Attachment 1 - Specifications.docx

Attachment 1 – SPECIFICATIONS Microchambers and Concentrator

SJVASC-CPQ needs a system for the quantitative monitoring of postharvest fumigant residues and off-gassing following treatment the treatment of horticultural commodities. The system needs to provide a controlled air or gas flow (up to 500 mL/min for air) across multiple chambers at a controlled temperature for downstream sampling (thermal desorption tubes). The system then needs to interface with existing equipment (Agilent GC-MSToF) to pre-concentrate and inject the collected sample into the GC-MS for quantitative analysis. The pre-concentrator should be able to collect, preconcentrate and inject headspace samples of treated commodity. We have conducted market research and determined that the Markes MCTE250 and Centri-180 are an example microchamber and automated sample concentration system will meet our needs. We request solicitation of a brand name or equal based on the specifications below

SPECIFICATIONS: Microchambers and Concentrator

· Thermal desorption tubes used for microchamber must be compatible with the sample concentrator.

Microchamber Specifications

· Compatibility

· Compatible with all major gas chromatograph manufacturers, including Agilent, Shimadzu, and Thermo Scientific.

· Compatible with PAL3 Series II RSI 85 Autosampler with the following hardware:

· 2 x PAL Tray Holders

· PAL Heatex Sample Stirrer

· PAL Agitator (6 position)

· PAL SPME Arrow Conditioning Module

· PAL Standard Wash Module

· Fully automated sample extraction–thermal desorption able to fully automate headspace (HS), HS–trap, solid-phase microextraction (SPME), SPME–trap, SPME Arrow, SPME Arrow–trap, and tube-based TD (via a tube autosampler) methods on a single platform.

· Able to simultaneously analyze volatile and semi-volatile compounds (e.g. n-C5 to n-C44) in a single analysis. Sample introduction ranging from split-less up to an overall split ratio of 110,000:1 (with a conventional 0.25 mm column) for the quantification of analytes at concentration levels ranging from trace (i.e. sub ppt) to high ppm / low %.

· Must have a capacity of at least 50 3.5” (89 mm) length x 0.25” (6.4 mm) O.D. thermal desorption (TD) tubes made of stainless steel, inert-coated stainless steel or glass for compliance with standard methods, e.g., ASTM D 6196, EN ISO 16017, ISO 16000-6, EN 14662-4, US EPA Method TO-17, NIOSH 2549 and the UK MDHS series.

· Focusing Trap

· Cryogen-Free Focusing Trap capable of reaching temperatures down to -30C (at a room temperature up to 30C)

· Desorption of the focusing trap must take place in a backflush mode i.e., analytes must enter the trap from one end and be desorbed from the same end to facilitate simultaneous analysis of volatiles and semi-volatiles.

· Rapid heating of the focusing trap at >90°C/sec, with optional, slower, programmed heating rates.

· The automated sample extraction–thermal desorption system must have the versatility to fully automate headspace (HS), HS–trap, solid-phase microextraction (SPME), SPME–trap, SPME Arrow, SPME Arrow–trap, high-capacity sorptive extraction and tube-based TD (via a tube autosampler) all on a single platform, extending the range of sample matrices that can be analyzed.

· The automated sample extraction–thermal desorption system must allow automatic re-collection of the outlet (trap) split flow for all methods (HS, SPME, high-capacity sorptive extraction and tube samples).

· The sample extraction–thermal desorption system must offer tube desorption temperatures up to 425ºC for efficient conditioning and analysis of tubes packed with stronger carbon sorbents.

· Sample Pathway

· A completely inert sample pathway with all metal fittings coated with Silonite, or equivalent inert coatings.

· Uniform sample pathway heating with allowable temperature settings of 100 to 200 C

· Carrier gas must only be allowed to pass through the internal path of the tube and not around the outside of the tube during the analysis process to minimize contamination.

· Sample Splitting

· Able to quantitatively split and re-collect samples for reanalysis during GC injections.

· Able to remove the split re-collection tube without causing a temporary leak (e.g. – able to isolate the tube from the carrier gas flow pathway).

· Analytical Sequences / Quality Control

· As required by relevant standard methods such as US EPA Method TO-17, the analytical sequence must include an ambient temperature, no-flow leak test of every high-capacity sorptive extraction device and tube prior to analysis, including an optional leak test for HS, SPME and SPME Arrow methods, to ensure data integrity.

· Able to purge TD tubes at ambient temperature (dry-purge) to prevent the introduction of excess oxygen / moisture into the GC-MS.

· Capable of performing automated, high temperature purges of the focusing trap.

· Carrier Gas Control

· The automated sample extraction–thermal desorption system should allow the electronic carrier gas control capability of the GC to control the carrier gas of the sample extraction–thermal desorption system through all stages of operation. Additionally, it should be possible to configure the automated sample extraction–thermal desorption system with electronic carrier gas control of column head pressure to offer retention time stability independent of split flow, trap temperature, tube/trap packing etc.

· Electronic mass flow control (MFC) of the split flows (between 2 and 500 mL/min) capable of setting different split flows for the various stages of desorption and automatic sequencing of desorption methods with varying split flows.

· Software

· Software must be capable of operating on the same computer as the GC-MS control software (Agilent Chem Station 12.1.938.3)

· Programmable with pre-loaded methods for analysis and conditioning should be readily available for quick set-up.

· The system control software must be capable of exporting history sequence files in .csv or .pdf format.

Chamber Specifications

· At least 4 chambers with all surfaces inert (e.g. Silonite coated metal) with a volume between 100 and 300 cm3.

· Gas/air flow to each chamber can be turned on/off independently.

· Precision gas flow control from 10 to 500 mL/min (for air / nitrogen).

· Chamber pressures kept to at or near ambient at the above flow rates.

· Chamber temperatures can be set from ambient up to 250C.

· Sampling can be performed with thermal desorption tubes compatible with the sample concentrator.

· Chambers can be configured to measure emissions from a bulk sample, surface, or permeating through a thin layer of material.

· Gas/air humidifier capable of humidifying incoming air to 50%

Delivery:

Please include shipping costs in the quote Delivery: 3 weeks ARO

Delivery Address:

USDA ARS

9611 S Riverbend Ave Parlier, CA 93648