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Determination of benzalkonium chloride in pharmaceutical
by UV-spectrophotometry
Vasil Karcev, Lence Nikolova, Liljana Ugrinova, Suzana Trajkovic-Jolevska
Faculty of Pharmacy, Ss Cyril and Methodius University,
Vodnjanska 17, 1000 Skopje, Macedonia
Benzalkonium chloride (alkyl dimethyl benzyl ammonium chloride) is a mixture of alkylbenzyl dimethy-
lammonium chlorides of various alkyl chain lengths. This product is a nitrogenous cationic surface-acting agent
belonging to the quaternary ammonium group. The greatest bactericidal activity is associated with the C12-C14 alkyl
derivatives. It is commonly used as an antiseptic and spermicide. Benzalkonium chloride has been considered one
of the safest synthetic biocides known and has a long history of efficacious use. The mechanism of bactericidal/micro-
bicidal action is thought to be due to disruption of intermolecular interactions. This can cause dissociation of cellu-
lar membrane bilayers, which compromises cellular permeability controls and induces leakage of cellular contents.
Other biomolecular complexes within the bacterial cell can also undergo dissociation.
The aim of our study was to develop UV-spectrophotometric method for determination of benzalkonium
chloride in pharmaceutical-disinfectant solution. Solution of benzalkonium chloride in water shows three well defined
absorption maxima - at 257 nm, 262 nm and 269 nm. The only excipient, flavour component antamarin, present in
the formulation, does not absorb at UV region. But, in water solution of benzalkonium chloride in the presence of
antamarin, the increase of absorbancies values have been noticed, without any changes in spectral distribution and
absorption maxima. Due to this, all the solutions were made with solvent prepared with antamarin, ethanol and water.
Validation of the method included linearity, range, accuracy and precision, in accordance with ICH guide-
lines. Investigations have been carried out at all three absorption maxima. Method was found to be linear in the con-
centration range of 0.1-0.9 mg/ml (r=0.9999) for all three wavelengths. The recovery and RSD values were: 99.62-
100.71% and 0.52-1.43%, respectively (at 257 nm); 97.67-101.17% and 0.23-0.73%, respectively (at 262 nm);
99.55-101.37% and 0.20-1.55%, respectively (at 269 nm). Determination of benzalkonium chloride in disinfectant
solution was carried out using the proposed method and titrimetric method previously validated, as well. Statistical
analysis revealed that there is no significant difference between the results obtained with two methods. 
According to the obtained results, the developed UV-spectrophotometric method is linear, accurate and pre-
cise. The proposed method is applicable in routine analysis for quick determination of benzalkonium chloride in
pharmaceutical-disinfectant solution.  
Macedonian pharmaceutical bulletin 53 (1,2) 221-222 (2007)
PP - 104
221
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Opredeluvawe na benzalkonium hlorid vo farmacevtski preparat
so UV-spektrofotometriski metod
Vasil Kar~ev, Len~e Nikolova, Liljana Ugrinova, Suzana Trajkovi}-Jolevska
Farmacevtski fakultet, Univerzitet "Sv. Kiril i Metodij"
Vodwanska 17, 1000 Skopje, Makedonija
Benzalkonium hlorid (alkil dimetil benzil amonium hlorid) pretstavuva smesa od alkil benzil
dimetil amonium hloridi so razli~na dol`ina na alkilnite lanci. Toj e azotna katjonska povr{inski
aktivna supstanca i pripa|a na grupata na kvaterni amoniumovi soli. Najgolemata baktericidna aktivnost
e povrzana so C12-C14 alkilnite derivati. Voobi~aeno se upotrebuva kako antiseptic i spermicid.
Benzalkonium hlorid e eden od najsigurnite poznati sintetski biocidi i ima dolga istorija na efikas-
na upotreba. Se smeta deka mehanizmot na baktericidnoto/ mikrobicidnoto dejstvo se dol`i na poreme-
tuvawe na intermolekularnite interakcii. Toa mo`e da predizvika disocijacija na dvoslojot na
kleto~nata  membrana, {to pak ja poremetuva permeabilnosta na membranata i predizvikuva gubewe na
kleto~nata sodr`ina. Pod dejstvo na benzalkonium hlorid mo`at da disociraat i drugi biomolekularni
kompleksi vo bakteriskata kletki.
