**6. Disadvantageous of derivative spectrophotometry**

Specific properties of derivative spectrophotometry can be a source of an additional errors. As it is mentioned previously a shape of derivative spectrum is closely connected with the shape of its parent zero-order spectrum. Small changes in a course of curve describing basic

An interesting application of derivative spectrophotometry was described by Wu and Zivanovic [46]. They proposed the use of the first derivative spectra for determination of the degree of acetylation of chitin and chitosan. They employed the evaluated procedure for

The provided short review shows good and bad sides of derivative spectrophotometry. It has mainly found application in pharmaceutical analysis for control of pharmaceuticals. It gives good results for samples with well defined composition. A main compound usually is present in its commercial forms at a relatively high level, convenient for spectrophotometric determination. An application of derivative spectrophotometry simplified procedure and allows to determine an active compound in presence of matrix (others ingredients, its

An analysis of scientific articles shows new trends in the use of derivative spectrophotometry. First direction of development is a combination of derivative spectra with chemometric methods [28, 36, 39, 42]. Procedures based on derivatisation of ratio spectra [24, 25,28, 30, 40, 44, 47] belong to the same group. An interesting modification of derivative spectrophotometric procedure described Eskandari [48]. A fusion of H-point standard addition method with the first derivative of mixture spectra was applied for simultaneous determination palladium and cobalt. The method was applied for their

The second observed trend is an association of derivatisation with others instrumental methods. Every set of digital data can be subjected derivatisation. So this mathematical approach was applied for data processing with synchronous fluorescence spectroscopy. The second derivative synchronous fluorimetry was used for simultaneous determination of sulpiride and its degradation product [49]. For quantification were used amplitudes of 2D peaks at 295.5 nm and at 342 nm corresponded to main compound and its degradate, respectively. The method was applied for studies of the kinetics of alkaline degradation of

Kang et al. [50] developed the first derivative synchronous fluorescence method for simultaneous assay of traces of some polycyclic aromatic hydrocarbons in human urine. Proposed method was fast, sensitive, selective and reliable. The results were comparable

Derivative spectrophotometry was applied for resolving and quantification of overlapped peaks in capillary electrophoresis [51]. Derivatisation of electropherogram improved separation of compounds. An elaborated procedure was used for determination of eleven

Specific properties of derivative spectrophotometry can be a source of an additional errors. As it is mentioned previously a shape of derivative spectrum is closely connected with the shape of its parent zero-order spectrum. Small changes in a course of curve describing basic

commercial samples.

drug.

**5. New trends in derivative spectrophotometry** 

degradation products) without primary sample preparation.

determination in synthetic mixtures and alloys.

with those obtained by HPLC method.

**6. Disadvantageous of derivative spectrophotometry** 

derivatives of benzoic acid.

spectrum are strongly magnified in derivative spectrum. Application of derivative spectrophotometry requires from analyst knowledge about its specific properties. The main disadvantage of derivative spectrophotometry is its poor reproducibility. It is result of strong dependence of derivative spectrum on recording parameters of used spectrophotometer like scan rate, spectral width of beam, integration time and interpoint distance[1, 5, 7]. Zero-order spectra of the same substance obtained on different spectrophotometers can be identical, but derivatisation of them gives different results. The generated derivative spectra can derived in intensity, shape and positions of maxima and minima. So restoration of given literature method requires to use the same type of apparatus with the same working parameters described in an article or reoptimisation parameters of method on an own spectrophotometer.

Optimisation of used working spectrophotometer parameters should be done when a new derivative-spectrophotometric method is elaborated. A construction of some spectrophotometers does not allow to check influence of whole factors, but if more advanced equipment is available it is worth to do.

As a result of derivatisation is closely connected with geometrical features of a zero-order spectrum, it is obvious that a method of spectrum registration is a key-point. The use of broad beams gives the averaged smoothed zero order spectra. Application of narrow beams results in intensification and narrowing of absorption bands. But from the other hands, the narrowing of monochromator' slit increases an effects connected with beams bending on edges of the slit. The edge phenomenon causes additional noises which are recorded with absorbance. So the absorption spectrum recorded with too narrow monochromator' slit can be distorted by high level of noise.

Interpoint distance of registered spectrum is very important parameter. Absorption spectrum obtained by spectrophotometer possess a digital structure which is the result of construction of a monochromator and a manner of registration. Spectra registered with large interpoint distance are averaged, flat without many spectral details.

A level of noise enclosed in zero order spectrum directly influences a quality of generated derivative spectrum. It was proved that spectra registered with low scan rates and long integration times are less biased by noise. This is advantageous if high order derivative are generated [7].

Taking into account above information, it is obvious that reproducibility of method based on derivative spectrophotometry depends on reproducibility of parameters of registration of zero-order spectra. So, adaptation of elaborated in another laboratory derivative spectrophotometric method, requires application the same working parameters as used by authors. But this problem is completely ignored by scientists. Based on analysis of articles concerned on application of derivative spectrophotometry it could be stated that working parameters of spectra registration are very rarely given [8]. There is noticeable lack of standardisation in description of procedures based on derivative spectra. Very often, authors of scientific articles give only information what model of apparatus they used without any details of its working parameters as well as algorithm for derivatisation of spectra. In this case the published procedure can be used only if our laboratory is equipped with the same model of spectrophotometer supplied with the same software. Otherwise verification of literature' method requires reoptimisation, adaptation to our conditions

Basic Principles and Analytical Application of Derivative Spectrophotometry 267

[18] V.M. Patel, J. A. Patel, S.S. Havele, S.R. Dhaneshwar, Int. J. Chem. Tech. Res. 2, 756-761,

[21] S. L. Abdel-Fattah, A. Z. El-Sherif, K. M. Kilani, D. A. El-Haddad, J. AOAC Int. 93, 1180-

[23] M. Sharma, D.V. Mhaske, M. Mahadik, S.S. Kadam, S. R. Dhaneshwar, Indian J. Pharm.

