Determination of Oxygenates & BTX in Beverage Grade CO2

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4/5/2005 PID Analyzers, LLC 1

Determination of Oxygenates & BTX in

Beverage Grade CO2Dr. Jack Driscoll & Jennifer Driscoll

PID Analyzers, LLCcopyright 2004-2005 PID Analyzers

Paper # 130Paper # 130--1 Pittsburgh Conference,1 Pittsburgh Conference,

Orlando, FL; Feb. 28, 2005 (8:30 AM) ;Orlando, FL; Feb. 28, 2005 (8:30 AM) ; RmRm S220CS220C




Abstract Abstract Last year, we (1) presented a method for the analysis of BTX at low ppb levels in beveragegrade CO2. In this paper, we describe a method for volatile oxgenates and demonstrate that itcan be combined with the previous BTX (1) method to perform multifunctional analyteanalyses. The photoionization detector (PID) has been improved to provide the sensitivity andppb detection limits required by the industry. The 301-B now has multiple valve switching

capability and multiple autozeros to smooth the baseline when columns are switched in or out.With these changes and system optimizations, we have achieved some complex separations atppb levels with a minimum of operator time or training required.

The following method on the 301-B was developed for the analysis of ppb levels of oxygenates(acetaldehyde, methanol & dimethyl ether) in beverage grade carbon dioxide. The detectionlimits required were 100 ppb for acetaldehyde and dimethyl ether.

The analysis can be automated via a PLC that controls the 301-B (start, calibrate, print report).An optional operating system is Windows XP. If the 301 GC is part of the plant network, thesystem can be operated from any PC on the network. Of course the system has passwords.The detection limit for this analysis was <100 ppb (acetaldehyde), & <50 ppb (dimethylether) for a direct injection with no concentration of the sample. The analysis time for thismulticomponent analysis was < 10 minutes.

===========================================================================

Driscoll, JN & J. Driscoll, “Detection of ppb Levels of BTX in Beverage Grade CO2”, Paper # 1700-1100P, Pitt. Conf. on Anal. Chem., Chicago, IL, March 2004




Presentation Objectives Presentation Objectives

A new Method has been developed for use withthe Model 301-B to analyze both oxygenates and

BTX at the same time. This involved the following:

•A second column (PLOT) was added toseparate acetaldehyde and dimethyl

ether from the CO2 and the BTX

A 4 port switching valve was used for columnselection

In addition, a number of improvements have beenmade in the original 301-B instrumentation




What are the improvements? What are the improvements?

USB based ADC System

Touch screen Color VGA display Windows XP Operating System

(embedded) with PW Chromatography

Software Detectors- PID improved New outputs- Modbus

Easier to expand features through USB




Floppy, USB Disk…NoUSB Peripherals

YesNoNetworkCapability

WindowsSpecialOperating Sys

YesNoWindows XP(Embedded)

YesNoPlug & Play

40 Gbyte HDvarysvarysMemory

500 MHz, 100 MHz BusvarysvarysSpeed

301-B PC BasedOther GCs uP

Comparison of uP and PC Based Process GCs




Model 301 Model 301-- B B

mousemouse

USB PortUSB Port




Rear View of Model 301Rear View of Model 301--BB

RelaysRelays

Fluidics I/OFluidics I/O

PCPC




GC Signal SchematicGC Signal Schematic

PCPCRS232RS232

KeyboardKeyboard

Digital I/ODigital I/O-- valvesvalvesDigital I/O AlarmsDigital I/O Alarms

DiagnosticsDiagnostics

DAC to 4DAC to 4--2020 mAmA

ADC 16 bitADC 16 bit

DisplayDisplay

Time clock, data calc & storage on hard driveTime clock, data calc & storage on hard drive

DetectorDetector

AMPAMP




301 301 - - B GC Fluidics B GC Fluidics




Photoionization Detector Photoionization Detector

R + hν = R + + e-

where

R= molecule hν = a photon with an

energy > IP of R

R+

= positive ion e- = electron

Process Process




PID Characteristics PID Characteristics

Linear dynamic range > 5 x107

Detection limit <0.5 ppb benzene Non destructive; other detectors can be run in-series

