Strategies For Selecting Air Sampling Methods AIHA-Florida Section Spring Conference

Transcription

1 Strategies For Selecting Air Sampling Methods 2011 AIHA-Florida Section Spring Conference

2 Course Outline What are we going to sample for Sampling media Active sampling, diffusive samplers, direct read instruments

3 Learning Objectives Use information on the MSDS to develop a practical step-by-step exposure assessment strategy to identify potential chemical exposures in the workplace and indoor air Determine the exposures when the information on the MSDS doesn t cover the employee exposures Navigate the maze of sampling media possible to use for exposure assessment, and discuss the different ones available Differentiate between active and passive sampling including advantages and disadvantages of both type of media, and when they can and cannot be used

4 Getting Started: What Information Do We Need? What are we going to sample for? How are we going to sample? What analytical method? Active, passive, direct reading? What kind of media? How long? What volume? Who will analyze the samples? What detection limit do we need?

5 If You Don't Know Where You Are Going, Any Road Will Take You There. Lewis Carroll, "Alice in Wonderland"

6 What Are We Going to Sample for? Use information in old exposure reports Material safety data sheets (MSDS) Inventory data Multiple chemical profile analysis Mini can VOC profile Aldehyde profile Metals profile Direct reading instruments / detector tubes

7 What are we going to sample for? MSDS Sheets Inventory Data Old Reports Chemical Profiles Direct Read Instruments Chemical Name Chemical Usage Past Exposures Mini Can Multi RAE CAS # Product Names Sampling Methods Organic Profile Detector Tubes OELs Laboratory Miran SapphIRe

8 What Information Can We Find In An MSDS MSD sheets must list the hazardous chemicals (CAS #) that are found in a product in quantities of 1% or greater Or greater than 0.1% if the chemical is a carcinogen The MSDS does not have to list the amount of the hazardous chemical present in the product.

9 Standard MSDS Information Product name Incompatibilities Hazardous ingredients and exposure limits Required personal protective equipment (PPE) Health hazards Exposure symptoms: chemical routes of entry Fire, explosion and reactivity hazards Manufacturer Precautions for safe handling, storage and use Chemical characteristics Disposal methods Spill or leak procedures Transportation requirements Regulatory reporting requirements First aid procedures

10 Sources for MSDS Sheets Manufacturer or vendor Commercial pay-for-service databases Major chemical manufacturers or providers

11 What Is a CAS Number? Stands for chemical abstracts services registry number A unique identifier that tells you methyl ethyl ketone and 2- butanone are the same compound Use CAS numbers when ever possible to avoid miss identification of chemicals.

12 Ok, Let s Say You Have Looked at All of These Sources, and You Still Can t Discover What Chemicals You Are Looking for. What Do You Do Now?

13 Spock, this atmosphere is highly toxic. Beam us out of Here!

14 Exposure Profiles

15 What Are Exposure Profiles? Multiple chemical compounds that can be analyzed by a single analytical method GC, GC/MS, ICP/MS, IC And collected on a single type of media Charcoal, filter, treated media, canister And desorbed by a single method CS2, acid, thermal, etc

16 IAQ Organic Vapors Minican OSHA PV2120

17 Information You Can Get From A Minican Sub ppm levels of 63 volatile organics by GC/MS OSHA pv2120 Quantitative analysis 5 ppb LOD for most compounds Library search for tentative identification compounds (115 K spectral entries) Estimated concentration only Qualitative identification Sampling times from grab to 24 hrs.

18 Stack samples Limitations-when Not To Use a Minican Dust Total hydrocarbons Gasoline, stoddard solvent, fuel oil Semi-volatile compounds Concentrations higher than 1 ppm Spills, confined spaces, head spaces Polymers Mercaptans, H 2 S MW less than 35

19 Volatile Organic Profile - GC Modification of OSHA 7 Some modifications use a universal solvent Increases recovery of polar compounds Dual 60 meter capillary columns 2 nd polar column for confirmation 2 ug limit of detection Can be used with multiple charcoal media types Passive monitors Large and small charcoal tubes

20 When Should The Organic Profile Be Used? Concentration higher than 1 ppm Spills, confined spaces, head spaces Total hydrocarbons Gasoline, stoddard solvent, fuel oil Stack samples Whenever higher exposures are suspected Identification of unknown vocs???

21 When Not to Use the GC/FID Organic Profile Complex hydrocarbon mixtures If you have no idea what you are looking for totally unknown matrix Very low sub ppm levels

22 Inorganic Acids - NIOSH 7903 HF Hydrofluoric Acid HCl H 3 PO 4 Hydrochloric Acid Phosphoric Acid HBr Hydrobromic Acid H 2 SO 4 Sulfuric Acid

23 Inorganic Acids - Sampling Collection media - washed silica gel Sampling rate lpm Max sample volume liters Analytical method - ion chromatography

24 Aldehyde Profile NIOSH 2016

25 Diisocyanate Profile OSHA 42 & 47

26 Isocheck

27 Polynuclear Aromatic Compounds NIOSH 5506

28 ICPAES Inductively Coupled Plasma Atomic Emission Spectroscopy Atoms in the plasma emit light (photons) with characteristic wavelengths for each element. This light is recorded by one or more optical spectrometers and when calibrated against standards the technique provides a quantitative analysis of the original sample.

