This document provides information on analytical methods for measuring various air pollutants including heavy metals, benzo(a)pyrene, and ozone. It describes sample preparation and extraction methods, parameters for gas chromatography and fluorescence analysis, and procedures for generating and measuring arsine gas to determine arsenic concentration. Calibration methods are outlined for analyzing benzene, benzo(a)pyrene, and ozone. The document also provides equations for calculating pollutant concentrations from analytical measurements.

1. Filter Extraction For
Heavy Metals and
Benzo(a)pyrene
Dr Rajendra Prasad
<ecotechinstruments@gmail.com>

2. Ambient Air Quality Standards of Notified Parameters and
Range of Analysis in Methods Recommended
S.No. Parameters Applicable Standard Range of the Analytical Methods
1. SO2 50 µg/m3
(6 µg/m3
to 1025 µg/m3
)
2 NO2 40 µg/m3
(9 µg/m3
to 900 µg/m3
)
3 NH3 100 µg/m3
(20 µg/m3
to 700 µg/m3
)
4 O3 100 µg/m3
(20 µg/m3
to 20,005 µg/m3
)
5 Pb 0.5 µg/m3
(0.01 µg/m3
to 2.5 µg/m3
)
6 Ni 20 ng/m3
(5 ng/m3
to 1000 ng/m3
)
7 As 6 ng/m3
(100 ng/m3
to 1500 ng/m3
)for 10 m3 sample
8 CO 2000 µg/m3
(1144 µg/m3
to 114400 µg/m3
)
9 Benzene 5 µg/m3
(1µg/m3
to10mg/m3
)
10 Benzo(a)pyrene 1ng/m3
(3 ng in extracted sample LDL)

3. Benzene Analysis
 Capilliary Column 624 having coating Cynopropyl Pheylpolysiloxane
length 30m, ID-0.25mm coating thickness 1.4 mm – 1No.
 CS2 Benzene free – 500ML
 Benzene (Chromatography Grade) – 250ml
 We will be sending ultrasonically extracted samples for analysis of
Benzene at your set up for its analysis.
 We suggest following conditions to be set on GC while analysis
A
 N2 gas flow – 30ml/min
 H2 gas flow – 30ml/min
 Air flow - 300ml/min
B. We need to inject at least 5ul sample or 10 ul sample
C. Set injection port temp – 250 oC
D Set FID Temp - 300o
C

4. Benzo(a)pyrene
 Four circles of 3.6cm diameter are cut from exposed filters
 These are kept in 30ml micro Soxhlet apparatus on glass wool (to prevent
carbon particles going in to solvent)
 Put 30ml fluorescence free Cylohexane
 Extracted solvent is evaporated to 2ml in current of nitrogen
 This 2ml extract is send to lab for analysis of Benzo(a)pyrene
 Analysis is done after passing extract through a chromatographic column
12cm long prepared by slurring activated alumina with toluene. Elution is
carried out using toluene. Collected elutant is air evaporated and final
volume is made as 5ml in toluene
 Fluorescence emission measurement of peak heights are now made at 307
& 387nm using Fluorimeter
 Blank filter paper is also run as above
 Standard is analyzed and peak heights are obtained for various range of
concentration and a calibration graph is prepared.
 Obtained peak height of sample is used to find out concentration of
Benzo(a)pyrene with the help of calibration curve.
Area taken for analysis 40.7 cm2 Total Exposed Area of filter 406.5cm2
Area factor for multiplication 406.5/40.7 = 9.99 say 10

5. Solvent Extraction of Benzo(a)pyrene
followed by HPLC/GC analysis
Soxhlet Apparatus GC, Capillary Column
Water In
Water Out
Condenser
Flask
s
Sample
Solvent

