There are many references on that but I'd like to know your experiences and opinion?
I used both of them and my recomendation in clear: ICP-OES,. The use of ICP-OES has many advantages over AAS for routine analysis, specifically for analysis of wastewater. Teams are easier to use, more stable and less maintenance.
Depends on the particular analytes and their concentration in the wastewater. Moreover, it depends on the wastewater and problematic matrix. In global we can say that multielementar technique ICP-OES is better, faster and has lower LODs - but one should be careful with limits of detection of particular elements, and in need - combine the flow injection analysis system for As and similar elements. In addition, sometimes the spectral interferences are so bad, that simple UV-VIS or AAS are more appropriate for particular elements. AAS would be beneficial for alkali and earth alkali elements in higher concentrations. Fir slurry samples and ultra trace element analysis I would recommend GF-AAS. Best luck!
depends on the metal concentration, for example for nuclear metals AAS is not suitable for the low concentration, but totally i preferred ICP
According to my own experience, I think that AAS works well in case of waste water components.
I recommend ICP-OES. ICP is very versatile for many other analytical tasks. We use it starting from trace analysis until main component analysis. You can measure many elements at different wavelength at the same time as well you can measure lines that monitor the state of the plasma. This is important for measurements with high precision and for measurement with a comlex or difficult matrix. In general, ICP-OES is much more robust to matrix effects than AAS. In the last years the ICP-OES systems were significantly improved e.g. detection limits, reduced Ar consumption, better generators etc. In fact, I'm not using longer all my AAS machines (flame AAS, Zeeman AAS, continuum source AAS) except for teaching.
The choice between AAS and ICP-OES for chemical analysis depend upon the concentration to be determined. ICP-OES may determine in ppb level also. However economically AAS is preferable.
If you have any idea regarding the concentration levels of the elements that are going to be analyzed then consider the following: AAS for ppm concentration levels and 1 or 2 elements and ICP for ppb/ppt concentration levels and simultaneous multi-element analysis. In general, ICP has excellent detection limits, simple spectra and capability for quick multi-elemental and isotopic determination. AAS requires a graphite furnace to measure concentrations in ppb levels and even then the method is time-consuming, and the accuracy is questionable. I would reccomend AAS only when high concentrtaion levels of toxic elements are expected (>100 ppm) and if the interest regards 1 or 2 elements. In all other cases, ICP will do just fine.
Depending on marginal condition! That means, how much money is available, how many samples, what are the standards of "wet chemistry"; uniform analytical questions may favor AAS, as well as operating expenses.
ICP-OES may work in ppb level, so is better than AAS which determine ppm concentration. In environmental field ICP is more versatile.
To comply with the limits imposed by environmental laws for the quality of treated wastewater is generally sufficient and economical a AAS or GF-AAS and in some cases a UV-VIS determination. However, if you have the necessary money, I recommend the ICP for all the above reasons.
You cannot directly analyze either boron nor sulfur on a flame AA - if these are important to you then you would prefer ICP. If you are purchasing newer equipment and you don't need sub 10-parts-per-billion (ug/Kg) sensitivity then you will find that there are ICP-OES systems available to you for under $30,000 US dollars that will do a wonderful job. With the exception of alkali and alkaline earth elements, I cannot think of a single application where an AA spectrophotometer would be preferred over an ICP-OES system.
ICP-OES has nowadays a better detection limit and robustness (two important parameters to consider with wastewater samples) than AAS. I would recommend the use of ICP-OES from self-experience for heavy metals, B and As.
ICP-OES is the perfered technique if it is available to you as it has high sensitivity compared to AA and there fore it is recommended.
I do recommend ICP-OES or ICP-MS due to the greater sensitivity, but if the sensitivity is not an issue you could also use AAS.
It is very difficult to measure S and B by AAS, so that ICP-OES is a good option.
Answer : For the analysis of metals and some metals (As, Sb, B) is better be used by the AAS for non- metals (ICP-OES) is recommended
ICP-OES being more sensitive would be the preferred technique . However the technique you choose would depend on the concentration of the analytes present in waste water
Dear All, thank you for the answers you gave so far.
