2. VACUUM WATER-JET PUMP TYPE

Transfer into school

We assembled and tested liquid chromatograph for educational purposes at vocational school for agriculture and food processing (Srednja agroživilska šola Ljubljana), following the instructions for Type 2. The chromatograph we assembled is presented in Picture 1. A sample of a Pear aroma (20 µL) was used for a performance test. Transmittance was measured in 5 second intervals using the blue LED. The experiment was repeated three times. The average values of transmittance were used for absorbance calculation. Results are given in Table 1 and presented in Picture 2. Our experiment was successful two separate peaks were observed on a chromatogram related to two different dyes contained in the Pear aroma.

Picture 1: Liquid chromatograph

Table 1: Absorbance vs. time

t/s	A
5	0.4975
10	0.4962
15	0.4948
20	0.4934
25	0.4934
30	0.4934
35	0.4934
40	0.4934
45	0.4975
50	0.4975
55	0.4948
60	0.4948
65	0.4962
70	0.4921
75	0.4975
80	0.4875
85	0.4975
90	0.4921
95	0.4934
100	0.4948
105	0.4934
110	0.4948
115	0.4962
120	0.4962
125	0.4975

t/s	A
130	0.4962
135	0.4867
140	0.4867
145	0.4987
150	0.4962
155	0.4948
160	0.4867
165	0.4962
170	0.4881
175	0.5171
180	0.5114
185	0.5171
190	0.6179
195	0.767
200	0.8124
205	0.8124
210	0.8446
215	0.889
220	0.8961
225	0.9065
230	0.9136
235	0.9172
240	0.9172
245	0.91
250	0.8962

t/s	A
255	0.8827
260	0.886
265	0.785
270	0.7695
275	0.7495
280	0.7212
285	0.7144
290	0.6989
295	0.6615
300	0.6345
305	0.6144
310	0.6326
315	0.585
320	0.567
325	0.545
330	0.5466
335	0.5482
340	0.5185
345	0.5185
350	0.5228
355	0.5287
360	0.5272
365	0.5528
370	0.585
375	0.5833

t/s	A
380	0.5883
385	0.5934
390	0.5985
395	0.609
400	0.6178
405	0.6178
410	0.6246
415	0.6161
420	0.6055
425	0.6252
430	0.6161
435	0.6144
440	0.6216
445	0.6363
450	0.6382
455	0.6478
460	0.6695
465	0.6777
470	0.6882
475	0.6968
480	0.6989
485	0.7055
490	0.7077
495	0.7121
500	0.7144

t/s	A
505	0.7189
510	0.7258
515	0.7375
520	0.7314
525	0.7033
530	0.6989
535	0.6946
540	0.6968
545	0.6882
550	0.6861
555	0.684
560	0.6777
565	0.6716
570	0.6615
575	0.609
580	0.6198
585	0.5883
590	0.5934
595	0.5833
600	0.5272
605	0.5287
610	0.5272
615	0.5287
620	0.5228
625	0.5214

Picture 2. A chromatogram obtained for the Pear aroma.

Prepared by: Alma Kapun Dolinar, Irena Štrumbelj-Drusany, Srednja agroživilska šola Ljubljana