Celta na na{eto ispituvawe be{e da se razvie ednostaven UV-spektrofotometriski metod za opre-
deluvawe na benzalkonium hlorid vo farmacevtski preparat-rastvor za dezinfekcija. Voden rastvor na
benzalkonium hlorid poka`uva tri dobro definirani apsorpcioni maksimumi- na 257 nm, na 262 nm i na
269 nm. Edinstvenata pomo{na supstanca, mirisnata komponenta antamarin, prisutna vo gotoviot proizvod,
ne poka`uva apsorpcija vo UV-podra~jeto. Me|utoa, vo voden rastvor na benzalkonium hlorid vo prisust-
vo na antamarin, be{e zabele`ano zgolemuvawe na vrednostite na absorbanciite vo odnos na standard-
niot rastvor na benzalkonium hlorid, bez pomestuvawe na apsorpcionite maksimumi i bez promena na
oblikot na spektarot na benzalkonium hlorid. Poradi toa, standardnite i probnite rastvori bea pod-
gotvuvani vo rastvoruva~ etanol/voda i antamarin.
Metodot be{e validiran preku ispituvawe na linearnosta, opsegot, to~nosta i preciznosta, vo
soglasnost so ICH vodi~ite. Merewa bea praveni na site tri branovi dol`ini na apsorpcioni maksimu-
mi. Metodot e linearen vo oblasta na koncentracii od 0,1-0,9 mg/ml (r=0,9999) za site tri branovi dol`ini.
Analiti~kiot prinos i RSD iznesuvaa: 99,62-100,71% i od 0,52-1,43%, soodvetno (na 257 nm); 97,67-101,17%
i 0,23-0,73%, soodvetno (na 262 nm); 99,55-1-1,37% i 0,20-1,55%, soodvetno (na 269 nm). Opredeluvawe na
sodr`inata na benzalkonium hlorid vo rastvor za dezinfekcija be{e izvr{eno so predlo`eniot metod
i so titrimetriski metod prethodno validiran. Statisti~kata obrabotka na rezultatite poka`a deka ne
postoi zna~ajna razlika pome|u rezultatite dobieni so dvete metodi. 
Spored dobienite rezultati, UV-spektrofotometriskiot metod e linearen, to~en i precizen.
Predlo`eniot metod e primenliv vo rutinskata kontrola za brzo opredeluvawe na benzalkonium hlorid
vo farmacevtski preparat-rastvor za dezinfekcija.
Macedonian pharmaceutical bulletin 53 (1,2) 221-222 (2007)
PP - 104
222
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Identification of metamizole sodium with the NIRS
(Near Infrared Spectroscopy) method
N. Stojanoska, B. Krstevska, V. Ajanovska, Z. Mironovski, J. Velevska, H. Babunovska
ALKALOID AD - Skopje, Pharmaceutical, Chemical and Cosmetics Company, 
Aleksandar Makedonski 12, 1000 Skopje, Republic of Macedonia
The ThermoNicolet ANTARIS FT-NIR (MDS) System is spectrophotometer who measures in NIR spectral
region that extends from 12000-4000 cm
-1
and is specifically designed for use in the industrial environment. This
instrument is used for qualitative and quantitative analysis. Using this technique there is no need for sample prepa-
ration, time for analysis is very short, the costs are decreased and it offers possibility to sample through glass and
transparent packaging materials.
Using The NIRS (Near Infrared Spectroscopy) method, the identification or qualification of the active sub-
stance Metamizole sodium (which is in composition of the pharmaceutical preparation Analgin tbl.), is based on
comparison of the spectra of the examine substance with the spectra of the several examples of standards collected
in a reference library of Metamizole sodium. The quality and identity of these standards collected in a reference
library, are verified previously with the conventional reference methods and standards included in the specification.
The spectra present in a reference library represent the normal variation in suppliers, physical parameters etc, i.e.
these batches are sufficiently representative to cover the normal variation of the examine substance.
The Identification of Metamizole sodium is made using two different techniques based on diffuse reflectance:
• Integrating Sphere, and
• Fiber Optic technique with The Sab IR probe.
The results using above stated techniques are positive with a high per cent of similarity of the spectral data
of Metamizole sodium with those from library.
Comparing these two techniques, it can also be concluded that the Fiber Optic technique with The Sab IR
probe gives satisfactory results with similarity higher than 95 per cent. This technique has an advantage because of
its flexibility characteristics, and it could be placed and used in warehouses for identification of every single pack-
age. The spectar is collected through transparent package material and therefore the package should not be opened.
