Osiguranje kvalitete u analitičkom laboratoriju (Quality Assurance in Analytical laboratory)

Osiguranje kvalitete je temeljni element u produciranju pouzdanih, vjerodostojnih i reproducibilnih rezultata. Postavke osiguranja kvalitete implementiraju se u rad laboratorija kroz sustav kvalitete laboratorija odnosno kroz izrađene radne postupke koji moraju obuhvatiti sve segmente rada laboratorija od uzorkovanja do ispitnog izvještaja. Svi postupci sustava kvalitete moraju biti temeljeni na sljedivosti što znači da se svaki postupak, podatak ili rezultat mora moći provjeriti. Osiguranje kvalitete je kontinuirani proces unaprjeđenja rada laboratorija kroz pronalaženje pogreški, rješavanje problema i poduzimanje popravnih radnji, unutarnju i vanjsku kontrolu rada laboratorija, sudjelovanje u ispitivanju osposobljenosti laboratorija (eng. Proficiency Testing) kao i u razvoju postupaka interne kontrole kvalitete.

Kontaminacija hrane organskim štetnim tvarima

Većina hrane koju konzumiramo sadrži određene potencijalno štetne tvari, bilo da se radi o tvarima koje su prirodni sastojci hrane ili se radi o tvarima koje su namjerno dodane u hranu odnosno o tvarima koje su nalaze u hrani kao posljedica kontaminacije hrane nekim vanjskim čimbenikom ili na neki drugi način. Međutim, prisutnost štetnih tvari u hrani ne znači nužno da je hrana koju konzumiramo štetna za naše zdravlje. Kada govorimo o sigurnosti hrane moramo razlikovati dva osnovna termina- zdravstveno ispravnu i zdravstveno neispravnu hranu. Hrana se smatra zdravstveno ispravnom ukoliko ne može prouzročiti štetne utjecaje na zdravlje ljudi ako je proizvedena, pripremljena i konzumirana u skladu sa njezinom namjenom dok se hrana smatra zdravstveno neispravnom ukoliko je štetna za zdravlje ljudi i neprikladna za ljudsku konzumaciju (Zakon o hrani, NN 117/2003).

Određivanje umjetnih sladila u osvježavajućim bezalkoholnim pićima i posebnim prehrambenim proizvodima metodom tekućinske kromatografije visoke djelotvornosti

This paper presents two high performance liquid chromatographic (HPLC) methods used for the separation and determination of artificial sweeteners aspartame, acesulphame K, sodium saccharin, and sodium cyclamate in beverages and special nutritional products (special food intended for specific population groups). All four compounds are soluble in aqueous solutions and can easily be separated and determined by HPLC with a diode array detector (DAD). The first method involved separation of aspartame, acesulphame K, and sodium saccharin on a C18 column with an isocratic elution of phosphate buffer and acetonitrile as mobile phase. The second method was used to separate sodium cyclamate on a C18 column with methanol and water as mobile phase. Under optimum conditions, both methods showed good analytical performance, such as linearity, precision, and recovery. The methods were successfully applied for the analysis of real samples of soft drinks and special nutritional products.Ovaj rad predstavlja dvije metode za separaciju i određivanje umjetnih sladila aspartama, acesulfama K, natrijeva saharina i natrijeva ciklamata u osvježavajućim bezalkoholnim pićima i posebnim prehrambenim proizvodima tehnikom tekućinske kromatografi je visoke djelotvornosti (HPLC). Sva četiri analita topljiva su u vodenim otopinama i lako se mogu razdvojiti i odrediti tekućinskom kromatografi jom uz primjenu detektora s nizom dioda (DAD). Prva je metoda kromatografsko razdvajanje aspartama, acesulfama K i natrij saharina na C18 koloni izokratnim ispiranjem fosfatnog pufera i acetonitrila kao mobilne faze. Druga metoda omogućava određivanje natrijeva ciklamata na C18 koloni sa metanolom i vodom kao mobilnom fazom. Pod najpovoljnijim eksperimentalnim uvjetima obadvije metode pokazale su dobre analitičke karakteristike, kao što su linearnost, preciznost i analitički povrat. Navedene su metode primijenjene za analize realnih uzoraka osvježavajućih bezalkoholnih pića i hrane za posebne prehrambene potrebe