Some of you asked what is the quality of wastewater I'm going to analyze. It will contain Cu, Fe, Pb, Mn, Zn, Ni, B, in the range of 0.005 ppm - 5 ppm, and S as sulfides or sulfate in the range of 10-300 mg/L. The wastewater will also contain methanol or lactate, N, and P.
I would be also grateful if you could give me the cost of the equipment (esp. ICP-OES)
As the range is 0.005 ppm to 5 ppm, ICP-MS or ICP-OES is recommended. It will be very difficult to reach accurately more than 0.5 ppm with AAS, even if some seller tell you that AAS can measure ppb.
ICP-OES is the best for determination of multielements in wastewaters and soils
If simultaneous analysis is needed, I prefer to use ICP-OES But anyhow, the analyte levels are also important for choosing analytical method. Sometimes, it might be needed to use both methods. (For example Arsenic with hydride generation AAS and Boron with ICP-OES.) Finally, special design ICO-OES is needed. (Wavelengths below 190 nm such as in S case, the monochromator have to be evacuated and the optical path between the monochromator and the plasma is purged with argon.) As a result, for a good solution of the question time, accuracy, investments and man power are the key factors that have to be optimized
If simultaneous analysis is needed, I prefer to use ICP-OES But anyhow, the analyte levels are also important for choosing analytical method. Sometimes, it might be needed to use both methods. (For example Arsenic with hydride generation AAS and Boron with ICP-OES.) Finally, special design ICP-OES is needed. (Wavelengths below 190 nm such as in S case, the monochromator have to be evacuated and the optical path between the monochromator and the plasma is purged with argon.) As a result, for a good solution of the question time, accuracy, investments and man power are the key factors that have to be optimized
My vote is for ICP-OES. For metalloids you can consider AAS though. For S (sulfide) you can use acid volatile sulfide (AVS) extraction method though the sensitivity of this process could be limiting in your case. You can check N and P with an autoanalyzer, if you need to do so. For ethanol or lactate you can use Gas Chromatography (FID). Please check with your preferred vendors for price. For e.g. Horiba, Aligent, PE, Shimadzu, etc. and many others make ICP-OES. Ask for a quotation for your chosen instrument. Please make sure to inquire about the quality of service from the chosen vendors in your area. All the very best...:-)
I suggest also ICP OES for its sensitivity and absence of interferencEs, the mixture of the elements may be analysed simultaneousely. Good luck
These techniques are available only for metals and metaloids. The SAA is recommended when the concentration of the metals is higher than 1ppm. If the concentration is less, you should use the ICP. For the non metals, it is more interested to ionize them by oxidation and analyze them by ionc chromatography
Actually both are good for analysis. but based on sensitivity the ICP-OES is better. Also when you said AAS, is it flame or graphite
ICP-OES has many advanced features than ASS. but most suitable one is ICP- MS. If you need simultaneous analysis, ICP-OES is very good. If you have vapor generation mode with AAS you can use that to analyse As st high levels. But ICP-OES is much better for low levels.
It really depends on your specific mixture, and whether you're looking for ELEMENTAL or COMPOUND analysis. It also depends A LOT on your sample matrix, particularly with "wastewater" which might mean you're looking at the chunky stuff that comes into the WW Treatment Plant from the sewer lines; the sludge in one of the tanks; or the "clean" effluent that gets pumped back into the river. Sample prep and minimizing matrix effects are key. Different methods are sensitive to different elements and compounds, and different instruments have different detection/quantification limits. You always want to stay within the upper and lower limits for your instrument's detection capability, so you may need to pre-concentrate or spike your samples if they're too low concentration, or dilute them if it's too high.
As for the methods themselves... I've heard that ICP-OES is very good and a lot of government work is switching over to that now, but I have not used it myself yet. ICP-MS can be useful if you know how to tweak the settings but the detectors and injectors can be a little bit finicky. It's good for a wide range of potential water contaminants though; I've seen it used for simultaneous determinations of Na, Ca, Fe, Hg, Pb, Cu, As, Mn, and a few others, though we have such high sodium and calcium here that it swamped the detector. Or if you are looking at compounds and not just atoms, you might try HPLC-UV or some variation of that but I'm not sure how well that would work for metals... it's good for certain pesticides, some pharmaceuticals, and other big organics though. You can also use some flame spectroscopy (atomic emission or atomic absorbance) but like ICP it will atomize your sample so you won't be looking at compounds only atoms.
