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18 Cards in this Set
- Front
- Back
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What does Atomic spectroscopy study? |
Metals, right hand side of the periodic table. (Pb,Fe etc) |
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Why do you need to know metal content in drugs? |
Somemetals are good catalysts in degradation reactions. These would decrease theshelflife of drug products. |
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Where do these metals come from? |
1.If these metals arepresent in a sample this is due to contamination from the productionprocess/starting materials. 2. Strong acids/Thiolsused in the production process attack vessels and this could end up in the drugproduct. |
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Metal limits in drugs? |
lessthan 10-20ppm |
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What are the 4 components in Atomic absorption spectroscopy? |
1.Source of light 2. Method of producing gaseous metal atoms (flame) 3.Monochromater to separate light. 4. Photomultiplier (detector) |
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How hot is the flame in atomic absorption spectroscopy and What gas is used to aid the flame? |
1. 2500-3150k 2. N2O since it gave a higher amount of oxygen (33%) |
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Linear range of atomic absorption spectroscopy? |
The liner range is 1-5mg L-1 |
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General Advantages/Disadvantages |
1. Wide range of metals can be detected, there is a lamp for almost every element. 2. Process can be automated. 3. Cannot be left overnight due to flame. |
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Interferences in AAS |
1. Chemical (due to insolubility) - Add a realising agent such as 10% lanthium solution/ EDTA 2.Alkaline and earth metals easily ionise , so add a large excess for determination 3.Transport of sample, solutions should have the same viscosity. |
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Why is Standard addition used in AAS? |
Thisis so that matrix effects are overcome however there are errors due to lineextrapolation and errors if the unstrument is not zero-ed. This also assumesline linearity. |
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Increasing sensitivity in AAS? |
1. Use better solvent extraction (less solvent -> higher concentration). Use an organic solvent 2. Generate hydrides using NaBH4 3. Cold vapour generation |
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Why is absorption used and not emission? |
1. Greater stability of spectrometer 2. Fewer interferences 3. Greater sensitivity 4. Different lamp for each experiment. |
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Advantages of AA? |
1. Rapid 2. Easily automated (however cannot be run unattended) 3. Generally free from interferences 4. Known interferences can be overcome.5. Little sample pre-treatment. |
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What is Flame photometry? |
Flame photometry is an atomic emission method for the routine detection of metal salts, principally Na, K, Li, Ca, and Ba |
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Advantages of flame photometry? |
1. Simple equipment, limited number of elements Na, Ca, K, Li, Rb 2. Linear range is 0-10 mgL-1 Na and K 3. Tends to drift over time. Needs to run standard at the same time assamples |
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What is ICP-OES/MS? |
Inductively coupled plasma atomic emission spectroscopy used to detect trace metals using plasma that has a temperature of 6000-10,000K (OES - Optical emission spec, MS- Mass spec) |
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Advantages of ICP-OES/MS? |
60 elements can betested simultaneously including halogens and non-metalsVery wide dynamicrange, sensitivity is better than flame AA.Can determine tracemetals and high concentrations at the same time. ICP-MS uses massspec, this is to overcome interference by overlapping emission lines. |
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Disadvantages of ICP-OES/MS? |
ICP-MS uses massspec, this is to overcome interference by overlapping emission lines. |