Risk Assessment of Human Exposure to Pesticides in Food

U ovome preglednom radu prikazane su metode procjene rizika od akutne i kronične izloženosti ljudi ostacima pesticida unesenih hranom. U hrani su često prisutni ostaci više različitih pesticida. Međutim rizik od istodobne izloženosti ostacima različitih pesticida nije moguće utvrditi jer trenutačno ne postoji međunarodno prihvaćeni postupak kumulativne procjene rizika. Stoga se procjena rizika temelji na toksikološkoj procjeni pojedinačnog spoja u određenoj vrsti hrane. Za izračun akutnog unosa najčešće se upotrebljava tzv. međunarodna procjena kratkoročnog unosa (engl. international estimation of short-term intake, IESTI). Model izračuna IESTI temelji se na tzv. metodi najgoreg scenarija uz pretpostavke da će osoba u kratkom vremenu konzumirati veliku količinu hrane koja sadržava najveći određeni maseni udio pesticida te uzimajući u obzir i nehomogenost distribucije ostataka pesticida u hrani. Kronična izloženost ostacima pesticida procjenjuje se uz primjenu tzv. determinističkog modela koji je analogan izračunu maksimalnoga dnevnog unosa.This review presents methods for the assessment of acute and chronic risk from pesticide residues in food. Multiple pesticide residues can often be found in food. Currently, there is no internationally accepted procedure for the assessment of cumulative exposure to multiple pesticide residues in food. Therefore, risk assessment is based on toxicological evaluation of single compounds in a food matrix. The international estimation of short-term intake model (IESTI) has been used to calculate acute intake. IESTI is based on "the worst-case scenario" and addresses the possibility that consumers sometimes eat large amounts of a food item, and such a large amount might contain residues at highest levels. However, it should take into account uneven distribution of pesticide residues in food. Chronic exposure is based on a deterministic approach, analogous to the calculation of the theoretical maximum daily intake

Colonic Vasoactive Intestinal Polypeptide (VIP) in ulcerative colitis - A radioimmunoassay and immunohistochemical study

Background/Aims: In this study, we present radioimmunoassay data describing the concentration of Vasoactive Intestinal Polypeptide (VIP) in both plasma and colonic biopsies, as well as immunostaining of VIPergic innervation in mucosal biopsies of normal subjects and patients with ulcerative colitis (UC). Patients and Methods: Thirty three patients with UC and 17 healthy subjects were investigated. All UC patients suffered from active disease. Fasting circulating levels of VIP in plasma as well as tissue concentrations were measured by radioimmunoassay. For the immunohistochemistry, polyclonal antibody against VIP and the streptavidin-biotin peroxidase complex technique were carried out. Results: Overall plasma VIP concentrations in the UC patients were similar to those in the controls. Significantly decreased concentrations of VIP were found in UC of rectum compared to the normal tissue. However, both plasma VIP values and tissue concentrations were found to be significantly lower in patients expressing minimal or mild active disease according to clinical activity index (AI) and histological activity index (HAI), but marked increase of plasma VIP was clear in UC patients with moderate or severe AI and HAI. There was a trend towards increased tissue concentrations of VIP in the group of patients with moderate or severe AI and HAI. Our immunohistochemical analysis of VIP fibers and nerve cell bodies revealed consistently weaker VIP-immunoreactivity in the rectum in UC patients with minimal or mild HAI. Simultaneously, in the rectal biopsies from UC patients with moderate and severe disease, the fibers in the lamina propria and ganglion cells in the submucous plexus were markedly increased in density and in degree of immunostaining. Very strong immunoreactivity was also found in inflammatory cells of the lamina propria as well as in the epithelial layer of the biopsies from UC patients with obvious disease. Conclusions: Our study shows clearly the heterogeneity in the response of VIP plasma level as well as rectum concentration and distribution in UC patients at different stages of the active disease. The possible role of VIP in the VIP in the colon suggests that further studies of the alterations of this gut peptide may be useful in the understanding of UC pathophysiology