29 ICP-MS ICP-MS is an acronym for inductively-coupled plasma mass spectrometry Plasma : a state of matter containing electrons and ionized atoms These ions can then be separated according to mass, using a quadrupole analyzer, and detected, multiplied, and counted The principle of mass spectrometry is the separation and counting of ions on the basis of their mass/charge ratio

30 Advantages of ICP/MS Provides excellent selectivity and sensitivity ten to ten thousand times lower than with conventional ICP and flame atomic absorption (AAS) techniques For most elements, detection limits are comparable to, or lower than, those attainable using graphite furnace AAS Produces a much wider dynamic range, isotope specific capability, and analysis on a cost-effective, simultaneous multi-elemental basis Spectral interference is greatly reduced compared to ICP-OES

31 Direct Reading Instruments and Detector Tubes Be aware of positive and negative interference's for you analyte New instrumentation comes on the market every year Use only as a screening tool - limitations before use Always check results with validated air sampling methods

32 Multirae Plus PGM-50 Industrial hygiene work Emergency response Confined space entry Measures up to 5 gases Simultaneously CO, H2S, O2, LEL, PID

33 Menu of Interchangeable Multirae Sensors NH 3 CO HCN H 2 S NO NO 2 SO 2 Cl 2 Ammonia Carbon Monoxide Cyanide Hydrogen Sulfide Nitric Oxide Nitrogen Dioxide Sulfur Dioxide Chlorine

34 Different Organic Chemicals Have Different Ionization Potentials So we can differentiate between chemicals by changing lamp energies Benzene has an IP of 9.2 ev Isopropyl alcohol has an IP of ev If we use an IP of say 9.5 we will measure benzene but not isopropyl alcohol even when both are present

35 PID Characteristics Sensitivity increases as the carbon number increases 10.2 ev lamp responds to > C 4, olefins, all aromatics And inorganics H 2 S, NH 3, Br 2, PH 3, AsH ev lamp has higher response for aromatics, less for aliphatics 11.7 ev lamp greater for halogenated compounds, methanol, formaldehyde

36 Detector Tubes Detector tubes are designed to analyze samples of air and gases Sealed glass tubes are filled with a reagent specifically sensitive to a target gas If the target gas is present in an air sample drawn through the tube, a color change will occur in the tube s reagent layer.

37 Miran Sapphire

38 Portable Miran Sapphire Uses infra red spectroscopy detection Industrial hygiene applications Emergency response analysis Indoor quality studies Fume hood containment analysis Data logging capability

39 Miran Thermomatch Identifies unknown airborne chemicals Stores infra red absorption data Downloads data to PC Performs library correlation of 150 chemicals Lists most appropriate matches

40 Sampling Media

41 What is a Diffusive Sampler? It is an air-sampling device that samples at rates controlled by molecular diffusion of gases and vapors through a membrane and a static air layer without the use of a sampling pump

42 Advantages of Diffusive Sampling Convenient, no sampling pump Small and intrinsically safe Can be used by relatively untrained personnel Promoted as equivalent, alternative, supplemental to active sampling

43 Disadvantages of Passive Monitors Sampling rates are fixed by sampler geometry Sampling rates affected by face velocity Method validation is expensive Sampling rates are low compared to active sampling methods Only works for gases and vapors

44 Applications of Diffusive Sampling Not the be all, end all Best applications are moderate to semi-volatile organic substances Use OSHA web site (osha.gov) to find OSHA tested applications

45 Attendant to Diffusive Sampling Every different chemical substance has a different sampling rate for every different brand diffusive sampler Accurate sampling rates can only be determined through laboratory work Using estimated sampling rates is like using a sampling pump that has not been calibrated

46 When Using Diffusive Samplers Remember They begin to sample immediately when packaging materials are opened They continue to sample until resealed in packaging materials Report sampling site temperature and pressure

47 Active Sampling Media Advantages Flexible sampling rates User chooses sampling rate Wide variety of sampling media Dozens of media types available Simultaneous use of two or more media types Splitters Wide range of analytes Vapors, dust, aerosols, metals

48 Active Sampling Media - Disadvantages Labor intensive - limits number of samples taken Require some kind of pump Require pre and post calibration checks Subject to pump failures Batteries and pumps are subject to failure & fluctuation Pumps are heavy and noisy Especially high volume pumps Pumps are expensive Can cost over $1,000 per pump Pumps require regular maintenance Requires training and is time consuming Workers don t like wearing pumps

49 Types of Active Sampling Media Charcoal Silica gel Tenax Xad

50 Charcoal Classic sampling medium Used for volatile organic compounds OSHA 7 / NIOSH 1500 Carbon disulfide is desorption solvent of choice Number of passive samplers use charcoal

51 Tenax Polystyrene based polymer High surface area Very unreactive Compounds with boiling points between 50 and 200 C Very good for thermal or solvent desorption

52 Silica Gel Used for very polar compounds Alcohols, organic acids, amines Treated with derivatizing agents for reactive compounds Aldehydes, ammonia, cyanoacrylate, anhydrides

53 XAD Polystyrene/divinylbenzene copolymer Used for: Poly aromatic hydrocarbons(pna) Chlorinated pesticides Treated with: HMP (2-hydroxymethyl piperidine) - aldehydes NITC (naphthylisothiocyanate) - amines

54 Questions???? Contact Information: Ed Stuber Estuber@galsonlabs.com