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Silver Nanoparticles in Water sources

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Silver Nanoparticles in Water sources Powered By Docstoc
					Norah Almadani
  Chem 4101
 12/04/2009
 Nanoparticles could be of the same dimension as some
  biological molecules like proteins and nuclic acids
  therefore, functulized nanoparticles might intrude into
  the fold of biomolecules structures.

 It is possible that nanosilver could pose a threat to the
  balance of human health. The toxicity of silver
  exhibited in liver cells was also shown to be mediated
  by oxidative stress, and silver nanoparticles were
  found to induce toxicity in germline stem cells2.

 Reduction in size to the nanoscale level results in an
  enormous increase of surface to volume ratio,
  therefore, more molecules of the chemical are present
  on the surface, thus enhancing the intrinsic toxicity
 Different shapes of Silver nanoparticles have
  different affects on bacterial cells; Ag NP’s in the sub
  50 nm exhibit increase efficiency in inhibiting wide
  range of bacteria.

 Ag NP’s of 10nm interact with bacterial cell
  producing electronic effect enhancing the reactivity
  of the NP’s.

 Depending on the geometry of Ag NP’s the toxicity
  ranges 1-100 microgram.
 silver is known to have an anti-microbial
      activity, and if presence in high
concentration in water sources silver may
     be highly toxic to living systems

              Hypothesis

Engineered silver nanoparticles having the
   size 20nm-200nm have the toxicity to
  destroy living systems cells and can be
 found in water sources using analytical
                techniques.
       Methods Considered to
        Solve The Problem 9

    Fluorescence                 FAAS
low detection limit 1-       inexpensive
  3 magnitude lower       equipment, simple,
     compared to           detection limit 1-
      Absorption         20ng/mL, accuracy 1-
  spectroscopy, high              2%
sensitivity, large liner
 concentration range,
  takes advantage of
 plasmon affect of Ag
         NP’s
Sample is pumped in to the
   nebulizer mixes with argon
   where the sample aresole
   forms, large droplets are
                                     Analyte ions are then focused by a
   removed from the aerosol as it
                                     series of ion lenses into a
   passes through the cool
                                     quadrupole mass analyzer, which
   chamber where the fine
                                     separates the ions based on their
   aerosol are swept to the Chanel
                                     m/z ratio. The mass analyzer
   of the plasma due to the
                                     consists of four parallel stainless
   electric field and travel
                                     steel rods to which a combination
   through high temperature Ar
                                     of AC and DC voltages are applied.
   plasma; there aerosol droplets
                                     The combination of these voltages
   are dried and decomposed and
                                     allows the analyzer to transmit
   finally ionized.
                                     only ions of a specific m/z ratio.
                                               The detector used is
                                               an electron multiplier
**www.cartage.org.lb/.../
Inductively/icp-sche.gi




                            **American Society of Mass
                            Spectrometry
Experimental Design
*Calibration standards

Calibration       0, 0.025, 0.05, 0.0, 0.25, 0.5, 1.0,2,5,
standards         5.0, 10, 20, 50, 100, 500, 1000, 2500,
microgram/L       5000
R2 0-5000         0.9992
microg/L
R2 0-100          0.9969
R2 0-5            0.9984
*Then having 6 samples
spiked with 100 micg/L Ag

Recovery        88.8%
RDS             5,6%
Detection limit 0.006 micg/L
s/n=3
 Preconcentrating Ag NP’s by Cloud Point Extraction
      (CPE) a method of Solid Phase Extraction

                                        Low coast and
         Advantages                         Safety.
                                         Preserve the
                                        natural size and
                                        shape of the Ag
Fast operation.                               NP
                    Requires small
  No need for       amount of non
                                        Used for separating
large quantities    flammable/non
                                                and
   of organic      volatile surfastat
                                         preconcentrating
   solvents.                            organic compounds
                                          and metal ions
                  Sampling
                  Procedure
Solution containing                  Buffer solution of pH
10ng/mL Ag, Triton X-                4 (100 mM acetate
144 (0.2%) v/v, dithizone            buffer)
(1X10-3 molL-1

        Centrifuging               Kept in 45°C thermostatic
        at 3500 rpm                bath for 15min
        for 10 min.

