ORIGINAL ARTICLE Quantifying glucose and lipid components in human serum by Raman spectroscopy and multivariate statistics Landulfo Silveira Jr. 1,2 & Rita de Cássia Fernandes Borges 3 & Ricardo Scarparo Navarro 3 & Hector Enrique Giana 4 & Renato Amaro Zângaro 1,2 & Marcos Tadeu Tavares Pacheco 1 & Adriana Barrinha Fernandes 1,2 Received: 15 September 2016 /Accepted: 13 February 2017 # Springer-Verlag London 2017 Abstract Raman spectroscopy has been employed in the quantitative analysis of biochemical components in human serum. This study aimed to develop a spectral model to esti- mate the concentration of glucose and lipid fractions in human serum, thus evaluating the feasibility of Raman spectroscopy technique for diagnostic purposes. A total of 44 samples of blood serum were collected from volunteers submitted to rou- tine blood biochemical assay analysis. The biochemical con- centrations of glucose, triglycerides, cholesterol, and high- density and low-density lipoproteins (HDL and LDL) were obtained by colorimetric method. Serum samples (200 μL) were submitted to Raman spectroscopy (830 nm, 250 mW, 50-s accumulation). The spectra of sera present peaks related to the main constituents, particularly proteins and lipids. A quantitative model based on partial least squares (PLS) regres- sion has been developed to estimate the concentration of these compounds, taking the biochemical concentrations assayed by the colorimetric method as sample’ s actual concentrations. The PLS model based on leave-one-out cross-validation ap- proach estimated the concentration of triglycerides and cholesterol with r = 0.98 and 0.96, and root mean square error of 35.4 and 15.9 mg/dL, respectively. For the other biochem- icals, the r was ranging from 0.75 to 0.86. These results evi- denced the possibility of performing biochemical assay in blood serum samples by Raman spectroscopy and PLS regres- sion and may be employed as a means of diagnosis in routine clinical analysis. Keywords Raman spectroscopy . Human serum . Triglycerides . Cholesterol . HDL . LDL . Glucose Introduction The biochemical composition of human serum is associated with the metabolic status of the organism, and is widely used to evaluate various disturbances in the functioning of tissues and organs and metabolic imbalances. The interpretation of the biochemical profile of the serum is complex due to the several mechanisms involved in the control of the level of various metabolites, and biochemical laboratory assays are commonly performed for detection of these alterations [1, 2]. These include the detection of circulating lipid fractions (triglycerides, cholesterol, low-density lipoproteins [LDL] high-density lipoproteins [HDL]), glucose and glycated he- moglobin, among other markers that have been used to detect the metabolic syndrome [3–5], and together with interrelated risks factors of metabolic origin, have been associated to the development of type 2 diabetes mellitus and atherosclerotic cardiovascular disease, following the guidelines of the American College of Cardiology (ACC) and the American Heart Association (AHA) [5]. The risk factors associated to the atherosclerotic disease may depend on the quantity and type of circulating lipids with potential to accumulate in the artery wall [4–6]. Also, the * Landulfo Silveira, Jr. landulfo.silveira@gmail.com 1 Biomedical Engineering Center, Universidade Anhembi Morumbi - UAM, Parque Tecnológico de São José dos Campos, Estr. Dr. Altino Bondensan, 500, São José dos Campos 12247-016, SP, Brazil 2 Center of Innovation, Technology and Education - CITE, Parque Tecnológico de São José dos Campos, Estr. Dr. Altino Bondensan, 500, São José dos Campos 12247-016, SP, Brazil 3 Graduate Program in Biomedical Engineering, Universidade Brasil, Rua Carolina Fonseca, 584, São Paulo 08230-030, SP, Brazil 4 Laboratório Oswaldo Cruz, Praça Cândida Maria C. Sawaya Giana, 128, São José dos Campos 12243-003, SP, Brazil Lasers Med Sci DOI 10.1007/s10103-017-2173-2