We are measuring B, As and S by ICP-OES with good results if one observe same questions:
B present memory effects and are so many papers about how to lower it (using manitol, or nitric acid etc. during the washing) Also it is advisable the use of internal standars..
As has a useful line at 288 nm that works very well.
S has a bad sensibility, but for ppm concentrations it is useful the ICP-OES technique.
This technique has the advantage that with the appropiate equiment it is possible to determinate all this element simultaneously.
ICP-OES will be a better option due to higher sensitivity. If you are a first time user of the equipment make sure you are guided by the technician in charge of the instrument.
Our lab technicians use ICP-OES to analyze predominantly metals. The molecules in the sample get atomized in the plasma and with ICP-OES you can measure a wide range of the most common elements (including metaloids and non-metals), except for the halogens and Hg. Another advantage of ICP-OES is the quantification - the calibration curve is linear over a range of nearly 6 orders of magnitude which makes it possible to measure a wide concentration spectrum, from trace to much higher concentrations.
In our lab they analyze As with hydride generaion AAS and for the determination of S in the wastewater samples the usually use ion chromatography.
Yes, ICP-OES has some merits as you can measure many metals at a time, quick and comperatively high sensitivity. However, graphite furnus AAS give a good accuracy (Pbb level) for single metal measurement at a time with less COST involvement. We also use hydride generation AAS for As measurement. If your sample has more contaminated and need measurement accuracy level at Ppm level, I would recommend Flame phot AAS. Ion chromatography is suitable for anion analysis.
Dr. Sochacki:
I have sent you a message about it.
Best regards
Ma. Teresa Rodríguez Salazar
Hi Adam
If possible you can useG AAS apparatus rather than AAS for metalic ions( regard to detection limits)
If there is no access to use ICP-MS; AAS (furnace not flame) if coupled with Zeeman effect it will give precise results for trace metals such as Cd, Cu, and Pb, while ICP_OES is suitable for non-metals.
For the elements you ask, B is not suitable by AAS because of the lack of sensitivity this technique presents. S is not amenable to analysis in AAS by no means. As: you can do it several ways: Hydryde Generation + FAAS, GFAAS, ICP, Hydryde Generation+ICP. Being the best option this last one in my humble opinion
I'll actually recommend ICP for these determinations. Regards,
if you suspect the results to be very high-ICP-OES would be appropriate but if they are expected to be low then ICP-MS is suitable
In principle, they can both be used. However, for concentrations in the order of ppb AAS can only work if provided with graphite furnace. Then, ICP analyses are much faster as you can measure many parameters in the same sample, at the same time
There is no multi-tool for all the problems you mention. Boron in AAS is hampered by forming carbides - so you have to use the C2H2-N2O-flame, which in most AAS apparatus is nasty - and the detection limit is bad, anyway. Also S does not work with AAS. On the other hand, S can be done easily by ICP-OES. Also boron is fine; however, you have to consider the high memory effects (due to the use of quartz glass torches) and you had to rinse thoroughly and countercheck the zero-drift by signals of blinds (acid). Arsenic is somehow special. It can be done by AAS (flame) using the hydride system. This runs very fine by using good peristaltic pumps (0.4 ppb is easily detected). Hydride systems can also be used for ICP-OES. In any case, you have to consider, that noble metals will hamper the As-detection; organics must be destroyed before analyses. To my experience, handling of AAS is easier when determing As (possibly new ICP systems will do better).
For the other metals it depends on: elements which tend to form carbide compounds (B. Al, REE, Mo, W….) should be run by ICP. Refractories can also be formed by combinations to form phosphates, borates or oxide compounds (like Ca-Al-Ox; lots of possibilities). So, in general I would prefer ICP, even if the tool is more expensive.
