Hello.

What is your preffered way of analyzing for chlorine in used oils?

Hi Mr Hughes
Mr Joe Ban is a chemical engineer we work with from J&M,
I asked him the question and he said;
"There is at least 3 ways to identify Cl atoms.
1. One is Infra Red, where the C-Cl atom bond has specific wavelength in IR spectra.
The IR spectra will also show different wavelengths for C-Cl , C- 2 Cl and C- 3 Cl bonds.
2. Chemical Oxidation, and collection of vapour by alkaline absorbent, and subsequent analysis by wet chemistry.
3 Fusion of materials with alkali salts to decompose organics, and capture Chlorine or Chloride into alkaline salts, and wet analysis carried out on dissolved ignition residue.
Infra red cannot see Sodium or Potassium Chloride as these are transparent to IR spectra analysis.
Other metal Chlorides may react with IR, but the person interested in analysis needs to consult an IR spectra handbook, where various bonds for Cl may be available that can be identified by IR analysis.
Regards RobS

If you mean the analysis of chlorine gas in hydrocarbon based oil, then it is very difficult because the chlorine oxidizes the oil very quickly. In fact, there have been explosions caused by chlorine reacting with oil in valve packings.

If mineral oil has been exposed to small amounts of chlorine, the oil will go black very quickly due to oxidation. The chlorine will normally be converted to chloride.

A simple qualitative test you may consider is to wash the oil with DI water, slightly acidify the water with nitric acid if necessary, and add silver nitrate dropwise to the water and check for turbidity (silver chloride). Visible turbidity is normally seen at 3 ppm and higher chloride. If you need quantitative analysis, ion selective electrode analysis of the water wash is usually sufficient and is relatively inexpensive.

Ion chromatography is another more expensive, but higher performing method for analyzing chloride in the water wash.

if you mean Chlorine as in chlor additives used in some oils or chlor as in solvents which make the used oil a hazard try Dexsil company they have a disaposable test that you can easily do will show down to 100ppm.
bruce

Thanks fo all replies.

We want to look for Chlorine as from contamination from chlorine containing cleaning agens and similar.

Currently we want to do so in phosphate esters (firesafe hydraulic oils), and NH3 diluted mineral oil (refrig systems). We have methods for detecting chlorides in water (titration with silvernitrate), but are looking for direct analysis for Chlorine (Cl).

What concentrations are you looking for with regard to contamination. Assuming you aren't looking for something highly sophisticated like a GC with a electron capture detector. For quantitative chlorides we use Chloride electrode in place of pH electrode and read pH meter in mV for chlorides presebt in water wash of steel/CFC refrigerant/mineral oil reaction products performed at 175C in sealed glass tubes. However, most chlorinated cleaning solvents will react with steel to produce iron chlorides in presence of water at 40 - 80C in minutes to a few hours. Iron fillings used in remediation of chlorinated solvent contamination of ground water at below room temperature. The more chlorinated the solvent (the less fluorinated), the faster the reaction.