Skupino vitaminov B kompleksa uvrščamo med vodotopne vitamine, ki se v telesu ne skladiščijo in jih moramo pridobiti s hrano na dnevni ravni. Namen magistrske naloge je bil razviti analizni postopek za HPLC-UV, ki omogoča zaznavo devetih vitaminov B kompleksa hkrati v prehranskih dopolnilih ter analizni postopek validirati po ICH smernicah. Ter s testom vsebnosti in enakomernost preveriti, kako se realne vsebnosti razlikuje glede na deklarirane vrednosti vitaminov B kompleksa v štirih prehranskih dopolnilih. Pri testu sproščanja, ki smo ga izvajali po Evropski farmakopeji z aparaturo 1 s košaricami, je bil cilj ugotoviti, ali imajo prehranska dopolnila res podaljšano sproščanje, kakor se lahko sklepa iz priloženih podatkov. Celotni eksperimentalni del naloge je potekal v skladu z dobro proizvodnjo prakse.Izvedli smo validacijo analiznega postopka na naslednjih validacijskih parametrih: linearnost, robustnost, specifičnost, meja zaznave, meja določitve, ponovljivost in stabilnost standardov. Izvedli smo test vsebnosti in enakomernosti v 6 paralelah. Pri testu sproščanja smo test izvajali 24 h na 6 paralelah in spremljali hitrost sproščanja posameznega vitamina v določenih časovnih točkah. Razviti analizni postopek nam omogoča detekcijo devetih vitaminov B kompleksa v 30 minutah. Potrdili smo validacijske parametre, ki so ustrezali postavljenim kriterijem. Rezultati testa vsebnosti v veliki večini ustrezajo predpisanim kriterijem. V vseh vzorcih smo zaznali vse vitamine, ki imajo navedeno vrednost. Pri testu sproščanja nismo v nobenem izdelku zaznali biotina zaradi prenizkih koncentracij. Rezultati so pokazali, da testirane tablete nimajo podaljšanega sproščanja glede na predpisan kriterij po Ameriški farmakopeji. A group of vitamin B is classified as water-soluble vitamins that are not stored in the body and must be obtained with food on a daily basis. The purpose of the master's thesis was to develop an analytical procedure based on HPLC-UV, which enables detection of nine B complex vitamins in dietary supplements at the same time. We performed the validation of the analytical procedure by validating the following validation parameters: linearity, robustness, selectivity, limit of detection, limit of quantification and stability. The validated analytical procedure was used on four dietary supplements to test the content and uniformity of the vitamin B complex content. We also carried out a European Pharmacopoeia release test with an apparatus 1 with baskets. The purpose of the release test was to determine whether the supplements had a real prolonged release, as can be deduced from the data of their wrappings. The analytical procedure we have developed allows us to do this within 30 minutes. We confirmed that our analytical procedure is suitable for the evaluation of B complex vitamins in samples. The results of the content test in the vast majority correspond to the prescribed criteria. We detected all the vitamins that have the declared value in all the samples. In the release test, no biotin was detected in any product due to its low concentrations. The results showed that the tested tablets do not have retard release according to the prescribed USP criterion. The whole experimental part has been conducted in accordance with the good manufacturing practice.