Villanova University Date: Oct 2011 Page 1 of 9 Villanova University Villanova Urban Stormwater Partnership Watersheds Laboratory Standard Operating Procedure VUSP F Zinc Metal Determination Perkin Elmer Atomic Absorption Spectrometer AAnalyst 800 - Procedures Author: Water Resources Laboratory Technician Sonali Joshi Approved: VUSP Director Robert G. Traver SOP-F-1
Villanova University Date: Oct 2011 Page 2 of 9 Distribution John Komlos Quality Assurance Officer Laboratory Copy, maintained by Quality Assurance Officer Revision Date Responsible Person Description of Change 0 01 Jan 2010 Sonali Joshi Initial 1 01 Oct 2011 Sonali Joshi Minor Update 2 The following laboratory staff have read and been trained on this Manual. A copy of this page will be maintained in the Laboratory. Training is good for one year. Signature Name / Position Date Trainer Robert G. Traver Director Sonali Joshi Laboratory Technician John Komlos Quality Assurance Officer SOP-F-2
Villanova University Date: Oct 2011 Page 3 of 9 TABLE OF CONTENTS 1.0 SCOPE AND APPLICATION 4 2.0. METHOD SUMMARY 4 3.0. DEFINITIONS 4 4.0 HEALTH AND SAFETY WARNINGS 4 5.0. INTERFERENCES 5 6.0. HANDLING AND PRESERVATION 5 7.0. EQUIPMENT AND SUPPLIES 5 8.0. QUALITY CONTROL 6 9.0 PROCEDURES 7 10.0. DATA ANALYSIS AND CALCULATIONS 8 11.0. WASTE MANAGEMENT 8 12.0. REFERENCES 8 SOP-F-3
Villanova University Date: Oct 2011 Page 4 of 9 1.0 Scope and Application The purpose of this standard operating procedure (SOP) is to show the proper set up, procedures, and operation steps for Zinc in stormwater samples using the Perkin Elmer AAnalyst 800 Flame Atomic Absorption Spectrometer. This document serves as the basis for maintaining accurate and reproducible results, and defines pertinent validation criteria for accepting/rejecting final data. Standards and blanks will be employed as a means of validating data within range of the instrument s detection limits. 2.0. Method Summary The Perkin-Elmer Model AAnalyst 800 is an atomic absorption spectrometer which measures the concentrations of metals in various matrices. For our purposes, it provides integrated readings in absorbances over a period selected by the user from 0.2 to 60 seconds. The liquid sample is sprayed by a pneumatic nebulizer into a flame. Sample particles vaporize and dissociate into free atoms due to the temperature and reducing power of the flame. The concentration of metal element in the sample is approximated in the parts per million range from the absorbance and standard calibration curve. 3.0. Definitions NA 4.0 Health and Safety Warnings 4.1 Close the door on the instrument before turning on the flame. Never look directly at the flame. The UV light can cause serious eye damage. 4.2 Do not use oxygen in the burner. 4.3 Be sure there an adequate ventilation system for the removal of exhaust gases. 4.4 Change the acetylene tank when the pressure falls to 520 kpa (75 psig). Do not set the acetylene outlet pressure above 110 kpa (15 psig). 4.5 If high concentrations of silver, copper, or mercury salts have been nebulized into an acetylene flame, clean the burner chamber immediately after use. SOP-F-4
Villanova University Date: Oct 2011 Page 5 of 9 4.6 The escape of fuel gas or fuel gas mixture from the drain tube, the burner system, the gas control, or the gas connections results in a serious explosion hazard. 4.7 Locate the acetylene tank away from sources of heat, open flames, or sparks. Make sure cylinder valves are closed when not in use. 5.0. Interferences NONE 6.0. Handling and Preservation All glassware and plastic ware used for collection, transportation, and laboratory analysis of the metal samples are acid-washed using the following procedure. The glassware and plastic ware are first cleaned with a laboratory detergent and rinsed with tap water. Next, the container is rinsed in 1:10 Nitric Acid Solution. The container is then rinsed with distilled water three times and allowed to air dry. The samples are preserved in a 2% nitric acid matrix and refrigerated. They are analyzed within six months of preservation. 7.0. Equipment and Supplies 7.1 Adequate ventilation system 7.2 Supply of compressed air. 7.3 Tank of acetylene 7.4 Zinc Source Lamp 7.5 Sample containers 7.6 Concentrated Nitric Acid 7.7 Stock Zinc Solution SOP-F-5