The Integrating Sphere technique is easer for use, there is no need for cleaning the instrument, and spectral
responses are more stable and repeatable. The Integrating Sphere technique has better reproducibility and it is rec-
ommended for laboratory analysis.
Macedonian pharmaceutical bulletin 53 (1,2) 223-224 (2007)
PP - 105
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Identifikacija na Metamizole sodium so NIRS 
(Near Infrared Spectroscops) metod
N. Stojanoska, B. Krstevska, V. Ajanovska, Z. Mironovski, J. Velevska, H. Babunovska
ALKALOID AD - Skopje, Farmacevtska Hemiska Kozmeti~ka Industrija, 
Aleksandar Makedonski 12, 1000 Skopje, R. Makedonija
ThermoNicolet ANTARIS FT-NIR (MDS) System-ot e spektrofotometar koj meri vo bliskata branova
oblast koja se prostira od 12000-4000 cm
-1
i e specijalno dizajniran za upotreba vo industriska sredina.
Ovoj instrument se upotrebuva za kvalitativna i kvantitativna analiza. Koristeweto na ovoj metod ne
bara prethodna podgotovka na materijalot za analiza, vremeto potrebno za analizata e mnogu kratko,
tro{ocite se namaleni i nudi mo`nost za snimawe na spektarot preku staklena i providna ambala`a.  
Koristej}i go NIRS (Near Infrared Spestroscopy) metodot, identifikacijata ili kvalifikacijata na
aktivnata komponenta Metamizole sodium (koja vleguva vo sostav na farmacevtskiot preparat Analgin tbl.)
se bazira na sporedba na spektarot na ispituvanata supstanca vo odnos na spektrite na pove}e primero-
ci standardi koi se snimeni vo soodvetnata standardoteka na Metamizole sodium. Kvalitetot i identite-
tot na standardite koi se snimeni vo standardotekata se potvrdeni prethodno so drugi referentnite meto-
di i standardi predvideni vo specifikacijata. Spektrite koi ja so~inuvaat standardotekata gi opfa}aat
varijaciite na spektralnite karakteristiki vo odnos na dobavuva~ot, fizi~kite parametri i drugo, t.e
ovie serii se dovolno reprezentativni i gi opfa}aat normalnite varijacii na ispituvanata supstanca.
Napravena e identifikacija na Metamizole sodium so upotreba na dve razli~ni tehniki koi se bazi-
raat na difuzna refleksija i toa:
Integraciona Sfera, i
Fiber Optik tehnika so Sab IR sonda
Dobienite rezultati so upotreba na dvete spomenati tehniki se pozitivni so visok procent na
sli~nost na spektralnite karakteristiki na Metamizole sodium so onie od standardotekata.
Sporeduvaj}i gi dvete tehniki mo`e isto taka da se zaklu~i deka Fiber Optik tehnikata so Sab IR
sonda dava zadovolitelni rezultati so sli~nost pogolema od 95%. Ovaa tehnika ima prednost poradi nejzi-
nite fleksibilnite karakteristiki, mo`e da se smesti i da se upotrebuva vo magacinskiot prostor za
identifikacija na sekoe poedine~no pakuvawe. Spektarot se snima preku providnata kesa koja e primar-
na ambala`a na supstancata i poradi toa pakuvaweto ne mora da se otvori.
Tehnikata so Integraciona Sfera e polesna za upotreba bidej}i se izbegnuva potrebata od
~istewe na instrumentot a dobienite spektri se popostojani i povtorlivi. Tehnikata so Integraciona
Sfera
ima podobra reproducibilnost i se prepora~uva za laboratorisko rabotewe.
Macedonian pharmaceutical bulletin 53 (1,2) 223-224 (2007)
PP - 105
224
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Sensitized luminescence of lanthanides as an analitical tool 
in Clarithromycin determination
Sober M., Marjanovic A., Djedjibegovic J., Skrbo A., Bilalagic N.