I think, wastewater's are rather high in contaminants and you must not use flamemless AAS (graphite furnace).
Additional remark:
The correct analytical instrumentation is but half the battle. As an example: when analyzing Sulfur in the form of sulfite by ICP-OES you will find values far beyond the same concentration in the form of sulfate. Both forms (and some more) might occur in wastewaters. So a careful digestion of the samples prior to analyzes is one of the crucial preconditions to get correct results.
The advantage of ICP-OES over AAS is that it can go for lower detection limits and it can measure many elements at the same time which will save you time and energy as well. If your AAs comes with graphite furnce in that case you can go for ppb values.
I would recommend the use of AAS. Because it may be difficult to prevent attempts by ICP-OES. But ICP-MS gives better results in ppb level.
Hi Adam
We analyzed your metals (Fe,Cu , Ni,...) with AAS apparatus more and more time in wastewater with an acceptable accuracy but regard to your concentration range, i suggest the AAS with Grafit Furnace(GAAS). This apparatus has a good detection limits (μg/l).But about S with range 5-300 mg/l i suggest the spectrophtometry method(see Standard Methods for Examination of Water and Wastewater) this method is very easy and cheaper than he other methods.
Normally AAS is for metals though some non-metals can be determined using indirect method. Thus ICP-OES is fine and can take care of non-metals though the detection limits for AA are better. Since wastewater is likely to contain high levels of these analytes the ICP-OES will be best recommended.
The choice of appropriate analytical technique depends upon the nature of sample, interfering specimens, concentration level, rapidity in measurement and finally the available instrument with you. AAS with grafite furnace can be used in most of the cases when concentration is in ppb level. Even you can use the technique with appropriate dilution of the sample. Spectophotometry can also be used for B and S. The method is reliable, inexpensive but careful attention of the analyst is required during sample processing. ICP-OES is also a faster technique for multielemental analysis. But it is used when concentration is very low and such instrument has limitted access to many laboratories.
AAS is a very useful techinque when used in flame. however if you want to analyse As, Se, Sb, you should use hydride generation to have low limits of detection (some ppb) .
To analyse B or S it is very important to know what sample we pretend to analyse and at level concentration. My experience with these two elements recommend to use ICP OES
i agree with Zachman, You can also use polarographic analyser for few metals as the detection limit is in ppt
AAS couple with hydride generation can detect lower concentration levels; yes I agree. However, when it comes to such analysis, the matrix also plays a very essential role in the choice of instrument. Considering the range of analyte to be determine, I will go in for the ICP-OES, if time and sensitivity are key in this analysis. I will even propose an ICP-MS if available to take care of any false positives that could arise due to the matrix in question; waste water.
For sulfur in (waste) water may be ion chromatography is the method of choice (S as sulfate).
The problem is: Do you remove all solids by filtration before hand? If not than there is the problem (or challenge) of digestion, contamination, sample taking and sample preparation (acidification or not) etc.In the case of arsenic if the content in the solid phase is about 10 ppm in the suspended matter, and the amount of suspended is 1%, this will lead to a total concentration of about 100ppb As, in most cases much higher than the dissolved concentration (and most probably less biogenic available). This is not only the case for As but for all elements.
Boron tends to be sticky on glassware and it is usually high in blanks( because it is present as neutral boric acid) as it is not filtered out by de- ionisation mineralised water installations. Also the wash out can be very long using ICPOES/MS.To prevent this manitol (sugar) is suggested as an additive to your sample stream. If you use icpms and add manitol beware of overlap of the tail of the 12C on 11B.
Hi Adam, There are different analytical techniques for use depending on the concentration of the entity in wastewater. The best method is ICP-OES which is fast, accurate and has a high concentration range and therefore is able to analyse almost all the wastewater samples that you can throw at it. Also the through put is excellent and the analysis can be automated while you do something else. For those metal and metalloids that have low concentration like Arsenic, then the best method is ICP-MS which has also a high throughput and can be automated. If these methods do not seem to work, then use UV/VIs spectrometry. In all cases insert standards, internal standards and international standards as well as replicates to get anaccurate answer.