6. Heavy Metals Pb,Ni and As in Particulates
Collected on Glass Micro Fiber Filter Paper
From Ambient Air
 It is desirable to take 24 hrs sample of Particulates on 8 x10’’ Filter Paper
 Extraction of filter paper:
 Take a strip of exposed filter as 2.5 x 17.5cm for urban sample 5.0 x 17.5cm for rural
sample
 This strip need to be ashed in low temperature asher (If not available leave the filter in
oven at 250o
C for 1hr at least
 Transfer ashed filter in extraction tube
 Take 125ML Erlenmeyer flask with 24/40 female Joint . Put 8mL concentrated HCL and
32ML 40% HNO3. Attach this flask to extraction tube and connect a Allihn condensor
and reflux it for 3hrs
 Now remove the extraction tube condenser. Extracted liquid is evaporated on hot plate
till volume is reduced to about 2ML
 Leave the contents overnight for cooling .
 Now transfer the contents to 15ML centrifuge (2000 rpm) tube with 3 washing by 5-10
drops by 1:20HCI for 30 minutes
 Transfer supernant liquid in the polypropylene tube with cap and send to AAS for
analysis.
 Dilution of this sample may be done using 1:10 HCI as per requirements.
 For analysis of Arsenic Hydride Converter is required with AAS fitted with Graphite
Furnace..

8. Analysis of Arsenic in particulates
Collected from Ambient Air
 Range: Concentration as low as 0.1 µg/m3 or 100ng/mg can be
measured in 10m3
sampled air
 Since limit of arsenic is 6ng/m3
it is difficult to analyzed the
arsenic concentration in such low concentration for small
duration sample.
 For Arsenic sampling duration need to be 24hrs 8hrs sample
must not be analyzed.
 Arsenic present in particulates as Arsenic Oxide and arsenate
 Particulate are dissolved in HCI. Extract is made to react with KI
and SnCI2. This give trivalent arsenic.
 This trivalent Arsenic is reduced to Arsine (ASH3) by Zinc in
acidic solution in Gutzeitt generator. This Arsine is passed
through H2S scrubber which contain glass wool impregnated with
lead acetate and then into absorber containing silver diethyl
thiocarbamate dissolved in pyridine. Here reaction take place
and red soluble complex is formed which is directly proportion to
the Arsenic. Intensity of this colour is measured at 535nm.

9. Analysis of Arsenic in particulates
Collected from Ambient Air
 Extraction of Filter
 Take filter strip 2.5cm x 17.5cm in flask. + 6N HCI digest
90.95o
C on water bath for 1hr. Cool and add 6N NaOH.
Now add 1ML KI and 8 drops of stanus chloride and mix.
Allow 15 minute for reduction of Arsenic in Trivalent state.
Cool solution in ice bath at 4o
C Impregnate glass wool with
lead acetate. 15ML lead acetate is good for 4cm length of
glass wool.
 Take 3ML of silver diethyl thiocarbamate solution in
absorber tube. Add 3gm of Zinc to the flask and immediate
connect to scrubber-absorber assembly allow 90minute for
complete evolution of Arisen gas. Color will form which is
directly proportional to the concentration of Arsenic. Blank
should also be handled in the also above. Read
absorbance against blank at 535nm.

10. Ozone
 Range 0.01 to 10PPM
 Absorbing Solution:
 13.6gmKH2PO4+14.2gm Na2HPO4 +10gm KI make up
contents up to 1000cc by distilled water. Adjust pH 6.8 .
Leave solution in dark place overnight before use.
 I2 Stock:
 0.025M(0.05N)Dissolve 16gm KI and 3.173gm of I2 and
make up this by distilled water up to 500ML.
 I2 working 0.001M
 Take 4ML of 0.025 M I2 in 100mL flask and dilute it with
absorbing solution up to the mark

11. Calibration Curve Preparation
 Take 4.09 mL 0.001 M I2 solution and dilute it up to
100mL using absorbing solution this will be 1ulO3/mL
 Take 10ML flask and put 1mL 2mL 3mL 5mL 8mL
10mL solution and make up to 10mL using
absorbing solution
 Read absorbance at 352nm against distilled water
and plot the calibration curve
 Analysis
 Read absorbance of exposed sample against blank and
find out concentration of 03ul/mL

12. Making of SO2 Trap for Ozone
sampling
 Take glass micro fiber filter 8*10 inches and cut a
piece of 400 cm2
 Drop 15 ml aqueous solution of 2.5gm chromium
trioxide mixed with 0.7 ml conc. H2SO4
 Dry this in oven at 90 degrees for 1 hour
 Quickly cut circles of 6mm dia and store in airtight
glass bottle.
 Fill these circles in trap after filling glass fibers just
before sampling.

13. CALCULATION
cal factor x 48 x 1000 x 25
 O3 (ug/m3) = ---------------------------
Vol. of air (lit) x 24.45 x 10

14. Thank you