Faculty of Pharmacy, University of Sarajevo, Cekalusa 90, Sarajevo, Bosnia and Herzegovina
Clarithromycin is one of macrolide antibiotics that have very important place in treatment of upper respira-
tory system infections. Since it is a product that does not pose a biological hazard like beta lactams, it can be pro-
duced on the same equipment used for production of other drugs as well, but only with an appropriate cleaning val-
idation. Cleaning validation in pharmaceutical industry requires use of very sensitive analytical methods for accurate
and precise determination of analyte traces. The only analytical method currently in use for determination of clar-
ithromycin in cleaning validation is HPLC with amperometric detection.
Luminescence intensity of lanthanides increases by 10
8
to 10
10
times after intramolecular energy transfer
between ligands and lanthanide ions. This phenomenon is used in determination of a numerous compounds by sen-
sitised luminescence of lanthanide complexes.
In this work the possibility for determination of clarithromycin ternary complexes with neodymium, erbium
and gadolinium was investigated. As ligands were used: tromethamin-2-amino-2-hydroxymethyl-1,3-propanediole
(TRIS), coumarinic acid and calceine. Linearity, limit of detection and limit of quantification, as basic parameters
of analytical method validation were determined. Influence of the pH (pH=8 and pH=10) and the solvents on the
luminescence intensity were also investigated.
The best results gave TRIS as a ligand, because it has increased luminescence intensity of investigated lan-
thanides for about 35 times. Maximum of the emission in complex TRIS-ligand did not differ much from the emis-
sion of the pure lanthanide, which proved that TRIS had a role in transfer of energy to electrons in 4f orbital of lan-
thanides. The best results were achieved with gadolinium TRIS complex. Addition of clarithromycin showed excellent
correlation with luminescence intensity of TRIS gadolinium complex with correlation coefficient of R
2
=1,000,
LD=0,468 
µg/mL and LQ=1,539 µg/mL. 
Emission at pH=10 showed better correlation with concentration of clarithromycin, with better linearity and
sensitivity of proposed method.
According to the results obtained, this method can be applied in a routine work in determination of clar-
ithromycin in cleaning validation process. This proposed method is simple and does not require expensive equipment.
Macedonian pharmaceutical bulletin 53 (1,2) 225 (2007)
PP - 106
225
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Spectrpophotometric determinarion of Thiomersal 
in eye preparations
S. Apostolovska
1
, A. Dimitrovska
2
, V. Karcev
2
1
Klinicka Bolnica Bitola R. Macedonia
2
Centar za ispituvanje i kontrola na lekovi, Farmacevtski fakultet, Skopje, R. Macedonia
In eye preparations the dithizon is used for antimicrobic protection in concentration from 0,001%-0,15%.In
acid medium it is bactericid, in alcal and neutral medium it is bacteriostatic and fungistatic. It contains
50%mercury(C
9
H
9
HgNaO
2
S, 404,8g).
There is a method for spectrophotometric determination in visual field by the use of dithizon as a chromogen
reagent.The method is validazed and used for thyomersal’s quantitative determination in eye preparations.
The dithizon’s method is very sensitive wich made him useful for mercury’s determination wich is little pre-
sented in solutions(
µg).The mercury from the thiomersal is extracted with dithizon’s solution in chlorophorm which
resulte with creation of complex – mercurydithizon which is orange.The colour’s intensity is spectrophotometricly
determinated on 
λ=470 µm. The extraction is repeated few more times until it becames green which is sign for free
dithizon.As materials are used example of Chlorodex eye drops, solution and Fluorescein sodium 1% eye drops,
solution which are made in Galenic laboratory in Clinical hospital in Bitola.
During the determination has been noticed interferation between the dithizon and the main substances and
with the excipiens in the examples of Chlorodex eye drops, solution in addition with the medium’s pH and the affin-
ity of the dithizon which explains the succesivity in the ekstractions of the dithizon’s complexes.These complexes
are deleted by the use of placebo-disolution for the standard.
The method’s validation for Chlorodex eye drops, solution tells about the linearity (0.002mg/mL-0.025mg/mL
and r=0.9935), precission (RSD=1.19%-3.48%), analytic contribution (96.0%-107,33%), and for Fluorescein sodi-
um 1% eye drops, solution the linearity (0.005mg/mL-0,05mg/mL and r=0,9906), precission (RSD=1.13%-4,08%),
and analytic contribution (93,4%-107,33%).