ICP-OES is better than AAS because:
1. Accuracy
2. quick result.
3. better calibrations.
4. reliable results.
5. but not cast effective
Cl is definately a problem in wastewater when trying to determine As using ICP-MS because most treatment plants use it during the floculation processes of treatment. So if you are looking at treated wastewater this can be an issue. I personally had many problems using ICP-MS with treated wastewater because of this. Finally I was able to eliminate the problem by evaporating my samples before digestion. I then compared my As results from ICP-MS to the AAS and they were almost exactly the same. I was sure to use a wastewater certified sample during my digestion process to make sure I did not experience any problems during my adapted protocol. Hope that helps.
Kind attention to Dr. Victoria: You mentioned that presence of chloride in waste water is a big issue for assay of As in waste water using ICP-MS. Hence you adopted evaporation technique. But how chloride was evaporated from the sample matrix?
Using a digi-prep (around 80 degrees C) in an ultra clean lab , using only materials that have undergone strict acid cleaning techniques. I have submitted recently an article Deycard et al. detailing the procedure.
Thank you. I want to know in which form chloride from the sample matrix is evaporated. It may be retained as residue which will be contaminated with sample.
I also wonder how the chloride can be evaporated from an aqueous matrix. As far as I know, excess dissolved HCl can be exsolved from acid aqueous solutions by slowing the pH of the solution adding 10% H2SO4, for instance. But how to remove the total chloride from an aqueous matrix is not an easy task. I would like to get a copy of the recent paper of Dr. Victoria Deycard.
it is in submission (the paper) so it will be a while. Each matrix is different for each system when it comes to wastewater clearly individiual testing must be made. Under normal protocols all samples (total or dissolved) are acidified (nitric) directly after sampling . Once evaporated a total digestion is performed using hf-hno3-hcl-h2o2. As said, certainly it is possible for residues etc to remain and whether or not this will interfere all depends in what you are interested in looking at (what it wil interfere with and or if the concentrations are high enough to cause instrument interferences). For Arsenic, using icp-ms after evaporation for our matrix eliminated interferences. (Of course there was a dilution as well before analysing with ICP-MS). Of course it is not a simple procedure or explaination. Wastewater has so many different sources, industrielle, household, etc, and treatment procedures (for example with or without FeCl) hence water matrices obviously differ. When analyzing total and dissolved wastewater with icp-ms I found many interferences, however, when I evaporated (especially the filtered samples) and digestioned them, this was eleviated. Wastewater is highly colloidal, and although you may filter your sample and feel it is okay to pass directly through icp-ms, it imay not due to the Cl. So it this instance, if you are only looking at As, use the AAS, but if you are looikng at a panel other metals then it is interesting to use ICP-MS, keeping in mind these isues, Cl being one of the most common for me in wastewater, why I took to the time to note it. I'm sure there are many other sources of interferences in my dissolved fractions, but my interest as a researcher is not specially to detail them all, simply test and eliminate and verify with additional procedures, for example AAS for As and using ceritifed samples. Certified samples are another fun topic in wasterwater and metals as well. Anyhoo.
In addition, I see a lot of publications out there looking at wastewater where they analyse the dissolved fraction and then the particulate (filter and digest) and make an addition. I see a big red flag with this procedure because if you do have interferences (mostly in your dissolved fractions >0.2) you will not see it because you are making an addition! If you analyze total water and dissolved and make a substraction, interferences will show instantly because your dissolved concentrations (highly colliodal again) may surpass your total concentrations for those elements interfered. You would not see this if making a simple addition and I assure you this problem is resolved when interferences are removed.
I really hopes this helps, and mostly I best get back to work. :)
Hydride generation with sodium borohydride for analysis of elements such as arsenic, selenium, antimony and bismuth form gaseous hydrides, coupled AAS, there is no loss of specimen in the nebulizer, the hydride/AAS technique appears to be largely unaffected by the major ionic components of samples. In summary, the hydride generation/ AAS technique offers very low detection limits.