Sensitivity increases as the carbon number increases(carbon counter)

For 10.2 eV lamp, responds to carbon aliphaticcompounds > C4, all olefins and all aromatics

The PID also responds to inorganic compounds such asH2S, NH3, Br2, I2, PH3, AsH3, e.g. any compound with anionization potential of < 10.6 eV

The PID is more sensitive than the FID; >200 x moresensitive for aromatics, 80 times for olefins, & 30 times for

alkanes > C6 Non destructive detector; other detectors can be run

downstream Concentration sensitive detector




301 301 - - B Process GC B Process GC

Analytical Column Mode for Specific Detection

Six detectors to choose from: SpecificSpecific to UniversalUniversal

Minimum Maintainance

Data Processing of Concentrations

X (Div. 1) or Z purge (Div. 2)

Outdoor Locations-




Optimization Parameters for Process Optimization Parameters for Process

GC GC ’ ’ s s

Pre columnPre column- to remove heavies, polar or non

polar species, protect analytical column Inject timeInject time- can be varied to remove heavier

species

DetectorDetector- Selectivity- HNU has 6 detectors tochoose from;PID lamp energy can be varied

Packed and capillary columns can be mixed

BackflushingBackflushing to remove heavies; foreflushingforeflushingto remove light compounds, heart cuttingheart cutting toremove a compound during the run



4/5/2005 PID Analyzers, LLC 14MethodMethod

OnOn--screen keyboardscreen keyboard

PID 10.6PID 10.6 eVeV



4/5/2005 PID Analyzers, LLC 15CalibrationCalibration



4/5/2005 PID Analyzers, LLC 16Detector ParametersDetector Parameters

PID 10.6PID 10.6 eVeV-- 3 ppb3 ppb



4/5/2005 PID Analyzers, LLC 175 ppb BTX5 ppb BTX

PID 10.2PID 10.2 eVeV




Low Level Linearity of Benzene & Ethyl Benzene

y = 972.99x - 16.272

R2

= 0.9999 y = 389.31x - 8.112

R2

= 0.9999

0

5000

10000

15000

20000

25000

0 5 10 15 20 25ppb Benzene/Ethyl Benzene

P e a k C o u n t s




Cal Curve for Oxygenates in CO2

DME (upper)

y = 0.1788x + 25.546

R2

= 0.9973

y = 0.4923x + 73.813

R2

= 0.9955

0

500

1000

1500

2000

2500

3000

0 1000 2000 3000 4000 5000 6000

ppm Acetaldehyde/DME







3030--50 ppb50 ppbdimethyldimethyl etherether

5050--100 ppb100 ppbacetaldehydeacetaldehyde

< 10 ppb< 10 ppbalkanesalkanes

<5 ppb<5 ppbalkenesalkenes

< 0.5 ppb< 0.5 ppbaromaticsaromatics

Detection LimitsDetection Limits

5 x 10exp75 x 10exp7Dynamic RangeDynamic Range

YYAromaticsAromatics

YYAlkenesAlkenes

YYC5+C5+ alkanesalkanes

NNC1C1--C4C4 alkanesalkanes

SpeciesSpecies

PIDPID

PID Characteristics




Summary Summary The instrument is PC based with considerable

expansion capability including LAN, RF modem,USB and additional sensors

The system is fully automatic and is controlled by aPLC

The reproducibility [coefficient of variation= 100(std.dev./mean)] at 50 ppm benzene is 1.5%; and at 5ppb- 5%

The detection limit for benzene with nopreconcentration is < 0.5 ppb; acetaldehyde <50

ppb & DME < 20 ppb BTX and oxygenates can be analyzed & detected

wth the same Analyzer

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Determination of Oxygenates & BTX in Beverage Grade CO2

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