The method is used in the rutin tests for quick and simple thiomersal's quantitative determination in case of
a) using primar plastic packing with membran's filtereted preparation for Chlorodex eye drops, solution 58,5%, for
Fluorescein sodium 1% eye drops, solution 70,85%  b) using primar glass packing with membran's filtereted prepa-
ration for Chlorodex eye drops, solution, 98,87%, for Fluorescein sodium 1% eye drops, solution 91,33%),  c) using
primar glass packing with membran's nonfiltereted preparation for Chlorodex eye drops, solution 100,5%, for
Fluorescein sodium 1% eye drops, solution 94,34%). There was used membranes filtrer 0,22 
µm.  The results which
were shown tell us that the thiomersal's adsorption on the primar plastical packing(which ingredient is a granulat of
polyetilen 300) is significant. The statistic analisis of security that were made shows 0,95 and n=4 for Chlorodex eye
drops, solution t
exp.=
1,296, and for Fluorescein sodium 1% eye drops, solution t
exp.=
2,4185. In conclusion we can
say that the adsorption of the thiomersal on the membran's filter is not significant.
Macedonian pharmaceutical bulletin 53 (1,2) 226-227 (2007)
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Spektrofotometrisko opredeluvawe na Tiomersal 
vo oftalmolo{ki preparati
S. Apostolovska
1
, A. Dimitrovska
2
, V. Kar~ev
2
1
JZU Klini~ka Bolnica, Bitola
2
Centar za ispituvawe i kontrola na lekovi, Farmacevtski fakultet, Skopje
Vo oftalmolo{kite preparati tiomersalot (etil 2-merkaptobenzoat(2)-0-S-merkurat(1)sodium)
se koristi kako antimikroben prezervativ (0,001%-0,15%). Vo kisela sredina e baktericid, a vo alkalna
ili neutralna bakteriostatik i fungistatik. Sodr`i 50% `iva (C
9
H
9
HgNaO
2
S, 404,8g).
Vospostaven e metod za spektrofotometrisko opredeluvawe vo vidlivo podra~je so primena diti-
zon kako hromogen reagens. Metodot e validiran i primenet za kvantitativno opredeluvawe na tiomersal-
ot vo oftalmolo{ki preparati. 
Ditizonskiot metod e mnogu osetliv {to go pravi primenliv za opredeluvawe koli~ini na `iva
prisutna vo tragovi vo rastvorot(
µg). @ivata od tiomersalot se ekstrahira so rastvor na ditizon(dife-
niltiokarbazon) vo hloroform pri {to se sozdava kompleks `ivin ditizonat so portokalova boja ~ii
intenzitet se odreduva spektrofotometriski na 
λ=470 µm. Ekstrakcijata e pove}ekratna i se vr{i do
pojava na stabilno zeleno obojuvawe(sloboden ditizon). Kako material za analiza koristeni se primero-
ci od Hlorodeks kapki za o~i, rastvor i Fluorescein natrium 1%kapki za o~i,rastvor.izraboteni vo
Galenskata labaratorija pri JZU Klini~ka Bolnica, Bitola.
Pri ispituvaweto zabele`ana e interferencija na ditizonot so aktivnite supstancii i so ekcip-
ientite vo primerocite od Hlorodeks kapki za o~i,rastvor vo zavisnost od afinitetot i od pH na sredina-
ta so {to se objasnuva sukcesivnosta vo ekstrakciite na ditizonskite kompleksi. Ovie interferira~ki
ditizonati se poni{tuvaat so koristewe placebo rastvoruva~ za standardot.
Izvr{enata validacija na vospostaveniot metod za Hlorodeks kapki za o~i, rastvor uka`uva na
linearnost (0.002mg/mL-0.025mg/mL i r=0.9935), preciznost (RSD=1.19%-3.48%), analiti~ki prinos(96.0%-
107,33%) a za Fluorescein natrium 1%kapki za o~i, rastvor linearnost(0.005mg/mL-0,05mg/mL i r=0,9906),
preciznost (RSD=1.13%-4,08%), analiti~ki prinos(93,4%-107,33%).
