Analytical Instrumentation

  • Organic Chloride in Crude per ASTM D4929 Part C
    Rigaku NEX CG advanced Cartesian geometry Energy Dispersive X-ray Fluorescence spectrometer
  • Figure 1 - D4929 Part C XRF Calibration
  • Figure 2 - Precision & Repeatability; Detection Limits

Organic Chloride in Crude per ASTM D4929 Part C

Aug 21 2019 Read 552 Times


The analysis of organic chloride in crude is demonstrated per ASTM D4929 Part C - determination of organic chloride in the washed naphtha fraction of crude oil by x-ray fluorescence spectrometry - using monochromatic energy dispersive x-ray fluorescence (MEDXRF).


Chlorides in crude contribute to corrosion in the piping at refineries during cracking as well as mid-stream in pipelines. Organic chlorides do not naturally occur in crude, however inorganic chlorides in the form of salts as well as residual organic chlorides from various natural sources as well as adulteration can contaminate crude. Contracts at the pipelines may contain clauses limiting the amount of organic chloride allowed in the crude. And at the refinery after desalting and desulfurization, crude needs to be analysed for any residual organic chlorides possibly still entrained in the feedstock to avoid potential damage during the refining process.


  1. Type: Monochromatic EDXRF (MEDXRF)
  2. 90◦ Cartesian Geometry Polarization
  3. Model: Rigaku NEX CG

Sample Preparation

ASTM D4929 is designed for the measurement of residual organic chlorides in crude. The crude sample is first prepared by distillation and wash to remove H2S and inorganic chlorides. After distillation and wash processes the resulting naphtha fraction is analysed for Cl content by XRF using Part C methodology. The naphtha fraction is typically stable containing less than 1000 mg/g S. XRF calibration is made using mineral oil calibration standards, as mineral oil models naphtha for X-ray response.

To prepare a sample for XRF analysis simply place 4.0g of the naphtha sample in a standard 32mm XRF sample cup and measure directly.

ASTM D4929 Calibration - Part C XRF

Empirical calibration was made using commercially available mineral oil standards. For optimum calibration the standards contain both S and Cl, with S content ranging from 100 to 1000 mg/kg. Alpha corrections are automatically employed to compensate for sulfur's effect on chlorine X-rays.

 * See Figure 1 - D4929 Part C XRF Calibration

Precision & Repeatability

To demonstrate recovery, precision and repeatability of the measurement, a few calibration standards were selected with results shown here.

Detection Limits

The empirical method is used to determine detection limits using 300 sec measurement time. Ten repeat analyses of a blank mineral sample are taken with the sample in static position and the standard deviation (σ) is determined. The Lower Limit of Detection (LLD) is then defined as three times the standard deviation (3σ).

* See Figure 2 - Precision & Repeatability; Detection Limits


NEX CG using Cartesian Geometry monochromatic EDXRF gives superior performance for the measurement of organic chloride in crude as per ASTM D4929 Part C. NEX CG also complies with many other ASTM methods and EPA requirements for critical measurements in the petroleum industry, making it an excellent choice as an all-in-one analyser for measuring sulfur and ultra-low sulfur, metals in crude and residual oil, and lube oils.

Reader comments

Do you like or dislike what you have read? Why not post a comment to tell others / the manufacturer and our Editor what you think. To leave comments please complete the form below. Providing the content is approved, your comment will be on screen in less than 24 hours. Leaving comments on product information and articles can assist with future editorial and article content. Post questions, thoughts or simply whether you like the content.

Post a Comment

Digital Edition

Petro Industry News Buyers Guide 2020

January 2020

In This Edition Fuel For Thought - Successful JASIS sees Tanaka announce appointment of new general manager - USA appointments underpin Signal Group growth plan - Leading European sensor tr...

View all digital editions


SLAS 2020

Jan 25 2020 San Diego, CA, USA

European Gas Conference

Jan 28 2020 Vienna, Austria

EGYPS (Egypt Petroleum Show)

Feb 11 2020 Cairo, Egypt

Smart Factory Expo (SFE 2020)

Feb 12 2020 Tokyo, Japan

ME-TECH 2020

Feb 18 2020 Abu Dhabi, UAE

View all events