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Sep-Pak Xposure Aldehyde Sampler

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Sep-Pak Xposure Aldehyde Sampler [ CARE CARE AND AND USE USE MANUAL MANUAL ] ] Sep-Pak XPoSure Aldehyde Sampler CONTENTS I. INTRODUCTION I. INTRODUCTION Waters Sep-Pak® XPoSure™ Aldehyde Samplers are convenient, a. Sep-Pak DNPH-Silica Cartridge Description reproducible sampling devices for quantifying formaldehyde concentrations in the workplace and indoor air within a range of II. USING THE SEP-PAK XPOSURE 0.001 to 5 parts per million (ppmv). ALDEHYDE SAMPLER a. Theory of Operation b. Preventing Contamination c. Collecting the Sample d. Eluting the Derivatives from the Sampler III. ANALYZING THE DNPH DERIVATIVES a. Theory of Operation b. Preventing Contamination c. Collecting the Sample d. Calculating Results IV. APPLICATION EXAMPLES a. Formaldehyde in Laboratory Air - STEL b. Glutaraldehyde in Laboratory Air – STEL V. STORAGE AND DISPOSAL OF THE SAMPLERS a. Storing Unused Samplers b. Storing Exposed Samplers c. Disposing of used cartridges VI. TROUBLESHOOTING VII. REFERENCES AND BIBLIOGRAPHY VIII. ORDERING INFORMATION IX. APPENDICES a. Appendix A: Measuring Acetontrile Purity b. Appendix B: Synthesizing the DNPH-Derivative Standards c. Appendix C: Measuring Breakthrough d. Appendix D: Useful Conversion Factors d.1. Carbonyl to Hydrazone Conversion Factors d.2. Equation for converting µg/L to ppmv d.3. Conversion Factors: µg/L to ppmv [ CARE AND USE MANUAL ] [ CARE AND USE MANUAL ] a. Sep-Pak XPoSure Aldehyde Sampler Description II. USING THE SEP-PAK XPOSURE and Features ALDEHYDE SAMPLER ■■ Sep-Pak XPoSure Aldehyde Samplers contain acidified a. Theory of Operation 2,4-Dinitrophenylhydrazine(DNPH)-coated silica, packed Sep-Pak XPoSure Aldehyde Samplers trap aldehydes in air by in Waters Sep-Pak Plus cartridges. reacting them with acidified 2,4-dinitrophenylhydrazine(DNPH), ■■ The samplers are constructed from high-purity and high- forming stable hydrazone derivatives. The derivitization reaction, density polyethylene components, triaxially-compressed as shown in Figure 2, takes place during sample collection. The packed beds and Luer fittings equipped with end caps and derivatives are later eluted and analyzed using HPLC. plugs. ■■ The samplers are designed for flow rates of up to 1.5 L/min with typical personal pumps. ■■ The gold-colored aluminum compression ring on the Sep-Pak XPoSure Aldehyde Sampler allows for easy identification. Luer Connector Polyethylene Filter Figure 2. Derivitization Reaction. DNPH-Silica b. Preventing Contamination Contamination is most likely to occur during sample collection. Aluminum Before eluting the derivatives, clean all glassware by rinsing with Compression Ring acetonitrile and heating to 60 °C in a vacuum oven for at least Polyethylene Filter 30 minutes. Eluting the samples in a nitrogen-purged glove box further reduces the risk of contamination. The acetonitrile you use to elute the DNPH derivatives can also be a source of contamination. Even HPLC-grade acetonitrile may have unacceptable levels of carbonyl contaminants and should be stored in a carbonyl-free environment. A concentration of 10 µg/L of Luer Connector any aldehyde or ketone contaminant will add 0.1 µg to the blank Figure 1. Cutaway View. values determined for the DNPH-derivatives per cartridge. Follow the procedure in Appendix A, Measuring Acetonitrile Purity, to Table 1: Physical and Chemical Properties pre-qualify your acetonitrile. Hold-up Volume 0.7 mL Collection Efficiency >95% for sampling rates up to 1.5 L/min Capacitya Approximately 70 µg formaldehyde Quantity of DNPH Silica 0.35 g/sampler (~1 mg DNPH) Sampling Temperatureb 10 °C to 100 °C 4.3 cm total length 2.0 cm o.d. at widest point Dimensions 1.0 cm i.d. 0.9 cm bed length a. Based on 50% consumption of DNPH. bEvaluate sampler performance for individual high-temperature method. Sep-Pak XPoSure Aldehyde Sampler 2 [ CARE AND USE MANUAL ] [ CARE AND USE MANUAL ] c. Collecting the Sample Sample Collection – STEL (0.02 to 2.0 ppmv) Caution: Beware of unintentional exposure of the samplers and To collect the STEL air sample: eluted samples to aldehyde and ketone sources. Laboratory air 1. 1Calibrate the sampling pump with a representative sampler often holds high concentrations of acetone. Labeling inks and in line. Set the flow to 1.5 L/min. Figure 3 shows the flow rate adhesives as well as packaging containers (including vials with through a sampler versus applied vacuum. Once calibrated, plastic caps) are all possible sources of contamination. remove and store this representative sampler for future Sampling methods have been developed and validated for both 15 calibrations. minute short-term exposure limit (STEL), and in 8 hour personal 2. Take a fresh sample from its pouch. Remove and save the end exposure limit (PEL) measurements following the National cap and plugs. Institute for Occupational Safety and Health (NIOSH) guidelines1,2. 