                            aqueou                Remove by syringe
        Cool                s
        in ice   Formation of
        bath     two layers
                                                      To reduce viscosit
                            Surfastant rich           Add 1.0 molL-1
                            phase                     HNO3 in MeOH
                                Most important technique for
   ICP torch serves as an            elemental analysis.
    atomizer and ionizer.
                                  Low detection limits 0.1-
 Simple spectra, consist of      10ppb.Good accuracy and
  isotopic peaks for each       precision. Dynamic range of
  element for quantitative         6 orders of magnitude.
detection and identification


                      Why ICP-
                       MS?9
  Quantitative analysis is           Positive metal ions
based on calibration curves        produced in a ICP torch
in which the ratio of the ion        sampled through a
count for the analyte to the        differentially pumped
    count of the internal        interfaced linked to a mass
  standard is plotted as a                 analyzer.
 function of concentration              High selectivity
     Instrument Selection8
                       Agilent 7500ce ICPMS




Key features of instrument:
High sensitivity.
Speed.
Removal of Ar- bace interfering species such as Ar2
   using H2 reaction mode.
The removal power of the Octapol Reaction System of
   matrix interference.
 Ag nanoparticles could pose a threat to the balance of human
  health

 Ag NP”s of different shape cause bacterial inhibition, where the
  toxicity depends on the geomery

 Analytical problem Ag NP’s presence in water sources

 Flouresence, FAAS and ICPM are possible methods of determing
  the concentration of Ag NP’s

 Mettod of choice ICPMS

 Ag NP’s are extracted from water by (CPE) solid extraction phase

 Quantitative measurment of Ag concentration is determined using
  standards and calibration curves.
 1. EUROPEAN COMMISSION HEALTH & CONSUMER
  PROTECTION DIRECTORATE-GENERAL SCIENTIFIC
  COMMITTEE ON EMERGINGAND NEWLY IDENTIFIED
  HEALTH RISKS (SCENIHR) “The appropriateness of
  existing methodologies to assess thepotential risks
  associated with engineered and adventitious products
  of nanotechnologies” Adopted by the SCENIHR during
  the 10th plenary meeting of 10 March 2006
 2. “Unique Cellular Interaction of Silver Nanoparticles:
  Size-Dependent Generation of Reactive Oxygen
  Species” C. Carlson, S. M. Hussain, A. M. Schrand, L.
  K. Braydich-Stolle, K. L. Hess, R. L. Jones, and J. J.
  Schlager† “J. Phys. Chem. B 2008, 112, 13608–13619”
 3.”Silver nanoparticles as a new generation of
  antimicrobials” Mahendra Rai, Alka Yadav, Aniket
  Gade
 4.”Cloud Point Extraction as an Advantageous Preconcentration
  Approach for Analysis of Trace Silver Nanoparticles in
  Environmental Waters” Jing-fu Liu, Jing-bo Chao, Rui Liu, Zhi-
  qiang Tan, Yong-guang Yin, Yuan Wu, and Gui-bin Jiang

6. “Fluorescence properties of Ag nanoparticles in water”,
  methanolandhexane Om ParkashSiwach,P.Sen _

 7. “Off-line determination of trace silver in water samples and
  standard reference materials by cloud point extraction–atomic
  absorption spectrometry” Ersin Kilinca*, Viia Lepaneb, Anu Viitakb,
  and Bahattin Gumgum

 8. aiglent 7500ce https://cp.chem.agilent.com/en-
  US/Newsletters/accessagilent/2009/jun/pages/envirolab.aspx

 9. Skoog, Holler and Crouch, “Principles of Instrumental Analysis”,
  6th

				
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