Metodot e primenet vo rutinskite testovi za brzo i ednostavno kvantitativno opredeluvawe na
tiomersalot vo slu~aj na   a)koristena primarna plasti~na ambala`a so membranski filtriran preparat
(Hlorodeks 58,5%, Fluorescein natrium 1% 70,85%),   b)koristena primarna staklena ambala`a so mem-
branski filtriran preparat (Hlorodeks 98,87%, Fluorescein natrium 1% 91,33%),   v) koristena primar-
na staklena ambala`a so membranski nefiltriran preparat (Hlorodeks 100,5%, Fluorescein natrium 1%
94,34%).Koristen e membranski filter 0,22
µm. Prezentiranite vrednosti uka`uvaat na zna~itelna apsorp-
cija na tiomersalot na primarnata plasti~na ambala`a(po sostav polietilen 300). Napravena e statisti~ka
analiza so sigurnost 0,95 i n=4 za Hlorodeks t
exp
.=1,296 a za Fluorescein natrium 1% t
exp.
= 2,4185, od {to se
zaklu~uva deka apsorpcijata na tiomersalot vrz membranskite filtri pri sterilizacijata ne e signi-
fikantna.
Macedonian pharmaceutical bulletin 53 (1,2) 226-227 (2007)
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Determination of Allantoin in Cosmetical and Pharmaceutical products
by spectrophotometric method in visible region
Maja Velichkovska
1
, Vasil Karcev
2
, Liljana Ugrinova
2
, Aneta Dimitrovska
2
1
Galafarm dooel, ul. 51 br. 23, Skopje, Macedonia,  
2
Center for drug quality control, Faculty of Pharmacy, 
The "St. Cyril and Methodius" University, Vodnjanska 17, 1000 Skopje, Macedonia
A spectrophotometric method for quantitative determination of allantoin in pharmaceutical ointment and
cosmetic cream is investigated, which is based on the method for determination of allantoin in biological samples
described by Young and Conway. Young and Conway's method is based on transformation of the analyzed substance
by chemical reactions to obtain highly absorbing compounds. Allantoin is hydrolyzed to glyoxylic acid which reacts
specifically with phenylhydrazine to give phenylhydrazone. Following oxidation by potassium hexacyanoferrate in
strong acidic solution, phenylhydrazone is converted to a purple complex, which is not a very stable compound, with
an absorption maximum at 522 nm. All reactions are stoichiometrical which enables spectrophotometric determina-
tion of allantoin. 
Important steps for the quantitative analysis of this method are: the extraction of allantoin from both cream
and ointment water-insoluble matrixes, the conditions controlling chemical reactions, and the incubation time from
adding potassium hexacyanoferrate to reading the absorbance. 
A separative extraction technique is used of which the first step includes liquid-solid extraction with
dichloromethane as organic solvent which removes the matrix from the investigated products, cream and ointment.
The second step is a liquid-liquid extraction with warm distilled water (about 45
0
C) in order to extract the allantoin.
Application of this analytical procedure, including the extraction, to a placebo of the ointment and cream formula-
tion showed no significant interference due to the product components.
The allantoin is completely hydrolyzed to allantoic acid by heating exactly seven minutes in a water bath at
90
0
C in alkaline solution (by adding 0.5 M NaOH). Allantoic acid is completely hydrolyzed to glyoxylic acid by
heating exactly seven minutes in a water bath at 90
0
C in acidic solution (by adding 0.5 M HCl). Side reactions are
inhibited by rapid cooling in icy alcohol bath (-10
0
C) which enables the reaction between glyoxylic acid and phenyl-
hydrazine to proceed to completition.   
Experimentally was examined the influence of the incubation time on the reading values of absorption. It was
shown that reading the absorbance of the samples exactly after 20 minutes contributes to the accuracy of this method.
The method was validated through the following validation parameters: repeatability,linearity, range, limit
of detection, limit of quantitation, accuracy and precision. The accuracy and precision are also evaluated from the
recovery values obtained from determination of allantoin in synthetic mixtures of the cream and the ointment, where
allantoin was added in range of 50 to 150 % of the test concentration. Recovery values between 96.05 and 102.82%
for the cream (RSD: 1.32-1.81%) and between 95.85 and 102.38% for the ointment (RSD: 1.45-2.19%) are obtained.
The method is based on a specific reaction and is with an acceptable sensitivity. The method can be applied in rou-
tine analysis for determination of low concentrations of allantoin in pharmaceutical and cosmetic products. 
Macedonian pharmaceutical bulletin 53 (1,2) 228-229 (2007)
PP - 108
228
^ETVRTI KONGRES NA FARMACIJATA NA MAKEDONIJA SO ME\UNARODNO U^ESTVO
FOURTH CONGRESS OF PHARMACY OF MACEDONIA WITH INTERNATIONAL PARTICIPATION