3. Connect the sampler to a pump with flexible plastic tubing. The XPoSure Aldehyde Samplers have been tested under controlled sampler is bidirectional (flow can be in either direction). laboratory conditions. Table 2 lists the equipment needed to 4. Draw air for 15 minutes, yielding a sample volume of collect air samples using XPoSure Aldehyde Samplers. The 22.5 liters. recommended measurement range for formaldehyde is: 5. Reseal the sampler with its end cap and plug. STEL: 0.022 to 2 ppmv 6. Store the sampler in the pouch provided with appropriate PEL: 0.01 to 1 ppmv identification. Seal the pouch by folding the edge over twice and stapling it shut. Avoid exposing the samplers to heat. Table 2: Sample Collection Equipment A 22.5 L air sample is sufficient for quantifying formaldehyde in Suggested Personal Pump Specifications the range of 0.02 to 2 ppmv. Formaldehyde concentrations lower Operating Range 100 to 1,500 mL/min than 0.02 ppmv in air will require longer sampling times and a Compensation Range 1,500 mL/min – 0 to 20 inches water larger air sample. Conversely, formaldehyde concentrations that Flow Control ±5% set point constant flow exceed 2.0 ppmv will require shorter sampling times or reduced Flow Indicatora Built-in flow indicatora sampling flow rates in order to avoid overloading the sampler and a. A flow calibrator may also be required. obtaining nonlinear results. The background levels of aldehydes and ketones in the sampler Note: The maximum recommended sampler capacity is determine the sensitivity of the method. The volume of air passed 2.3 µmoles total carbonyl species. This calculates to 50% of through the sampler must be large enough for the quantity of the DNPH consumed. Contaminated air may contain significant DNPH derivatives formed to be several times greater than the concentrations of other aldehydes and ketones and the total may background level. The United States Environmental Protection exceed the capacity of the sampling device. Follow the procedure in Agency (US EPA) recommends that this level be at least 10 times Appendix C, Measuring Breakthrough for more information. the background level.3 Table 3 lists the sampler background specifications. Table 3: Sampler Background Specifications µg DNPH Derivatives µg Carbonyl Compounds Compound per Sampler per Sampler Formaldehyde <0.45 <0.06 Adetaldehyde <0.75 <0.15 Acetone <1.5 <0.38 Othersa <0.75 - a. Individually, as acetone-DNPH. Sep-Pak XPoSure Aldehyde Sampler 3 [ CARE AND USE MANUAL ] [ CARE AND USE MANUAL ] 2.0 Note: The maximum recommended sampler capacity is 2.3 µmoles 1.8 total carbonyl species. This calculates to 50% of the DNPH consumed. 1.6 Contaminated air may contain significant concentrations of other aldehydes and ketones and the total may exceed the capacity 1.4 of the sampling device. Follow the procedure in Appendix C, 1.2 Measuring Breakthrough for more information. 1.0 0.8 d. Eluting the Derivatives from the Sampler 0.6 To elute the derivatives from the sampler: 0.4 1. Remove the sampler from the stapled pouch. 0.2 2. Elute the DNPH derivatives from the sampler with pre-qualified acetonitrile directly into a 10 mL volumetric flask. Use a flow 5 15 25 30 Vacuum (inches water) rate of <3 mL/min. Higher flow rates (>3 mL/min) can result in Figure 3: Typical Sampler Backpressure Profile. reduced recovery. 3. Cap the volumetric flask and mix by inverting it several times. 4. Analyze the eluate using HPLC. Sample Collection – PEL (0.01 to 1.0 ppmv) To collect the PEL air sample: Note: Since background levels may change during storage, always compare samples to a blank sampler from the same lot, stored 1. Calibrate the sampling pump with a representative sampler in under the same conditions. line. Set the flow to 100 mL/min. Figure 3 shows the flow rate through a sampler versus applied vacuum. Once calibrated, remove and store this representative sampler for future III. ANALYZING THE DNPH DERIVATIVES calibrations. 2. Take a fresh sample from its pouch. Remove and save the end a. Operating Guidelines cap and plugs. To ensure success in your HPLC analysis: 3. Connect the sampler to a pump with flexible plastic tubing. The ■■ Use a pre-column filter between the injector and column. sampler is bidirectional (flow can be in either direction). ■■ Use HPLC-grade water and HPLC-grade acetonitrile. ■■ Degas the mobile phases by simultaneously applying 4. Draw air for 8 hours, yielding a sample volume of 48 liters. vacuum and ultrasound to the mobile phases for 30 seconds. 5. Reseal the sampler with its end cap and plug. If you are using a low-pressure mixing gradient system, 6. Store the sampler in the pouch provided with appropriate sparging with helium may be necessary. ■■ ® identification. Seal the pouch by folding the edge over twice Waters Symmetry C18 columns are shipped containing and stapling it shut. Avoid exposing the samplers to heat. water/acetonitrile. Before the first analysis, equilibrate the column with mobile phase at 1.3 mL/min for 10 minutes in A 48 L air sample is sufficient for quantifying formaldehyde in the mobile phase or until the baseline is stable.
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