Hello there,
You can do all of the elements you mentioned by ICP-OES and ICP-MS. Depending on the concentration of these elements in the wastewater, you can choose which method to use. If the element you are interested is less than 500 ppb, then ICP-MS is the best option, otherwise use ICP-OES. Both of these methods require operational standards, quality assurance standards and international standards inserted into the analytical batch for accuracy and validation purposes. Both of these methods are cost effective since they can be automated and the instuments run overnight without the operator being there. I hope this helps.
Hi people,
I am fortunate to have all the instruments previously mentioned, and then some....I wouldn't use any one single technique, in isolation. But firstly I'd try to profile my sample, essentially to determine where problems, if any, may exist for the analysis. Wastewater can vary enormously .... what technique works for one may not work, as well, for another. Suitable SRM's are a must. It generally boils down to the analyst.
Cheers all
ICP-MS is the best option for metals analysis in wastewater.
In order to apply ICP-MS for waste water analysis sample pretreatment is one of the major factors. Matrix interference takes a key role which will change the entire results.
i suggest ICP-OES rather than AAS. Because in that case you can go upto a ppb level.
ICP-OES and ICP-MS. are the recommended techniques for your analysis.
Boron in AAS so you have to use the C2H2-N2O-flame-
S can be done easily by ICP-OES.
Arsenic can be done by AAS (flame) using the hydride system and hydride systems can also be used for ICP-OES or flamemless AAS (graphite furnace).
For the other metals it depends on: elements should be run by ICP-OES and ICP-MS (even if the tool is more expensive).
I think, wastewater's are rather high in contaminants and you must not use flamemless AAS (graphite furnace).
There is no harm in using flameless AAS with graphite furnace for waste water analysis. With appropriate dilution flameless AAS can give better results.
Sono d'accordo con il dr. Parashuram Sahoo. Nelle acque reflue, la concentrazione di alcuni analiti può essere molto alto e uno strumento come ICP-MS può essere in alcuni casi, non idoneo. Utilizzando un buon AAS con sistema di fornetto di grafite, che utilizza l'effetto Zeeman come correzione del fondo, si possono ottenere buoni risultati per quasi tutti i metalli, tra cui metalli che evaporano facilmente come As e Se. Come lei ha giustamente notato il dottor Zachmann, uno strumento che può risolvere ogni problema che si verifica non esiste, per esempio, se si rimane nel campo della AAS per la determinazione del mercurio è assolutamente necessario un generatore di idruri volatili. Sarebbe bello
avere tutti gli strumenti che abbiamo elencato .. fortunati coloro che possono permetterselo.
Kind attention to Dr. Sergio. May I request you to communicate your comments and suggestions in English.
I agree with dr. Parashuram Sahoo. In wastewater, the concentration of some analytes can be very high and a tool such as ICP-MS can be in some cases, unsuitable. Using a good AAS with graphite furnace system, which uses the Zeeman effect as background correction, you can get good results for almost all metals, including metals that evaporate easily as As and Se. As you rightly noted Dr. Zachmann, a tool that can solve every problem that occurs does not exist, for example, if you stay in the field of AAS for the determination of mercury is absolutely necessary to a generator of volatile hydrides. It would be nice
have all the tools that we have listed .. lucky those who can afford it.
I'm sorry for the low level of my English
My manuscript was recently accepted ( Deycard et al., Marine Chemistry, in press) regarding metals in wastewater using ICP-MS. Although the paper does not focus on solely on measurement protocols, the protocols are in there. It is the unedited version that is available online at this time. If you have any questions please do not hesitate to ask. :)
I do know the instrument that you use and i've no doubt about the validity of ICP-MS.
I use the AAS because usually for the analyze of wastewater it's enough to please my requirments. I'd like to use the ACP-MS (that I can't afford), and I would use it for sure but basically for the analyze of ultratracks. ;)
ICP-OES is fast technique and forgives you more analitycal mistakes. As need more operation - I recomend you HG-ICP-OES technique for As and Se. If you havea free time and you can determine very precisely with ICP-MS.
Hi, I would like to know if hydrides generation is really necessary to analyse those elements simultaneously by ICP-OES ?
Regards
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