dye analysis

Fourier Transform Infrared Spectrometer (FTIR) – polymer identification, plastics, packaging testing

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Formaldehyde Spot Test Procedure
* Cut the sample in approximately 1 inch x1 inch
* Place the sample on a white paper towel at the top of a glass plate.
* Drop 3-5 drops of Formaldehyde Spot Test Solution 1 onto the fabric.
* Wait for 30 seconds to let the solution absorb into the sample and react with the formaldehyde if the sample contains formaldehyde.
* Observe any fiber dissolving, or color leaching.
* If fiber is dissolving, or colour leaching is drawn and test can be stopped.
* If no fiber dossilving or colour leaching is observed, add 3-5 drops of Formaldehyde Spot Test Solution 2 onto the fabric.
* Wait for an additional 30 seconds to let the solution absorb into the sample and react with the ferric chloride.
* Dap the sample with a white paper towel and inspect the two white paper towels.
* If pink color is observed, this indicates that the sample contains formaldehyde and POSITIVE result is drawn.
* If no observed difference is noted, NEGATIVE result is drawn.
* If fiber dissolving, or colour leaching is observed, INCONCLUSIVE result is drawn.

Method blank:
* Perform the method blank using the white paper towel as sample.
Note 3: If the droplet beads up and does not pe*****te into the fabric, use a glass rod to rub the driplet into the fabric.
Note 4: The conclusion should be drawn once after the testing, otherwise, the pink color for positive result will change to purple colour after a period of time (i.e. 3hrs). A slight pink colour will appear after 5 minutes even for a negative result.

Reporting:
* Formation of pink colour: Positive result
* No observed difference: Negative result
* Fiber dissilving or Color leaching: Inconclusive result.

Formaldehyde Spot Test Procedure

Formaldehyde Spot Test Method
Test Procedure:
1. Sampling and sample preparation:
* Cut the sample in approximately 1 inch x 1 inch.
Note: for multi-colour fabric, choose an area, which can cover all the color if possible, for testing.
Formaldehyde is a volatile compound, the test sample should be submitted in a sealed package, and the package should not be opened until the testing is ready to proceed.
* Perform the formaldehyde spot test on main fabric with one result rather than per colouring. In case there is test line included trims and fabric, perform spot test on both main body and trims with major component.

Formaldehyde Spot Test (Reference method: AATCC Test Method: 94-2020)

Applicability:
Applicable to textile fabrics that may retain a residue of formaldehyde from the chemical finishing process.

Apparatus and Equipment:
* Disposable pipettes
* Glass rod
* Glass plate
* White blotting paper (also called paper towel)
* Brown reagent bottle
* Beaker, 400mL
* Measuring clinder

Reagents and Consumables:
* De-ionized water
* Sulfuric Acid (95-98%)
* Phenyl hydrazine
* Anhydrous ferric chloride

Reagent preparation:
Foemaldehyde Spot Test Solution 1:
* Take 41.7g (approximately 22.7mL) of 95- 98% sulfuric acid in 38.3 mL of DI water in a 400 mL beaker.
* Cool the mixture to room temperature
* Add 1.0g (approximately 0.91mL of phynyl hydrazine and an additional 19.0 mL of DI water.
* Cool the mixture to room temperature.
* Transfer the mixture into a brown reagent bottle and label it.
Note: Formaldehyde Spot Test Solution 1, prepared monthly (self life 30 days if stored appropriately)

Formaldehyde Spot Test Solution 2:
* Dissolve 10.0 g of anhydrous ferric chloride in 90.0mL of DI water
* Transfer the mixture into a brown reagent bottle and label it.
Note: Formaldehyde Spot Test Solution 2, prepared monthly (self life of 30 days if stored appropriately)

Quality Control:
* Check the validity of Formaldehyde Spot Test Solution 1 & 2 after preparation and before testing with formaldehyde contained fabric.
*Check the white blotting paper (paper towel) before the test and perform a method blank at a minimum frequency of one per preparation batch of samples, in order to check the concentration. Positive, or inconclusive result is not accepted.

Interferences:
* Any aldehydes and ketones will react with phenyl hydrazine to give the respective hydrazine.
* Some blend fabric composed of synthetic fibers such as polyester, nylon or PU can be tested by this method. However, interference may be encountered
when fiber is dissolving or color is leaching to solution.
* Colour leaching will affect the result.

Formaldehyde Spot Test (Reference method: AATCC Test Method: 94-2020)

Applicability:
Applicable to textile fabrics that may retain a residue of formaldehyde from the chemical finishing process.

Apparatus and Equipment:
* Disposable pipettes
* Glass rod
* Glass plate
* White blotting paper (also called paper towel)
* Brown reagent bottle
* Beaker, 400mL
* Measuring clinder

Reagents and Consumables:
* De-ionized water
* Sulfuric Acid (95-98%)
* Phenyl hydrazine
* Anhydrous ferric chloride

Reagent preparation:
Foemaldehyde Spot Test Solution 1:
* Take 41.7g (approximately 22.7mL) of 95- 98% sulfuric acid in 38.3 mL of DI water in a 400 mL beaker.
* Cool the mixture to room temperature
* Add 1.0g (approximately 0.91mL of phynyl hydrazine and an additional 19.0 mL of DI water.
* Cool the mixture to room temperature.
* Transfer the mixture into a brown reagent bottle and label it.
Note: Formaldehyde Spot Test Solution 1, prepared monthly (self life 30 days if stored appropriately)

Formaldehyde Spot Test Solution 2:
* Dissolve 10.0 g of anhydrous ferric chloride in 90.0mL of DI water
* Transfer the mixture into a brown reagent bottle and label it.
Note: Formaldehyde Spot Test Solution 2, prepared monthly (self life of 30 days if stored appropriately)
(To be continued)