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Water Determination in Liquefied Petroleum Gas using GC BID and Ionic Liquid Column Watercol

Shimadzu Application Data Sheet No.18

Water in petrochemical feedstocksWater in petrochemical feedstocks can cause problems for processors. Freezing of pipe lines and valves and poisoning of expensive catalysts are just a few examples.

Monitoring water in petroleum from an upstream source to the downstream processing plant is critical to insure uninterrupted operation.

A new determination option by GC can bypass undesirable chemical interference effects from the petroleum to the “Sulfur interaction” that can skew results obtained by traditional water determination techniques. Shimadzu’s proprietary Barrier Ionization Discharge (BID) detector and Supelco’s water analysis column “Watercol” are combined to separate and measure the water in a formulation of feedstock (Figure 1) and provide a sensitive and accurate result (Table 1). Measurements can be made down to sub-ppm level of water detection.

Chromatogram for water determination

Figure 1. Chromatogram for water determination (25 ppm) in LPG. Quantification of Limit(S/N=10) and Detection of Limit(S/N=3.3) can be down to 0.66 ppm and 0.22 ppm respectively


Gas chromatograph: Tracera (GC-2010 Plus A + BID-2010 Plus)
Sample injection: Valco Internal Liquid Sample Injector with Splitter Injection Unit
Gas purifier: Supelco High Capacity Gas Purifier (Cat.#29541-U)
Analysis Conditions  
Column: Watercol™ 1910, 60 m x 0.25 mm ID, 0.20 μm
Oven: 35°C (2.0 min) – 5°C/min – 150°C (15 min) Total. 40 min
Carrier gas: Helium 45 cm/sec (Column flow rate 3.78 mL/min)
Inj. volume: 2 μL
Split: 1:5
Transfer line temp.: 175°C (After Internal Liquid Sample Injector to GC column Oven)

Table 1: Repeatability of Water analysis(n=5).

Water No.1 No.2 No.3 No.4 No.5 Average Standard Deviation %RSD
RT(min) 14.285 14.288 14.286 14.296 14.304 14.292 0.008 0.06
Area(mV•s) 244,037 249,854 246,884 242,950 238,428 244,430 4,296 1.76
Height(mV) 12,418 12,600 12,468 12,045 11,851 12,276 315 2.57
Conc.(ppm) 24.96 25.56 25.25 24.85 24.39 25.00 0.44 1.76

This application is also subject of the ASTM Work Item

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