[24] N. E. Wagiem, M.A. Pegazy, M. Abdelkawy, E. A. Abdelaleem, Talanta 80, 2007-2015

[25] N.Y.Hassan, E. M. Abel-Moety, N.A. Elragey, M.R. Rezk, Spectrochim. Acta Part A 72,

[27] P.Patel, V. Vaghela, S. Rathi, N. Rajgor, V. Bhaskar, J. Young Pharm. 1, 354-360 (2009). [28] G. M. Hadad, A. El-Gindy, W. M. M. Mahmoud, Spectrochim. Acta Part A 70, 655-663

[29] A. B. Thomas, N. G. Dumbre, R. K. Nanda, L. P. Kothapalli, A.A. Chaudari, A.D.

[30] S. S. Sabnis, N. D. Dhavale, V. Y. Jadhav, S. V. Gandhi, Spectrochim. Acta Part A 69,

[31] R. B. Patel, M. R. Patelb, M. B. Shankara, K. K. Bhattb, Eurasian J. Anal. Chem. 4,76-86

[35] E. Souri, M. Amanlou, E-Journal of Chemistry, http://www.e-journals.net, 7(S1), S197-

[36] N. Aguerssif, M. Benamor, M. Kachbi, M.T. Draa, J. Trace Elements Med. Biol. 22, 175-

[39] M. De Luca, F. Oliviero, G. Ioele, G. Ragno, Chemometr. Intell. Lab. Sys. 96, 14-21

[43] T.M.Coelho, E. C. Vidotti, M. C. Rollemberg, A. N. Medina, M. L. Baesso, N. Celle, A. C.

[45] B. Markovic, S. Vladimirov, O. Caudina, V. Savic, K. Karljikovic-Rajic, Spectrochim.

[47] F. A. El-Yazbi, H. H. Hammud, S. A. Assi, Spectrochim. Acta Part A 68, 275-278 (2007).

[40] J.S. Millership, F.McCaffrey, D. Tierney, J. Pharm. Biomed. Anal. 48, 408-413 (2008).

[32] J. D. Patel, B. A. Patel, B. P. Raval, V. M. Vaghela, J. Pharm. Res, 3,566-569, (2010). [33] L. Sriphong, A. Chaidedgumjorn, K. Chaisuroj, World Acad. Sci., Eng. Technol. 55, 573-

[34] M. D.Game, D. M. Sakarkar , Inter. J. Chem. Tech. Res. 2, 1886-1891 (2010).

[37] M. Benamor, N. Aguerssif, Spectrochim. Acta Part A 69, 676-681 (2008). [38] V. Kaur, A. K. Malik, N. Verma, Anal. Letters 40, 2360-2373 (2007).

[41] V. K. Sharma, J. S. Aulakh, A.K. Malik, Talanta 65, 375-379 (2005). [42] G. Zhang, J. Pan, Spectrochim. Acta Part A 78, 238-242 (2011).

[44] K. A. Idriss, H. Sedaira, S.S. Ahmed, Talanta 78, 81-87 (2009).

[46] T. Wu, S. Zivanovic, Carbohyd. Polym. 73, 248-253 (2008).

[48] H. Eskandari, Spectrochim. Acta Part A 63, 391-397 (2006).

Bento, Talanta 81, 202-207 (2010).

Acta Part A 75, 930-935 (2010).

[19] K. Mittal, R. Kaushal, R. Mashru, A. Thakkar, J. Biomed. Sci. Eng. 3, 439-441 (2010). [20] J. Cielecka-Piontek, A. Jelińska, Spectrochim. Acta Part A. 77, (554-557 (2010).

[22] M. Stolarczyk, A. Apola, J. Krzek, A. Sajdak, Acta Pol. Pharm. 66, 351-356 (2009).

(2010).

(2010).

(2008).

(2009).

577 (2009).

S202 (2010).

182 (2008).

(2009).

915-921 (2009).

849-852 (2008).

1191 (2010).

Sci. 70, 258-260 (2008).

[26] A.R.G.Prasad, V. S. Rao, Sci. World 8, 34-38 (2010).

Deshpande, Chromatographia 68, 843-847 (2008).

A geometrical features of derivative spectra can be a source of analytical errors. A course of derivative curve is different than its initial spectrum. A main band gets narrowing but additional satellite bands appear. If basic spectrum of mixture is subjected to derivatisation a resulted derivative spectrum of mixture is a sum of derivative spectra of each individual components. New peaks in the final spectrum can be the result of addition or subtraction, so their intensity undergo amplification or reduction. Very often their positions are shifted in comparison to their position in derivative spectra of individual components. Some analytical information can be lost during derivatisation or new false peaks can be generated. A careful analysis of course of derivative spectra of components and their mixtures at different compositions should be done to avoid such errors. A selection of optimal derivatisation parameters should be make taking into account influence of others components on intensity of derivative peaks of determined analyte. This procedure seems to be time- and labourconsuming but gives good results. Properly done selection of mathematical parameters of derivatisation and instrumental parameters of spectral analysis allows to elaborate selective method of determination and leads to minimise errors connected with features of derivative spectra.
