There might be a problem in the calibration of standard solutions or in preparation of standards.

Please try as Dr. Rawat has mentioned. Good luck!

Ahmad,

At first, if it is possible, compare your own analytical results of the same solution/s (own fertilizer digests) with another lab.

Try, please, application of recovery test (standard addition) for these elements assessing (i) percentual recovery; (ii) declination (slopes) of the calibration curve and this one, developed by "points" of standard addition (at least with 4 "spikes").

Follow as mentioned Dr. Rawat.

I wish you Good Luck!

Thank you all. I have problem with Kieserite sample. My lab got result around 26 constantly but when doing crosscheck with external lab, they got around 28. I will try doing standard addition method as per suggestion.

Ahmad,

As I understood, as a part of cross-check, the Mg content in fertilizer (Kieserite) digestate prepared in your lab has been analyzed both in your and external lab. And your lab results were lower again (?). I assume that both labs followed the same conditions of analysis (addition of La-salt, the same type of flame…). If you have not already checked this, it might be appropriate to measure at least 2 standard solutions (“points”) of the calibration curve with each other with external lab (ideally, whole calibration range). In case of only 2 points, these should be so different as it is possible (the first Mg-concentration near to the initial part of curve, second one near to (or just that) the highest Mg concentration to verify slopes of both calibration. May be, this is an advice of Dr. Rawat.

In article:

Ahmad, If I understood, as a part of cross-check, the Mg content in fertilizer (Kieserite) digestate prepared in your lab has been analyzed both in your and external lab. And your lab results were lower again (?). I assume that both labs followed the same conditions of analysis (addition of La-salt, the same type of flame…). If you have not already checked this, it might be appropriate to measure at least 2 standard solutions (“points”) of the calibration curve with each other with external lab (ideally, whole calibration range). In case of only 2 points, these should be so different as it is possible (the first Mg-concentration near to the initial part of curve, second one near to (or just that) the highest Mg concentration to verify slopes of both calibration. May be, this is advice Dr. Rawat.ct. Study on enhancing the solubility of clay containing magnesium

Actually, there might be a different sample preparation between my lab and external lab but the result should be the same as the sample came from the same source. So my objective is to increase my instrument performance so that I will not hesitant to use my result.

For precaution in lab, I already prepare standard calibration every day. So I'm suspecting either type of nebulizer (plastic or stainless steel), capillary tube diameter, absorbance (flame angle), flow rate, or our micropipette.

If you can suggest what are you doing to maintain atomic absorbance spectrometry in your lab. What is the important thing to focus on or any precaution?

Thank you.

Dear Ahmad,

When you determined MgO, Do you use LaCl3? when you determine K2O, Do you use CsCl2? It's an ionization buffer, If you don't use it, your results will low than actual.

I am using strontium nitrate as ionization buffer for analysis of both K2O and MgO

Ionization Energy of Strontium more than potassium, so strontium can't ionization buffer for K2O.

It sounds like a matrix effect. You might also titrate the acidity because that may be part of any mismatch. After fixing any acidity problem spike into the extracts and compare the slope with the calibration slope.

I think the major problem might be in the preparation of standard solutions. In old solution might be the precipitate the chemicals, which decreases the efficiency of calibration.

The main chemical component in your samples is magnesium sulfate monohydrate, probably. It is soluble in water. Just use slightly acidified (HCl) water to dissolve. There is no need for concentrated acids, long heating, etc. You can use ultrasound to speed up dissolution. You can, of course, apply the FAAS technique to both elements (Mg, K), but it would be better to first apply a classical titration with e.g. EDTA to determine the sum of Mg, Ca, Sr, etc. And then use FAAS or FAES to determine concentrations of Ca, Sr, etc., and calculate the concentration of Mg. The results obtained will be the real ones that you should achieve with the FAAS technique. You assume that the results from another lab are correct, but your results are too low. You should prepare new Mg (and K) calibration solutions from properly dried MgSO4 and KCl preparations, or from commercial solutions. For measurements, you should prepare solutions that are many times more diluted than the initial solutions. The spectrometric measurements themselves can also be performed under various combinations of conditions and instrumental parameters. Potassium (from solutions with the addition of CsCl (+ HCl) to a concentration of 1-2 g / L), in a stoichiometric acetylene-air flame, with a long-slot burner, positioned parallel (to the axis of the light beam) or obliquely to perpendicular, depending on on the strength of the potassium signal. Measurements with the most sensitive or adjacent, less sensitive line. Instead of the FAAS technique, the FAES technique can be used, especially for higher K concentrations. In the case of magnesium, there is practically only one very sensitive analytical line to be used. You can use non-parallel burner settings, lower solution suction intensity, also acetylene-nitrous oxide flame, if it is stable, in which the measurement sensitivity is several times lower. If the Mg signal is still too high (over 0.8 AU), more dilute solutions must be prepared. The addition of LaCl3 (+ HCl) to a concentration of 1-5 g / L (the higher the sulfate concentration, the higher) is needed. Preferably, the addition of Cs or La is carried out with the aid of a system of two capillary tubes, simultaneously with an additional dilution of the measured solutions.

It would be advisable to have and use a reference, certified sample for checking your analytical methodology and for ongoing quality control of the results.

Greetings.

ZJ

Performance of atomic absorption spectroscopy is a quantitative analytical method that means the absorption of light at a certain wavelength and constant for a single element by its free atoms, and the amount of absorbed radiation at this wavelength increases with the increase in the number of atoms of the element in the radiation path, where the spectrum is related to the concentration, so by a method we can know More than 60 components of a single sample with very high accuracy, down to 1 in a million, thus the components of the sample can be known, even if in a very small proportion. This method is based on converting mineral matter into free atoms, meaning converting matter into an atomic state and estimating the radiation energy absorbed by these atoms, "where the degree of absorption is proportional to the number of atoms in the sample of the element to be assigned directly proportional to the concentration of this element, and the atoms in their natural state." Light rays are absorbed at a certain wavelength and the atom moves to the outgoing atom, and the amount of absorbed radiation at this wavelength increases with the increase in the number of atoms of the wave element in the path of the ray?

Ahmad... MgO in samples when analyzed by AAS, the procedure is great and a stable performance . HCl is the best acid for the dissolution of the sample when flame is used. The sensitivity is great. The interferences are marginal. Potassium is best analyzed by flame photometry which a capability of your AAS system. The sensitivity is great. AAS undergoes ionization interference that may only be be overcome by adding easily ionizable species like CsCl solution.

Good luck