Villanova University Date: Oct 2011 Page 6 of 9 8.0. Quality Control A system of standard solutions and blanks are used to check the laboratory techniques for the AA800 Atomic Absorption Spectrometer. The blanks are samples of 2% nitric acid that are treated in the same manner as the samples to be tested. A set of four to five standards ranging from 0.05 to 10 ppm of Zinc is used to attain a linear absorbance-concentration curve, with a correlation coefficient greater than or equal to 0.995. To ensure accuracy, a check standard must be applied for at least every 10 samples (note start with the lowest standard). The check standard must agree with the initial reading as seen on the calibration curve by 25%. If agreement fails, it is presumed that the readings of the set of samples run before the check standard are unreliable and must be rerun. Trouble shooting begins with checking the instrument and procedure for any obvious flaws. Next, the reagents should be checked and re-prepared, if necessary. Finally, at least one set of duplicate samples are run for every batch analyzed. In this test, one sampling site is chosen at random in which two separate samples are taken and treated/analyzed separately. Both samples should render readings within 10% of each other to be considered valid. If they do not fall within this range, procedures are examined to be sure that all samples were treated in the same manner. SOP-F-6
Villanova University Date: Oct 2011 Page 7 of 9 9.0. Procedures 9.1 Matrix preparation Sample matrix: 2%v Trace Metal grade nitric acid (HNO 3 ) prepared with MQ water. 9.2 Standards preparation Master stock solutions are available for Zn. These have expiration dates and must be replaced on a regular basis. Four to five standards are prepared by weight from the stock, and diluted using the 2% Nitric Acid as the matrix. 9.3 Switching ON the system 9.3.1 Switch the spectrometer ON. 9.3.2 Set the acetylene tank output pressure to 69 kpa (10 psig). 9.3.3 Set the air supply pressure to 500-600 kpa (80-90psig). 9.3.5 Press FLAME ON/OFF to ignite the flame. 9.3.6 Allow burner head to warm up. 9.3.7 If necessary, readjust the acetylene pressure to 69 kpa (10 psig). 9.3.8 Turn on the computer and start the software by clicking on the icon WinLab32 for AA 9.3.9 The computer interface will start communicating with the equipment 9.3.10 When the communication is successful, check marks appear on the screen 9.4 Installing and aligning lamps Always wear ultraviolet-absorbing safety glasses when viewing the following sources: the flame; hollow cathode or electrodeless discharge lamps; and deuterium lamps. The ultraviolet radiation emitted by these sources can harm your eyes. 9.4.1. Install cathode lamp for the element to be analyzed in the AA Spectrophotometer. 9.4.2. On the computer interface, click LAMP. AA 800 has the capability of adjusting the lamp on its own and there is no need for manual intervention. 9.5 Analysis Once the system is set up, start by running four to five standards of known concentration and ensure that the calibration curve is obtained as per the conditions mentioned in section 8. The nebulizer pulls in 20 µl of the standards and displays the absorbance. Once the calibration curve is obtained, the samples can be analyzed. SOP-F-7
Villanova University Date: Oct 2011 Page 8 of 9 10.0 Data Analysis and Calculations All data analysis and sample calculations are performed in the AA Laboratory Benchtop Software. The results obtained from the analysis is in the form of print outs. The concentration of the metals calculated using AA spectroscopy is populated into the excel sheet Metals Testing in the WREE folder. Care is taken to include only those concentrations that lie between the lowest and highest calibrant. Concentrations below the lowest calibrant are given a designation ND. Note: The Lab Manager may disregard one excessive outlier as long as the standards bound the data. SOP-F-8
Villanova University Date: Oct 2011 Page 9 of 9 Note: Data obtained from flame analysis for Zn is in ppm range (while all other metals are reported in ppb). To maintain consistency in the designated excel sheet where the results are entered, ppm units are converted to ppb units. To do so, the results of Zn analysis from the print out are multiplied by 1000 and entered into the excel sheet. 11.0. Waste Management All waste is disposed of in the Metals Waste Container. 12.0. References Perkin Elmer Corporation (1982) Analytical Methods for Atomic Absorption Spectrophotometry, Norwalk, CT. Perkin Elmer Corporation (1982) Perkin Elmer Atomic Absorption Spectrophotometer: System Description and Maintainence, Norwalk, CT. U.S. Environmental Protection Agency (USEPA). Urban Stormwater BMP Performance Monitoring U.S. Environmental Protection Agency, 2002a. SOP-F-9